HLA--Dw4 and rheumatoid arthritis

Meta-analyses of the association of HLA-DRB1 alleles with rheumatoid arthritis among Arabs

AIM

Various studies incorporating Arab populations have reported on specific associations between HLA-DRB1 variants and rheumatoid arthritis (RA). We sought to provide an overview on the association of HLA-DRB1 with RA in Arabs using meta-analysis tools.

METHODS

Data on allele counts and frequencies were compiled from the relevant literature (published before 16 February 2016) and the associations of 13 -DRB1 variants with RA were assessed; relationships were defined in terms of odds ratios (ORs) with a 95% confidence interval.

RESULTS

Based on a collection of six studies, risk conferring or protective allele associations were derived from allele counts in 475 RA patients and 1213 controls. Two HLA-DRB1 alleles (-DRB1*04, *10) significantly conferred an increased risk for RA (OR > 2; P < 0.0001). Conversely, four alleles (-DRB1*03, *07, *11 and *13) significantly conferred a protective effect against RA (OR < 1; P < 0.05). No significant associations with RA were found for seven -DRB1 variants (-DRB1*01, *08, *09, *12, *14, *15 and *16).

CONCLUSION

With increased statistical power and effect size over individual studies, we present a more robust profile on the association of HLA-DRB1 variants with RA in the Arab ethnicity, and contribute to the global geo-ethnic picture in this context.

New insights into the genetics of immune responses in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease with a strong genetic component. Numerous aberrant immune responses have been described during the evolution of the disease. In later years, the appearance of anti-citrullinated protein antibodies (ACPAs) has become a hallmark for the diagnosis and prognosis of RA. The post-translational transformation of arginine residues of proteins and peptides into citrulline (citrullination) is a natural process in the body, but for unknown reasons autoreactivity towards citrullinated residues may develop in disposed individuals. ACPAs are often found years before clinical manifestations. ACPAs are present in about 70% of RA patients and constitute an important disease marker, distinguishing patient groups with different prognoses and different responses to various treatments. Inside the human leukocyte antigen (HLA) region, some HLA-DRB1 alleles are strongly associated with their production. Genome-wide association studies in large patient cohorts have defined a great number of single nucleotide polymorphisms (SNPs) outside of the HLA region that are associated with ACPA positive (ACPA+) RA. The SNPs are generally located close to or within genes involved in the immune response or signal transduction in immune cells. Some environmental factors such as tobacco smoking are also positively correlated with ACPA production. In this review, we will describe the genes and loci associated with ACPA+ RA or ACPA- RA and attempt to clarify their potential role in the development of the disease.

Adjusting for HLA-DRbeta1 in a genome-wide association analysis of rheumatoid arthritis and related biomarkers

Background

There is a long-established association between rheumatoid arthritis and HLA-DRβ1. The shared epitope (SE) allele is an indicator of the presence of any of the HLA-DRβ1 alleles associated with RA. Other autoantibodies are also associated with RA, specifically rheumatoid factor IgM (RFUW) and anti-cyclic citrullinated peptide (anti-CCP).

Methods

Using the Genetic Analysis Workshop 16 North American Rheumatoid Arthritis Consortium genome-wide association data, we sought to find non-HLA-DRβ1 genetic associations by stratifying across SE status, and using the continuous biomarker phenotypes of RFUW and anti-CCP. To evaluate the binary RA phenotype, we applied the recently developed FP test and compared it to logistic regression or a genotype count-based test. We adjusted for multiple testing using the Bonferroni correction, the Q value approach, or permutation-based p-values. A case-only analysis of the biomarkers RFUW and anti-CCP used linear regression and ANOVAs.

Results

The initial genome-wide association analysis using all cases and controls provides substantial evidence of an association on chromosomes 9 and 2 within the immune system-related gene UBXD2. In SE-positive subjects, many single-nucleotide polymorphisms were significant, including some on chromosome 6. Due to very few SE negative cases, we had limited power to detect associations in SE negative subjects. We were also unable to find genetic associations with either RFUW or anti-CCP.

