Humoral and cellular autoimmunity in autoimmune bullous skin disorders

Autoimmune bullous skin diseases, such as pemphigus vulgaris (PV) and bullous pemphigoid (BP), are severe, frequently life-threatening skin disorders. Immunologically, they are characterized by the presence of serum autoantibodies (auto-Ab) targeting distinct adhesion molecules of the epidermis or dermoepidermal basement membrane zone. Antibody (Ab) binding interferes with the adhesive function of these molecules, leading to detachment and subsequently blister formation. PV is the classical example of an Ab-mediated autoimmune disease affecting epidermal adhesion. Auto-Ab against the desmosomal adhesion molecule, desmoglein 3 (Dsg3), are critical in the pathogenesis of this disease, since the transfer of serum IgG Ab reactive with Dsg3 into newborn mice induces a bullous skin disease resembling PV. Autoreactive T cell responses to Dsg3 may be critical in the pathogenesis of PV because: (1) Ab production generally requires T cell help; (2) the involvement of CD4+ T lymphocytes in PV has been suggested by the strong association with distinct HLA class II alleles, and (3) T cell recognition of epitopes of Dsg3 may be crucial for the initiation and perpetuation of the production of Dsg3-specific auto-Ab by B cells. In PV and BP, autoreactive CD4+ T cells recognize distinct epitopes of the extracellular portions of Dsg3 and BP180 [BP antigen 2 (BPAG2) or type XVII collagen], respectively, and produce preferentially T helper type 2 (TH2) cytokines. Auto-Ab of the TH2-dependent IgG4 subtype are preferentially seen in the active stages of both PV and BP, while auto-Ab of the TH1-dependent IgG1 subclass are predominant during the chronic course of these disorders. These observations suggest that autoreactive TH2 cells may provide targets to specifically modulate the T cell-dependent production of pathogenic auto-Ab in these disorders.     

Detection of low avidity desmoglein 3-reactive T cells in pemphigus vulgaris using HLA-DR beta 1*0402 tetramers

In the present study, we developed a HLA class II tetramer-based detection system utilizing DRB1*0402 tetramers loaded with recently identified immunodominant peptides of desmoglein 3 (Dsg3), the major autoantigen of pemphigus vulgaris (PV). Initial experiments demonstrated staining of a Dsg3-reactive T cell hybridoma which was derived from HLA-DR0402-transgenic mice with loaded PE-labeled DRbeta1*0402 tetramers. However, staining of autoreactive T cell clones (TCC) derived from PV patients resulted only in positive staining by addition of exogenous peptides to the staining reactions. There was a dose-dependent specific binding of TCC to the tetramers with the agonistic Dsg3 peptide which was not altered by exogenous unrelated Dsg3 peptide. Noteworthy, the TCC did not stain with HLA-DR4 tetramers complexed with unrelated Dsg3 peptides. The findings of this study suggest that HLA class II tetramers may provide a highly specific approach to monitor ex vivo the T cellular autoimmune response against Dsg3 in patients with PV.     

HLA class II restriction of autoreactive T cell responses in pemphigus vulgaris: review of the literature and potential applications for the development of a specific immunotherapy.

Pemphigus vulgaris (PV) is a life-threatening autoimmune bullous disease of the skin and mucous membranes which requires immunosuppressive therapy, most commonly a combination of glucocorticoids and additional immunosuppressive agents. Since the side effects of long-term immunosuppressive therapy contribute to the poor prognosis of this disorder, there is considerable interest in a more specific treatment of this severe skin disease. PV may serve as a model disease for the development of a specific immunotherapy, because its pathogenesis as well as involved immunogenetic factors are well-characterized. This review focuses on the characterization of autoreactive T cell responses to desmoglein 3 (Dsg3), the autoantigen of PV, that presumably regulate the production of autoantibodies by providing help to the autoreactive B cells. Current knowledge on T cell epitopes of Dsg3 and the HLA class II alleles that restrict Dsg3-specific autoreactive T cell responses, as well as potential applications for a specific immunotherapy of PV, are described.     

