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1
Zhang, Jinyi, Amro Shehabeldin, Luis A. G. da Cruz, Jeffrey Butler, Ally-Khan Somani, Mary McGavin, Ivona Kozieradzki et al. „Antigen Receptor–Induced Activation and Cytoskeletal Rearrangement Are Impaired in Wiskott-Aldrich Syndrome Protein–Deficient Lymphocytes“. Journal of Experimental Medicine 190, Nr. 9 (01.11.1999): 1329–42. http://dx.doi.org/10.1084/jem.190.9.1329.
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The Wiskott-Aldrich syndrome protein (WASp) has been implicated in modulation of lymphocyte activation and cytoskeletal reorganization. To address the mechanisms whereby WASp subserves such functions, we have examined WASp roles in lymphocyte development and activation using mice carrying a WAS null allele (WAS−/−). Enumeration of hemopoietic cells in these animals revealed total numbers of thymocytes, peripheral B and T lymphocytes, and platelets to be significantly diminished relative to wild-type mice. In the thymus, this abnormality was associated with impaired progression from the CD44−CD25+ to the CD44−CD25− stage of differentiation. WASp-deficient thymocytes and T cells also exhibited impaired proliferation and interleukin (IL)-2 production in response to T cell antigen receptor (TCR) stimulation, but proliferated normally in response to phorbol ester/ionomycin. This defect in TCR signaling was associated with a reduction in TCR-evoked upregulation of the early activation marker CD69 and in TCR-triggered apoptosis. While induction of TCR-ζ, ZAP70, and total protein tyrosine phosphorylation as well as mitogen-activated protein kinase (MAPK) and stress-activated protein/c-Jun NH2-terminal kinase (SAPK/JNK) activation appeared normal in TCR-stimulated WAS−/− cells, TCR-evoked increases in intracellular calcium concentration were decreased in WASp-deficient relative to wild-type cells. WAS−/− lymphocytes also manifested a marked reduction in actin polymerization and both antigen receptor capping and endocytosis after TCR stimulation, whereas WAS−/− neutrophils exhibited reduced phagocytic activity. Together, these results provide evidence of roles for WASp in driving lymphocyte development, as well as in the translation of antigen receptor stimulation to proliferative or apoptotic responses, cytokine production, and cytoskeletal rearrangement. The data also reveal a role for WASp in modulating endocytosis and phagocytosis and, accordingly, suggest that the immune deficit conferred by WASp deficiency reflects the disruption of a broad range of cellular behaviors.
2
Nakayama, K., K. Nakayama, L. B. Dustin und D. Y. Loh. „T-B cell interaction inhibits spontaneous apoptosis of mature lymphocytes in Bcl-2-deficient mice.“ Journal of Experimental Medicine 182, Nr. 4 (01.10.1995): 1101–9. http://dx.doi.org/10.1084/jem.182.4.1101.
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Bcl-2 expression is tightly regulated during lymphocyte development. Mature lymphocytes in Bcl-2-deficient mice show accelerated spontaneous apoptosis in vivo and in vitro. Stimulation of Bcl-2-deficient lymphocytes by anti-CD3 antibody inhibited the spontaneous apoptosis not only in T cells but also in B cells. The rescue of B cells was dependent on the presence of T cells, mainly through CD40L and interleukin (IL)-4. Furthermore, we generated Bcl-2-deficient mice transgenic for a T cell receptor or an immunoglobulin, both specific for chicken ovalbumin, to test for antigen-specific T-B cell interaction in the inhibition of the spontaneous apoptosis. The initial T cell activation by antigenic peptides presented by B cells suppressed apoptosis in T cells. Subsequently, T cells expressed CD40L and released ILs, leading to the protection of B cells from spontaneous apoptosis. These results suggest that the antiapoptotic signaling via CD40 or IL-4 may be largely independent of Bcl-2. Engagement of the Ig alone was not sufficient for the inhibition of B cell apoptosis. Thus, the physiological role of Bcl-2 in mature lymphocytes may be to protect cells from spontaneous apoptosis and to extend their lifespans to increase the opportunity for T cells and B cells to interact with each other and specific antigens in secondary lymphoid tissues. Bcl-2, however, appears to be dispensable for survival once mature lymphocytes are activated by antigen-specific T-B cell collaboration.
3
Maltzman, J. S., J. A. Carman und J. G. Monroe. „Role of EGR1 in regulation of stimulus-dependent CD44 transcription in B lymphocytes.“ Molecular and Cellular Biology 16, Nr. 5 (Mai 1996): 2283–94. http://dx.doi.org/10.1128/mcb.16.5.2283.
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The immediate-early gene egr-1 encodes a transcription factor (EGR1) that links B-cell antigen receptor (BCR) signals to downstream activation events through the regulation of previously unidentified target genes. Here we identify the gene encoding the lymphocyte homing and migration protein CD44 as a target of EGR1 regulation in B cells. BCR-induced increases in CD44 mRNA expression and transcription levels are shown to occur in EGR1-expressing but not in nonexpressing subclones of the B-cell line WEHI-231. Kinetics of egr-1 transcription and the appearance of nuclear EGR1 protein precede CD44 induction and occur within 30 min after stimulation in the EGR1-expressing subclone. A single EGR1 binding motif is demonstrated at bp -301 of the human CD44 promoter. Cotransfection of a CD44 promoter-chloramphenicol acetyltransferase reporter construct with an egr-1 expression vector resulted in a 6.5- to 8.5-fold induction of transcriptional activity relative to an empty expression vector. The EGR1 binding motif was shown to be necessary for stimulus-induced expression of a CD44 promoter-chloramphenicol acetyltransferase reporter construct in nontransformed B lymphocytes and was required for transactivation by an EGR1 expression vector in a B-cell line. These studies identify EGR1 as an intermediary linking BCR-derived signals to the induction of CD44. The relevance of these molecular events to BCR signal transduction and antigen-stimulated B-cell-mediated immune responses is discussed.
4
DeGrendele, H. C., P. Estess, L. J. Picker und M. H. Siegelman. „CD44 and its ligand hyaluronate mediate rolling under physiologic flow: a novel lymphocyte-endothelial cell primary adhesion pathway.“ Journal of Experimental Medicine 183, Nr. 3 (01.03.1996): 1119–30. http://dx.doi.org/10.1084/jem.183.3.1119.
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The extravasation of leukocytes from the blood into tissues occurs as a multistep process: an initial transient interaction ("rolling"), generally thought to be mediated by the selectin family of adhesion molecules, followed by firm adhesion, usually mediated by integrins. Using a parallel plate flow chamber designed to approximate physiologic flow in postcapillary venules, we have characterized a rolling interaction between lymphoid cells and adherent primary and cultured endothelial cells that is not selectin mediated. Studies using blocking monoclonal antibodies indicate that this novel interaction is mediated by CD44. Abrogation of the rolling interaction could be specifically achieved using both soluble hyaluronate (HA) and treatment of the adherent cells with HA-reactive substances, indicating that HA is the ligand supporting this rolling interaction. Some B and T cell lines, as well as normal lymphocytes, either constitutively exhibit rolling or can be induced to do so by phorbol ester or in vivo antigen activation. These studies indicate that CD44 and its principal ligand hyaluronate represent another receptor/carbohydrate ligand pair mediating a novel activation-dependent pathway of lymphocyte/endothelial cell adhesion.
5
Krinzman, S. J., G. T. De Sanctis, M. Cernadas, L. Kobzik, J. A. Listman, D. C. Christiani, D. L. Perkins und P. W. Finn. „T cell activation in a murine model of asthma“. American Journal of Physiology-Lung Cellular and Molecular Physiology 271, Nr. 3 (01.09.1996): L476—L483. http://dx.doi.org/10.1152/ajplung.1996.271.3.l476.
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To determine the mechanisms by which inhaled antigens produce pulmonary inflammation and bronchial hyperreactivity, we have developed a murine model of asthma. BALB/c mice are sensitized and challenged with ovalbumin (OVA). Compared with mice treated with phosphate-buffered saline (PBS), OVA-treated mice developed increased lung resistance, decreased dynamic compliance, and greater methacholine reactivity. Bronchoalveolar lavage fluid revealed significant increases in the proportion of neutrophils and eosinophils. Tissue sections of OVA-treated mice demonstrated goblet cell metaplasia and focal perivascular and peribronchial infiltrates composed of lymphocytes, neutrophils, and eosinophils. Analysis of thoracic lymphocytes via flow cytometry revealed an expansion of both CD4+ and B cell populations, with increased expression of interleukin-2 receptor on CD4+ T cells, indicated increased activation. There was also increased expression of CD44 on CD4+ and CD8+ lymphocytes, suggesting an expansion of the local memory cell population. These findings support the hypothesis that activation of T lymphocytes mediates allergic pulmonary inflammation and bronchial reactivity in asthma.
6
Maltzman, J. S., J. A. Carmen und J. G. Monroe. „Transcriptional regulation of the Icam-1 gene in antigen receptor- and phorbol ester-stimulated B lymphocytes: role for transcription factor EGR1.“ Journal of Experimental Medicine 183, Nr. 4 (01.04.1996): 1747–59. http://dx.doi.org/10.1084/jem.183.4.1747.
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Intercellular adhesion molecule (ICAM) 1/CD54 plays an important role in T cell dependent B cell activation and for function of B lymphocytes as antigen-presenting cells. ICAM-1 expression is upregulated as a consequence of B lymphocyte antigen receptor (BCR) signaling, thereby serving to render antigen-stimulated B cells more receptive to T cell-mediated costimulatory signals. We have investigated BCR-induced expression of the Icam-1 gene in primary B cells and B cell lines and have found it to be dependent on BCR-induced expression of the transcription factor EGR1. Icam-1 transcription, induced by BCR cross-linking or bypassing the BCR with phorbol ester, is absent in a B cell line in which the EGR1-encoding gene (egr-1) is methylated and not expressed. A potential EGR1-binding site was located at -701 bp upstream of the murine Icam-1 gene transcription start site and shown by electrophoretic mobility shift assay to bind to murine EGR1. Mutation of this site in the context of 1.1 kb of the Icam-1 promoter significantly abrogated transcriptional induction by phorbol ester and anti-mu stimulation in primary B cells. A direct effect of EGR1 on the Icam-1 promoter is suggested by the ability of EGR1 expressed from an SV40-driven expression vector transactivate the wild-type Icam-1 promoter, whereas mutation of the EGR1 mutation of the EGR1 binding motif at -701 bp markedly compromises this induction. These data identify EGR1 as a signaling intermediate in BCR-stimulated B cell functional responses, specifically linking BCR signal transduction to induction of the Icam-1 gene. Furthermore, similar findings for BCR-induced CD44 gene induction (Maltzman, J.S., J.A. Carman, and J.G. Monroe. 1996. Role of EGR1 in regulation of stimulus-dependent CD44 transcription in B lymphocytes. Mol. Cell. Biol. In press) suggest that EGR1 may be an important signaling molecule for regulating levels of migration and adhesion molecules during humoral immune responses.
7
Zanetta, J. P., J. Wantyghem, S. Kuchler-Bopp, A. Badache und M. Aubery. „Human lymphocyte activation is associated with the early and high-level expression of the endogenous lectin CSL at the cell surface“. Biochemical Journal 311, Nr. 2 (15.10.1995): 629–36. http://dx.doi.org/10.1042/bj3110629.
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Lymphocytes undergo activation in response to antigens, cytokines, lectins and antibodies interacting with specific cell-surface molecules or through substances influencing signal transduction pathways. This study shows that human T- and B-cells stimulated using phorbol esters or plant lectins express early (2 h using phorbol esters and 24 h using plant lectins) a high level of a polyvalent carbohydrate-binding protein, the cerebellar soluble lectin (CSL), which is in part externalized. The lectin, immunologically related to CDw70, interacts with specific glycoprotein ligands of the lymphocyte surface, including CD3 on T-cells and CD24 on B-cells. Major changes in phosphorylations associated with activation appear as largely CSL-dependent since they are specifically inhibited by anti-CSL Fab fragments. It is suggested that the lectin induces the clustering of specific cell-surface glycoproteins and plays the role of an endogenous amplifier of activation signals.
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Maynadie, Marc M., Romain Casey, Karine Piazzon, Jean Claude Capiod und Paule-Marie Carli. „Peripheral Blood Lymphocytes Subpopulations and Apoptotic Markers in Patients with Lymphoid Malignancies and in Controls: An Epidemiologic Case-Control Study.“ Blood 104, Nr. 11 (16.11.2004): 3858. http://dx.doi.org/10.1182/blood.v104.11.3858.3858.
