Dissertations / Theses on the topic 'HLA-B Antigens'

INTRODUÇÃO: Pênfigo Vulgar é uma doença bolhosa mucocutânea autoimune caracterizada pela formação de bolhas ou ulcerações dolorosas que afetam as superfícies cutâneas e/ou mucosas. A perda do contato célulacélula entre os queratinócitos do epitélio (acantólise) resulta na manifestação clínica do Pênfigo Vulgar. Autoanticorpos IgG se ligam às desmogleínas - anti-desmogleína 3 (Dsg3) e/ou anti-desmogleína 1 (Dsg1) -e são críticos na patogênese da doença. A predisposição genética ao PV, principalmente com alelos HLA DR e DQ, foi revelada desde a década de 80 e foi comprovada por análises genéticas e sorológicas, repetidas vezes. As características singulares da população brasileira favorecem estudos genéticos exploratórios. PACIENTES E MÉTODO: O grupo em estudo incluiu 51 pacientes com diagnóstico confirmado de Pênfigo Vulgar de um hospital terciário da cidade de São Paulo, estado de São Paulo, sudeste do Brasil. Foi realizada a extração de DNA e a tipificação de HLA A, B, C, DR e DQ por meio de kits QIagen (QIAamp DNA Mini Kit®). O grupo controle foi composto a partir de um banco de dados de 297 doadores falecidos não relacionados da cidade de São Paulo, que foram tipados pelo mesmo método. Este banco faz parte do Sistema Estadual de Transplantes da Secretaria de Saúde do Governo do Estado de São Paulo e contém a idade do paciente na coleta. O nível de significância dos testes estatísticos foi ajustado pela correção de Bonferroni, dependendo da quantidade de frequências fenotípicas avaliadas para o HLA A, HLA B, HLA C, HLA DRB1 e HLA DQB1. RESULTADOS: Os alelos HLAB* 57, HLA-C*15, HLA-DRB1*04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 e o DQB1*05:03 estiveram associados com a susceptibilidade. Ambos os alelos HLA DRB1*04:02 e HLA-DRB1*14:01 e seus respectivos haplótipos DRB1*04-DQA1*03:01-DQB1*03:02 e DRB1*14- DQA1*01:01-DQB1*05:03 conferiram risco à doença. DISCUSSÃO: Os alelos DRB1*04:02 e DQB1*05:03 estão associados com o Pênfigo Vulgar no presente estudo, bem como a diversas populações do mundo. A associação aqui estudada com o DRB1*08:04 foi confirmada por causa deste alelo específico e não do desequilíbrio de ligação a algum gene adjacente. A associação do alelo HLA-B*57 ao pênfigo vulgar é reportada pela primeira vez pelo presente estudo. CONCLUSÕES: Os alelos HLA-B*57, HLA-C*15, HLADRB1* 04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 e DQB1*05:03 estão associados ao Pênfigo Vulgar em pacientes brasileiros
BACKGROUND: Pemphigus vulgaris is a mucocutaneous blistering autoimune disease that manifests as painful blisters or ulcerations on the skin and/or mucosal surfaces. The loss of cell-cell adhesion among the epithelial keratinocytes (acantholisis) leads to pemphigus vulgaris clinical findings. IgG autoantibodies target desmoglein - anti-Desmoglein 3 (Dsg3) and/or 1 (Dsg1) - play a major role in the disease pathogenesis. Genetic predisposal to pemphigus vulgaris, especially the HLA DR and DQ alleles, was revealed since the 80s and has been proven through genetic and serologic analysis repeatedly. The unique constitution of the Brazilian population favours genetics exploratory studies. PATIENTS AND METHODS: The study group included fifty-one patients with confirmed diagnosis of Pemphigus Vulgaris from a tertiary hospital in Sao Paulo\'s city and state, southeast Brazil. DNA extraction and HLA A, B, C, DR and DQ typing using Qiagen kits (QIAamp DNA Mini Kit®). The control group was composed by a database of 297 unrelated deceased donors from the city of São Paulo that were typed through the same method. This database is a part of the Transplants State System of the Government\'s Health Secretary from the State of Sao Paulo. The statistical significance level was adjusted by using the Bonferroni correction depending on the phenotypic frequencies evaluated to HLA A, HLA B, HLA C, HLA DRB1 e HLA DQB1. RESULTS: The alleles HLA-B*57, HLA-C*15, HLADRB1* 04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 and DQB1*05:03 were associated with susceptibility. Both alleles HLA DRB1*04:02 and HLA-DRB1*14:01 and their respective haplotypes DRB1*04-DQA1*03:01-DQB1*03:02 and DRB1*14-DQA1*01:01-DQB1*05:03 conferred risk to the disease. DISCUSSION: The DRB1*04:02 and DQB1*05:03 alleles are associated with Pemphigus Vulgaris in our study, as well in various populations. The association in our study with HLA-DRB1*08:04 was confirmed to be specific to this allele and not to linkage disequilibrium to any adjacent gene. The association between HLA-B*57 and pemphigus vulgaris is being reported for the first time at the present study. CONCLUSIONS: The alleles HLA-B*57, HLA-C*15, HLA-DRB1*04:02, HLADRB1* 08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 and DQB1*05:03 were associated with Pemphigus Vulgaris in Brazilian patients

The aim of this study was to design a resolution typing system for the HLA-B gene. This technique involves a one-step PCR reaction utilizing genomic DNA and sequence-specific primers to determine the specificity of each allele and to produce a larger primer data base ideal for serological analysis. The application of this technique to serological analysis can improve serology detection which is currently hindered by antibody cross-reactivity and the unavailability of useful typing reagents.