寻常型天疱疮的Dsg3特异性抗体反应及其基因限制性

探讨寻常型天疱疮中的自身抗原桥粒芯蛋白（Dsg3)特异性抗体反应及其基因限制性，为自身免疫性疾病机制的研究提供依据。采用RT－PCR法克隆自身抗原Dsg3E1,E2,E3,E4,E5多肽片段的cDNA，定向插入表达载体PGEX－2T，导入大肠杆菌JM109中表达重组融合蛋白并经GST层析柱纯化，进一步经免疫印迹法与PV患者阳性血清反应；应用序列特异性引物聚合酶链式反应（SSP－PCR）技术对HLA－Ⅱ类等位基因进行特异性体外扩增，分析了天疱疮患者HLA基因的DR位点的DRB1、DQB1多态性。Dsg3 E1,E2和E4可与PV患者阳性血清反应，而不与疾病对照组、正常对照组反应。在10个PV患者中，均携带HLA的DR4或／和DR14抗原，有7个DRB1*0402,4个DRB1*1401,7个DQB1*0302,4个DQB1*0503.Dsg3 E1,E2和E4中包含抗体反应相关的抗原表位，HLA DRB1*0402t DQB1＊0302与PV发病中抗E4抗体反应密切相关。     

Cognate Th2–B Cell Interaction is Essential for the Autoantibody Production in Pemphigus Vulgaris

Pemphigus vulgaris (PV) is a Th2-dominant autoimmune skin disease. We showed that indeed active PV patients had a biased Th2 response and specific IgG4 autoantibodies were dominant. To further investigate the role of antigen-specific Th2 cells in the regulation of pathogenic Dsg3-IgG antibody production, we used recombined Dsg3 protein to immunize wild-type C57BL/6 mice with aluminum hydroxide or complete Freund’s adjuvant as adjuvant. CD4⁺ T cells from Dsg3-immunized mice were adoptively transferred into TCR-β chain deficient mice. The transferred CD4⁺ T cells were readily seen in the peripheral blood and spleen, and interacted with B cells, resulting in B-cell activation. Furthermore, transferred CD4⁺ T cells from mice immunized with Dsg3 plus Alum with Th2 phenotype were able to render unprimed B cells to secrete Dsg3-specific IgG1 antibody in vivo. Taken together, these results provide the first demonstration of direct role of Dsg3-reactive CD4⁺ T (Th2) cells in the regulation of pathologic anti-Dsg3 antibody production.     

Autoantibody epitopes to the smaller isoform of glutamate decarboxylase do not differ in Swedish and Japanese type 1 diabetes patients and may be associated with high-risk human leucocyte antigen class II alleles

Type 1 diabetes (T1D) is an autoimmune disease with a strong human leucocyte antigen (HLA) class II association. Depending on geographic locations, the disease-associated HLA class II alleles vary. We evaluated the beta cell-specific autoimmunity reflected in autoantibodies directed to the smaller isoform of glutamate decarboxylase (GAD65) in Japanese and Swedish T1D patients. GAD65Ab epitope specificities were assessed using GAD65-specific recombinant Fab. GAD65Ab epitope specificities did not differ between Swedish and Japanese patients. Only recognition of the MICA-4-defined middle epitope was significantly stronger in the Japanese T1D patient group compared to the Swedish T1D patients (P = 0.001). Binding to the b96.11-defined middle epitope was substantial in both groups and showed significant associations with high-risk HLA class II haplotypes. In the Japanese T1D group the association was with haplotype DRB1*0802-DQB1*0302 (P = 0.0008), while in the Swedish T1D patients binding to the b96.11-defined epitope as associated with the presence of high-risk HLA genotypes DR3-DQB1*0201 and/or DR4-DQB1*0302 (P = 0.02). A significant association between reduction in binding in the presence of recombinant Fab (rFab) DPD and high-risk allele DQB1*0201 was found (P = 0.008) in the Swedish T1D patients only. We hypothesize that epitope-specific autoantibodies effect the peptide presentation on HLA class II molecules by modulating antigen uptake and processing. Molecular modelling of the high-risk HLA class II molecules will be necessary to test whether these different molecules present similar peptide-binding specificities.     