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Abstract Few references ranges of normal peripheral blood lymphocytes subpopulations are available in the literature and fewer data were available regarding activation, proliferation and apoptosis antigen expression on such populations. We studied these parameters in patients included in an epidemiologic case-control study on risk factors of lymphoid malignancies conducted within European countries. Cell surface staining of peripheral blood lymphocyte antigens were analysed by multicolour flow cytometry in 300 cases and 300 controls. We determined CD3+, CD3+/CD4+, CD3+/CD8+, CD3−/CD56+CD16+, CD19+, CD19+/CD5+, CD19+/CD5− and CD57+ populations. Expression of CD25, CD16, CD40, CD154, CD95 and CD178 were studied on these populations. CD expressions were compared by multiple regressions between controls and diseases, after stratification on circulating phase. In controls we observed a significant decrease of B cells and an increase of NK cells with age. No difference was found according to sex, smoking status and Body Mass Index. In Follicular Lymphoma, Diffuse Large B Cell Lymphoma and Marginal Zone Lymphoma (MZL) without circulating phase cases, we observed a decrease of the B cell subset and an increase of the NK cell subset instead of only a trend was found in Multiple Myeloma, Mycosis Fongoides, Hodgkin Disease and Lymphoplasmacytic Lymphoma. CD95 expression was increased in HD, DLBCL, MZL without circulating phase and Hairy Cell Leukemia but decreased in B-cell Chronic Lymphocytic Leukemia and MZL with circulating phase. CD40 was decreased on B cells in HD, FL, MZL, B-ALL and CLL. This study was one of the most important, in term of number of patients included, particularly concerning data on activation, proliferation and apoptosis markers in normal subjects but also in several lymphoid malignancies.
9
Cooke, M. P., A. W. Heath, K. M. Shokat, Y. Zeng, F. D. Finkelman, P. S. Linsley, M. Howard und C. C. Goodnow. „Immunoglobulin signal transduction guides the specificity of B cell-T cell interactions and is blocked in tolerant self-reactive B cells.“ Journal of Experimental Medicine 179, Nr. 2 (01.02.1994): 425–38. http://dx.doi.org/10.1084/jem.179.2.425.
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The specificity of antibody (Ab) responses depends on focusing helper T (Th) lymphocyte signals to suitable B lymphocytes capable of binding foreign antigens (Ags), and away from nonspecific or self-reactive B cells. To investigate the molecular mechanisms that prevent the activation of self-reactive B lymphocytes, the activation requirements of B cells specific for the Ag hen egg lysozyme (HEL) obtained from immunoglobulin (Ig)-transgenic mice were compared with those of functionally tolerant B cells isolated from Ig-transgenic mice which also express soluble HEL. To eliminate the need for surface (s)Ig-mediated Ag uptake and presentation and allow the effects of sIg signaling to be studied in isolation, we assessed the ability of allogeneic T cells from bm12 strain mice to provide in vivo help to C57BL/6 strain-transgenic B cells. Interestingly, non-tolerant Ig-transgenic B cells required both allogeneic Th cells and binding of soluble HEL for efficient activation and Ab production. By contrast, tolerant self-reactive B cells from Ig/HEL double transgenic mice responded poorly to the same combination of allogeneic T cells and soluble HEL. The tolerant B cells were nevertheless normally responsive to stimulation with interleukin 4 and anti-CD40 Abs in vitro, suggesting that they retained the capacity to respond to mediators of T cell help. However, the tolerant B cells exhibited a proximal block in the sIg signaling pathway which prevented activation of receptor-associated tyrosine kinases in response to the binding of soluble HEL. The functional significance of this sIg signaling defect was confirmed by using a more potent membrane-bound form of HEL capable of triggering sIg signaling in tolerant B cells, which markedly restored their ability to collaborate with allogeneic Th cells and produce Ab. These findings indicate that Ag-specific B cells require two signals for mounting a T cell-dependent Ab response and identify regulation of sIg signaling as a mechanism for controlling self-reactive B cells.
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Boumedine, Radia Sidi, Gorazd Krosl, Marc Vaillancourt, Claude Perreault und Denis-Claude Roy. „Specific Elimination of Alloreactive T Lymphocytes Using Photodynamic Therapy Prevents GVHD and Enables Rapid Immune Reconstitution.“ Blood 104, Nr. 11 (16.11.2004): 4987. http://dx.doi.org/10.1182/blood.v104.11.4987.4987.
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Abstract Graft-versus-host disease (GVHD) and impaired immune reconstitution are the primary obstacles limiting the efficacy of allogeneic stem cell transplantation (SCT). Graft-versus-host disease (GVHD) and impaired immune reconstitution are the primary obstacles limiting the efficacy of allogeneic stem cell transplantation (SCT). The purpose of this study was to determine whether selective depletion of donor alloantigen-specific T lymphocytes using photodynamic therapy (PDT) would prevent GVHD and enable immune reconstitution in the context of MHC-mismatched SCT. This question was addressed in an MHC-incompatible mouse model of GVHD. The donor (C57BL/6; H-2b) derived spleen cells were first activated against C3H/HeJ (H-2k) host spleen cells in a one-way mixed lymphocyte culture and then exposed to photodynamic treatment, using dibromorhodamine methyl ester (TH9402) as a photosensitizer. Activated T cells showed preferential retention of this photosensitizer compared to resting lymphocytes. In addition, in vitro experiments revealed that PDT eradicated a significantly higher proportion of activated than resting T cells. When lethally irradiated H-2k mice (C3H/HeJ and B10BR) were transplanted with C57BL/6 derived T cell-depleted bone marrow cells supplemented with C57BL/6 derived spleen cells activated with C3H/HeJ targets, they rapidly succumbed to acute GVHD (within 10–47 days). In contrast, both mouse strains receiving histoincompatible C57BL/6 T cells previously exposed to PDT after activation against C3H/HeJ survived until the end of the observation period (>100 days)(p<0.0001). Additionally, transplantation of treated T cells induced lethal GVHD in C57BL/6 histoincompatible strains of mice (third party), suggesting PDT specifically eradicated activated T cells while sparing most resting T lymphocytes. Analysis of immune recovery, evaluating T and B cell populations in thymus and spleen, activated T cells components (CD44, CD62L, CD69), proliferative responses (anti-CD3 and conA), and Vβ repertoire indicated that T and B cell reconstitution in MHC-mismatched mice transplanted with treated primed cells was similar to that of mice transplanted with treated or control autologous cells indicating that immune cells were preserved and functional. These results demonstrate that PDT can selectively eliminate alloreactive T cells and prevent the development of GVHD, while sparing T cells reactive against non-host antigens, thus offering protection against infection and disease relapse.
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Carsetti, R., G. Köhler und M. C. Lamers. „Transitional B cells are the target of negative selection in the B cell compartment.“ Journal of Experimental Medicine 181, Nr. 6 (01.06.1995): 2129–40. http://dx.doi.org/10.1084/jem.181.6.2129.
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B lymphocytes recognize antigen through membrane-bound antigen-receptors, membrane IgM and IgD (mIgM and mIgD). Binding to foreign antigens initiates a cascade of biochemical events that lead to activation and differentiation. In contrast, binding to self-antigens leads to death or to inactivation. It is commonly believed that the B cells acquire the ability to discriminate between self and nonself in the early phases of development. We report here that immature B cells, which have just emerged from the mIgMneg, B220pos pool, are not deleted upon binding of self-antigen. In vivo, developing B cells become sensitive to tolerance induction in a relatively late window of differentiation, when they are in transition from the immature (HSAbright, B220dull) to the mature (HSAdull, B220bright) stage. In the transitional B cells, early markers of differentiation such as Pgp1 (CD44) and ThB reach the highest level of expression, while the expression of CD23 and mIgD, late markers of differentiation, and expression of class II MHC, progressively increases. Most of the transitional B cells, but only few of the mature and of the immature B cells, express the fas antigen, while mature B cells, but not immature and transitional B cells, express bcl-2 protein. mIgM is present in low amounts in immature B cells, reaches the highest level of expression in transitional B cells and is down-regulated in mature resting B cells, where it is coexpressed with mIgD. The high expression of mIgM, the presence of the fas antigen and the absence of bcl-2 protein is compatible with the high sensitivity of transitional B cells to negative selection. In vitro, immature B cells die rapidly by apoptosis after cross-linking of mIgM. This result, combined with the resistance of immature B cells to elimination in vivo, suggests that early in development the stroma cell microenvironment modulates signals transduced through mIgM. The functional and phenotypic division of IgMpos bone marrow B cells in three compartments not only allows to define the target population of physiological processes like negative selection, but will also be a helpful tool for an accurate description of possible developmental blocks in mutant mice.
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Qiao, Zhenhua, und Lihui Ma. „Study On Mechanism of Bone Marrow Mesenchymal Stem Cell in Treating Patients with Rheumatoid Arthritis.“ Blood 114, Nr. 22 (20.11.2009): 4486. http://dx.doi.org/10.1182/blood.v114.22.4486.4486.
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Abstract Abstract 4486 Objective To explore mechanism of Mesenchymal stem cells in treating Rheumatoid arthritis. Methods (1) MSCs were isolated from Bone marrow samples of Rheumatoid arthritis(RA)patients and purified by density gradient centrifagation and cultured in vitro. Morphology, immunophenotype, and proliferative property of bMSC and colony forming unit-fibroblast (CFU-F) were measured and analyzed. (2) In an in vitro co-culture system, MSCs were observed to modulate proliferation,activation, and maturation of T and B lymphocytes of Rheumatoid arthritis(RA)patients. The expression of IL-1?ATNF-a?ATGF-β were obviously changed.(3) Bone marrow- derived BMSCs of wistar rats were isolated and cultured in vitro routinely and the fourth passage as taken for identification of specific surface antigens by flowcytometry, then were labled with 5- BrdU in vitro. The model of collagen-induced arthritis (CIA) rats were established. 5- BrdU labled BMSCs were implanted through tail vein to model rats. At 4 weeks after BMSCs transplantation, immunohistochemical examinations were used to investigate BMSCs aggregate around the knee joints.and identify the contribution of bone marrow– derived cells to joints damage repair. Results (1) The culture expanded cells from RA patients presented a typical fibroblast-like morphology. Cells were positive for SH2(CD105),CD71,and CD44, but negative for CD45.Their proliferative capacity and CFU-F number were similar to those of bMSCs from healthy donors. (2) MSCs significantly inhibited T,B cell proliferation. MSCs also could down-regulating the levels of IL-1, TNF and up-regulating TGF-β. (3) Flow cytometry showed that BMSCs expressed CD44, CD71and CD105, but no CD45,CD34. At 4 weeks after the cells transplantation, the implanted cells were detected in the damaged joints of the model rats, which is not founded in normal knee joints of the rats'.and at same time there are more OPG(osteoprotegerin) positive. Conclusion (1) In the aspect of morphology, immuno -phenotypen, proliferative property and colony forming unit-fibroblast (CFU-F),MSCs from bone marrow of RA patients are not different from those of MSCs isolated from bone marrow of normal donors,MSCs from the bone marrow of RA patients have the potentiality in clinical application.(2) Human bone marrow MSCs inhibited Tcell and Bcell activation and proliferation in patients with RA in vitro. And these immuno –modulatory effects were not MHC-restricted. (3) bone marrow mesenchymal stem cells prevents tissue damage in arthritis. Allogeneic MSCs can engraft at sites of tissue damage,and prepair damage. That provided positive results for developing effective therapy for Rheumatoid arthritis. Disclosures: No relevant conflicts of interest to declare.
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Runarsson, Gudmundur, Anquan Liu, Yilmaz Mahshid, Stina Feltenmark, Annika Pettersson, Eva Klein, Magnus Björkholm und Hans-Erik Claesson. „Leukotriene B4 plays a pivotal role in CD40-dependent activation of chronic B lymphocytic leukemia cells“. Blood 105, Nr. 3 (01.02.2005): 1274–79. http://dx.doi.org/10.1182/blood-2004-07-2546.
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AbstractBiosynthesis of leukotrienes (LTs) occurs in human myeloid cells and B lymphocytes. However, the function of leukotrienes in B lymphocytes is unclear. Here, we report that B-cell chronic lymphocytic leukemia (B-CLL) cells produce leukotriene B4, and that specific leukotriene biosynthesis inhibitors counteracted CD40-dependent activation of B-CLL cells. Studies on the expression of the high-affinity receptor for LTB4 (BLT1) by flow cytometry analysis showed that the receptor was expressed, to a varying degree, in all investigated B-CLL clones. At a concentration of 100 nM, the drugs BWA4C (a specific 5-lipoxygenase inhibitor) and MK-886 (a specific 5-lipoxygenase activating protein inhibitor) markedly inhibited CD40-induced DNA synthesis (45% and 38%, respectively) and CD40-induced expression of CD23, CD54, and CD150. Addition of exogenous LTB4 (150 nM) almost completely reversed the effect of the inhibitors on DNA synthesis and antigen expression. Taken together, the results of the present study suggest that leukotriene biosynthesis inhibitors may have a therapeutic role in B-CLL.
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Markushin, S. G., N. K. Akhmatova, V. N. Stolpnikova, I. Iv Akopova, A. A. Rtishchev und E. O. Kalinichenko. „Examining immune arms in mice immunized with site-specific influenza virus mutants“. Russian Journal of Infection and Immunity 10, Nr. 2 (22.05.2020): 295–304. http://dx.doi.org/10.15789/2220-7619-eia-1175.