INTRODUÇÃO: O Pênfigo Vulgar é uma doença bolhosa crônica que acomente pele e mucosas. A perda de adesão epitelial ocorre por agressão autoimune às desmogleínas presentes nos desmossomos, mediada por anticorpos IgG. Estudos sobre a gênese da autoimunidade no pênfigo indicam associação entre alelos do sistema HLA, especialmente dos loci DR e DQ. A população brasileira apresenta características favoráveis a estudos exploratórios em genética decorrente de sua origem mista e intensa miscigenação. PACIENTES E MÉTODO: O grupo em estudo incluiu trinta e seis pacientes não consanguíneos com diagnóstico de Pênfigo Vulgar comprovado por imunopatologia provenientes do estado de São Paulo, Brasil. Foram tipados para os loci HLA-A, HLA-B e HLA-DR utilizando-se oligonucleotídeos sequência-específica (PCR-SSO). As frequências alélicas e fenotípicas encontradas foram comparadas com as de um grupo controle composto de dados de 712 indivíduos doadores voluntários cadastrados no Registro Nacional de Doadores de Medula Óssea (REDOME) provenientes de São Paulo e tipados pelo mesmo método. O valor de P crítico foi corrigido utilizando-se o método False Discovery Rate. RESULTADOS: Os alelos HLA-DRB1*04:02, DRB1*08:04 e DRB1*14 estiveram associados à doença com riscos relativos de 44,6, 18,6 e 4,8, respectivamente (p<0,001). Não houve diferença estatisticamente significante entre as frequências de nenhum alelo dos loci HLA-A ou HLA-B entre os grupos. DISCUSSÃO: O alelo DRB1*04:02, diretamente, e o alelo DRB1*14, indiretamente por desequilíbrio de ligação com DQB1*05:03, estão associados com Pênfigo Vulgar em diversas populações ao redor do mundo, porém nenhum estudo semelhante observou associação com o alelo DRB1*08:04 em tamanha magnitude. Acreditamos que as associações encontradas em nosso estudo não sejam decorrentes de viés de estratificação populacional. É necessária, no entanto, a tipagem de loci adjascentes ao HLA-DR dos indivíduos do grupo em estudo para diferenciar se o risco à doença é inerente a estes alelos ou a algum outro nas proximidades, com o qual estariam em desequilíbrio de ligação. CONCLUSÕES: Os alelos HLA-DRB1*04:02, DRB1*08:04 e DRB1*14 estiveram associados ao Pênfigo Vulgar em pacientes brasileiros.
BACKGROUND: Pemphigus vulgaris is a chronic blistering disease affecting skin and mucous membranes. Autoimmune aggression to desmoglein in desmosomes, mediated by IgG antibodies, leads to loss of epithelial cell adhesion. Studies indicate association between some alleles of the HLA system and pemphigus vulgaris, mainly at the DR and DQ loci. Brazilian population characteristics are conducive to genetic exploratory studies because of its various origins and intense ethnically admixture. PATIENTS AND METHODS: The study group consisted of thirty-six unrelated patients with clinical and immunopathological diagnosis of pemphigus vulgaris from a tertiary hospital in Sao Paulo - Brazil. HLA allele typing at the A, B and DR loci was performed after DNA extraction using polymerase chain reaction and sequence-specific oligonucleotide probes (PCR-SSO). Allele and phenotypic frequencies were compared to those from a control group composed by 712 individuals volunteer donors registered in a national registry of bone marrow donors (REDOME) from Sao Paulo, typed using the same method. False Discovery Rate method was used to adjust level of critical P values. RESULTS: The HLADRB1* 04:02, DRB1*08:04 and DRB1*14 were associated with pemphigus vulgaris with relative risks of 44.6, 18.6 and 4.8, respectively (p <0.001). There was no significant difference between the frequencies of any allele of loci HLAA or HLA-B among the groups. DISCUSSION: The alleles DRB1*04:02 and DRB1*14 (indirectly through linkage disequilibrium with the DQB1*05:03) are associated with pemphigus vulgaris in several populations worldwide, however, no similar study reported such magnitude of association between pemphigus vulgaris and DRB1*08:04 allele. We consider that the association is not secondary to population stratification bias. HLA typing of nearby loci is required to differentiate if the association with pemphigus vulgaris is inherent to the HLA-DRB1*08:04 allele or to another gene which is in linkage disequilibrium. CONCLUSIONS: The HLA-DRB1*04:02, DRB1*08:04 and DRB1*14 were associated with pemphigus vulgaris in Brazilian patients

A asma é uma doença heterogênea caracterizada por um processo inflamatório crônico das vias aéreas inferiores que está associado ao desenvolvimento da hiperresponsividade brônquica e remodelamento da via aérea. Atualmente, a asma é considerada uma síndrome, ou ao menos uma doença com diversos fenótipos. Tradicionalmente, dois fenótipos são bem definidos pela clínica e exames subsidiários: asma alérgica e asma não alérgica. Eles são diferentes quanto á idade de início, apresentação clínica, história pessoal e familiar de atopia e resposta ao tratamento. Ao contrário da asma alérgica, cuja fisiopatologia está bem caracterizada, a etiologia e mecanismos envolvidos na asma não alérgica não estão bem elucidados. Algumas possibilidades incluem alergia desencadeada por antígenos desconhecidos (fungos), infecção persistente (Chlamydia trachomatis, Mycoplasma sp) e auto-imunidade. Estudos têm descrito em diferentes populações associações entre a asma e alelos/antígenos HLA classe I e II, mas os resultados têm sido inconclusivos. O objetivo deste estudo foi identificar possíveis associações do antígeno leucocitário humano (HLA) classe I (A, B, C) e II (DR, DQ, DP) em pacientes brasileiros com asma alérgica e não alérgica. Um total de 109 pacientes com o diagnóstico de asma (56 com asma alérgica e 53 com asma não alérgica) que estavam em acompanhamento no Serviço de Imunologia Clínica e Alergia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, e 297 controles (doadores falecidos de órgãos sólidos) tiveram seu sistema HLA classe I (A, B e C) e II (DR, DQ e DP) tipificado. Os pacientes também