Dissection of the multiple sclerosis associated DR2 haplotype

Epidemiological and genetic data have consistently identified associations with HLA class II alleles in many autoimmune diseases. In multiple sclerosis (MS), an autoimmune disease targeting central nervous system (CNS) myelin, the DR2 haplotype (DRB1*1501, DRB5*0101 and DQB1*0602) remains the strongest identified genetic risk factor in Caucasians. However, it is hard to tease apart the precise contributions of its constituent individual alleles and their modes of action remain poorly understood, due in part to the strong linkage disequilibrium in this region. Recent work in humanized mice indicates functional epistatic interactions whereby DRB5*0101 directly modulates the severity of the ensuing disease through activation-induced cell death (AICD) of encephalitogenic T cells which are restricted by DRB1*1501. Complementary structural studies help to explain how these alleles may facilitate thymic escape of autoreactive T cells and contribute to peripheral T cell activation via suboptimal binding interactions and mechanisms of molecular mimicry. Here we discuss the emerging role of the constituent alleles of the DR2 haplotype and our ongoing efforts to uncover the mechanisms by which they influence MS pathogenesis.     

HLA-DRB1 polymorphisms and autoimmune responses to desmogleins in Japanese patients with pemphigus.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are caused by autoantibodies against keratinocyte adhesion molecules desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1), respectively. To determine possible major histocompatibility complex (MHC) class II associations with autoantibody responses to desmogleins, haplotype and allele distributions, along with molecular polymorphisms of HLA-DR and -DQ genes were analyzed based on the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) results in 85 Japanese patients with pemphigus. Each of 55 PV patients carried at least one allele of HLA-DRB1*04 and DRB1*14 subtypes, with significant increases of HLA-DRB1*0406/DQA1*0301/DQB1*0302, DRB1*14/DQA1*0104/DQB1*05 and DRB1*1406/DQA1*0503/ DQB1*0301 haplotypes compared to normal controls. The HLA-DRB1*04 and DRB*14 alleles carried by PV patients shared hydrophobic amino acid residues Phe26, Leu67 and Val86, as well as hydrophilic amino acid residues at positions 70 and 71 on the DRB1 beta chain. HLA-DR/DQ distributions did not differ among PV patients according to the presence or absence of anti-Dsg1 co-existing with anti-Dsg3. Thirty PF patients, all producing autoantibodies only to Dsg1, showed more diverse HLA-DR/DQ distributions, sharing hydrophobic amino acid residues at positions 26 and 67, as well as hydrophilic amino acid residues at positions 70 and 71, of the DRB1 chain. These findings suggest that autoantibody responses to desmogleins might be regulated by amino acid residues at positions 26, 67, 70, 71 and 86 at peptide binding sites of HLA-DRB1 molecules, and that autoimmune responses to Dsg3 might be more strictly regulated by specific amino acid residues at these positions on the HLA-DRB1 chain than responses to Dsg1.     

The molecular basis for the presence of two autoimmune diseases occurring simultaneously – Preliminary observations based on computer analysis

Specific Human Leukocyte Antigen Class II (HLA II) molecules associated with pemphigus vulgaris (PV), mucous membraine pemphigoid (MMP), and mixed connective tissue disease (MCTD) may react with multiple T cell epitopes within desmoglein 3 (Dsg 3), bullous pemphigoid antigen 2 (BPAG 2), and 70 kDa polypeptide small nuclear ribonucleoproteins (snRNP70) in autoantibody production. We report a group of patients with simultaneous occurrences of PV with MCTD, and MMP with MCTD. In one patient group, we performed serological studies to show presence of antibodies to Dsg 3, Dsg 1, and snRNP70 simultaneously. In the second group, we performed serological studies to show presence of antibodies to BPAG 1, BPAG 2, β4 integrin, and snRNP70 simultaneously. In both groups, HLA II genes were analyzed and the observations were consistent with previously described associations with PV, MMP, and MCTD. It is possible that HLA-DQβ1*0301 allele, present in 10 of 17 patients and DRβ1*04 in some of the others, may have the ability to bind to several relevant T cell epitopes in the snRNP70 molecule. We have utilized a computer model to demonstrate that HLA II-restricted T cell epitopes present within the known autoantigens may be capable of eliciting an immune response. While other explanations and mechanisms exist, the authors suggest that epitope spreading may be one possible mechanism, amongst others, that may result in the simultaneous presence of two separate pathogenic autoantibodies.     