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Site-specific mutants as candidates for live influenza vaccines were resulted from directly introducing into the genome of the pathogenic influenza virus A/WSN/33 (H1N1) strain ts mutations derived from the genes encoding the polymerase complex proteins from some cold-adapted strains serving as attenuation donor. Here we present the data of a comparative study examining immune system arms in mice immunized intranasally with influenza virus mutants and classical cold-adapted reassortant obtained by crossing cold-adapted strain Donor A/Krasnodar/101/35/59 (H2N2) with strain A/WSN/33 (H1N1) bearing surface antigens (hemagglutinin and neuraminidase) similar to mutants. Immunophenotyping mononuclear leukocytes from immunized mice indicated at moderate suppressive effect after using site-specific mutant and the HA reassortant viruses on some immune cell subsets. All viruses in immunized mice resulted in activation of certain lymphocyte subsets including MHC II-positive cells, CD45+/CD19+ B lymphocytes and natural killer cells (CD16/32+/CD3–). Timescale and magnitude of activation markedly differed for each cell subsets. Mice immunized with mutants M26 and U2 peaked with count of CD16/32+/CD3– expressing cells on day 2 after the second immunization compared with control (p < 0.05) that may suggest about an important role for NK cells in activating immune response. In contrast, no significant changes were observed during the study in percentage of CD4+/CD25+/Fox P3 regulatory T cells, CD4+ T helpers and CD8+ cytotoxic cells, except for a sharply decreased count of activated CD4+/CD25+ cells (4-fold) on day 7 after immunization with mutant virus M26. Moreover, mutants U2 and M26 more moderately increased percentage of TLR2- and TLR4-positive cells. The viruses studied ambiguously affected count of TLR9-expressing cells in immunized animals. All viruses increased phagocytic activity in monocytes, but not neutrophils. Despite the moderate activation of innate and adaptive immunity arms, site-specific mutants more profoundly affected humoral reactions inducing increased antibody titers, so that immunogenicity of mutant viruses was higher than that of the cold-adapted reassortant. Thus, the findings hold a promise of using site-specific mutants as live influenza vaccines.
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Claesson, Hans-Erik, Gudmundur Runarsson, Anquan Liu, Yilmaz Mahshid, Stina Feltenmark, Eva Klein und Magnus Bjorkholm. „Leukotriene B4 Plays a Pivotal Role in CD40 Dependent Activation of Chronic B Lymphocytic Leukemia Cells.“ Blood 104, Nr. 11 (16.11.2004): 4808. http://dx.doi.org/10.1182/blood.v104.11.4808.4808.
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Abstract Biosynthesis of leukotrienes occurs in human myeloid cells and B lymphocytes. However, the function of leukotrienes in B lymphocytes is unclear. Here we report that B-cell chronic lymphocytic leukemia (B-CLL) cells produce leukotriene (LT) B4 and that specific leukotriene biosynthesis inhibitors counteracted CD40-dependent activation of B-CLL cells. Studies on the expression of the high affinity receptor for LTB4 (BLT1) by flow cytometry analysis showed that the receptor was expressed, to a varying degree, in all investigated B-CLL clones. The drugs BWA4C (a specific 5-lipoxygenase inhibitor) and MK-886 (a specific 5-lipoxygenase activating protein inhibitor), at a concentration of 100 nM, markedly inhibited CD40-induced DNA synthesis (45% and 38%, respectively) and CD40-induced expression of CD23, CD54 and CD150. Addition of exogenous LTB4 (150 nM) almost completely reversed the effect of the inhibitors on DNA synthesis and antigen expression. Taken together, the results of the present study suggest that leukotriene biosynthesis inhibitors may have a therapeutic role in B-CLL.
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Piller, F., F. Le Deist, K. I. Weinberg, R. Parkman und M. Fukuda. „Altered O-glycan synthesis in lymphocytes from patients with Wiskott-Aldrich syndrome.“ Journal of Experimental Medicine 173, Nr. 6 (01.06.1991): 1501–10. http://dx.doi.org/10.1084/jem.173.6.1501.
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The only molecular defect reported for the X-linked immunodeficiency Wiskott-Aldrich syndrome (WAS) is the abnormal electrophoretic behavior of the major T lymphocyte sialoglycoprotein CD43. Since the 70 to 80 O-linked carbohydrate chains of CD43 are known to influence markedly its electrophoretic mobility, we analyzed the structure and the biosynthesis of O-glycans of CD43 in lymphocytes from patients with WAS. Immunofluorescence analysis with the carbohydrate dependent anti-CD43 antibody T305 revealed that in 10 out of the 12 WAS patients tested increased numbers of T lymphocytes carry on CD43 an epitope which on normal lymphocytes is expressed only after activation. Other activation antigens were absent from WAS lymphocytes. Western blots of WAS cell lysates displayed a high molecular mass form of CD43 which reacted with the T305 antibody and which could be found on in vivo activated lymphocytes but was absent from normal unstimulated lymphocytes. To examine the O-glycan structures, carbohydrate labeled CD43 was immunoprecipitated and the released oligosaccharides identified. WAS lymphocyte CD43 was found to carry predominantly the branched structure NeuNAc alpha 2----3Gal beta 1----3 (NeuNAc alpha 2----3Gal beta 1----4G1cNAc beta 1----6) GalNAcOH whereas normal lymphocytes carry the structure NeuNAc alpha 2----3Gal beta 1----3 (NeuNAc alpha 2----6) GalNAcOH. Only after activation NeuNAc alpha 2----3Gal beta 1----3 (NeuNAc alpha 2----3Gal beta 1----4GlcNAc beta 1----6) GalNAcOH becomes the principal oligosaccharide on CD43 from normal lymphocytes. Analyzing the six glycosyltransferases involved in the biosynthesis of these O-glycan structures it was found that in WAS lymphocytes high levels of beta 1----6 N-acetyl-glucosaminyl transferase are responsible for the expression of NeuNAc alpha 2----3Gal beta 1----3 (NeuNAc alpha 2----3Gal beta 1----4GlcNAc beta 1----6) GalNAcOH on CD43. The gene responsible for WAS has not yet been identified but the results presented in this study suggest that the primary defect in WAS may affect a gene which is involved in the regulation of O-glycosylation.
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Visconte, Valeria, Nalini Raghavachari, Keyvan Keyvanfar, Delong Liu, Marie Desierto, Jichun Chen und Neal S. Young. „Clonally-Restricted T-Lymphocytes in PigA Mutant Mice.“ Blood 112, Nr. 11 (16.11.2008): 2040. http://dx.doi.org/10.1182/blood.v112.11.2040.2040.
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Abstract Somatic mutation in the X-linked phosphatydylinositol glycan class A (PIG-A) gene causes glycosyl phosphatidylinositol (GPI) anchor deficiency in hematopoietic stem and progenitor cells, in humans, a requirement for the development of the disease paroxysmal nocturnal hemoglobinuria (PNH). While progress has been made in understanding PNH and especially in treatment of intravascular hemolysis secondary to cell surface deficiency of CD59, why PIG-A mutant stem cells expand in the setting of immune-mediated bone marrow failure remains obscure. We produced a conditional PigA knock-out animal model (PigA−/−) by cross-breeding mice carrying germline insertion of two lox sites flanking exon 6 of PigA gene with mice carrying the transgene Cre-recombinase driven by the human c-fes promoter. The resultant B6 Fes-cre PigAflox (PigA−/−) mice had PigA gene inactivation specifically in hematopoietic cells. We observed that GPI-deficient (GPI−) bone marrow (BM) and spleen cells from PigA−/− mice contained much larger proportions of lymphocytes, especially CD8+ T cells, in comparison to GPI+ cells. The expansion of GPI−CD8+ T cells was not associated with any obvious hematological phenotype, and blood and BM cell counts were relatively normal in PigA−/− mice. In comparison to GPI+ cells analyzed by microarray, GPI− BM cells showed up-regulation in expression of genes important for immune function responses. Pathway analysis revealed that differentially-expressed genes were clustered in several groups related to immunological function, such as lymphocyte markers (CD8b1, CD8a, CD3e, CD3d, CD7, CD2, CD5, CD6, CD28, CD96, CD27), proteins related to T cell activation (Lck, Zap70, Fyn, Zeta, Lat, Traf1, Tcf7, Ctla2a/Ctla2b), TCR components (Tcr-beta-V13, Tcr-beta-V8.2, Tcr-alpha, Tcr-beta- J, Tcr-gamma), chemokines and C-C motifs (Ccl5, CXCR6, Ccr7), and molecules of the killer lectin-like receptor subfamily (Klrc1, Klrc2, Klra7, Klra8). We transplanted into lethally-irradiated recipients BM cells from PigA−/− mice (pre-incubated with aerolysin to lyse GPI+ cells) or BM cells from normal PigA+/+ donors. By microarray, transplanted GPI− cells retained the phenotype of untransplanted GPI− cells, with a much increased CD8+ T cell proportion and up-regulated immune function gene expression in comparison to transplanted normal BM cells. The enlarged GPI−CD8+ T cell pool had a significantly lower proportion of CD11a+ cells than did GPI+CD8+ T cells, suggesting that GPI−CD8+ T cells were generally less active. There was no difference in the proportion of CD44− naive T cells between GPI−CD8+ and GPI+CD8+ T cells; GPI−CD8+ T cells were not NK cells as they lacked surface NK1.1 staining. The percentage of CD4+CD25+FoxP3+ regulatory T cells in GPI− cells was only 10% of that in GPI+ cells in peripheral blood in both untransplanted and transplanted animals, indicating that the expanded T cell population in the GPI− cell fraction contained few cells with immunosuppressive property. We further investigated T cell clonality by usage of T cell receptor beta variable region (Vbeta); approximately 5-6 Vbeta subfamilies were over represented in the GPI− CD8+ T cells. In particular, Vbeta 5.1/5.2 was prominent in GPI−CD8+ T cells, constituting 22-23 ± 5% GPI− T cells from untransplanted and transplanted animals; a significant increase in comparison to 8-9.1 ± 0.5% Vbeta 5.1/5.2 clonal representation in GPI+CD8+ T cells. Our results are consistent with an antigen-driven T cell response in the GPI− lymphocyte population, independent of pancytopenia. Functionally, GPI−CD8 T cells showed no response to lectin stimulation as measured by gamma interferon production, but they were capable of effecting target cell apoptosis when co-incubated with minor-H antigen mismatched BM cells in vitro. Our data agrees with observations in humans, in which an immune process driven by a restricted set of (unknown) antigens appears active in the pathogenesis of PNH (Gargiulo et al., Blood 2007). We conclude that deletion of PigA gene in hematopoietic cells, independent of frank hematopoietic failure, leads to enrichment of lymphocytes, especially CD8 T cells, in the GPI− cell fraction that have an inactive and naive phenotype. These expanded, clonally-restricted, T cells may provide an initial pool of immune effectors, which in the proper immune activated environment, contribute to bone marrow failure in PNH.
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Bottrel, R. L. A., W. O. Dutra, F. A. Martins, B. Gontijo, E. Carvalho, M. Barral-Netto, A. Barral et al. „Flow Cytometric Determination of Cellular Sources and Frequencies of Key Cytokine-Producing Lymphocytes Directed against Recombinant LACK and Soluble Leishmania Antigen in Human Cutaneous Leishmaniasis“. Infection and Immunity 69, Nr. 5 (01.05.2001): 3232–39. http://dx.doi.org/10.1128/iai.69.5.3232-3239.2001.
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ABSTRACT Leishmaniasis, caused by infection with the protozoan parasiteLeishmania, affects millions of individuals worldwide, causing serious morbidity and mortality. This study directly determined the frequency of cells producing key immunoregulatory cytokines in response to the recombinant antigen Leishmania homolog of receptors for activated kinase C (LACK) and soluble leishmania antigen (SLA), and it determined relative contributions of these antigens to the overall cytokine profile in individuals infected for the first time with Leishmania braziliensis. All individuals presented with the cutaneous clinical form of leishmaniasis and were analyzed for proliferative responses to LACK antigen and SLA, frequency of lymphocyte subpopulations (analyzed ex vivo), and antigen-induced (LACK and SLA) cytokine production at the single-cell level (determined by flow cytometry). The following were determined. (i) The Th1-type response previously seen in patients with cutaneous leishmaniasis is due to gamma interferon (IFN-γ) production by several different sources, listed in order of contribution: CD4+ T lymphocytes, CD4−, CD8− lymphocytes, and CD8+ T lymphocytes. (ii) SLA induced a higher frequency of lymphocytes producing IFN-γ and tumor necrosis factor alpha (TNF-α) than did LACK. (iii) LACK induced an activation of monocyte populations as reflected by an increased percentage of CD14-positive cells. (iv) Neither SLA nor LACK induced detectable frequencies of cells producing interleukin-4 (IL-4) or IL-5. These data demonstrated a multifaceted immune response to SLA in human leishmaniasis involving Th1 CD4+ T lymphocytes (IFN-γ+ and IL-10−/IL-4−), Tc1 CD8+ T cells (IFN-γ+, and IL-10−/IL-4−), and a high frequency of TNF-α-producing lymphocytes. Moreover, it was determined that the recombinant antigen LACK acts as a weak inducer of Th1-type lymphocyte responses compared to SLA.
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McEvoy, Leslie M., Hailing Sun, John G. Frelinger und Eugene C. Butcher. „Anti-CD43 Inhibition of T Cell Homing“. Journal of Experimental Medicine 185, Nr. 8 (21.04.1997): 1493–98. http://dx.doi.org/10.1084/jem.185.8.1493.
