Identification and modulation of a naturally processed T cell epitope from the diabetes-associated autoantigen human glutamic acid decarboxylase 65 (hGAD65).

T cell recognition of autoantigens is critical to progressive immune-mediated destruction of islet cells, which leads to autoimmune diabetes. We identified a naturally presented autoantigen from the human islet antigen glutamic acid decarboxylase, 65-kDa isoform (GAD65), by using a combination of chromatography and mass spectrometry of peptides bound by the type I diabetes (insulin-dependent diabetes mellitus, IDDM)-associated HLA-DR4 molecule. Peptides encompassing this epitope-stimulated GAD65-specific T cells from diabetic patients and a DR4-positive individual at high risk for developing IDDM. T cell responses were antagonized by altered peptide ligands containing single amino acid modifications. This direct identification and manipulation of GAD65 epitope recognition provides an approach toward dissection of the complex CD4(+) T cell response in IDDM.

HLA-DRB1 typing in rheumatoid arthritis: predicting response to specific treatments.

OBJECTIVE: To determine the predictive value of shared epitope alleles for response to treatment in patients with rheumatoid arthritis. METHODS: Patients from our previously published triple DMARD study were tested for the presence of shared epitope alleles (DRB1 *0401, 0404/0408, 0405, 0101, 1001, and 1402). Patients who were shared epitope positive were then compared with those who were negative to see if there was a differential effect on therapeutic response. RESULTS: Shared epitope positive patients were much more likely to achieve a 50% response if treated with methotrexate-sulphasalazine-hydroxychloroquine compared with methotrexate alone (94% responders versus 32%, p < 0.0001). In contrast shared epitope negative patients did equally well regardless of treatment (88% responders for methotrexate-sulphasalazine-hydroxychloroquine versus 83% for methotrexate). Additionally, a trend toward an inverse relation of the gene dose was seen for response to methotrexate treatment (p = 0.05). CONCLUSIONS: These data suggest that determining shared epitope status may provide clinical information useful in selecting among treatment options.

Immunogenetic similarities between patients with Felty's syndrome and those with clonal expansions of large granular lymphocytes in rheumatoid arthritis.

OBJECTIVE: Patients with chronic clonal proliferation of large granular lymphocytes (LGL leukemia) often have splenomegaly, neutropenia, and rheumatoid arthritis (RA), thereby resembling the manifestations observed in patients with Felty's syndrome. The present study sought to determine whether patients with these disorders represent 2 distinct subsets of neutropenic RA. METHODS: Prospective cohort study of outpatients attending clinics in university and private hospitals and in offices of private practice physicians. Twenty-two patients with Felty's syndrome and 22 patients with LGL leukemia, 10 of whom had RA, were studied. HLA genotyping was performed on peripheral blood mononuclear leukocyte genomic DNA. RESULTS: Nineteen of the 22 patients with Felty's syndrome (86%) were DR4 positive. Nine of the 10 patients with LGL leukemia plus RA were also DR4 positive. In contrast, only 4 of the 12 patients with LGL leukemia without RA (33%) were DR4 positive, a frequency that was within the normal range. CONCLUSION: The finding of an equally high prevalence of DR4 in patients with Felty's syndrome and in those with LGL leukemia plus RA suggests that both disorders have a similar immunogenetic basis and are parts of a single disease process rather than 2 separate disorders.

Critical contribution of beta chain residue 57 in peptide binding ability of both HLA-DR and -DQ molecules.

Position 57 in the beta chain of HLA class II molecules maintains an Asp/non-Asp dimorphism that has been conserved through evolution and is implicated in susceptibility to some autoimmune diseases. The latter effect may be due to the influence of this residue on the ability of class II alleles to bind specific pathogenic peptides. We utilized highly homologous pairs of both DR and DQ alleles that varied at residue 57 to investigate the impact of this dimorphism on binding of model peptides. Using a direct binding assay of biotinylated peptides on whole cells expressing the desired alleles, we report several peptides that bind differentially to the allele pairs depending on the presence or absence of Asp at position 57. Peptides with negatively charged residues at anchor position 9 bind well to alleles not containing Asp at position 57 in the beta chain but cannot bind well to homologous Asp-positive alleles. By changing the peptides at the single residue predicted to interact with this position 57, we demonstrate a drastically altered or reversed pattern of binding. Ala analog peptides confirm these interactions and identify a limited set of interaction sites between the bound peptides and the class II molecules. Clarification of the impact of specific class II polymorphisms on generating unique allele-specific peptide binding "repertoires" will aid in our understanding of the development of specific immune responses and HLA-associated diseases.

Prognostic implications of HLA genotyping in the early assessment of patients with rheumatoid arthritis.