The molecular basis for the presence of two autoimmune diseases occurring simultaneously--preliminary observations based on computer analysis

Specific Human Leukocyte Antigen Class II (HLA II) molecules associated with pemphigus vulgaris (PV), mucous membraine pemphigoid (MMP), and mixed connective tissue disease (MCTD) may react with multiple T cell epitopes within desmoglein 3 (Dsg 3), bullous pemphigoid antigen 2 (BPAG 2), and 70?kDa polypeptide small nuclear ribonucleoproteins (snRNP70) in autoantibody production. We report a group of patients with simultaneous occurrences of PV with MCTD, and MMP with MCTD. In one patient group, we performed serological studies to show presence of antibodies to Dsg 3, Dsg 1, and snRNP70 simultaneously. In the second group, we performed serological studies to show presence of antibodies to BPAG 1, BPAG 2, β4 integrin, and snRNP70 simultaneously. In both groups, HLA II genes were analyzed and the observations were consistent with previously described associations with PV, MMP, and MCTD. It is possible that HLA-DQβ1*0301 allele, present in 10 of 17 patients and DRβ1*04 in some of the others, may have the ability to bind to several relevant T cell epitopes in the snRNP70 molecule. We have utilized a computer model to demonstrate that HLA II-restricted T cell epitopes present within the known autoantigens may be capable of eliciting an immune response. While other explanations and mechanisms exist, the authors suggest that epitope spreading may be one possible mechanism, amongst others, that may result in the simultaneous presence of two separate pathogenic autoantibodies.     

Japanese cedar pollinosis and HLA-DP5

Japanese cedar pollinosis is a type I allergic disease caused by Japanese cedar ( Cryptomeria japonica ) pollen. We investigated the association between the disease and HLA class II alleles by HLA-DNA typing using a PCR-SSOP method and found that the frequency of HLA-DP5 (DPA1*02022 and DPB1*0501) was significantly increased in the patients. To investigate whether the HLA-DP5 molecule is directly involved in the pathogenesis of the disease, Japanese cedar pollen antigen (CPAg)-specific T cell lines were established from 3 patients who possessed HLA-DP5 (DPA1*02022/DPB1*0501). By using these CPAg-specific T cell lines and HLA class II-expressing L-cell transfectants, we found that disease-associated HLA-DP5 restricted T cells specific for CPAg existed in the patients. Furthermore, among 38 synthesized overlapping peptides spanning the entire length of one of the major Japanese cedar pollen allergens, Cry j 1, an immunodominant peptide which induced HLA-DP5 restricted Th2 was identified. These observations suggest that the HLA-DP5 may be involved, at least in part, in the pathogenesis, by helping the IgE antibody production against CPAg.     

Peptide-based molecular analyses of HLA class II-associated susceptibility to autoimmune diseases

Recent advances in knowledge of crystal structures of MHC class II molecules has advanced understanding of the molecular basis for interactions between peptides and HLA class II molecules. Polymorphism of HLA class II molecules influences structures of peptides bound to HLA class II molecules. To better understand mechanisms related to particular HLA class II alleles and autoimmune diseases, it is important to identify self-peptides presented by disease-susceptible HLA class II molecules and triggering disease-causative autoreactive T cells. Autoimmune diseases occur in Caucasians, Blacks and Asians, albeit with a different incidence. In some autoimmune diseases, disease-susceptible HLA class II alleles are closely related but different, and clinical manifestations of diseases differ among ethnic groups. These phenomena strongly suggest that difference in autoimmune self-peptide(s) in the context of disease-susceptible HLA class II molecules may explain the different clinical manifestations of diseases. Therefore, a comparison among disease-susceptible HLA class II alleles, autoimmune self-peptides and clinical manifestations of autoimmune diseases in different ethnic groups would be instructive. We directed efforts to determining: (1) HLA-class II alleles specific to Asian populations and which are associated with susceptibility to autoimmune diseases, (2) binding-peptide motifs for these HLA class II molecules, and (3) self-peptides presented by susceptible HLA class II molecules to stimulate autoreactive T cells related to the development of autoimmune diseases in Asians. In this review, our related recent investigations are described and the uniqueness of HLA class II-associated autoimmune diseases in Asians is given emphasis.     