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The homing of lymphocytes from the blood is controlled by specialized processes of lymphocyte–endothelial cell interaction. Interference with these processes offers the potential to manipulate lymphocyte traffic, and thus to modulate normal and pathologic immune and inflammatory responses. We selected antilymphocyte monoclonal antibodies (mAbs) for inhibition of lymphocyte binding in vitro to lymph node high endothelial venules (HEV), specialized vessels that support lymphocyte recruitment into lymph nodes. mAb L11 blocks T cell binding to lymph node and Peyer's patch HEV and inhibits T cell extravasation from the blood into organized secondary lymphoid tissues. In contrast, L11 has no effect on lymphocyte binding to purified vascular ligands for L-selectin, α4β7, or LFA-1, suggesting that it inhibits by a novel mechanism. The L11 antigen is CD43, a sialomucin implicated in vitro in regulation of lymphocyte activation, whose expression is often dysregulated in the Wiskott-Aldrich syndrome. CD43 represents a novel target for experimental and therapeutic manipulation of lymphocyte traffic and may help regulate T cell distribution in vivo.
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Perico, N., D. Ostermann, M. Bontempeill, M. Morigi, C. S. Amuchastegui, C. Zoja, E. Akalin, M. H. Sayegh und G. Remuzzi. „Colchicine interferes with L-selectin and leukocyte function-associated antigen-1 expression on human T lymphocytes and inhibits T cell activation.“ Journal of the American Society of Nephrology 7, Nr. 4 (April 1996): 594–601. http://dx.doi.org/10.1681/asn.v74594.
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Colchicine, which inhibits cell microtubule assembly by preventing polymerization of tubulin monomers, inhibits cell-mediated immune responses and promotes long-term survival of major histocompatibility complex-incompatible renal allografts in rats. Here we evaluated the effect of blocking cell microtubule assembly by colchicine on T cell and endothelial cell adhesion receptors involved in transducing signals for T cell activation. By using immunofluorescence flow cytometry analysis, evidence is presented that colchicine, in a dose-dependent fashion, downregulated L-selectin and leukocyte function-associated antigen-1, but not CD2 and CD44 on the surface of naive human peripheral blood lymphocytes. This effect was confirmed in two subsets of T lymphocytes, namely, CD45RA- and CD45RO-positive cells. However, colchicine did not influence the rapid shedding of L-selectin from T lymphocytes exposed to activating stimuli. Colchicine inhibited expression of interleukin-2 receptor on activated T lymphocytes. This effect was observed when T lymphocytes were stimulated with both anti-CD3 and anti L-selectin monoclonal antibodies. Colchicine also inhibited lymphocyte function in vitro as documented by inhibition of the human mixed lymphocyte response in a dose-dependent fashion. Moreover, colchicine downregulated surface expression of intercellular adhesion molecule-1 and E-selectin on activated human umbilical vein endothelial cells. These results indicate that blocking cell microfubule assembly inhibits surface expression of adhesion molecules on T cells and endothelial cells, and provides insights into the complex mechanisms of the action of colchicine in vivo.
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Galibert, L., N. Burdin, C. Barthélémy, G. Meffre, I. Durand, E. Garcia, P. Garrone, F. Rousset, J. Banchereau und Y. J. Liu. „Negative selection of human germinal center B cells by prolonged BCR cross-linking.“ Journal of Experimental Medicine 183, Nr. 5 (01.05.1996): 2075–85. http://dx.doi.org/10.1084/jem.183.5.2075.
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The antigen receptors on T and B lymphocytes can transduce both agonist and antagonist signals leading either to activation/survival or anergy/death. The outcome of B lymphocyte antigen receptor (BCR) triggering depends upon multiple parameters which include (a) antigen concentration and valency, (b) duration of BCR occupancy, (c) receptor affinity, and (d) B cell differentiation stages. Herein, using anti-immunoglobulin kappa and lambda light chain antibodies, we analyzed the response of human naive, germinal center (GC) or memory B cells to BCR cross-linking regardless of heavy chain Ig isotype or intrinsic BCR specificity. We show that after CD40-activation, anti-BCR (kappa + gamma) can elicit an intracellular calcium flux on both GC and non-GC cells. However, prolonged BCR cross-linking induces death of CD40-activated GC B cells but enhances proliferation of naive or memory cells. Anti-kappa antibody only kills kappa + GC B cells without affecting surrounding gamma + GC B cells, thus demonstrating that BCR-mediated killing of GC B lymphocytes is a direct effect that does not involve a paracrine mechanism. BCR-mediated killing of CD40-activated GC B cells could be partially antagonized by the addition of IL-4. Moreover, in the presence of IL-4, prestimulation through CD40 could prevent subsequent anti-Ig-mediated cell death, suggesting a specific role of this combination in selection of GC B cells. This report provides evidence that in human, susceptibility to BCR killing is regulated along peripheral B cell differentiation pathway.
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Murakami, S., und H. Okada. „Lymphocyte-Fibroblast Interactions“. Critical Reviews in Oral Biology & Medicine 8, Nr. 1 (Januar 1997): 40–50. http://dx.doi.org/10.1177/10454411970080010201.
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Chronic inflammatory reactions are usually characterized by inflammatory cell accumulation in the extravascular connective tissue. In such sites, inappropriate activation of circulating or resident lymphocytes becomes self-perpetuating and can lead to chronic tissue destruction. In addition to that, the locally infiltrated lymphocytes should have an opportunity to interact directly with fibroblasts composing the connective tissue. The direct interactions of those different cell types seem to play important roles in lymphocyte lodging and retention in such sites. Thus, for clarification of the immunopathogenesis of the chronic inflammatory diseases, including periodontitis, it is important that the molecular mechanisms involved in the heterotypic cell-cell interactions be revealed. In fact, it has been demonstrated that lymphocytes interact with various non-hematopoietic cells, such as epithelial cells and endothelial cells. Regarding interactions with fibroblasts, it has been shown that IFNγ-stimulated fibroblasts can regulate the proliferative responses of T-lymphocytes both positively and negatively. Furthermore, activated lymphocytes have demonstrated strong binding ability to various fibroblast cell lines. Blocking experiments utilizing monoclonal antibodies specific to various cell adhesion molecules revealed that very late antigen (VLA) integrins, lymphocyte-function-associated antigen (LFA-1)/intercellular adhesion molecule-1 (ICAM-1), CD44/hyarulonate are, at least in part, involved in lymphocyte-fibroblast interactions. In addition, recent findings raised the possibility that the adhesive interactions between lymphocytes and fibroblasts influenced the various cellular functions of each cell type. In fact, it was recently demonstrated that the adhesive interactions stimulated fibroblasts to increase expression of inflammatory cytokine mRNA. These results strongly suggest that fibroblasts are not merely innocent bystanders but actively participate in local inflammatory reactions by directly interacting with locally infiltrated lymphocytes.
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Cohen, Nicolas, Enguerran Mouly, Haifa Hamdi, Marie-Christine Maillot, Marc Pallardy, Véronique Godot, Francis Capel et al. „GILZ expression in human dendritic cells redirects their maturation and prevents antigen-specific T lymphocyte response“. Blood 107, Nr. 5 (01.03.2006): 2037–44. http://dx.doi.org/10.1182/blood-2005-07-2760.
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Interleukin (IL)-10 and glucocorticoids (GCs) inhibit the ability of antigen-presenting dendritic cells (DCs) to stimulate T lymphocytes. We show that induction of GILZ (GC-induced leucine zipper) is involved in this phenomenon. IL-10, dexamethasone (DEX), and transforming growth factor (TGF)β stimulate GILZ production in human immature DCs derived from monocytes and from CD34+ cells. GILZ is necessary and sufficient for DEX, IL-10, and TGFβ modulation of CD80, CD83, CD86, immunoglobulin-like transcript (ILT)-3, and B7-H1 expression by DCs, and alteration of DC functions. GILZ stimulates the production of IL-10 by immature DCs and prevents the production of inflammatory chemokines by CD40L-activated DCs. In contrast, GILZ does not prevent CD40 ligand-mediated inhibition of phagocytosis, indicating that it affects some but not all aspects of DC maturation. GILZ prevents DCs from activating antigen-specific T lymphocyte responses. Administration of GCs to patients stimulates GILZ expression in their circulating antigen-presenting cells, and this contributes to the weak lymphocyte responses of GC-treated patients. Thus, regulation of GILZ expression is an important factor determining the decision of DCs whether or not to stimulate T lymphocytes, and IL-10, GCs, and TGFβ share this mechanism for influencing DC functions and the balance between immune response and tolerance.
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Greil, Johann, Tobias Rausch, Thomas Giese, Obul Reddy Bandapalli, Volker Daniel, Isabelle Bekeredjian-Ding, Adrian M. Stuetz et al. „Whole-Exome Sequencing Links CARD11 Inactivation with SCID“. Blood 120, Nr. 21 (16.11.2012): 258. http://dx.doi.org/10.1182/blood.v120.21.258.258.
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Abstract Abstract 258 Primary immunodeficiencies represent model diseases for the mechanistic understanding of the human innate and the adaptive immune response and are per se clinically highly relevant, because in SCID patients infections by opportunistic pathogens are typically life-threatening early in life. We identified an infant of consanguineous parents suffering from a novel form of SCID, who presented with a life-threatening Pneumocystis jirovecii pneumonia. This entity was characterized by agammaglobulinemia and profoundly deficient T-cell function despite quantitatively normal T- and B-lymphocytes. Lymphocyte proliferation was strongly inhibited after stimulation of PBMCs with T-cell mitogens such as PHA, Con A, or anti-CD3 monoclonal antibody. The expression of several T-cell response associated cytokines upon stimulation with PMA/ionomycin was dramatically reduced in comparison to normal controls. By contrast, proliferation induced by the classical B-cell mitogen PWM was almost comparable to healthy controls. Immunophenotyping revealed a predominantly naïve phenotype (CD45RA+ CCR7+) in CD4+ and CD8+ T-lymphocytes, whereas central memory T-lymphocytes (CD45RA− CCR7+) were nearly absent. B-lymphocytes from peripheral blood were mainly naïve B-cells (CD27−) with a uniformly immature transitional B-lymphocyte phenotype (CD24++, CD38++). Patient B-lymphocytes retained the ability to proliferate and differentiate in response to BCR-independent stimuli, while their response to BCR activation was defective. Our findings thus revealed a combined defect of TCR-mediated T-lymphocyte functions and BCR-mediated B-lymphocyte functions but did not enable us to link the immunological phenotype with one of the known molecularly defined categories of SCID. Diagnostic whole-exome sequencing and systematic variant categorization revealed a single pathogenic homozygous nonsense mutation of the caspase recruitment domain 11 (CARD11) gene. CARD11 is a scaffold protein that is known to be required for the assembly and activation of the NF-kB complex. In reconstitution assays we demonstrated that the patient derived truncated CARD11 protein is defective in antigen receptor signaling and NF-kB activation. Several lines of evidence substantiate the involvement of the identified CARD11 mutation in the new form of SCID that we report here. First, PCR and Sanger re-sequencing validated the truncating CARD11 mutation to be homozygous in the patient and heterozygous in the parents, in agreement with the recessive transmission of the mutation through the healthy consanguineous parents. Second, CARD11 is a scaffold protein required for TCR- and BCR-induced NF-kB activation as well as lymphocyte activation and proliferation, which is specifically expressed in hematopoietic cells, consistent with a causative role of CARD11 mutations in the context of an immune disorder. Third, the GUK domain of CARD11, which is missing in the mutated form of CARD11 due to truncation, was previously reported to be necessary for NF-kB activation by PMA/ionomycin treatment, further supporting the presumed damaging nature of the homozygous CARD11 mutation observed in the female patient reported here. Finally, the immunological findings in this patient are compatible with the phenotype of a previously described Card11 −/− k.o. mouse, which shows a selective defect in NF-κB activation leading to diminished antigen receptor or PKC mediated proliferation and defective cytokine production in T-cells and B-cells. Thus, we have identified an inactivating CARD11 mutation linking defective NF-kB signaling with a novel cause of autosomal recessive SCID, which must be considered in the diagnostic assessment of patients with suspected SCID but with quantitatively normal T-cells. Disclosures: No relevant conflicts of interest to declare.
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Hughes, J. M., W. A. Sewell, J. L. Black und C. L. Armour. „Effect of dexamethasone on expression of adhesion molecules on CD4+ lymphocytes“. American Journal of Physiology-Lung Cellular and Molecular Physiology 271, Nr. 1 (01.07.1996): L79—L84. http://dx.doi.org/10.1152/ajplung.1996.271.1.l79.
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Despite the widespread use of corticosteroids in asthma therapy, little is known of the effects of corticosteroids on cell surface markers involved in T lymphocyte activation and adhesion. We used flow cytometry to analyze the effects of 1, 10, and 100 nM dexamethasone on expression of markers on resting and phytohemagglutinin (PHA)-stimulated peripheral blood CD4+ T lymphocytes. Expression of the leukocyte common antigen CD45 was significantly (P = 0.016, n = 3) increased from an average mean fluorescence intensity of 215.8 [95% confidence intervals (CI): 100.5, 463.5] on cells from unstimulated cultures to 334.2 (CI: 167.9, 663.7) on cells from PHA-stimulated cultures after 70-h incubation. At the same time, the percentage of cells also expressing the CD45RO isoform, a marker of memory T lymphocytes, increased significantly (P = 0.0006, n = 3) from 54.4 +/- 1.3% (unstimulated) to 92.8 +/- 0.6% (stimulated). Dexamethasone had no significant effect on expression of CD45 or CD45RO, including the observed changes. Dexamethasone also did not affect expression of the beta 1-integrin VLA-4. These results suggest that corticosteroids do not modulate the cell surface expression of these molecules involved in CD4+ T lymphocyte activation, adhesion, and recirculation.