Current methods and approaches for the use of HLA markers in the assessment of rheumatoid arthritis (RA) are not optimal. Improved strategies for application of HLA susceptibility genetic typing in patients were evaluated and a new system for rapid determination of these RA susceptibility alleles was developed. Retrospective data summarizing the prevalence of HLA susceptibility alleles in patients with distinct clinical outcomes was analyzed to estimate the sensitivity and specificity of HLA genetic testing as a prognostic marker for erosive disease. A rapid allele specific DNA hybridization assay was performed on an automated instrument using a solid phase nonradioactive hybridization and detection system. Depending on the patient population being tested, from 70-80 percent of patients with progressive erosive disease carry one or more of the DR4 cluster of RA susceptibility genes (DRB1*0401, 0404, 0405). Sensitivity is increased by including other shared epitope positive alleles, but at the expense of specificity. The rapid automated genetic testing system correctly identified each of more than 200 samples tested, with no false positives. HLA genetic testing for RA susceptibility alleles can be performed rapidly and accurately. Prognosis for erosive disease can be facilitated in the patient with early pre-erosive RA using HLA testing in combination with other clinical assessment variables.

HLA and T cell receptor beta-chain DNA polymorphisms identify a distinct subset of patients with pauciarticular-onset juvenile rheumatoid arthritis.

OBJECTIVE: To evaluate and extend upon a reported association of a T cell receptor (TCR) V beta coding region polymorphism with pauciarticular-onset juvenile rheumatoid arthritis (JRA). METHODS: TCR V beta 6.1 genotypes and haplotypes in JRA and control groups were determined by DNA amplification. RESULTS: Haplotypes of the V beta 6.1 gene which encode a nonfunctional form of V beta 6.1 were significantly associated with pauciarticular JRA in patients possessing the HLA-DQA1*0101 allele (P = 0.0073). CONCLUSION: A TCR V beta gene segment in the vicinity of V beta 6.1, possibly V beta 6.1, is apparently involved in the pathogenesis of pauciarticular-onset JRA in DQA1*0101-positive individuals.

Erosive rheumatoid factor negative and positive rheumatoid arthritis are immunogenetically similar.

OBJECTIVE: The relationship between rheumatoid factor positive (RF+) and rheumatoid factor negative (RF-) rheumatoid arthritis (RA) is controversial. We sought to determine whether the HLA genes conferring susceptibility for erosive RF+RA are also prevalent in patients with erosive RF-RA. METHODS: DNA-based HLA typing for DRB1, DQB1, and DPB1 was performed on 16 consistently RF--patients with erosive RA. RESULTS: Thirteen of 16 (81%) RF-RA patients had the HLA susceptibility genes DRB1 *0401, *0404, or *0101, which are associated with RF+RA, as compared to 46% of normal controls (p = 0.017). By contrast, no associations with HLA-DQB1 and HLA-DPB1 alleles were apparent. CONCLUSION: Specific HLA susceptibility alleles are prevalent in patients with erosive RA, regardless of RF status, suggesting a similar immunogenetic basis for RA in these patients.

The role of the major histocompatibility complex in autoimmunity.

In the case of many autoimmune diseases, HLA genes are the genes most closely associated with disease susceptibility. Recent major advances in the ability to determine particular HLA genotypes in individuals now allow us to identify the precise alleles most closely associated with disease. Rheumatoid arthritis, long known to be associated with HLA-DR4, provides a good model for review of this progress, demonstrating how methodologic advances have led to an improved understanding of the immunogenetic basis of this disease, with implications for both pathogenesis and potential therapeutic interventions.

Prediction of susceptibility to rheumatoid arthritis by human leukocyte antigen genotyping.

Recent methodologic advances now allow the precise identification of HLA genes in individuals. Population studies using these methods have pinpointed the HLA alleles strongly associated with rheumatoid arthritis (RA). This article summarizes the current status of these RA-associated HLA genes in disease susceptibility and uses that information to derive estimates of risk ratios for prediction of disease in an individual.

HLA-DR alleles and sterile ulcerative keratitis.

Human leukocyte antigen-DR typing was performed on 18 unrelated white patients with sterile ulcerative keratitis (SUK) to determine whether these patients share common immunogenetic susceptibility genes. There was no statistically significant increase in any DR allele among the entire group of SUK patients. There was a trend in the frequency of DR1 in the rheumatoid arthritis (RA) patients (5 of 8, 63%) versus the non-RA patients (1 of 10, 10%), which was not statistically significant, possibly due to the small number of patients in the study. Screening patients with RA without known SUK from our RA register revealed one DR1-positive patient with an inactive peripheral marginal melt. These findings suggest a possible relationship between DR1 and RA sterile corneal melting, which will need to be confirmed with a larger study.

Juvenile rheumatoid arthritis and HLA: report of the Park City III workshop.

The workshop held during the Park City Meeting was directed toward developing a consensus about HLA associations in juvenile rheumatoid arthritis (JRA). Most agreement was achieved in pauciarticular JRA where the strongest associations were with the HLA-DRB1 alleles as is also the case in IgM rheumatoid factor positive polyarticular disease. In addition, HLA-DP associations are being identified although roles for linked genes are still possible. The critical nucleotides among HLA genes are not known; however, disease specific mutations have not been shown.

HLA and T cell receptor polymorphisms in pauciarticular-onset juvenile rheumatoid arthritis.

The immunogenetic basis of pauciarticular-onset juvenile rheumatoid arthritis is unclear. We therefore analyzed the HLA and T cell receptor genes present in a clinically well-defined group of patients. We found that the DR8 haplotype contributes most of the HLA-associated risk, although alleles at other loci contribute independently. A candidate disease-associated T cell receptor polymorphism, in contrast, was not identified in this population. Mechanistic implications of these findings are discussed.