Peptide-Based Molecular Analyses of HLA class II-Associated Susceptibility to Autoimmune Diseases

Recent advances in knowledge of crystal structures of MHC class II molecules has advanced understanding of the molecular basis for interactions between peptides and HLA class II molecules. Polymorphism of HLA class II molecules influences structures of peptides bound to HLA class II molecules. To better understand mechanisms related to particular HLA class II alleles and autoimmune diseases, it is important to identify self-peptides presented by disease-susceptible HLA class II molecules and triggering disease-causative autoreactive T cells. Autoimmune diseases occur in Caucasians, Blacks and Asians, albeit with a different incidence. In some autoimmune diseases, disease-susceptible HLA class II alleles are closely related but different, and clinical manifestations of diseases differ among ethnic groups. These phenomena strongly suggest that difference in autoimmune self-peptide(s) in the context of disease-susceptible HLA class II molecules may explain the different clinical manifestations of diseases. Therefore, a comparison among disease-susceptible HLA class II alleles, autoimmune self-peptides and clinical manifestations of autoimmune diseases in different ethnic groups would be instructive. We directed efforts to determining: (1) HLA-class II alleles specific to Asian populations and which are associated with susceptibility to autoimmune diseases, (2) binding-peptide motifs for these HLA class II molecules, and (3) self-peptides presented by susceptible HLA class II molecules to stimulate autoreactive T cells related to the development of autoimmune diseases in Asians. In this review, our related recent investigations are described and the uniqueness of HLA class II-associated autoimmune diseases in Asians is given emphasis.     

The association of CTLA-4 and HLA class II autoimmune risk genotype with regulatory T cell marker expression in 5-year-old children

Regulatory T cells (Treg) are involved in the maintenance of peripheral tolerance by suppression of autoreactive lymphocytes that have avoided thymic depletion. The defective function of Treg cells has recently attracted attention in autoimmune diseases such as type 1 diabetes (T1D), rheumatoid arthritis and multiple sclerosis. Susceptibility to these diseases is associated with specific human leucocyte antigen (HLA) class II and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) gene polymorphisms. This study aimed to investigate the relationship between HLA class II and CTLA +49 A/G polymorphisms associated with susceptibility to T1D and the number and characteristics of Treg cells in children. Samples from 47 5-year-old children who participated in the All Babies in South-east Sweden (ABIS) follow-up study were grouped according to the presence of the T1D risk-associated HLA genotype (DQA1*0501-DQB1*0201, DQA1*0301-DQB1*0302) or neutral HLA genotypes. Lower percentages of CD4+ T cells (P = 0.03) and CD4+ CD25high cells (P = 0.06) expressing intracellular CTLA-4 were detected in samples from children with CTLA-4 +49GG compared to children with the +49AA genotype. Similarly, lower percentages of CD4+ (P = 0.002) and CD4+ CD25high (P = 0.002) cells expressing CTLA-4 were observed in children positive for HLA DQA1*0501-DQB1*0201 and DQA1*0301-DQB1*0302 (P = 0.04 for CD4+ and P = 0.02 for CD4+ CD25high) risk haplotypes when compared to children without these alleles. The percentage of CD25high cells among CD4+ cells was correlated inversely with CTLA-4 mRNA expression in PBMC (r = -0.56, P = 0.03). Decreased levels of CTLA-4 in CD4+ and CD4+ CD25high cells in individuals with CTLA-4 and HLA class II alleles associated with T1D may contribute to the initiation and/or progression of autoimmune response.     