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Mak, T. W. „Insights into the ontogeny and activation of T cells“. Clinical Chemistry 40, Nr. 11 (01.11.1994): 2128–31. http://dx.doi.org/10.1093/clinchem/40.11.2128.
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Abstract T lymphocytes recognize antigen peptides and major histocompatibility complex products through their T-cell antigen receptors (TcR), consisting of alpha and beta chains. The interaction between T cells and their target cells or antigen-presenting cells is also assisted by a series of other cell-surface polypeptides, most notably CD4 and CD8, which are selectively expressed on mature helper/inducer and killer/suppressor T cells, respectively. Upon engagement of their ligands, a series of signals is transduced intracytoplasmically via some of these molecules and their associated proteins. Perhaps the most important enzyme in this signal transduction process is the lymphocyte-specific tyrosine kinase lck. Another important component is the cell-surface tyrosine phosphatase CD45. This molecule is alternatively spliced and the different isoforms are expressed on the various hematopoietic and lymphopoietic cells. Signaling through the TcR-CD4 D8-lck-CD45 complex is thought to be insufficient to activate T lymphocytes. A costimulatory signal is believed to be essential, and many investigators have suggested that CD28, a ligand for B7/BB1, is such a signal. Immune responses are also controlled by a number of cytokines and soluble factors. Signaling through the tumor necrosis factor receptor p55 is required for clearance of intracellular pathogens. Transcriptional factors involved in controlling interferon production are also important in T-cell development and immune responses. In an attempt to gain a better understanding of the roles of these molecules in T-lymphocyte functions and ontogeny, we generated a series of mutant mice with disruptions in the genes coding for these molecules. We are analyzing the mutant mice to evaluate the importance of these genes in T-cell development.
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Schirren, CA, H. Volpel und SC Meuer. „Adhesion molecules on freshly recovered T leukemias promote tumor- directed lympholysis“. Blood 79, Nr. 1 (01.01.1992): 138–43. http://dx.doi.org/10.1182/blood.v79.1.138.138.
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Abstract Besides facilitating cell to cell adhesion, the molecular interactions between CD2 and its ligand CD58 (lymphocyte function-associated antigen- 3 [LFA-3]), as well as between CD11a/18 (LFA-1) and CD54 (intercellular adhesion molecule-1) have recently been recognized to participate in lymphocyte activation, recirculation, and effector function, including cytolytic activity towards tumor cells. We have investigated the role of CD2/CD58 and CD11a/18/CD54 interactions in cellular immune responses directed towards freshly recovered human T-cell leukemias. The data support the notion that downregulation of CD54 and CD58 correlates with enhanced numbers of blasts in circulation and unsusceptibility to killing by autologous cytotoxic lymphocytes. Importantly, after induction of CD54 and CD58 expression on leukemic cells by recombinant cytokines such as tumor necrosis factor-alpha, tumor cells become highly susceptible to lymphocyte-mediated lysis in vitro. Our findings, therefore, stress the point that successful immunotherapy of malignant disease may be facilitated by influencing not only the immune response itself, but also adhesion molecules on the malignant tumor targets.
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Schirren, CA, H. Volpel und SC Meuer. „Adhesion molecules on freshly recovered T leukemias promote tumor- directed lympholysis“. Blood 79, Nr. 1 (01.01.1992): 138–43. http://dx.doi.org/10.1182/blood.v79.1.138.bloodjournal791138.
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Besides facilitating cell to cell adhesion, the molecular interactions between CD2 and its ligand CD58 (lymphocyte function-associated antigen- 3 [LFA-3]), as well as between CD11a/18 (LFA-1) and CD54 (intercellular adhesion molecule-1) have recently been recognized to participate in lymphocyte activation, recirculation, and effector function, including cytolytic activity towards tumor cells. We have investigated the role of CD2/CD58 and CD11a/18/CD54 interactions in cellular immune responses directed towards freshly recovered human T-cell leukemias. The data support the notion that downregulation of CD54 and CD58 correlates with enhanced numbers of blasts in circulation and unsusceptibility to killing by autologous cytotoxic lymphocytes. Importantly, after induction of CD54 and CD58 expression on leukemic cells by recombinant cytokines such as tumor necrosis factor-alpha, tumor cells become highly susceptible to lymphocyte-mediated lysis in vitro. Our findings, therefore, stress the point that successful immunotherapy of malignant disease may be facilitated by influencing not only the immune response itself, but also adhesion molecules on the malignant tumor targets.
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Imbert, V., J. F. Peyron, D. Farahi Far, B. Mari, P. Auberger und B. Rossi. „Induction of tyrosine phosphorylation and T-cell activation by vanadate peroxide, an inhibitor of protein tyrosine phosphatases“. Biochemical Journal 297, Nr. 1 (01.01.1994): 163–73. http://dx.doi.org/10.1042/bj2970163.
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Rapid tyrosine phosphorylation of key cellular proteins is a crucial event in the transduction of activation signals to T-lymphocytes. The regulatory role of protein tyrosine phosphatases (PTPases) in this process was explored by studying the effects of a powerful PTPase inhibitor, vanadate peroxide (pervanadate), on the activation cascade of Jurkat human leukaemic T-cells. Pervanadate induced activation of the tyrosine kinases lck and fyn (4- and 3-fold respectively) and a dramatic increase in tyrosine phosphorylation of cellular proteins, notably phospholipase C gamma 1. After this event, we observed a rise in intracellular Ca2+ concentration, corresponding to an influx. This effect required surface expression of the CD45 PTPase and was not observed in CD45-deficient variants of Jurkat cells. In the CD45-negative variant, the effect of pervanadate on tyrosine phosphorylation was globally decreased and some phosphorylated substrates were specifically missing. Pervanadate also stimulated transcription of the c-fos gene and accumulation of its mRNA as well as several other hallmarks of T-lymphocyte activation such as surface expression of the CD69 antigen and the interleukin 2 receptor alpha-chain (CD25). Pervanadate synergized with signals delivered by T-cell antigen receptor engagement or by a phorbol ester to induce interleukin 2 production. Pervanadate activated NF-kappa B, as shown by an increase in DNA-binding activity of this transcription factor. We thus conclude that PTPases play a crucial role in the negative regulation of signal transduction culminating in T-lymphocyte activation. Moreover, induction of tyrosine phosphorylation appears sufficient per se to initiate a complete activation programme.
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Sandmaier, BM, R. Storb, FR Appelbaum und WM Gallatin. „An antibody that facilitates hematopoietic engraftment recognizes CD44“. Blood 76, Nr. 3 (01.08.1990): 630–35. http://dx.doi.org/10.1182/blood.v76.3.630.630.
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Abstract Pretreatment of recipients with the monoclonal antibody (MoAb) S5 facilitates engraftment of bone marrow from mismatched, unrelated donors in the canine transplantation model. In the direct comparisons reported here, the S5 glycoprotein (gp) was found to have structural homology to CD44 that in humans has been implicated in adhesive interactions of one type of effector cell, the lymphocyte. The S5 antigen and gp90Hermes-1 exhibited codistribution on canine peripheral blood cells. Both S5 and Hermes-1 (anti-CD44) MoAbs recognized 90-Kd species in radioimmune precipitations of 125I surface-labeled canine peripheral blood lymphocytes and bone marrow cells. Competitive antibody binding experiments showed that the epitope detected by S5 was distinct from that bound by Hermes-1 but overlapped with those defined by two other known anti-CD44 reagents, IM7 and Hutch-1. Sequential immunoprecipitation with S5 and Hermes-1 indicated that the two antibodies recognize the same or overlapping subsets of membrane gps. Tryptic digestion of S5 and anti-CD44 immunoprecipitates generated two major iodinated peptides of 27 and 35 Kd in both cases, a further indication of structural homology. Similarly, after N-glycanase digestion, S5 and CD44 immunoprecipitates were resolved to a single 68- Kd species. These findings suggest that CD44-mediated adhesive events may affect the fate of transplanted hematopoietic cells. The previous implications of this gp in T-lymphocyte activation and lymphocyte adhesion to endothelium thus provide useful paradigms to analyze its function in the bone marrow transplant setting.
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Sandmaier, BM, R. Storb, FR Appelbaum und WM Gallatin. „An antibody that facilitates hematopoietic engraftment recognizes CD44“. Blood 76, Nr. 3 (01.08.1990): 630–35. http://dx.doi.org/10.1182/blood.v76.3.630.bloodjournal763630.
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Pretreatment of recipients with the monoclonal antibody (MoAb) S5 facilitates engraftment of bone marrow from mismatched, unrelated donors in the canine transplantation model. In the direct comparisons reported here, the S5 glycoprotein (gp) was found to have structural homology to CD44 that in humans has been implicated in adhesive interactions of one type of effector cell, the lymphocyte. The S5 antigen and gp90Hermes-1 exhibited codistribution on canine peripheral blood cells. Both S5 and Hermes-1 (anti-CD44) MoAbs recognized 90-Kd species in radioimmune precipitations of 125I surface-labeled canine peripheral blood lymphocytes and bone marrow cells. Competitive antibody binding experiments showed that the epitope detected by S5 was distinct from that bound by Hermes-1 but overlapped with those defined by two other known anti-CD44 reagents, IM7 and Hutch-1. Sequential immunoprecipitation with S5 and Hermes-1 indicated that the two antibodies recognize the same or overlapping subsets of membrane gps. Tryptic digestion of S5 and anti-CD44 immunoprecipitates generated two major iodinated peptides of 27 and 35 Kd in both cases, a further indication of structural homology. Similarly, after N-glycanase digestion, S5 and CD44 immunoprecipitates were resolved to a single 68- Kd species. These findings suggest that CD44-mediated adhesive events may affect the fate of transplanted hematopoietic cells. The previous implications of this gp in T-lymphocyte activation and lymphocyte adhesion to endothelium thus provide useful paradigms to analyze its function in the bone marrow transplant setting.
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Imlach, S., S. McBreen, T. Shirafuji, C. Leen, J. E. Bell und P. Simmonds. „Activated Peripheral CD8 Lymphocytes Express CD4 In Vivo and Are Targets for Infection by Human Immunodeficiency Virus Type 1“. Journal of Virology 75, Nr. 23 (01.12.2001): 11555–64. http://dx.doi.org/10.1128/jvi.75.23.11555-11564.2001.
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ABSTRACT There is increasing evidence that CD8 lymphocytes may represent targets for infection by human immunodeficiency virus type 1 (HIV-1) in vivo whose destruction may contribute to the loss of immune function underlying AIDS. HIV-1 may infect thymic precursor cells destined to become CD4 and CD8 lymphocytes and contribute to the numerical decline in both subsets on disease progression. There is also evidence for the induction of CD4 expression and susceptibility to infection by HIV-1 of CD8 lymphocytes activated in vitro. To investigate the relationship between CD8 activation and infection by HIV-1 in vivo, activated subsets of CD8 lymphocytes in peripheral blood mononuclear cells (PBMCs) of HIV-seropositive individuals were investigated for CD4 expression and HIV infection. Activated CD8 lymphocytes were identified by expression of CD69, CD71, and the human leukocyte antigen (HLA) class II, the β-chain of CD8, and the RO isoform of CD45. CD4+ and CD4− CD8 lymphocytes, CD4 lymphocytes, other T cells, and non-T cells were purified using paramagnetic beads, and proviral sequences were quantified by PCR using primers from the long terminal repeat region. Frequencies of activated CD8 lymphocytes were higher in HIV-infected study subjects than in seronegative controls, and they frequently coexpressed CD4 (mean frequencies on CD69+, CD71+, and HLA class II+ cells of 23, 37, and 8%, respectively, compared with 1 to 2% for nonactivated CD8 lymphocytes). The level of CD4 expression of the double-positive population approached that of mature CD4 lymphocytes. That CD4 expression renders CD8 cell susceptible to infection was indicated by their high frequency of infection in vivo; infected CD4+ CD8 lymphocytes accounted for between 3 and 72% of the total proviral load in PBMCs from five of the eight study subjects investigated, despite these cells representing a small component of the PBMC population (<3%). Combined, these findings provide evidence that antigenic stimulation of CD8 lymphocytes in vivo induces CD4 expression that renders them susceptible to HIV infection and destruction. The specific targeting of responding CD8 lymphocytes may provide a functional explanation for the previously observed impairment of cytotoxic T-lymphocyte (CTL) function disproportionate to their numerical decline in AIDS and for the deletion of specific clones of CTLs responding to HIV antigens.
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Ravanel, Kissia, Claire Castelle, Thierry Defrance, T. Fabian Wild, Dominique Charron, Vincent Lotteau und Chantal Rabourdin-Combe. „Measles Virus Nucleocapsid Protein Binds to FcγRII and Inhibits Human B Cell Antibody Production“. Journal of Experimental Medicine 186, Nr. 2 (21.07.1997): 269–78. http://dx.doi.org/10.1084/jem.186.2.269.