realizaram espirometria e coletaram sangue para a quantificação da imunoglobulina E (IgE) sérica total e nível sérico de eosinófilos. Além disso, foram avaliados quanto à IgE específica para aeroalergenos através do teste cutâneo de puntura e a pesquisa da IgE sérica específica (ImmunoCAP). O grupo com asma alérgica foi constituído por pacientes que apresentavam resultado positivo para a pesquisa da IgE específica em ambos teste cutâneo de puntura e na investigação in vitro. E o grupo com asma não alérgica apresentava resultados negativos nos dois testes. A comparação do HLA classe I nos grupos estudados identificou frequência significativamente maior do HLA-B*42 e HLA-C*17 no grupo com asma alérgica, enquanto o HLA-B*48 estava estatisticamente associado com o fenótipo não alérgico. Na análise do HLA classe II, o HLA-DPA1*03 e HLA-DPB1*105 apresentou associação com os pacientes com asma alérgica. Concluindo, o estudo observou diferentes associações dos alelos HLA classe I e II com asma alérgica e não alérgica na população brasileira, a qual é caracterizada pela diversidade de origens e miscigenação. Porém, a predisposição genética para asma é poligênica e novos estudos em grandes populações são necessários para confirmar a associação do HLA como fator protetor ou causador da doença
Asthma is a heterogeneous chronic inflammatory disease of lower airways associated with the development of bronchial hyperresponsiveness and airway remodeling. Currently, asthma is regarded as a syndrome or at least a disease with several phenotypes.Traditionally, two phenotypes of asthma have been defined according to clinical and laboratory features: allergic and non-allergic asthma. Each of them has distint age of onset, clinical presentation, personal and family history of allergy and response to therapy. In contrast to allergic asthma, which pathophysiology is well characterized, the etiology and mechanisms involved in non-allergic asthma remain unclear. Some possibilities include allergy triggered by unknow antigens (fungi), persistent infection (Chlamydia trachomatis, Mycoplasma sp) and autoimmunity. Studies have reported associations between asthma and HLA class I and II alleles/antigens in different populations, but the results have been inconclusive. The objective of this study was to identify possible associations of the human leukocyte antigens (HLA) class I (A, B and C) and II (DR, DQ and DP) in Brazilian patients with allergic and non-allergic asthma. A total of 109 patients with asthma (56 with allergic asthma and 53 with non-allergic asthma), who were being followed at the Service of Clinical Immunology and Allergy of the Hospital das Clínicas of the University of São Paulo Medical School, and 297 controls (deceased solid organ donors) had their HLA class I (A,B and C) and II (DR, DQ and DP) typing. Patients performed spirometry and had their blood drawn to measure total serum immunoglobulin E (IgE) levels and eosinophil count. Furthermore, they were assessed for specific IgE to aeroallergens with skin prick test and serum tests (ImmunoCAP). The allergic asthma group was composed of patient presenting positive results for specific IgE in both skin prick test and in vitro assay. And the non-allergic asthma group had negative results in both tests. There were significantly higher frequencies of HLA-B*42 and HLA-C*17 in the allergic asthma group, whereas the HLA-B*48 was associated with the non-allergic group. Regarding HLA class II analysis, HLA-DPA1*03 and HLA DPB1*105 were associated with allergic asthma patients. In conclusion, the study identified different associations of HLA class I and II with allergic and non-allergic asthma in the Brazilian population, which is characterized by diversity of origins and miscegenation. However, the genetic predisposition of asthma is polygenic and new studies on large populations are needed to confirm the role of HLA as a protective or predisposing factor of disease

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Introduction. The spondyloarthritis encomprises a group of diseases strongly associated with HLA-B*27 gene. It has been proposed that genes not belonging to the major histocompatibility complex human influence the genesis of these diseases especially in patients HLA-B*27 negative. Objectives. The aim of this study was to test the hypothesis that the antigens of the ABO, Secretor and Lewis histo-blood systems are associated with spondyloarthritis, especially ankylosing spondylitis (AS). Material and methods. Three hundred and ninety-four patients with clinical suspicion of spondyloarthritis sent for identification of HLA-B*27 gene were analyzed. One hundred and nineteen (30.2%) had confirmed the diagnosis of spondyloarthritis according to the ASAS criteria. The remaining 275 (69.8%) were used as controls. The identification of HLA-B*27 gene was performed using the PCR-SSOP method. The identification of the antigens of the ABO, Secretor and Lewis histo-blood systems was performed using hemagglutination and PCR-RFLP methods. The exact Fisher's test, the chi-square, and the values of Odds Ratio (OR) and Confidence Interval set at 95% were calculated using the GraphPad INSTAT software, accepting the error of 5%. Results. No statistically significant differences were observed in the frequency of antigenic profiles of ABO (χ2: 1.152; p = 0.764; GL: 3), Secreto (χ2: 0.779; p = 0.377; GL: 1) and Lewis (χ2: 1.853; p = 0.396; GL: 2) histo-blood groups between patients and controls. The Lea antigen was more frequent in patients with AS compared to controls (OR: 1.833; 95% CI: 1025- 3284, p = 0.053). This antigen was strongly associated with AS in HLA-B*27 negative patients compared to controls (OR: 4.469; 95% CI: 1931-10342; p = 0.0007). This association remained only in males in the absence of HLA-B*27 gene (OR: 6.880; 95% CI: 1852-25564; p = 0.004). Conclusions. AS is associated to the Lea antigen in HLAB* 27 negative male patients.