Conclusion

Our analyses have confirmed previous findings for genes PTPN22 and C5. We also identified a novel candidate gene on chromosome 2, UBXD2. Results suggest FP test may be more powerful than the genotype count-based test.

HLA-A, B, C, D, DR antigens and primed lymphocyte typing (PLT) defined DP-antigens in juvenile chronic arthritis

A total of 48 patients with juvenile chronic arthritis (JCA) were typed for HLA-A, -B, -C, -D and -DR antigens and 36 patients were also typed for HLA-D/DR associated "DR"-antigens with the primed lymphocyte typing technique. In the total group of patients, we found increased frequencies of HLA-B27, HLA-Dw/DP5 and HLA-Dw/DP8, and decreased frequencies of HLA-Dw/-DR/DP2. The increased frequencies of HLA-Dw/DP8 and the decreased frequencies of HLA-Dw/-DR/DP2 were primarily found among patients with persistent pauciarticular arthritis. The frequencies of HLA-Dw/-DR/DP4 were increased in patients with polyarticular arthritis. The frequencies of HLA-B27 and -Dw/DP5 were increased in both pauciarticular and polyarticular arthritis. The results indicate (i) that genetic factors controlled by HLA confer susceptibility and/or resistance to JCA, and (ii) that the clinical subdivision of JCA into pauciarticular and polyarticular JCA can be supported by the presence of different genetic markers (HLA-antigens) in the two groups of JCA-patients. If these data can be confirmed HLA-D, -DR or DP typing may be of value in the prognostic evaluation of patients with pauciarticular onset JCA.

Shared-epitope HLA-DRB1 alleles and sex ratio in Italian patients with rheumatoid arthritis

OBJECTIVE

To investigate the association between the HLA-DRB1 alleles sharing the epitope (Q/R)(K/R)RAA and rheumatoid arthritis (RA) in a large sample of Italian patients (N = 264) recruited from a single centre over the last 5 years.

METHODS

Patients' classification according to the ACR criteria. DNA typing of HLA-DRB1 alleles by conventional polymerase chain reaction sequence specific oligonucleotide probing techniques.

RESULTS

Low-resolution DRB1 "generic" typing showed a significantly higher frequency of DR4+ RA patients as compared to normal controls. Both DR1 and DR10 specificities were over-represented in our patients, but neither reached the statistically significant P level of 0.05 after Bonferroni's correction. However, direct search of Q(K/R)RAA epitopes, which are present in most DR4+ and DRl+ samples, demonstrated that these motifs were found at increased frequencies in RA patients. Stratification according to gender did not show differences in the proportion of disease-associated HLA alleles.

CONCLUSIONS

Our study confirms the association of HLA-DR4, and -DR1 alleles, and more generally speaking of the shared epitopes Q(K/R)RAA, with disease susceptibility in Italian patients.

HLA class II association with rheumatoid arthritis: facts and interpretations

We have reviewed the literature on the association of HLA class II with rheumatoid arthritis (RA). Strong linkage disequilibrium among DQB1, DQA1 and DRB1 alleles makes it difficult to evaluate the individual contribution of each locus. Nonetheless, there is a strong case for the role of DQB1*03 and *04 combined with DQA1*03 in susceptibility to severe RA while DQB1*0501 combined with DQA1*0101 and *0104 weakly predisposes to a mild form of RA. However, it is also clear that DRB1*0401 has a particular role in predisposition to the most severe form of the disease while other DRB1 alleles might provide protection. We would like to propose that in RA, as in type I diabetes, both DQ and DR loci contribute to predisposition to the disease.

Multiplex ARMS-RFLP: a simple and rapid method for HLA-DR4 subtyping

We have developed a simple and rapid non-radioactive technique for HLA-DR4 subtyping. A multiplex ARMS-RFLP (Amplification Refractory Mutation System--Restriction Fragment Length Polymorphism) system allows HLA-DR4 subtyping by analysis of the products of two multiplex ARMS reaction mixtures. For some cases, restriction enzyme digests (Hae II and/or SacII) of the products are analysed. The technique relies on the fact that an ARMS primer with a mismatch at its 3'-end with respect to the template will not be elongated under PCR conditions. Hence, by designing ARMS primers such that different HLA-DR4 alleles yield PCR products of different lengths, only two reactions, each using a mixture of different ARMS primers, are sufficient to type all of the known HLA-DR4 alleles. This system can distinguish between HLA-DR4 'homozygotes' and 'heterozygotes' since every HLA-DR4 allele can be detected. The ARMS conditions were optimized using DNA from cell lines. This technique has now been used to type a panel of rheumatoid arthritis patients and controls.