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Despite the development of an efficient specific immune response during measles virus (MV) infection, an immunosuppression occurs contributing to secondary infections. To study the role of nucleocapsid protein (NP) in MV-induced immunosuppression, we produced recombinant MV NP. Purified recombinant NP exhibited biochemical, antigenic, and tridimensional structure similar to viral NP. By flow cytometry, we showed that viral or recombinant NP bound to human and murine B lymphocytes, but not to T lymphocytes. This binding was specific, independent of MHC class II expression, and dependent of the B lymphocyte activation state. The murine IIA1.6 B cell line, deficient in the Fc receptor for IgG (FcγRII) expression, did not bind NP efficiently. Transfected IIA1.6 cells expressing either murine FcγRIIb1 or b2, or human FcγRIIa, b1*, or b2 isoforms efficiently bound NP. Furthermore, this binding was inhibited up to 90% by monoclonal antibodies 2.4G2 or KB61 specific for murine and human FcγRII, respectively. Finally, the in vitro Ig synthesis of CD40- or Ig-activated human B lymphocytes in the presence of interleukin (IL)-2 and IL-10 was reduced by 50% in the presence of recombinant NP. These data demonstrate that MV NP binds to human and murine FcγRII and inhibits in vitro antibody production, and therefore suggests a role for NP in MV-induced immunosuppression.
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Galli, Grazia, Sandra Nuti, Simona Tavarini, Luisa Galli-Stampino, Claudia De Lalla, Giulia Casorati, Paolo Dellabona und Sergio Abrignani. „CD1d-restricted Help To B Cells By Human Invariant Natural Killer T Lymphocytes“. Journal of Experimental Medicine 197, Nr. 8 (14.04.2003): 1051–57. http://dx.doi.org/10.1084/jem.20021616.
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Invariant natural killer T (NKT) cells are a highly conserved subset of T lymphocytes expressing a semi-invariant T cell receptor (TCR), which is restricted to CD1d and specific for the glycosphingolipid antigen α-galactosylceramide. Their ability to secrete a variety of cytokines, which in turn modulate the activation of cells of both innate and acquired immune responses, suggests that invariant NKT cells exert a regulatory role mainly via indirect mechanisms. A relevant question is whether invariant NKT cells can directly help B cells. We document here that human invariant NKT cells are as efficient as conventional CD4+ Th0 lymphocytes in promoting proliferation of autologous memory and naive B lymphocytes in vitro, and in inducing immunoglobulin production. Help to B cells by invariant NKT cells is CD1d-dependent and delivered also in the absence of α-galactosylceramide, suggesting that NKT cells recognize an endogenous ligand presented by CD1d on B cells. The two major subsets of invariant NKT cells, CD4+ and double negative (CD4−CD8−), express comparable levels of CD40 ligand and cytokines, but differ in helper functions. Indeed, both subsets induce similar levels of B cell proliferation, whereas CD4+ NKT cells induce higher levels of immunoglobulin production. These results suggest a direct role for invariant NKT cells in regulating B lymphocyte proliferation and effector functions.
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Tandon, N., C. Dinsdale, T. Tamatani, M. Miyasaka und A. P. Weetman. „Adhesion molecule expression by the FRTL-5 rat thyroid cell line“. Journal of Endocrinology 130, Nr. 3 (September 1991): 451–56. http://dx.doi.org/10.1677/joe.0.1300451.
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ABSTRACT We have examined the expression and function of rat CD54, a homologue of human intercellular adhesion molecule-1 (ICAM-1), by the continuously growing rat thyroid cell line FRTL-5. Approximately 10% of FRTL-5 cells express CD54 under basal conditions and this is not influenced by thyrotrophin. Expression of CD54 is increased by cytokines (γ-interferon, tumour necrosis factor, interleukin-1) and by an activator of C-kinase, phorbol 12-myristate 13-acetate. Blocking ICAM-1 with a monoclonal antibody directed against this molecule significantly (P <0·01) reduced the binding of splenic lymphocytes to FRTL-5 cells but inhibition was consistently greater (P <0·01) in the presence of antibodies against a rat homologue of lymphocyte function-associated antigen-1, the receptor on T cells for ICAM-1. In no case was complete blocking of cluster formation observed. These results show that a pure line of rat thyroid cells can express an ICAM-1 homologue and this is directly enhanced by cytokines. Expression of this homologue is partially responsible for lymphocyte adhesion to thyroid cells, which is likely to be a major event in T cell recognition of thyroid antigens in autoimmune thyroiditis. Journal of Endocrinology (1991) 130, 451–456
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Zola, H., J. V. Melo, H. N. Zowtyj, A. Nikoloutsopoulos und J. Skinner. „The leukocyte-common antigen (CD45) complex and b-lymphocyte activation“. Human Immunology 27, Nr. 4 (April 1990): 368–77. http://dx.doi.org/10.1016/0198-8859(90)90087-6.
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Shameli, Afshin, Yan Zheng, Clifford Harding, Howard Meyerson und Robert Maitta. „Alpha-Synuclein Deficiency Is Associated with Defective Th2 Differentiation and Enhanced Regulatory T Cell Development“. Blood 124, Nr. 21 (06.12.2014): 1424. http://dx.doi.org/10.1182/blood.v124.21.1424.1424.
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Abstract Synucleins (including α-, β- and γ-synucleins) are a group of proteins that are highly expressed in the central nervous system. Alpha-synuclein, in particular, has been implicated in the pathogenesis of neurodegenerative disorders known as synucleinopathies. The function of these proteins in other organ systems is largely unknown. Some studies have demonstrated expression of α-synuclein on peripheral blood mononuclear cells (PBMC), including B and T lymphocytes, NK cells and monocytes; and its expression has been shown to be higher in PBMCs of individuals with Parkinson’s compared to healthy controls. We have recently shown that α-synuclein-deficiency is associated with marked defect in development of mature B and T lymphocytes. In particular, we showed enhanced negative selection of developing thymic T cells in the absence α-synuclein. Furthermore, we demonstrated that α-synuclein-deficiency is associated with an impaired IgG response to T cell-dependent antigens. Here we used age and sex-matched α-synuclein knock-out (KO) and wild type (WT) mice to further investigate the lineage differentiation and activation of T cells. We found that few splenic T cells that develop in KO mice contain a higher percentage of CD8+ T cell expressing early activation markers CD69 (7.6 ± 0.09 for KO vs. 5.3 ± 0.23 for WT, p=0.005, figure 1A) and CD49d (12.97 ± 0.3 for KO vs. 7.32 ± 0.6 for WT, p=0.006, figure 1A). A similar trend was noted for CD4+ CD49d+ T cells, although the difference did not reach statistical significance (23.90 ± 3.48 for KO vs.13.23 ± 0.73 for WT, p=0.086, figure 1A). No difference was noted in the expression of late activation marker CD44, and lymph node homing marker CD62L. This was associated with significantly increased IL-2 production from KO CD4+ T cells (OD 2.70 ± 0.12 for KO vs.1.05 ± 0.39 for WT, p=0.002, figure 1B) and a trend for increased IFN-γ production from KO CD4+ T cells (OD 2.89 ± 0.33 for KO vs.2.12 ± 0.59 for WT, p=0.12) after in vitro activation with anti-CD3/anti-CD28 beads. Interestingly, In vitro activation of splenic CD4+ T cells resulted in significantly reduced IL-4 production from KO T cells (OD 0.20 ± 0.14 for KO, vs. 0.74 ± 0.31 for WT, p=0.05, Figure 2) suggesting a defective Th2 differentiation in KO CD4+ T cells. Further flow cytometric analysis of T cells showed that while thymic Foxp3+ CD4+ regulatory T cells are significantly reduced in KO mice (3.07 ±0.35 for KO vs. 5.00 ± 0.87 for WT, p=0.02, Figure 3), the percentage of splenic Foxp3+ CD4+ T cells is higher in the KO mice compared to WT mice (18.33 ± 4.90 for KO vs.10.33 ± 1.39 for WT, p=0.05, Figure 3). No difference was noted among NK cells from KO and WT mice. In summary, we demonstrate a role for α-synuclein in lineage differentiation and function of T cells. While α-synuclein-deficiency leads to a significant defect in development of mature T cells, the small population of cells that do mature, express higher levels of early activation markers, and produce higher levels of IL-2 upon antigenic stimulation. Of interest, these cells are defective in IL-4 production. Additionally, we also show that α-synuclein-deficiency is associated with a higher percentage of peripheral CD4+ Foxp3+ T cells, a finding that might be explained by higher levels of IL-2 production by α-synuclein-deficient CD4+ T cells, although a direct effect of α-synuclein on the survival of regulatory T cells cannot be excluded. The underlying mechanism for the function α-synuclein in development and function of T cells is subject of future studies. Disclosures No relevant conflicts of interest to declare.
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Dubois, Bertrand, Béatrice Vanbervliet, Jérome Fayette, Catherine Massacrier, Cees Van Kooten, Francine Brière, Jacques Banchereau und Christophe Caux. „Dendritic Cells Enhance Growth and Differentiation of CD40-activated B Lymphocytes“. Journal of Experimental Medicine 185, Nr. 5 (03.03.1997): 941–52. http://dx.doi.org/10.1084/jem.185.5.941.
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After antigen capture, dendritic cells (DC) migrate into T cell–rich areas of secondary lymphoid organs, where they induce T cell activation, that subsequently drives B cell activation. Here, we investigate whether DC, generated in vitro, can directly modulate B cell responses, using CD40L-transfected L cells as surrogate activated T cells. DC, through the production of soluble mediators, stimulated by 3- to 6-fold the proliferation and subsequent recovery of B cells. Furthermore, after CD40 ligation, DC enhanced by 30–300-fold the secretion of IgG and IgA by sIgD− B cells (essentially memory B cells). In the presence of DC, naive sIgD+ B cells produced, in response to interleukin-2, large amounts of IgM. Thus, in addition to activating naive T cells in the extrafollicular areas of secondary lymphoid organs, DC may directly modulate B cell growth and differentiation.
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Schattner, E. J., K. B. Elkon, D. H. Yoo, J. Tumang, P. H. Krammer, M. K. Crow und S. M. Friedman. „CD40 ligation induces Apo-1/Fas expression on human B lymphocytes and facilitates apoptosis through the Apo-1/Fas pathway.“ Journal of Experimental Medicine 182, Nr. 5 (01.11.1995): 1557–65. http://dx.doi.org/10.1084/jem.182.5.1557.
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The Apo-1/Fas antigen (CD95) mediates programmed cell death of lymphocytes when bound by Fas ligand or anti-Apo-1/Fas antibody. In contrast, the CD40 antigen provides a potent activation and survival signal to B lymphocytes when it is engaged by its T cell ligand (CD40L, gp39) or cross-linked by anti-CD40 antibody. In this study, we use human tonsillar B cells and the Ramos Burkitt's lymphoma B cell line, which serves as a model for human germinal center B lymphocytes, to study the effectors of Apo-1/Fas expression and apoptosis of human B cells. We found that Apo-1/Fas expression was upregulated on both malignant and normal human B lymphocytes after CD40 ligation induced by (a) cognate T helper-B cell interaction mediated by microbial superantigen (SAg); (b) contact-dependent interaction with CD40L+, but not CD40L- Jurkat mutant T cell clones; and (c) monoclonal anti-CD40, but not any of a panel of control antibodies. Enhanced B cell Fas/Apo-1 expression is functionally significant. Coculture of Ramos Burkitt's lymphoma line cells with irradiated SAg-reactive CD4+ T cells with SAg or CD40L+ Jurkat T cells results in B cell apoptosis, evidenced by reduced cell viability and DNA laddering. This process is augmented by the addition of anti-Apo-1/Fas monoclonal antibody, consistent with an acquired susceptibility to Apo-1/Fas-mediated apoptosis. These data support an immunoregulatory pathway in which seemingly contradictory signals involving the B cell proliferation/survival antigen CD40, as well as the Apo-1/Fas molecule, which mediates programmed cell death of lymphocytes, are linked in the process of human B cell activation.
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Yoshihiro, Michishita, Makoto Hirokawa, Naohito Fujishima, Yukiko Abe, Masumi Fujishima, Yong-Mei Guo, Kumi Ubukawa et al. „CDR3-Independent Expansion of Vδ1 γδ T Lymphocytes and Depletion of Vδ2 T Cells Are Unique Features in Acquired Chronic Pure Red Cell Aplasia“,. Blood 118, Nr. 21 (18.11.2011): 3429. http://dx.doi.org/10.1182/blood.v118.21.3429.3429.