Introdução. As espondiloartrites compreendem um grupo de doenças fortemente associadas ao gene HLA-B*27. Tem sido proposto que genes não pertencentes ao complexo principal de histocompatibilidade humano influenciam a gênese destas doenças especialmente nos pacientes HLA-B*27 negativos. Objetivos. O objetivo deste estudo foi testar a hipótese de que os antígenos dos sistemas histo-sanguíneos ABO, Secretor e Lewis estão associados à espondiloartrites, especialmente a espondilite anquilosante (EA). Material e método. Foram analisados 394 pacientes com suspeita clínica de espondiloartrites encaminhados para identificação do gene HLA-B*27. Cento e dezenove (30,2%) tiveram o diagnóstico de espondiloartrite confirmado de acordo com os critérios ASAS. Os 275 (69,8%) restantes compuseram o grupo controle. A identificação do gene HLA-B*27 foi realizada com o uso do método PCR-SSOP. A caracterização dos antígenos dos sistemas histo-sanguíneos ABO, Secretor e Lewis foi realizada com o uso dos métodos hemaglutinação e PCR-RFLP. O teste exato de Fisher, o qui-quadrado, os valores de Odds Ratio (OR) e do intervalo de confiança a 95% foram calculados com o uso do software GraphPad Instat, aceitando o erro de 5%. Resultados. Não foram observadas diferenças estatisticamente significantes nas frequências dos perfis antigênicos dos sistemas histo-sanguíneos ABO (χ2: 1.152; p=0,764; GL: 3), Secretor (χ2: 0.779; p=0,377; GL: 1) e Lewis (χ2: 1.853; p=0,396; GL: 2) de pacientes e controles. Foi observada maior frequência do antígeno Lea em pacientes com EA, comparados aos controles (OR: 1.833; IC 95%: 1.025 – 3.284; p=0,053). Este antígeno mostrou-se fortemente associado à EA em pacientes HLA-B*27 negativos comparados aos controles (OR: 4.469; IC 95%: 1.931 – 10.342; p=0,0007). Esta associação se manteve apenas no gênero masculino na ausência do gene HLA-B*27 (OR: 6.880; IC 95%: 1.852 – 25.564; p = 0,004). Conclusões. A EA está associada ao antígeno Lea nos pacientes masculinos HLA-B*27 negativos.

Variation in the sequence of T cell epitopes between dengue virus (DENV) serotypes is believed to alter memory T cell responses during second heterologous infections contributing to pathology following DENV infection. We identified a highly conserved, novel, HLA-B57-restricted epitope on the DENV NS1 protein, NS126-34. We predicted higher frequencies of NS126-34-specific CD8+ T cells in PBMC from individuals undergoing secondary, rather than primary, DENV infection due to the expansion of memory CD8+T cells. We generated a tetramer against this epitope (B57-NS126-34TET) and used it to assess the frequencies and phenotype of antigen-specific T cells in samples from a clinical cohort of children with acute DENV infection established in Bangkok, Thailand. High tetramer-positive T cell frequencies during acute infection were seen in only 1 of 9 subjects with secondary infection. B57-NS126-34-specific, other DENV epitope-specific CD8+ T cells, as well as total CD8+ T cells, expressed an activated phenotype (CD69+ and/or CD38+) during acute infection. In contrast, expression of CD71 was largely limited to DENV-specific CD8+ T cells. In vitro stimulation of CD8+ T cell lines, generated against three different DENV epitopes, indicated that CD71 expression was differentially sensitive to stimulation by homologous and heterologous variant peptides with substantial upregulation of CD71 detected to peptides which also elicited strong functional responses. CD71 may therefore represent a useful marker of antigenspecific T cell activation. During the course of our analysis we found substantial binding of B57-NS126-34 TET to CD8- cells. We demonstrated that the B57-NS126-34 TET bound KIR3DL1, an inhibitory receptor on natural killer (NK) cells. NK sensitive target cells presenting the NS126-34 peptide in the context of HLA-B57 were able to dampen functional responses of only KIR3DL1+ NK cells. Analysis of the activation of an NK enriched population in our Thai cohort revealed peak activation during the critical time phase in patients with severe dengue illness, dengue hemorrhagic fever, compared to people with mild illness. Our data identified CD71 as biologically useful marker to study DENV-specific CD8+ T cell responses and highlighted the role of viral peptides in modulating NK cell activation through KIR-MHC class I interactions during DENV infection.

