Academic literature on the topic 'Immunoglobulin gamma-Chains'

Abstract Stimulation of human B lymphoblastoid cell lines, CESS and SKW6-CL4 with BCDF induced an increase in IgG- and IgM-secreting cells, as well as a slight increase in IgG and IgM expression on their respective surfaces. Biosynthetic labeling demonstrated that BCDF stimulation induced an increase in synthesis of secretory gamma- and mu-chains, as well as their precursors. A slight but significant increase in synthesis of membrane-bound gamma- and mu-chains and their precursors was also observed by BCDF stimulation. However, an increase in synthesis of secretory heavy chains was much higher than that in membrane-bound heavy chains in both cell lines. Pulse-chase experiments showed that increased synthesis of secretory heavy chains was not due to a decrease in degradation. BCDF stimulation induced a preferential increase in mRNA specific for secretory gamma- and mu-chains in CESS and SKW6-CL4 cells, respectively. These results suggest that BCDF induces an increase in the level of mRNA specific for secretory heavy chains, and then induces final maturation of B cells into immunoglobulin-secreting cells.

Fc epsilon RI is a tetrameric receptor, composed of a ligand recognition subunit, alpha, a beta chain, and dimeric gamma chains. Previous studies have indicated that the dimeric gamma chain is associated with Fc gamma RIIIA (CD16) on natural killer cells and macrophages as well as the clonotypic T cell receptor. Here we show that in mast cells, in addition to the dimeric gamma chains, the beta subunit is associated not only with Fc epsilon RI, but also with Fc gamma RIIIA. Functional reconstitution studies with a mastocytoma cell line indicate that Fc gamma RIIIA composed of alpha, beta, and gamma subunits has the capacity for signal transduction. These studies suggest that through the association of alternative ligand recognition subunits (alpha epsilon, alpha gamma), a common signal transduction complex (beta gamma 2) mediates similar biochemical and effector functions in response to immunoglobulin G (IgG) and IgE.

Abstract Germline genes encoding C mu, C gamma, C alpha, and C epsilon heavy chains of rabbit immunoglobulins have been isolated from recombinant phage and cosmid libraries. The JH, C mu, C gamma, and C epsilon are found in a 5'-JH-C mu-C gamma-C epsilon-3' orientation on a 90kb stretch of DNA. Four C alpha genes have been cloned and presumably reside 3' to the other CH genes. Southern blot analysis of rabbit sperm DNA indicates that the rabbit genome contains a single C gamma gene, one C mu gene, and as many as 10 C alpha genes. Restriction site polymorphism is found for C mu, C gamma, and C alpha genes of rabbits of various heavy chain haplotypes. The organization of the rabbit CH genes differs from that of mouse and human CH genes in that the rabbit has multiple C alpha genes, whereas mouse and human have one or two C alpha genes, respectively. In addition, mouse and human have four C gamma genes, whereas rabbit has only one C gamma gene. The presence of a single C gamma gene indicates that at least in the rabbits examined, no germline gene encoding latent or unexpected, C gamma allotypes is present. The genetic control of the expression of latent C gamma allotypes is discussed.

Abstract Introduction/Objective In rare cases, the conventional immunofixation gel electrophoresis technique fails to detect the light chain of an M-protein. We report a case of immunoglobulin (Ig) D multiple myeloma with a hidden lambda (λ) light chain. Methods/Case Report Capillary electrophoresis (CE) (Sebia CAPILLARYS 2) was used to detect and quantify M- proteins in serum specimens. Immunosubtraction (IS) on the CAPILLARYS 2 systems was used to identify the classes of M-proteins. Conventional gel immunofixation electrophoresis (IFE) was performed, using monospecific antisera for IgD, IgE, kappa (κ) or λ in the Sebia HYDRASYS system, and IgG, IgA, IgM, κ or λ in the Helena SPIFE3000 system. Beta-mercaptoethanol (BME) with Fluidil were used as reduction agents. Results (if a Case Study enter NA) Results of serum CE showed two abnormal peaks in beta 2 and gamma regions, suspected to be positive for M-proteins. IS results showed subtraction for λ light chain only in both peaks, suggesting two monoclonal λ light chains. In contrary, no monoclonal λ light chain was detected in gamma region by IFE (Sebia). Epitope masking in the folded monoclonal protein was suspected to cause the “hidden λ light chain” and was further investigated by two laboratory approaches. IFE performed on the Helena SPIFE3000 system found two λ bands in beta 2 and gamma regions, which was consistent with the results from IS. The treatment of BME with Fluidil helped unmasking the hidden epitope and revealed the λ band in gamma region on IFE (Sebia). Conclusion The medical laboratories should be aware of the described scenario. The failure to detect light chains of certain intact M-proteins is most likely due to the structurally inaccessibility of light chains. It is recommended that treatment with reduction agents or use of an alternative methodology or IS might be helpful for investigating suspected heavy chain only cases, due to the limitation of conventional methodology.