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Abstract Abstract 3429 Background: Idiopathic PRCA and secondary PRCA associated with thymoma and large granular lymphocyte leukemia are major subtypes of adult-onset chronic PRCA. We have previously shown that these types of PRCA are responsive to immunosuppressive therapy but most patients require long-term maintenance immunosuppressive treatment. These results suggest that acquired chronic PRCA is an autoimmune disorder mediated by T lymphocytes and pathogenic T cell clones may be persistently present during remission. We have previously made an interesting observation that a thymoma-associated PRCA patient had an increase of Vd1 gd T cells in blood. We have also reported that recipients of allogeneic hematopoietic stem cell grafts had an oligoclonal expansion of Vd1 gd T cells and that Vd1 gd T clones had cytotoxicity against autologous EBV-transformed B cell line. Thus, gd T cell repertoires may be altered in PRCA patients in response to certain antigens. Objective: In order to clarify the role for gd T cells in the pathogenesis of chronic acquired PRCA, we have examined the gd T cell receptor repertoire in acquired chronic PRCA patients. Materials and Methods: Nineteen PRCA (8 idiopathic, 6 thymoma, 3 LGL-leukemia and 2 SLE) and 107 healthy volunteer donors were included in the study. This study was approved by the Institutional Review Board at Akita University and conducted in accordance with the Declaration of Helsinki. Blood lymphocyte subsets were analyzed by flow cytometry. Clonality of T cells was determined by complementarity-determining region 3 (CDR3) size distribution analysis and junctional sequence was determined by subcloning of PCR products and DNA sequencing. In some experiments, purified gd T cells from PRCA patients were co-cultured with allogeneic erythroid progenitor cells derived from CD34-positive cells in vitro in order to learn whether patient's gd T cells would exert cytotoxic or growth-inhibitory effect on erythroid progenitor cells. Results: The absolute numbers of ab T cells and gd T cells were normal in patients with PRCA, but there were an increase of Vd1 gd T cells and a decrease of Vd2 T cells (Table 1). More than 50% of Vd1 T cells from PRCA patients expressed HLA-DR, while 20 to 30% of those from healthy individuals expressed HLA-DR (Fig. 1). CDR3 size spectratyping revealed that CDR3 size distribution patterns were skewed in 9 out of 13 PRCA patients examined, although skewed CDR3 size distribution patterns were also observed in 7 out of 10 healthy individuals. In order to determine whether a particular Vd1-Jd rearrangement size was selected in PRCA patients, we performed statistical analysis comparing the CDR3 size distribution of 115 Vd1 TCR clones obtained by subcloning of PCR products in 7 PRCA patients versus 7 controls. No significant difference was found between the two groups (p=0.795 by Mann-Whitney test). Moreover, no apparent consensus amino acid motifs were identified in PRCA patients. Although the T cell clone carrying the -YWGIR- sequence in the CDR3d region was detected in 3 PRCA patients, the T cell clone carrying the -YWGIR- sequence was also detected in one healthy donor. Purified gdT lymphocytes from idiopathic PRCA neither showed an inhibitory effect on proliferation nor cytotoxicity against erythroid progenitor cells in vitro. Adjusted p value was calculated by Kruskal-Wallis ANOVA test. Conclusions: Expansion of Vd1 T cells and depletion of Vd2 T cells are unique features for chronic acquired PRCA. Expansion of Vd1 T cells does not seem to be the consequence of CDR3-dependent selection. Depletion of Vd2 T cells may be the result of chronic stimulation, because our previous study has revealed that the numbers of Vd2 T cells show an age-dependent decrease and Vd2 T cells are susceptible to activation-induced cell death (Int J Hematol, in press). Failure to demonstrate the cytotoxicity of gd T cells from a PRCA patient against erythroid progenitor cells suggests that expanded gd T cells are not effector T cells. Disclosures: No relevant conflicts of interest to declare.
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Abrams, Judith R., Susan L. Kelley, Elizabeth Hayes, Toyoko Kikuchi, Michael J. Brown, Sewon Kang, Mark G. Lebwohl et al. „Blockade of T Lymphocyte Costimulation with Cytotoxic T Lymphocyte–Associated Antigen 4–Immunoglobulin (Ctla4ig) Reverses the Cellular Pathology of Psoriatic Plaques, Including the Activation of Keratinocytes, Dendritic Cells, and Endothelial Cells“. Journal of Experimental Medicine 192, Nr. 5 (05.09.2000): 681–94. http://dx.doi.org/10.1084/jem.192.5.681.
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Efficient T cell activation is dependent on the intimate contact between antigen-presenting cells (APCs) and T cells. The engagement of the B7 family of molecules on APCs with CD28 and CD152 (cytotoxic T lymphocyte–associated antigen 4 [CTLA-4]) receptors on T cells delivers costimulatory signal(s) important in T cell activation. We investigated the dependence of pathologic cellular activation in psoriatic plaques on B7-mediated T cell costimulation. Patients with psoriasis vulgaris received four intravenous infusions of the soluble chimeric protein CTLA4Ig (BMS-188667) in a 26-wk, phase I, open label dose escalation study. Clinical improvement was associated with reduced cellular activation of lesional T cells, keratinocytes, dendritic cells (DCs), and vascular endothelium. Expression of CD40, CD54, and major histocompatibility complex (MHC) class II HLA-DR antigens by lesional keratinocytes was markedly reduced in serial biopsy specimens. Concurrent reductions in B7-1 (CD80), B7-2 (CD86), CD40, MHC class II, CD83, DC–lysosomal-associated membrane glycoprotein (DC-LAMP), and CD11c expression were detected on lesional DCs, which also decreased in number within lesional biopsies. Skin explant experiments suggested that these alterations in activated or mature DCs were not the result of direct toxicity of CTLA4Ig for DCs. Decreased lesional vascular ectasia and tortuosity were also observed and were accompanied by reduced presence of E-selectin, P-selectin, and CD54 on vascular endothelium. This study highlights the critical and proximal role of T cell activation through the B7-CD28/CD152 costimulatory pathway in maintaining the pathology of psoriasis, including the newly recognized accumulation of mature DCs in the epidermis.
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Vigouroux, Stéphane, Eric Yvon, Hans-Joachim Wagner, Ettore Biagi, Gianpietro Dotti, Uluhan Sili, Cecilia Lira, Cliona M. Rooney und Malcolm K. Brenner. „Induction of Antigen-Specific Regulatory T Cells following Overexpression of a Notch Ligand by Human B Lymphocytes“. Journal of Virology 77, Nr. 20 (15.10.2003): 10872–80. http://dx.doi.org/10.1128/jvi.77.20.10872-10880.2003.
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ABSTRACT In mice, activation of the Notch pathway in T cells by antigen-presenting cells overexpressing Notch ligands favors differentiation of regulatory T lymphocytes responsible for antigen-specific tolerance. To determine whether this mechanism operates in human T cells, we used Epstein-Barr virus-positive lymphoblastoid cell lines (EBV-LCL) as our (viral) antigen-presenting cells and overexpressed the Notch ligand Jagged-1 (EBV-LCL J1) by adenoviral transduction. The EBV-LCL J1s were cocultured with autologous T cells, and the proliferative and cytotoxic responses to EBV antigens were measured. Transduction had no effect on EBV-LCL expression of major histocompatibility complex (MHC) antigens or of costimulatory molecules CD80, CD86, and CD40. However, we observed a 35% inhibition of proliferation and a >65% reduction in cytotoxic-T-cell activity, and interleukin 10 production was increased ninefold. These EBV-LCL J1-stimulated T lymphocytes act as antigen-specific regulatory cells, since their addition to fresh autologous T cells cultured with autologous nontransduced EBV-LCL cells significantly inhibited both proliferation and cytotoxic effector function. Within the inhibitory population, CD4+CD25+ and CD8+CD25− T cells had the greatest activity. This inhibition appears to be antigen-specific, since responses to Candida and cytomegalovirus antigens were unaffected. Hence, transgenic expression of Jagged-1 by antigen-presenting cells can induce antigen-specific regulatory T cells in humans and modify immune responses to viral antigens.
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Réthi, Bence, Péter Gogolák, Istvan Szatmari, Ágota Veres, Erika Erdôs, Laszlo Nagy, Éva Rajnavölgyi, Cox Terhorst und Árpád Lányi. „SLAM/SLAM interactions inhibit CD40-induced production of inflammatory cytokines in monocyte-derived dendritic cells“. Blood 107, Nr. 7 (01.04.2006): 2821–29. http://dx.doi.org/10.1182/blood-2005-06-2265.
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AbstractSignaling lymphocyte activation molecule (SLAM, CD150, or SLAMF1) is a self-ligand receptor on the surface of activated T- and B-lymphocytes, macrophages, and dendritic cells (DCs). Here we examine the effect of SLAM/SLAM interactions on CD40L-induced CD40 signaling pathways in human DCs. CD40L-expressing L929 cells induced DCs to produce interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-12, which was strongly inhibited by coexpression of SLAM on the surface of the L929 cells. Similarly, transfection of DCs with SLAM strongly reduced CD40L-induced IL-12 production. Furthermore, the negative effect of SLAM/SLAM interactions on CD40L-induced DC activation was also detected in the presence of lipopolysaccharide (LPS). LPS-induced IL-12 secretion, however, was not inhibited by SLAM engagement. CD40L-activated DCs affected by exposure to SLAM/SLAM engagement were impaired in their ability to induce differentiation of naive T lymphocytes into interferon-γ (IFN-γ)–producing T-helper 1 (Th1) effector cells. These inhibitory effects were not the result of a general unresponsiveness of DCs to CD40L, as SLAM/SLAM interactions did not prevent CD40L-induced up-regulation of CD83, CD86, or human leukocyte antigen (HLA)–DQ on the surface of DCs. Taken together, the results indicate that SLAM/SLAM interactions inhibit CD40-induced signal transduction in monocyte-derived dendritic cells, an effect that was not detectable in earlier studies using anti-SLAM monoclonal antibodies.
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Garza, Kristine M., Steven M. Chan, Rakesh Suri, Linh T. Nguyen, Bernhard Odermatt, Stephen P. Schoenberger und Pamela S. Ohashi. „Role of Antigen-Presenting Cells in Mediating Tolerance and Autoimmunity“. Journal of Experimental Medicine 191, Nr. 11 (06.06.1999): 2021–28. http://dx.doi.org/10.1084/jem.191.11.2021.
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The mechanisms that determine whether receptor stimulation leads to lymphocyte tolerance versus activation remain poorly understood. We have used rat insulin promoter (RIP)-gp/P14 double-transgenic mice expressing the lymphocytic choriomeningitis virus (LCMV) glycoprotein (gp) on pancreatic β-islet cells together with T cells expressing an LCMV-gp–specific T cell receptor to assess the requirements for the induction of autoimmunity. Our studies have shown that administration of the gp peptide gp33 leads to the activation of P14-transgenic T cells, as measured by the upregulation of activation markers and the induction of effector cytotoxic activity. This treatment also leads to expansion and deletion of P14 T cells. Despite the induction of cytotoxic T lymphocyte activity, peptide administration is not sufficient to induce diabetes. However, the administration of gp peptide together with an activating anti-CD40 antibody rapidly induces diabetes. These findings suggest that the induction of tolerance versus autoimmunity is determined by resting versus activated antigen-presenting cells.
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Merlo, Andrea, Daniele Saverino, Claudya Tenca, Carlo Enrico Grossi, Silvia Bruno und Ermanno Ciccone. „CD85/LIR-1/ILT2 and CD152 (Cytotoxic T Lymphocyte Antigen 4) Inhibitory Molecules Down-Regulate the Cytolytic Activity of Human CD4+ T-Cell Clones Specific forMycobacterium tuberculosis“. Infection and Immunity 69, Nr. 10 (01.10.2001): 6022–29. http://dx.doi.org/10.1128/iai.69.10.6022-6029.2001.
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ABSTRACT Antigen-specific cytolytic CD4+ T lymphocytes controlMycobacterium tuberculosis infection by secreting cytokines and by killing macrophages that have phagocytosed the pathogen. However, lysis of the latter cells promotes microbial dissemination, and other macrophages engulf the released bacteria. Subsequently, CD4+ T-cell-mediated killing of macrophages goes on, and this persistent process may hamper control of infection, unless regulatory mechanisms maintain a subtle balance between lysis of macrophages by cytolytic CD4+ cells and activation of cytolytic CD4+ cells by infected macrophages. We asked whether inhibitory molecules expressed by CD4+ cytolytic T lymphocytes could play a role in such a balance. To this end, human CD4+ T-cell clones specific for M. tuberculosis were produced that displayed an autologous major histocompatibility complex class II-restricted lytic ability against purified protein derivative (PPD)-pulsed antigen-presenting cells. All T-cell clones expressed CD152 (cytotoxic T-lymphocyte antigen 4 [CTLA-4]) and CD85/leukocyte immunoglobulin-like receptor 1 (LIR-1)/immunoglobulin-like transcript 2 (ILT2) inhibitory receptors, but not CD94 and the killer inhibitory receptor (or killer immunoglobulin-like receptor [KIR]) p58.2. CD3-mediated activation of the clones was inhibited in a redirected killing assay in which CD152 and CD85/LIR-1/ILT2 were cross-linked. Specific antigen-mediated proliferation of the clones was also sharply reduced when CD152 and CD85/LIR-1/ILT2 were cross-linked by specific monoclonal antibody (MAb) followed by goat anti-mouse antiserum. In contrast, blockade of the receptors by specific MAb only increased their proliferation. Production of interleukin 2 (IL-2) and gamma interferon (IFN-γ) by the T-cell clones was also strongly reduced when CD152 and CD85/LIR-1/ILT2 were cross-linked. The lytic activity of the T-cell clones against PPD-pulsed autologous monocytes or Epstein-Barr virus-activated B cells was increased by blockade and decreased by cross-linking of the receptors. These results indicate that CD152 and CD85/LIR-1/ILT2 play a role in the regulation of the antigen-specific activity of CD4+ cytolytic T lymphocytes against PPD-presenting cells.
