The HLA-DR4 family of haplotypes consists of series of distinct DR and DS molecules.

Among DR4-associated HLA-D antigens, distinct and consistent structural variations were found for the products of two human "Ia-like" loci, DR and DS. Analysis of neuraminidase-treated immunoprecipitated DR molecules from 15 HLA-DR4-associated HLA-D homozygous B-lymphoblastoid cell lines by two dimensional polyacrylamide gel electrophoresis identified five distinct DR beta chains. In addition, gel analysis of immunoprecipitated DS molecules identified three distinct DS beta chains. Altogether, five distinct DR4 haplotypes were defined according to the observed structural diversity of the DR and DS beta chains. These gene products presumably contribute the dominant polymorphisms recognized by T cells in mixed lymphocyte reaction (MLR). Thus, these studies indicate that the serologic specificity known as HLA-DR4 is not a single haplotype, but a determinant present on products of individual loci arrayed into distinctly different haplotypes. These findings suggest that distinct products of individual loci, rather than conventional HLA specificities defined by alloimmune sera, may represent the genetic markers relevant to HLA-D/DR associated diseases.

Specific genomic markers for the HLA-DQ subregion discriminate between DR4+ insulin-dependent diabetes mellitus and DR4+ seropositive juvenile rheumatoid arthritis.

HLA-DR4, Dw4-associated haplotypes associated with IDDM and JRA were compared using genomic DNA restriction fragment analysis to distinguish among DQ beta and alpha alleles linked to DR4. DQ beta polymorphisms that subdivide the HLA-DQw3 specificity into DQ3.1 and 3.2 alleles were identified. More than 90% of DR4+ IDDM patients express one of these alleles, DQ3.2; restriction enzyme mapping indicates that the presence of this allele also accounts for the genomic fragment patterns previously reported in IDDM. Furthermore, haplo-identical siblings of DQ3.2 IDDM patients also carry the DQ3.2 allele, regardless of clinical presentation. In contrast, DR4+ JRA patients show no allelic preference at DQ beta, implicating different HLA genetic contributions in these two DR4-associated diseases.

Specific HLA-DR4-associated histocompatibility molecules characterize patients with seropositive juvenile rheumatoid arthritis.

The structural and functional heterogeneity of HLA-DR4-associated specificities was investigated in patients with seropositive juvenile rheumatoid arthritis, a DR4-associated disease. Using a combination of HLA-D analysis by mixed lymphocyte culture and electrophoretic analysis of immunoprecipitated Ia molecules by two-dimensional polyacrylamide gels, we observed a surprisingly homogeneous pattern of HLA-D antigen expression. All patients expressed common structural products of the DR and DS loci, and 7/12 homozygous DR4 patients expressed a rare and subtle HLA-D heterozygous phenotype.

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.

Transcomplementation of HLA genes in IDDM. HLA-DQ alpha- and beta-chains produce hybrid molecules in DR3/4 heterozygotes.

The HLA association with insulin-dependent diabetes mellitus is highest among individuals heterozygous for DR3 and DR4. To investigate potential mechanisms to account for this association, we performed two-dimensional gel-electrophoretic analysis of HLA molecules from DR3/4 heterozygous patients. These studies demonstrated hybrid molecular dimers corresponding to products of HLA-DQ genes linked to DR3 and DR4, i.e., the DQw2 and DQw3 genes, respectively. Two types of DQ molecules were found: immunoprecipitation by DQw3-specific monoclonal antibody 17.15 identified a DQw3 beta-chain associating with a DQw3 alpha-chain and a DQw3 beta-chain associating with a DQw2 alpha-chain. The identity of alpha- and beta-chains comprising these hybrid molecules was confirmed by HPLC peptide-map analysis. Several characteristic peptide peaks identified both DQw2 and DQw3 alpha-chains associated with DQw3 beta-chains. The formation of such DQ alpha (DQw2)-Dq beta (DQw3) dimers potentially contributes a direct molecular mechanism for HLA-associated contributions to disease in DR3/DR4 heterozygotes.

Functional polymorphisms among HLA-DR4+ DR beta chains associated with limited peptide diversity.

Tryptic peptide map analysis by high-pressure liquid chromatography of DR4- associated DR beta chains revealed limited structural variation within DR beta polypeptides. Comparison of 3H-leucine-labelled tryptic peptide maps of Dw4 and Dw14 homozygous cells identified distinct peaks corresponding to Dw4 and Dw14-associated DR beta polypeptides. HPLC analysis of cell line 256, heterozygous for two DR4-related specificities, Dw4 and Dw14, displayed both peptides, corresponding to the variable Dw4 and Dw14 chromatograms. This observation was confirmed using a deletion mutant cell line derived from 256 lacking Dw4-associated class II genes. The observed peptide variation correlated precisely with predicted nucleotide-derived amino acid sequences implicating amino acids 66-71 of the DR beta chain as contributing to HLA-D structural and functional polymorphisms.