Heavy chain disease (HCD) is a rare B-cell proliferative neoplasm that is characterised by the production of truncated monoclonal immunoglobulin heavy chains without light chains. Gamma HCD is a subgroup of HCD. A 67-year-old man was admitted to our hospital with dyspnoea and lower leg oedema. Based on the results of heart catheterisation, he was diagnosed with pulmonary hypertension. Laboratory tests revealed an elevated level of IgG, and serum immunoelectrophoresis showed that IgG was a monoclonal gamma heavy chain without light chains. Finally, he was diagnosed with gamma HCD complicated by pulmonary hypertension. Bortezomib and dexamethasone therapy was initiated, but became refractory within 8 months. Therefore, the treatment was switched to lenalidomide and dexamethasone therapy, and the disease has been stably controlled for more than 2 years. To the best of our knowledge, this is the first case of gamma HCD being successfully treated by lenalidomide and dexamethasone therapy.

The intracellular fates of membrane and secretory immunoglobulin heavy chains were examined in a pre-B cell line that has switched to the gamma isotype. The membrane form of the heavy chain (gamma m) was rapidly degraded while the secretory form (gamma s) was retained intracellularly in association with BiP. The degradation of gamma m could not be inhibited by ammonium chloride, chloroquine, or monensin suggesting that it occurred in a nonlysosomal compartment. The inability to detect any Endo H-resistant form of gamma m before its degradation suggested that degradation occurs before entry into the Golgi compartment. Degradation of gamma m could be inhibited by incubation at 24 degrees C. In a derivative of this cell line expressing a transfected kappa gene, gamma s formed disulfide linked tetramers with kappa and was secreted, while gamma m, although associated with kappa, continued to be rapidly degraded. These observations suggest that membrane and secretory heavy chain proteins are retained by distinct intracellular mechanisms. Although masking of the CH1 domain abrogates gamma s retention, this domain does not influence the intracellular fate of gamma m.

Abstract Covalent binding of gamma chains of IgG, whole IgA, and mu chains of IgM on polyfunctional hydrophilic microspheres (MS) yields MS-Ig conjugates, usable as reagents in new microparticle-enhanced nephelometric immunoassays (Nephelia). The principle of the assays is inhibition by free analyte (IgG, IgA, and IgM) of agglutination of the MS-Ig conjugate with specific antiserum, the light scattered by the aggregates being measured with a nephelometer. The immunoglobulin assays developed are easy to perform (single-step assays, no washing or phase separation) and sensitive (high dilution of biological samples to exclude interferences and pretreatment). Analytical recovery results (95.4-101.2%) and correlations with generally used commercial assays (r = 0.86-0.98) indicate that the assays are accurate for large concentration ranges of immunoglobulins. Precision sxtudy gives CVs = 2.8-9.6%. Nephelia appears to be useful for quantifying a large variety of biological molecules.

Abstract We subjected cerebrospinal fluid (CSF) samples from over 200 patients with various neurological diseases to two-dimensional electrophoresis. The series included non-inflammatory diseases such as epilepsy, amyotrophic lateral sclerosis, and polyneuropathy; and inflammatory diseases such as multiple sclerosis and neurolues. In the resulting electrophoretograms we considered mainly the region of CSF-specific proteins and the area corresponding to the immunoglobulin light chains. The former, at Mr 35 000-38 000, shows some interesting variations from one CSF to another. Samples from patients with various brain tumors show a specific change. A zone of oligoclonal immunoglobulin light chains appeared in all CSF samples with above-normal gamma-globulin content. These oligoclonal patterns remained constant and characteristic during the course of different diseases for several patients so examined. As expected, differences appeared in the patterns of immunoglobulin light chains from one individual to another, even among a group of patients with the same disease. The extent of the correlation of certain basic patterns with certain diseases cannot yet be determined.