Association of HLA-Dw16 with rheumatoid arthritis in Yakima Indians. Further evidence for the "shared epitope" hypothesis.

Rheumatoid arthritis (RA) is prevalent in Yakima Indians, a Native American tribe. HLA-DR4, the HLA specificity commonly associated with RA in Caucasians, is rare among the Yakima. Using a specific oligonucleotide probe that recognizes DR4 nucleotide sequences associated with RA, a rare HLA-Dw16 gene was identified in 83% of Yakima patients with RA and in 60% of Yakima control subjects. This shared sequence encodes a discrete class II epitope that is highly correlated with RA in both DR4 positive and DR4 negative individuals.

HLA susceptibility genes in rheumatoid factor positive juvenile rheumatoid arthritis.

Rheumatoid factor positive (seropositive) juvenile rheumatoid arthritis (JRA) is a relatively uncommon but severe form of JRA which shares clinical features with classical adult onset rheumatoid arthritis. Immunogenetic analysis of these patients supports the concept that this likely represents childhood onset of the same disease process. In this report, we review the clinical features as well as previous HLA studies of this disease. We report complete DNA based HLA typing of a small group of these patients, and discuss mechanistic implications of the results.

A specific HLA-DP beta allele is associated with pauciarticular juvenile rheumatoid arthritis but not adult rheumatoid arthritis.

Nonradioactive sequence-specific oligonucleotide probes specific for the HLA-DP beta locus have been used in a simple dot-blot format to type samples amplified by the polymerase chain reaction from 44 patients with pauciarticular juvenile rheumatoid arthritis, 32 patients with adult rheumatoid arthritis, and 50 random controls. The sequences of four new DP beta alleles derived from these patients and controls are reported, bringing the total number of alleles identified thus far to 19. The DPB2.1 allele is significantly increased in juvenile rheumatoid arthritis patients over controls; this allele is not increased in patients with adult rheumatoid arthritis. The association of juvenile rheumatoid arthritis with the DPB2.1 allele is independent of linkage with previously defined HLA-D region markers of disease. Analysis of the DPB2.1 sequence shows that it differs from the nonsusceptible DPB4.2 allele by only 1 amino acid at position 69 in the beta 1 domain.

HLA-DQ alpha polymorphisms: oligonucleotide probes characterize the contribution of first and second domains to electrophoretic variants.

Polymorphism is known to exist within the HLA-DQ alpha locus in the human major histocompatibility complex, although such polymorphism may be "silent" in standard HLA typing. However, DQ alpha polymorphism may be functionally significant, either through DQ alpha epitopes functioning directly in the immune response or by affecting tertiary conformation of Ia molecules through differential alpha/beta pairing. We have previously defined a particular DQ alpha polymorphism through reactivity with a monoclonal antibody and restriction fragment length polymorphism pattern. We now characterize this DQ alpha polymorphism through two-dimensional gel electrophoretic analysis and identify a subset of DQ alpha molecules with unique characteristics. Investigation of these allelic variants using synthetic oligonucleotide probe analysis of genomic DNA suggests a localization of the DNA region encoding the DQ alpha 5 epitope and suggests possible evolutionary mechanisms accounting for these unique patterns.

A diabetes-susceptible HLA haplotype is best defined by a combination of HLA-DR and -DQ alleles.

HLA-DR4 is associated with insulin-dependent diabetes mellitus (IDDM) in many populations. Many recent studies suggest that the DR4 effect is really due to DQ3.2, an allele of the nearby DQB1 locus. We used T cell clones, MAb, and allele-specific oligonucleotides to test IDDM and control subjects for DR4 subtypes (Dw4, Dw10, Dw13, and Dw14) and for DR4-associated DQB1 alleles (DQ3.1 and DQ3.2). We find that (a) IDDM is approximately equally associated with alleles of the DRB1 locus (Dw4 and Dw10, combined relative risk, RR = 6.4) and the DQB1 locus (DQ3.2, RR = 5.9); and (b) there is significant interaction, in a statistical sense, between these DR and DQ alleles in IDDM. The only IDDM-associated DR4 haplotypes were those carrying the IDDM-associated alleles at both loci (RR = 12.1); haplotypes with Dw4 or 10 but not DQ3.2, or vice versa, had a RR less than 1. Alternative explanations include: (a) that susceptibility requires specific allelic products of both DR and DQ loci; (b) that the combination of certain DR and DQ alleles marks haplotypes with the true susceptibility allele at a third locus; or (c) that Dw4 and 10 mark haplotypes with an allele at another locus that interacts with DQ3.2. As discussed, this third locus is unlikely to be DQA1 (DQ alpha). The data thus are not easily reconciled with an exclusive effect of HLA-DQ. This information increases our ability to predict IDDM by genetic typing: in the population studied, heterozygotes DR3/[DQ3.2, Dw4] or DR3/[DQ3.2, Dw10] had a relative risk of 38.0 and an absolute risk of 1 in 15.