Variation in the sequence of T cell epitopes between dengue virus (DENV) serotypes is believed to alter memory T cell responses during second heterologous infections contributing to pathology following DENV infection. We identified a highly conserved, novel, HLA-B57-restricted epitope on the DENV NS1 protein, NS126-34. We predicted higher frequencies of NS126-34-specific CD8+ T cells in PBMC from individuals undergoing secondary, rather than primary, DENV infection due to the expansion of memory CD8+T cells. We generated a tetramer against this epitope (B57-NS126-34TET) and used it to assess the frequencies and phenotype of antigen-specific T cells in samples from a clinical cohort of children with acute DENV infection established in Bangkok, Thailand. High tetramer-positive T cell frequencies during acute infection were seen in only 1 of 9 subjects with secondary infection. B57-NS126-34-specific, other DENV epitope-specific CD8+ T cells, as well as total CD8+ T cells, expressed an activated phenotype (CD69+ and/or CD38+) during acute infection. In contrast, expression of CD71 was largely limited to DENV-specific CD8+ T cells. In vitro stimulation of CD8+ T cell lines, generated against three different DENV epitopes, indicated that CD71 expression was differentially sensitive to stimulation by homologous and heterologous variant peptides with substantial upregulation of CD71 detected to peptides which also elicited strong functional responses. CD71 may therefore represent a useful marker of antigenspecific T cell activation. During the course of our analysis we found substantial binding of B57-NS126-34 TET to CD8- cells. We demonstrated that the B57-NS126-34 TET bound KIR3DL1, an inhibitory receptor on natural killer (NK) cells. NK sensitive target cells presenting the NS126-34 peptide in the context of HLA-B57 were able to dampen functional responses of only KIR3DL1+ NK cells. Analysis of the activation of an NK enriched population in our Thai cohort revealed peak activation during the critical time phase in patients with severe dengue illness, dengue hemorrhagic fever, compared to people with mild illness. Our data identified CD71 as biologically useful marker to study DENV-specific CD8+ T cell responses and highlighted the role of viral peptides in modulating NK cell activation through KIR-MHC class I interactions during DENV infection.

Orientador: Manoel Barros Bértolo
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: O objetivo do presente estudo foi avaliar a freqüência e a associação clínica do HLA classe I e II em pacientes brasileiros com vasculite reumatóide (VR). Nós avaliamos 57 pacientes com artrite reumatóide (AR) estabelecida pelos critérios do Colégio Americano de Reumatologia (ACR) - 1987. Dezessete apresentavam VR de acordo com os critérios de Scott e Bacon - 1984. Foram avaliados nestes pacientes dados demográficos, fator reumatóide (FR), anticorpo anti-peptídio citrulinado cíclico (anti-CCP), tempo de diagnóstico da AR e a atividade da doença pelo escore de atividade da doença (DAS 28). Os alelos HLA foram tipados usando a reação em cadeia da polimerase hibridizado com seqüências específicas de "primers" de baixa resolução. Quanto à atividade da doença nos pacientes sem VR observou-se freqüência aumentada do HLA-B*15 (p=0.033) e HLA-DRB1*01 (p=0.014) com média de DAS 28 >3.2 _ 5.1 e o HLA-Cw*16 (p=0.027) e HLA-B*07 (p=0.027) com média de DAS 28>5.1. Não houve significância estatística de qualquer classe do HLA com o DAS 28 nos pacientes com VR. A comparação entre os 2 grupos mostrou diferença estatística (p=0.001) para o DAS 28 com rank médio = 39.94 para os pacientes com VR. O HLADQB1* 05 (p=0.035) esteve presente em 5 pacientes com VR com média de tempo de diagnóstico de AR de 17 anos e ausente em 12 pacientes com VR com média de tempo de diagnóstico AR de 11.45 anos. Os pacientes com VR tiveram freqüência aumentada do HLA-B*14 (p=0.006) e HLA-Cw*08 (p=0.006). Uma freqüência aumentada do HLA-DRB5*01 (p=0.048) foi encontrada em pacientes sem VR. Nossos resultados mostram na amostra estudada que a VR está associada ao sexo feminino, raça branca, FR e anti-CCP positivos. O HLA-B*15 e HLA-DRB1*01 podem estar envolvidos na atividade moderada da AR sem VR e o HLA-Cw*16 e HLA-B*07 podem estar envolvidos na atividade intensa da AR sem VR. Não houve diferença estatística das classes do HLA com o DAS 28 para VR, porém a doença foi mais ativa em pacientes com VR quando comparados com pacientes sem VR. O HLA-DQB1*05 pode estar envolvido nos casos tardios de AR para a manifestação da VR. O HLA-B*14 e HLACw* 08 podem estar envolvidos na suscetibilidade para VR. O HLA-DRB5*01 pode conferir proteção contra esta manifestação extra-articular da AR
Abstract: Our purpose was to evaluate the frequency and clinical association of HLA class I and class II in Brazilian patients with rheumatoid vasculitis (RV). We evaluated 57 patients with rheumatoid arthritis (RA) (American College of Rheumatology -ACR, 1987 criteria). Seventeen had RV according to Scott and Bacon's criteria - 1984. Demographic data, time of RA diagnosis, disease activity by the Disease Activity Score (DAS 28), rheumatoid factor (RF) and cyclic citrullinated peptide (anti-CCP) were analyzed. HLA alleles were typed using polymerase chain reaction-amplified DNA hybridized with low-resolution sequence-specific primers. HLA-B*15 (p=0.033) and HLA-DRB1*01 (p=0.014) were associated with moderate activity of RA without RV, and HLA-B*07 (p=0.027) and HLA-Cw*16 (p=0.027) with intense activity of RA without RV; no statistical significance of HLA class and DAS 28 was observed in RV. HLA-DQB1*05 (p=0.035) was related to RV in patients with late RA. The comparison between the groups showed an increased frequency of HLA-B*14 (p = 0.006) and HLA-Cw*08 (p = 0.006) in patients with RV, and an increased frequency of HLADRB5* 01 (p = 0.048) in patients without RV. In conclusion, the HLA-B*14 and HLACw* 08 may be involved in susceptibility to RV and HLA-DRB5*01 may confer protection against this extra articular manifestation of RA