High susceptibility to pemphigus vulgaris due to HLA‐DRB1*14:54 in the Slovak population

The current work describes an association between pemphigus vulgaris (PV) and class II HLA alleles in the Slovak population, the first such study in Slovakia on the ‘high‐resolution level’. This work takes into account the new HLA allele nomenclature, officially adopted in 2010. In particular, we have focused on the associations between PV and DRB1*14:54 and DRB1*14:01. This case–control study was performed in a cohort of 43 PV Caucasian patients and 113 Caucasian control subjects from Slovakia. HLA typing was performed using PCR‐SSP (polymerase chain reaction with sequence‐specific primers). We found significantly positive associations between PV and the HLA alleles DRB1*04:02, DRB1*04:04, DRB1*14:54, DRB1*14:04, DRB1*14:05, DQB1*03:02 and DQB1*05:03. In contrast, HLA‐DQB1*06, DRB1*07 and DRB1*13 were negatively associated with PV. Importantly, 93% of PV patients possessed at least one of two HLA haplotypes, DRB1*04–DQB1*03 or HLA‐DRB1*14–DQB1*05. We confirmed the previously reported associations between HLA class II alleles and PV and described a new association between PV and DRB1*14:54. This allele was first described in 2005, and there has been only one report of its association with PV to date.     

Pemphigus vulgaris in Jewish patients is associated with HLA-A region genes: mapping by microsatellite markers

Pemphigus vulgaris (PV) is the most severe autoimmune blistering disorder of the skin that is mediated by circulating autoantibodies against desmoglein 3 (Dsg3). It has been reported that in Jews the associated haplotype in PV is human leukocyte antigen (HLA) B38, DRB1*0402, DQB1*0302. Significant associations with HLA were observed also in non-Jews. Dsg3-specific T-cell responses were detected in PV patients but also in healthy individuals who were either carriers of the PV-associated DRB1*0402 allele or alleles that share similar or identical peptide binding motifs to DRB1*0402. This suggests that genes other than the classical major histocompatibility complex (MHC) genes are associated with the development of the autoimmune response. We used 16 microsatellite probes that span the entire MHC region to screen DNA samples from 38 PV patients and 76 healthy controls. Results demonstrated that some markers were associated with class II region including a TAP associated marker. However, four probes, D6S265, C_527, D6S510, and MOGC, which are all mapped to the region of HLA-A, were highly associated with PV. These results suggest that a gene, or genes in the class I region are important in the initiation of the autoimmune cascade. Activation/suppression of these genes might act as the trigger mechanism that starts the autoimmune destructive process.     

Dsg3刺激诱导天疱疮患者一级亲属T细胞活化的研究

目的 研究在特异抗原桥粒芯糖蛋白3(desmoglein3,Dsg3)刺激下寻常型天疱疮(PV)患者一级亲属淋巴细胞Th1/Th2、Tc1/Tc2极化状态的变化,探讨PV发生机制.方法 PV患者一级亲属外周血单个核细胞(PBMC)在Dsg3刺激下体外培养3 d,流式细胞仪四色胞内染色分析PV患者一级亲属CD4~+ T细胞和CD8~+T细胞中IFN-γ~+和IL-4~+细胞的百分率,观察PV患者一级亲属Th1/Th2、Tc1/Tc2比例的变化.结果 PV抗体阳性一级亲属中的PBMC经Dsg3刺激培养者与未经Dsg3刺激者比较,Th2、Tc2百分率均显著升高(10.13%±3.72%vs 7.28%±3.58%,20.01%±10.43% vs 14.91%±8.06%,P<0.05);经Dsg3刺激培养后PV抗体阳性一级亲属组与正常对照组比较Th2、Tc2百分率均显著升高(10.13%±3.72%VS 6.10%±2.82%,20.01%±10.43% vs9.58%±5.49%,P<0.05).结论 特异性抗原Dsg3刺激下,自身反应性T细胞活化,Th1/Th2、Tc1/Tc2细胞分化失衡,可能在PV的启动阶段发挥重要作用.     