Transgenic mice with a gamma 2b transgene were produced to investigate whether gamma 2b can replace mu in the development of B lymphocytes. Transgenic gamma 2b is present on the surface of B cells. Young transgenic mice have a dramatic decrease in B cell numbers, however, older mice have almost normal B cell numbers. Strikingly, all gamma 2b-expressing B cells in the spleen also express mu. The same is true for mice with a hybrid transgene in which the mu transmembrane and intracytoplasmic sequences replace those of gamma 2b (gamma 2b-mumem). The B cell defect is not due to toxicity of gamma 2b since crosses between gamma 2b transgenic and mu transgenic mice have normal numbers of B cells. Presence of the gamma 2b transgene strongly enhances the feedback inhibition of endogenous heavy chain gene rearrangement. Light chain genes are expressed normally, and the early expression of transgenic light chains does not improve B cell maturation. When the endogenous mu locus is inactivated, B cells do not develop at all in gamma 2b transgenic mice. The data suggest that gamma 2b cannot replace mu in promoting the developmental maturation of B cells, but that it can cause feedback inhibition of heavy chain gene rearrangement. Thus, the signals for heavy chain feedback and B cell maturation appear to be different.

Proteins, which are T cell-dependent antigens, preferentially induce antibodies of the IgG1 class in mouse, whereas LPS, which is a T-independent antigen, preferentially induces IgG3 and IgG2b. Interaction between CD40 on B cells and CD40 ligand (CD40L) on T cells has been shown to mediate T cell contact help for B cell proliferation, differentiation and immunoglobulin isotype switching. In addition, it has been shown that membranes from activated T cells induce germline γ1 transcripts, and that CD40 signaling induces germline γ1 transcripts. These results indicate that T cell contact help mediated by CD40 ligand (CD40L)-CD40 interaction may contribute to this preferential IgG1 isotype selection in response to T-dependent antigens by inducing transcription of germline Ig γ1 transcripts. Here we show that signaling via CD40 increases expression of a transiently transfected luciferase reporter plasmid driven by the germline γ1 promoter in M12.4.1 B lymphoma cells. By linker scanning mutation analysis of the promoter, we have identified a CD40 responsive region (CD40RR) which is able to confer inducibility by CD40L to a minimal c-fos promoter. The CD40RR contains three NF-кB-binding sites, each of which is required for maximal induction of the γ1 promoter activity by CD40L. Binding of the NF-кB/Re1 proteins p50, Re1A, c-Re1 and Re1B to the CD40RR can be induced by CD40 signaling in M12.4.1 cells or in splenic B cells. Co-transfection of expression plasmids for p50 together with Re1A or Re1B, but not p50 alone or p50 and c-Re1, transactivates the CD40RR in transient transfection assays in M12.4.1 cells. These data demonstrate NFкB/Re1 proteins activated by CD40 engagement play an important role in regulation of the germline γ1 promoter. Further support for this conclusion is provided by the finding that treatment of splenic B cells with NF-кB inhibitors prevents induction of germline γ1 transcripts by CD40L. Although LPS also induces NF-кB activation, it poorly induces germline γ1 promoter activity in M12.4.1 cells and it also poorly induces germline γ1 transcripts in splenic B cells and in the mouse B cell line, 1B4.B6. Western blot analyses show that LPS predominantly activates p50 and c-Re1, whereas CD40L induces all NF-кB/Re1 proteins (Re1A, Re1B, c-Re1 and p50). Likewise, in nuclear extracts from LPS-treated cells, p50/cRe1 and p50/p50 dimers are the major NF-кB/Re1 proteins which bind to the promoter for germline γ1 transcripts in electrophoretic mobility shift assays, whereas in nuclear extracts from CD40L-treated cells, p50/Re1A and p50/Re1B dimers are the major complexes. Reporter gene assay by over expressing NF-кB/Re1 fusion proteins indicates that p50/Re1A and p50/Re1B dimers, but not p50/c-Re1 or p50/p50 dimer, can transactivate the germline γ1 promoter. Despite their inability to activate the promoter, p50/c-Re1 and p50/p50 can bind to the promoter and suppress the transactivation activity of p50/Re1A and p50/Re1B. Therefore, the effect of NF-кB activation on the germline γ1 promoter depends on the Relative amounts of transactivating and non-trans activating NF-кB/Re1 dimers. The inability of LPS to induce germline γ1 transcripts can be explained by induction of non-transactivating NF-кB/Re1 dimers and the ability of CD40L to activate the promoter by a greater induction of Re1A and Re1B Re1ative to c-Re1.