Mestrado
Clinica Medica
Mestre em Clinica Medica

Les lymphocytes b de sang de cordon sont des cellules matures mais protegees des rencontresantigeniques exogenes. Les molecules hla de classe ii sont le support de la presentation antigenique et de la transmission de signaux intracellulaires d'activation ou de mort cellulaire programmee. Les cellules b de sang de cordon presentent de grandes quantites de molecules hla de classe ii vides mais la capacite d'allostimulation est preservee. Ces molecules hla de classe ii se presentent comme chez l'adulte sous forme de dimeres de dimeres, mais a la surface des lymphocytes b adultes la quantite de molecules vides est faible. En revanche, plusieurs milliers de sites vides existent a la surface des monocytes. L'etude de la signalisation via les molecules hla-dr montre un deficit de la mobilisation du calcium intracellulairedans les lymphocytes b de cordon avec deficit de l'agregation homotypique et de l'induction de l'apoptose. Ce deficit de l'apoptose est relie a l'absence de flux calcique. Des similitudes existent entre la signalisation via hla dr des cellules b de cordon et de certaines hemopathies lymphoides bchroniques (leucemie lymphoide chronique) et lymphome du manteau) avec une difference importante en ce qui concerne l'activation de la proteine kinase c. Ces donnees permettent d'approfondir nos connaissances sur les premiers stades de l'ontogenie des lymphocytes b apres la sortie de la moelle en apportant des elements sur la fonction des molecules hla de classe ii au cours de l'ontogenie.

Des lignées de souris transgéniques (Tg) pour les protéines d'enveloppe du VHB et les molécules de classe I (HLA-A2) et II (DRB1) du complexe majeur d'histocompatibilité humain ont été créées dans le but de caractériser l'implication de l'antigène HBs (AgHBs) porté par les protéines d'enveloppe lors l'infection chronique par le VHB. Ces souris expriment de manière constitutive l'AgHBs à des taux élevés dans le foie. L'AgHBs est sécrété dans le sérum en l'absence de toute production d'anticorps anti-HBs et de pathologie hépatique. Le statut immunologique des souris triple Tg (AgHBs/HLA-A2/HLA-DRBl) est comparable par plusieurs aspects à celui des porteurs chroniques du VHB infectés à la naissance chez lesquels le virus se multiplie à bas bruit. L'injection d'un plasmide (pCMV-S2. S) codant pour deux des protéines d'enveloppe du VHB permet de rompre la tolérance au niveau des cellules T CD8+. Par contre, le compartiment T CD4+ est tolérisé. La présence mutuellement exclusive des lymphocytes T CD4+ et de F AgHBs souligne le rôle de ce dernier dans le maintien de la tolérance vis à vis des lymphocytes T CD4+. Parrallélement à cette étude, la sécurité et l'immunogénicité d'un vaccin à base d'ADN a été apprécié chez dix porteurs chroniques du VHB dans un essai de phase I de vaccination thérapeutique. Les injections de pCMV-S2. S ont entraîné une diminution marquée de la charge virale chez deux patients et une baisse transitoire de la charge virale de plus de 50% chez quatre autres patients. Des cellules T CD8+ et CD4+ mémoires spécifiques de l'enveloppe du VHB ont été mises en évidence chez tous les patients après vaccination
By using HLA-A2-/HLA-DRl-transgenic H-2 class Wclass II-knockout mice, we have generated transgenic (Tg) mouse lineages expressing the HBV enveloppe proteins in a context of human MHC molecules. The Tg mice express high amount of hepatitis B surface antigen (HBsAg) carried by the envelope proteins in the liver. The HBsAg is secreted and present in the serum of mice during the animal's lifetime. This preclinical humanized mice model mimics in some aspects the tolerance to HBsAg observed in chronic HBV carriers. As a therapeutic tool, a DNA plasmid encoding the small and the middle protein of HBV was used to immunize Tg mice. Despite a high concentration of HBsAg in sera, injection of this DNA induced a high frequency of CD8+ T cells secreting IFNgamma. Nevertheless, the DNA-based immunization elicited no CD4+ T cell responses. However, when pro-inflammatory stimuli were given before or after DNA-based immunization, the HBsAg was cleared from the serum. This model provides evidence that HBsAg displayed a strong tolerogenic effect on the CD4+ T cell compartment. We also carried out a phase I trial evaluating tolerance to vaccination with a naked DNA vaccine encoding the small and middle envelope proteins in ten patients chronically infected with HBV who did not respond to existing treatments. This vaccination was well tolerated. In two patients a decrease in viral DNA levels accompanied by an HBe/anti-HBe seroconversion was observed. In four other patients the decrease was only transient, even if a fourth injection was given. However, after genetic vaccination, we demonstrated the induction or reactivation of IFNgamma-secreting envelope-specific T-cells in ail patients