A deletion mutant defines DQ beta variants with DR4 positive DQw3 positive haplotypes.

We describe the production of an HLA deletion mutation by radiation mutagenesis of a DR4- and DQw3-homozygous, Dw4- and Dw14-heterozygous cell line designed to analyze polymorphisms associated with DR4 and DQw3. Southern blot analysis confirms a deletion of class I and class II genes on one haplotype. Variation in DQ beta alleles associated with DQw3 was previously described by characteristic RFLP patterns for a DQ beta bene. One pattern, which correlated precisely with A-10-83 monoclonal antibody reactivity (TA10), defined an allele which we call DQ"3.1". The mutant cell line has lost the polymorphic bands on Southern blots corresponding to the DQ"3.1" allele, while the intact Dw14 haplotype retains the alternate allele at DQ beta which is DQw-3 positive. TA10-negative. These data demonstrate the segregation of two DQw3 positive DQ beta allelic variants, both associated with DR4, which can be distinguished on the basis of both RFLP and monoclonal antibody reactivity.

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.

Multiple Ia-like molecules characterize HLA-DR2-associated haplotypes which differ in HLA-D.

Two-dimensional gel electrophoresis of immunoprecipitated human Ia-like molecules was used to investigate the structural relationship between HLA-D and HLA-DR2. Eight different lymphoblastoid lines derived from HLA-DR2-associated homozygous typing cells, representing five distinct HLA-D clusters, were compared. Two or three distinct beta chain molecules from DR-like loci were identified in the DR2 homozygous cell lines studied. Furthermore, one of these molecules was present in all lines tested, while the others were highly variable. The electrophoretic mobility of these variable DR-like molecules correlated very well with HLA-D typing studies, suggesting that the HLA-DR specificity and the HLA-D specificity on these DR2 cells may be present on separate, but related, molecules.

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.

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 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.

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.

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.

The molecular basis for HLA class II associations with rheumatoid arthritis.

The association of HLA-DR4 with rheumatoid arthritis strongly implicates genes of the major histocompatibility complex (MHC) as contributing to disease susceptibility. Molecular analysis of MHC genes expressed on haplotypes in association with HLA-DR4 reveals that at least six different alleles of the DR beta 1 locus and at least three different alleles of the DQ beta locus occur on different DR4+ haplotypes. Some of these allelic differences are quite substantial, and others are rather subtle, involving as few as two amino acids. The analysis of individual DR and DQ alleles in rheumatoid arthritis identifies some DR4+ genes strongly associated with disease susceptibility and some DR4+ genes which are not. The Dw4(DR4) and Dw14(DR4) DR beta 1 genes appear to represent specific alleles which confer disease risk in RA; other DR beta 1 genes, such as Dw10(DR4), may represent DR beta genes altered during evolution which have lost their contribution to RA susceptibility. DQ beta 3.1(DQw3) and DQ beta 3.2(DQw3) DQ beta genes, which are present on DR4+ haplotypes, represent discrete variable alleles not directly implicated in RA, but which account for HLA-DR4 associations with other diseases, such as the association of DQ beta 3.2(DQw3) with Type I diabetes.

Immunogenetics of disease susceptibility: new perspectives in HLA.

Structural analysis of HLA class II molecular variation occurring within haplotypes implicated in specific HLA-associated diseases now provides more specific and sensitive mechanisms for investigation of genetic susceptibility to disease. Using the HLA-DR4 association with two distinct diseases, IDDM and JRA, as a model, we can conclude the following: There are at least seven distinct haplotypes which share the HLA DR4 specificity; these haplotypes include six alleles at the DR-beta genetic locus. These allelic differences are subtle, encompassing a very few clustered amino acid changes, but are sufficient to generate different patterns of T cell alloreactivity; there are at least three different alleles of DQ-beta genes associated with DR4+ haplotypes, with major structural differences recognized by biochemical analysis and by specific antibodies; different DR4-associated diseases are associated with different specific allelic variants of DR and DQ genes. DR4+ IDDM is most closely associated with the DQ 3.2 allele at DQ-beta; DR4+ JRA, on the other hand, appears to be highly associated with rare alleles at DR-beta, but not DQ. Notably, there are many alleles, and therefore DR4+ haplotypes, which are not implicated in 'HLA-DR4-associated' diseases.

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.