HLA class II transgenic mice authenticate restriction of myelin oligodendrocyte glycoprotein-specific immune response implicated in multiple sclerosis pathogenesis

Myelin oligodendrocyte glycoprotein (MOG) is a potential target antigen of the central nervous system (CNS), known to induce autoreactive T cell response and demyelinating anti-MOG antibodies in multiple sclerosis (MS) patients. Association of HLA class II genes with MS is well established. To better understand the role of HLA class II molecules in disease pathogenesis, we generated transgenic mice that express HLA-DR2, -DR3, -DR4, -DQB1*0601, -DQB1*0604 and -DQ8 without mouse class II (Abeta(0)). We have for the first time characterized the T and B cell epitopes of human MOG restricted by different HLA class II molecules. Immunization with recombinant MOG (rMOG) generated a strong CD4(+) T cell-mediated response in an HLA class II-restricted manner. Cytokine analysis revealed an increase in pro-inflammatory (IFN-gamma, IL-12 and IL-6) and anti-inflammatory (IL-10) cytokines. T cell autoreactivity to MOG was directed against peptides 1-20, 31-50, 61-80 and 91-110, of which three are also immunodominant epitopes for MOG in MS. A strong B cell response to MOG was observed in all transgenic mice, and major B cell epitopes recognized were located within amino acids 1-30, 51-80 and 101-120 of human MOG, which consists of two epitopes reported in MS. Transgenic mice used in this study recognized the immunodominant MOG epitopes similar to HLA class II-restricted human T cells, and would therefore be valuable in elucidating the roles of HLA class II genes and autoantigens in MS.     

Influence of HLA-DRB1 alleles on lymphoproliferative responses to a naturally processed and presented measles virus phosphoprotein in measles immunized individuals

Identification of stimulatory T-cell epitopes recognized by CD4+ T lymphocytes is important for vaccine development. Our previous studies using mass spectrometry identified a naturally processed HLA class II restricted DRB1*0301 T cell epitope in the measles virus phosphoprotein, MV-P1 (residues 179-197). Here we provide lymphocyte proliferation data from peripheral blood mononuclear cells (PBMC) obtained from 131 HLA-DRB1*0301-positive and HLA-DRB1*0301-negative (HLA discordant) individuals previously immunized against measles and report that a single amino acid substitution in the MV-P1 T cell epitope can reduce T cell proliferation and CD4+ T-cell recognition. Measles virus and measles peptide-specific lymphoproliferative responses and HLA-DRB1 allele associations reveal that the DRB1*0701 allele provided suggestive evidence of association with both measles virus (p = 0.03) and MV-P1 peptide (p = 0.06) lymphoproliferation. A marginally significant increase in the frequency of the *0301 allele (p = 0.10) was found among subjects who demonstrated low cellular responses to the measles virus. We found no associations between proliferation levels to the MV-P1 and MV-P2 peptides with *0301 alleles. We speculate that the glutamic acid at position 192 of the measles phosphoprotein is a critical immunogenicity factor and may influence the antigenicity of the naturally processed HLA class II MV-P1 epitope.     

HLA class II polymorphism contributes to specify desmoglein derived peptides in pemphigus vulgaris and pemphigus foliaceus

Susceptibility to Pemphigus, an autoimmune disease of the skin, has been previously linked to DRB1*0402, 1401/04 and DQB1*0503 in pemphigus vulgaris (PV), to DRB1*0102, 0404, 1402/06 in endemic pemphigus foliaceus in Brazil and to DRB1*04 in Italian patients suffering from pemphigus foliaceus (PF). The disease is caused by autoantibodies against desmoglein (Dsg1 in PF, Dsg3 in PV).Molecular typing of 57 French patients suffering from PV (37) and from PF (20) confirmed previous results concerning PV and showed that DRB1*0102 and 0404 are susceptible molecules to PF in France.We have analysed the characteristics of the 'pockets' of the susceptibility-associated molecules to PV and PF and we showed that (i) in PV, two kinds of Dsg3 derived peptides may be presented by HLA-DR according to HLA polymorphism (DRB1*0402 or DRB1*14/0406), (ii) the same Dsg1 peptides may be presented by DRB1*0102, DQB1*0404 or DRB1*14 in PF, (iii) the DRB1*14/0406 PV-related molecules may be able to present Dsg1 and Dsg3 peptides thereby providing an explanation for the cases of PV with combined responses to Dsg1 and to Dsg3 which are typified by a muco-cutaneous clinical phenotype.