Les lymphomes b non-hodgkiniens font partie des rares tumeurs a exprimer des molecules hla de classe ii. Ceci leur permet d'interagir directement avec les lymphocytes t cd4+ qui infiltrent la tumeur (til-t). La signalisation induite par les molecules hla-dr peut induire soit l'apoptose, soit la proliferation. La premiere partie de ce travail a ete d'etudier le role joue par les molecules hla de classe ii dans l'interaction entre les til-t cd4+ et les lymphocytes b malins de lymphome folliculaire. Par l'intermediaire des molecules hla de classe ii, des clones de til-t cd4+ sont capables d'induire l'activation des lymphocytes b malins et leur entree en phase g1 du cycle cellulaire (induction du ki-67). Afin de determiner si les lymphocytes b malins presentent des anomalies intrinseques les empechant de progresser dans le cycle cellulaire, nous avons etudie dans une deuxieme partie l'effet d'une signalisation induite par les molecules hla-dr dans des lymphocytes b normaux. Nous avons d'abord montre que l'orientation vers une voie apoptotique ou proliferative ne depend pas de l'etat d'activation du lymphocyte b, mais de la capacite du ligand a regrouper les molecules hla-dr a la surface de la cellule. En effet, un ac anti-hla-dr couple a des billes de sepharose (qui mime la relation avec un lymphocyte t cd4+) induit la proliferation des lymphocytes b normaux alors qu'un ac anti-hla-dr couple a un ac secondaire, induit l'apoptose, sans entree prealable dans le cycle cellulaire. Ces resultats montrent que dans les lymphocytes b tumoraux, l'entree en cycle correspond bien a un debut de proliferation et non a un prelude a l'apoptose. Nous avons replace la signalisation hla-dr dans un contexte physiologique : les lymphocytes b recoivent d'abord un signal induit par l'interaction d'un antigene sur le recepteur a l'ag du lymphocyte b, ce qui induit une proliferation. Ensuite, ils interagissent avec des lymphocytes t cd4+, entrainant une signalisation par les molecules hla-dr dans le lymphocyte b. La proliferation induite par la stimulation du recepteur a l'ag est regulee negativement par co-stimulation avec un ac anti-hla-dr lie a un ac secondaire. Ceci se traduit au niveau du cycle cellulaire, par une diminution de la phosphorylation de la proteine prb due a une diminution d'expression des cdk2, 4 et 6 et des cyclines e et a, et a un retard d'expression de la cycline d2. Les cdkis p21 et p27 ne sont pas impliques. Nos resultats montrent qu'un signal induit par hla-dr est suffisant pour induire une proliferation. L'absence de proliferation dans les lymphocytes b tumoraux suggerent fortement la presence d'une (ou plusieurs) anomalie(s) intrinseque(s) empechant la progression dans le cycle cellulaire. Ce blocage semble etre general puisqu'il n'affecte pas que la voie hla de classe ii mais egalement la voie il4/cd40.

Antigen presented to CD4+ T cells by major histocompatibility complex class II molecules (MHCII) plays a key role in adaptive immunity. Antigen presentation is initiated by the proteolytic cleavage of pathogenic or self proteins and loading of resultant peptides to MHCII. The loading and exchange of peptides to MHCII is catalyzed by a nonclassical MHCII molecule, HLA-DM (DM). It is well established that DM promotes peptide exchange in vitro and in vivo. However, the mechanism of DM-catalyzed peptide association and dissociation, and how this would affect epitope selection in human responses to infectious disease remain unclear. The work presented in this thesis was directed towards the understanding of mechanism of DM-mediated peptide exchange and its role in epitope selection. In Chapter II, I measured the binding affinity, intrinsic dissociation half-life and DM-mediated dissociation half-life for a large set of peptides derived from vaccinia virus and compared these properties to the peptide-specific CD4+ T cell responses. These data indicated that DM shapes the peptide repertoire during epitope selection by favoring the presentation of peptides with greater DM-mediated kinetic stability, and DM-susceptibility is a strong and independent factor governing peptide immunogenicity. In Chapter III, I computationally simulated peptide binding competition reactions and found that DM influences the IC50 (50% inhibition concentration) of peptides based on their susceptibility to DM, which was confirmed by experimental data. Therefore, I developed a novel fluorescence polarization-based method to measure DM-susceptibility, reported as a IC50 (change in IC50 in the absence and presence of DM). Traditional assays to measure DM-susceptibility based on differential peptide dissociation rates are cumbersome because each test peptide has to be individually labeled and multiple time point samples have to be collected. However, in this method developed here only single probe peptide has to be labeled and only single reading have to be done, which allows for fast and high throughput measure of DM-susceptibility for a large set of peptides. In Chapter IV, we generated a series of peptide and MHCII mutants, and investigated their interactions with DM. We found that peptides with non-optimal P1 pocket residues exhibit low MHCII affinity, low kinetic stability and high DM-susceptibility. These changes were accompanied with conformational alterations detected by surface plasmon resonance, gel filtration, dynamic light scattering, small-angle X-ray light scattering, antibody-binding, and nuclear magnetic resonance assays. Surprisingly, all these kinetic and conformational changes could be reversed by reconstitution with a more optimal P9 pocket residue. Taken together, our data demonstrated that conformation of