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Autero, M., J. Saharinen, T. Pessa-Morikawa, M. Soula-Rothhut, C. Oetken, M. Gassmann, M. Bergman, K. Alitalo, P. Burn und C. G. Gahmberg. „Tyrosine phosphorylation of CD45 phosphotyrosine phosphatase by p50csk kinase creates a binding site for p56lck tyrosine kinase and activates the phosphatase.“ Molecular and Cellular Biology 14, Nr. 2 (Februar 1994): 1308–21. http://dx.doi.org/10.1128/mcb.14.2.1308.
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Src family protein tyrosine kinases (PTKs) play an essential role in antigen receptor-initiated lymphocyte activation. Their activity is largely regulated by a negative regulatory tyrosine which is a substrate for the activating action of the CD45 phosphotyrosine phosphatase (PTPase) or, conversely, the suppressing action of the cytosolic p50csk PTK. Here we report that CD45 was phosphorylated by p50csk on two tyrosine residues, one of them identified as Tyr-1193. This residue was not phosphorylated by T-cell PTKs p56lck and p59fyn. Tyr-1193 was phosphorylated in intact T cells, and phosphorylation increased upon treatment with PTPase inhibitors, indicating that this tyrosine is a target for a constitutively active PTK. Cotransfection of CD45 and csk into COS-1 cells caused tyrosine phosphorylation of CD45 in the intact cells. Tyrosine-phosphorylated CD45 bound p56lck through the SH2 domain of the kinase. Finally, p50csk-mediated phosphorylation of CD45 caused a severalfold increase in its PTPase activity. Our results show that direct tyrosine phosphorylation of CD45 can affect its activity and association with Src family PTKs and that this phosphorylation could be mediated by p50csk. If this is also true in the intact cells, it adds a new dimension to the physiological function of p50csk in T lymphocytes.
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Autero, M., J. Saharinen, T. Pessa-Morikawa, M. Soula-Rothhut, C. Oetken, M. Gassmann, M. Bergman, K. Alitalo, P. Burn und C. G. Gahmberg. „Tyrosine phosphorylation of CD45 phosphotyrosine phosphatase by p50csk kinase creates a binding site for p56lck tyrosine kinase and activates the phosphatase“. Molecular and Cellular Biology 14, Nr. 2 (Februar 1994): 1308–21. http://dx.doi.org/10.1128/mcb.14.2.1308-1321.1994.
Der volle Inhalt der QuelleAnnotation:
Src family protein tyrosine kinases (PTKs) play an essential role in antigen receptor-initiated lymphocyte activation. Their activity is largely regulated by a negative regulatory tyrosine which is a substrate for the activating action of the CD45 phosphotyrosine phosphatase (PTPase) or, conversely, the suppressing action of the cytosolic p50csk PTK. Here we report that CD45 was phosphorylated by p50csk on two tyrosine residues, one of them identified as Tyr-1193. This residue was not phosphorylated by T-cell PTKs p56lck and p59fyn. Tyr-1193 was phosphorylated in intact T cells, and phosphorylation increased upon treatment with PTPase inhibitors, indicating that this tyrosine is a target for a constitutively active PTK. Cotransfection of CD45 and csk into COS-1 cells caused tyrosine phosphorylation of CD45 in the intact cells. Tyrosine-phosphorylated CD45 bound p56lck through the SH2 domain of the kinase. Finally, p50csk-mediated phosphorylation of CD45 caused a severalfold increase in its PTPase activity. Our results show that direct tyrosine phosphorylation of CD45 can affect its activity and association with Src family PTKs and that this phosphorylation could be mediated by p50csk. If this is also true in the intact cells, it adds a new dimension to the physiological function of p50csk in T lymphocytes.
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Bonnefoy, Nathalie, Daniel Olive und Bernard Vanhove. „Les futures générations d’anticorps modulateurs des points de contrôle de la réponse immunitaire“. médecine/sciences 35, Nr. 12 (Dezember 2019): 966–74. http://dx.doi.org/10.1051/medsci/2019193.
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Les points de contrôle du système immunitaire sont des systèmes moléculaires qui complètent les processus déclenchés par la reconnaissance antigénique en contrôlant l’inhibition ou l’activation des lymphocytes et des cellules myéloïdes, notamment celle des lymphocytes T régulateurs (Treg), permettant ainsi de combiner réponses immunes et maintien de la tolérance au soi. En cancérologie, l’inhibition de points de contrôle inhibiteurs vise à amplifier les réponses immunitaires existantes dirigées contre les tumeurs. Parmi ces points de contrôle inhibiteurs, dont des antagonistes sont en utilisation clinique, se trouvent CTLA-4 (cytolytic T-lymphocyte-associated antigen 4 ou CD152), PD-1 (programmed cell death 1, ou CD279), PD-L1 (programmed cell death-ligand 1, ou CD274), LAG-3 (Lymphocyte-activation gene 3, ou CD223), TIM3 (T-cell immunoglobulin and mucin-domain containing-3), TIGIT (T cell immunoreceptor with Ig and ITIM domains), VISTA (V-domain Ig suppressor of T cell activation), ou B7/H3 (ou CD276). La stimulation de points de contrôle activateurs tels que les molécules de co-activation CD28, CD137 (aussi appelé 4-1BB), OX40 [aussi appelé tumor necrosis factor receptor superfamily, member 4 (TNFRSF4)], GITR (Glucocorticoid-induced tumor necrosis factor receptor family-related protein) ou CD40, est également testée en cancérologie, le plus souvent en combinaison avec un antagoniste de point de contrôle inhibiteur. Dans les maladies auto-immunes et inflammatoires, des antagonistes de points de contrôle activateurs (CD28, CD40) et des agonistes de points de contrôle inhibiteurs (LAG-3) sont également à l’essai. Dans cette revue, nous mettons l’accent sur certains modulateurs de points de contrôle pour lesquels le mécanisme d’action a été particulièrement étudié. Cette description ne pouvant être exhaustive, nous avons regroupé dans le Tableau I l’ensemble des anticorps monoclonaux (AcM) ou protéines recombinantes en usage clinique à notre connaissance, modulant l’action d’un point de contrôle du système immunitaire.
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Garrone, P., E. M. Neidhardt, E. Garcia, L. Galibert, C. van Kooten und J. Banchereau. „Fas ligation induces apoptosis of CD40-activated human B lymphocytes.“ Journal of Experimental Medicine 182, Nr. 5 (01.11.1995): 1265–73. http://dx.doi.org/10.1084/jem.182.5.1265.
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Since CD40/CD40 ligand (CD40Lig) interactions are essential in vivo for the generation of germinal center B cells that express Fas (Apo-1/CD95), we explored whether CD40 engagement may modulate Fas expression and function on human B lymphocytes. Resting tonsil B cells, isolated by density gradient centrifugation, express either absent or low levels of Fas. They could be induced to promptly express Fas after ligation of their CD40, however, using either a recombinant human CD40Lig or a cross-linked anti-CD40 mAb. In contrast, engagement of the B cell antigen receptor by immobilized anti-kappa and -lambda antibodies did not turn on Fas expression. Addition of anti-Fas mAb CH11 inhibited the later phases of CD40-induced B cell growth as a result of apoptotic cell death. Furthermore, Fas ligation inhibited proliferation and Ig secretion of CD40-activated B cells in response to recombinant cytokines such as interleukin (IL)-2, IL-4, and IL-10, as well as a cytokine-rich supernatant of phytohemagglutinin-activated T cells, indicating that none of those B cell tropic factors were able to prevent the Fas-induced death. Taken together, the present results show that engagement of CD40 antigen on B cells induces Fas expression and sensitizes them to Fas-mediated apoptosis. The delayed functional response to Fas ligation after CD40 activation may represent a way to limit the size of a specific B cell clone that is generated during T-B cell interactions.
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Arruga, Francesca, Giulia Guerra, Denis Baev, Catherine Hoofd, Marta Coscia, Giovanni Francesco D'Arena, Gianluca Gaidano, Richard R. Furman und Silvia Deaglio. „Expression of the Tigit/CD226/CD155 Receptors/Ligand System in Chronic Lymphocytic Leukemia“. Blood 134, Supplement_1 (13.11.2019): 5454. http://dx.doi.org/10.1182/blood-2019-128308.
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Introduction: T cell immunoreceptor with Ig and ITIM domains (TIGIT) is a surface receptor mainly expressed by CD8+, regulatory T lymphocytes and natural killer (NK) cells, but not by normal B cells. It performs as an inhibitory immune checkpoint, activated through binding of CD155. TIGIT competes with CD226 for CD155 binding, resulting in opposite outcomes: while CD226 enhances cytotoxicity of T lymphocytes and NK cells, TIGIT exerts immunosuppressive effects. Whether TIGIT engagement triggers an alternative signaling cascade, or whether it simply prevents CD226 activation, remains an open point. Tumor-infiltrating T lymphocytes generally express high levels of the molecule, together with the other checkpoint inhibitor PD-1. On this basis, antagonist antibodies targeting TIGIT are under evaluation to restore immunity and treat cancer patients, alone or in various combinations. Chronic lymphocytic leukemia (CLL), the most common adult leukemia, is characterized by a highly heterogeneous clinical outcome. Several molecular markers can help in stratifying patients, including the presence or absence of somatic mutations in B cell receptor, cytogenetic aberrations and single gene mutations. Interestingly, CLL cells express several T cell specific antigens, including CD5. A previous report indicates that, in CLL, TIGIT is expressed by circulating CD4+T cells, increasing during disease progression, while nothing is known about its expression on CLL cells. Aim:This work was undertaken with the aim of studying expression of the TIGIT/CD226/CD155 axis in CLL. Methods:We assembled a cohort of 101 primary CLL samples (40% females, mean age of 61). All patients were either untreated or had not received treatment in the 6 months prior to analysis. PBMC samples were tested for expression of TIGIT, CD155 and CD226 in both T and B subsets. A multiparametric flow cytometry strategy was designed, combining anti-TIGIT, anti-CD155 and anti-CD226 antibodies with a panel of B- (anti-CD19, anti-CD5, anti-CD38, anti-CD49d and anti-CD73) and T-mono/NK specific (anti-CD3, anti-CD8, anti-CD4, anti-CD14 and anti-CD56) markers. The number of TIGIT molecules on leukemic cells was estimated by interpolating values of mean fluorescence intensity (MFI) of each sample with that of PE-Quantibrite beads. Results:CLL cells heterogeneously express surface TIGIT, ranging from 0.2 to 81% (mean value 20%, median 10%, SEM ±2.145). The estimated number of molecules per cell was in the range of 32.5-3571 (mean 1140, median 841.1, SEM ±83.6). Expression of TIGIT was independent of gender or age at diagnosis and there was no correlation between TIGIT levels and lymphocyte counts in peripheral blood. In contrast, in this cohort of untreated patients, we observed a significantly lower TIGIT expression in samples with advanced disease (RAI III-IV) compared to early stages (RAI 0-I). Accordingly, low TIGIT associated with unmutated (UM) IGHVgenes and with an unfavorable FISH profile (trisomy 12, deletion 17 and deletion 11 vs. deletion 13 or normal karyotype). Lower, although not significant, TIGIT levels were observed in NOTCH1-mutated CLL samples (n=11) compared to counterpart (n=89). Looking at the T cell population, we observed overall higher TIGIT levels in the CD8+vs CD4+subset (mean %TIGIT+cells in CD8+56.7±1.8 vs 27.2±1.3 in CD4+). In line with reported observations, we found a modest but significant increase of TIGIT+T cells in advanced stage CLLs, at variance with what observed on the leukemic B cell side. Accordingly, we observed higher percentages of TIGIT+/CD4+cells in CLL samples carrying UM IGHVgenes. CD226 and CD155 were more homogeneously expressed in all subsets without significant differences, both in CLL and T cell components. Conclusions: This work shows that CLL cells express the immunomodulatory molecule TIGIT, particularly in the early stages of the disease in untreated patients. While further studies are needed to characterize its functional implications as well as treatment effect on TIGIT expression, it is tempting to speculate that TIGIT expression by CLL cells may serve to trigger an immunosuppressive behavior in these cells, which is no longer needed when the disease becomes advanced. This observation represents a starting point for future studies investigating the role of TIGIT in CLL and hints to a possible use of anti-TIGIT antibodies to target different cellular components of the disease. Disclosures Hoofd: iTeos Therapeutics: Employment. Coscia:Abbvie: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm Therapeutics: Research Funding. Gaidano:Sunesys: Consultancy, Honoraria; AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra-Zeneca: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Furman:Acerta Pharma: Consultancy; Beigene: Consultancy; Incyte: Consultancy; Janssen: Consultancy; Oncotracker: Consultancy; Pharmacyclics: Consultancy; Sunesis: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy; Genentech: Consultancy; Abbvie: Consultancy; AstraZeneca: Consultancy. Deaglio:VelosBio Inc.: Research Funding; Verastem Inc: Research Funding; iTeos Therapeutics: Research Funding.