MHCII-peptide complex constrained by interactions throughout the peptide binding groove is a key determinant of DM-susceptibility. B cells recognizing cognate antigen on the virion can internalize and process the whole virion for antigen presentation to CD4+ T cells specific for an epitope from any of the virion proteins. In turn, the epitope-specific CD4+ T cells provide intermolecular (also known as noncognate or heterotypic) help to B cells to generate antibody responses against any protein from the whole virion. This viral intermolecular help model in which CD4+ T cells provide help to B cells with different protein specificities was established in small size influenza virus, hepatitis B virus and viral particle systems. For large and complex pathogens such as vaccinia virus and bacteria, the CD4+ T cell-B cell interaction model may be complicated because B cells might not be able to internalize the large whole pathogen. Recently, a study in mice observed that CD4+ T cell help is preferentially provided to B cells with the same protein specificity to generate antibody responses against vaccinia virus. However, for larger pathogens such as vaccinia virus and bacteria the CD4+ T cell-B cell interaction model has yet to be tested in humans. In Chapter V, I measured in 90 recently vaccinated and 7 long-term vaccinia-immunized human donors the CD4+ T cell responses and antibody responses against four vaccinia viral proteins (A27L, A33R, B5R and L1R) known to be strongly targeted by cellular and humoral responses. We found that there is no direct linkage between antibody and CD4+ T cell responses against each protein. However, the presence of immune responses against these four proteins is linked together within donors. Taken together, our data indicated that individual viral proteins are not the primary recognition unit and CD4+ T cells provide intermolecular help to B cells to generate robust antibody responses against large and complicated vaccinia virus in humans.

La molécule HLA-G, molécule HLA de classe I non classique, joue un rôle dans la tolérance immunitaire et participe notamment à l'échappement tumoral. Dans une première partie de ce travail, nous rapportons que le TNF-alpha ou le phorbol 12-myristate 13-acétate diminue l'expression de surface de HLA-G 1 tout en augmentant l'expression du niveau interne de la molécule. Seule la diminution de surface de HLA-G est dépendante de l'activation de NF-kappa B et met enjeu l'activité des métalloprotéases. La molécule HLA-G 1 soluble produite conduit à la réduction de la cytotoxicité de cellules NK. Cette régulation de HLA-G forme un moyen supplémentaire d'échappement tumoral. Dans un e seconde partie de ce travail, n ous m ontrons que HLA-G 1 conduit à un e activation de la voie classique NF-kappa B dans les cellules NK. Le domaine alphal de HLA-G, à l'origine de cette signalisation, lie vraisemblablement le récepteur KIR2DL4. NF-kappa B activé est fonctionnel puisqu'il conduit à une néosynthèse de Ikappa B-alpha, gène cible de NF-kappa B, suggérant un rôle supplémentaire de HLA-G dans l'immunité innée
HLA-G is a non classical HLA class I molecule involved in immunotolerance. It contributes to the evasion of tumors from immunosurveillance. We investigated in the fïrst part of this work, the role of NF-kappa B in modulating HLA-G expression in HLA-G positive tumor cell lines. The treatment of tunior cells with TNF-alpha or phorbol 12-myristate 13-acetate, decreased HLA-G1 expression and increased in the same time the level of intracytoplasmic HLA-G proteins. The reduction of HLA-G cell surface expression which is dependant from NF-kappa B involves métalloproteases activity. Soluble HLA-G 1 produced reduces significatively the cytotoxicity of NK cells. This regulation of HLA-G expression may have a relevance in tumor escape. In a second part of this work, we demonstrated that HLA-G 1 activates the classical NF-kappa B pathway in NK cells. This activation occurs through the alphal domain of HLA-G molecule and may involve KIR2DL4 receptor. Activated NF-kappa B is functionnal because it induces the expression of an NF-kappa B target gene : Ikappa B-alpha. All these results suggest an additional role of HLA-G in innate immunity

Kidney transplantation is the best treatment for patients with end-stage renal failure. The main problem of kidney transplantation is however the development of a cellular and antibody-mediated (humoral) rejection. During the last decade, thanks to the advanced immunosuppression, prognosis of survival and function of transplanted organs has significantly improved. Nevertheless, humoral rejection remains very serious obstacle in high-risk patients, because it can permanently damage the graft. Therefore, before transplantation it is necessary to stratify patients into high and low risk groups for development of antibody-mediated rejection. Current immunogenetic tests performed before transplantation include, in addition to HLA typing, detection of panel-reactive antibodies. However, this test does not provide information about B cells which participate in the humoral response of the kidney recipient. Therefore, in the presented thesis we studied B cell reactivity and its regulation in transplanted patients. In this retrospective analysis we measured levels of the B cell activating factor, a cytokine regulating the function of B lymphocytes (BAFF). Current reports suggest that BAFF could serve as a marker of humoral rejection. Furthermore, we focused on B lymphocytes and their capacity to produce...