HLA-DRB1 gene sequences in HLA-DR4 positive and negative patients with rheumatoid arthritis

The second exon of the DRB1 gene encoding for the first domain of the HLA-DR beta 1-chain was sequenced in 16 patients (10 DR4/DR1 positive, 6 DR4/DR1 negative) with seropositive rheumatoid arthritis (RA). We could confirm the strong association of susceptibility to RA with functionally equivalent conformations on otherwise distinct MHC molecules. At least one HLA-DR allele in all of the analysed DR4 or DR1 positive patients showed such an epitope with a minimal variability limited to residue 71. However, in HLA-DR4 and -DR1 negative patients such a similar epitope could not be detected.

Dw14(DRB1*0404) is a Dw4-dependent risk factor for rheumatoid arthritis. Rethinking the "shared epitope" hypothesis

HLA-DR4 has been shown to be associated with risk for developing rheumatoid arthritis (RA) in multiple populations and racial groups. The allelic variants of DR4 share the DR4 serologic specificity but differ by 1 to 3 amino acids in the third hypervariable region (positions 67 to 74) and at positions 57 and 86 of the DR beta 1 chain. We have examined DR4 variants in 61 DR4+ RA cases and 55 DR4+ healthy controls. Dw14 was not associated with RA risk in DR4 heterozygous (DR4,X) cases. Only 15% of DR4,X cases had the Dw14 allele compared with 28% of DR4,X controls. In homozygous (DR4,4) individuals who also expressed Dw4, however, Dw14 was associated with increased RA risk. Moreover, the relative risk for Dw4,Dw14 (16.1, p = 0.001) actually exceeded that of Dw4,Dw4 (2.2, p = ns). Thus Dw14 is not an independent risk factor for RA but is a synergistic risk factor for individuals who also have the Dw4 allele.

Association of HLA-DR4 with a more progressive disease course in patients with rheumatoid arthritis. Results of a followup study

The association between HLA-DR antigens and rheumatoid arthritis (RA) was investigated in a well-characterized cohort of RA patients who were followed from the beginning of the disease (mean followup 6 years). The frequencies of HLA-DR antigens in patients with possible or probable RA (n = 49) were similar to those in controls. In patients with definite RA (n = 134), the frequencies of DR1, DR4, and DRw53 were increased, whereas the frequencies of DR2, DR3, DRw6, DRw13, and DRw52 were decreased, compared with controls. Comparison of HLA-DR frequencies in patients with definite RA subclassified according to the severity of the disease at the end of the followup period revealed a difference only in the frequency of DR4, which was increased in patients with progressive RA (59.2%) compared with those who had mild RA (34.8%). Further analysis showed that, compared with DR4-negative RA patients, DR4-positive patients had more swollen joints, higher scores on the Ritchie articular index, the Health Assessment Questionnaire, and the Steinbrocker functional classification, more radiologic abnormalities, and more use of second-line drugs. Also, the rate of progression of radiologic abnormalities, functional classification, and use of second-line drugs was higher in DR4-positive patients. We conclude that DR4 is associated with a more severe disease course, and is a prognostic marker in early RA.

HLA-DR alleles with naturally occurring amino acid substitutions and risk for development of rheumatoid arthritis

To determine the HLA-DR4 subtypes associated with rheumatoid arthritis (RA), we performed amplification of DR4 DRB1 genes by the polymerase chain reaction and dot-blots with oligonucleotide probes. In 52 HLA-DR4+ RA patients, Dw4 was the predominant subtype. This subtype was found in 45 of 52 patients (86.5%) compared with 33 of 59 DR4+ controls (55.9%; P less than 0.001). In the whole population, Dw4 also gave the highest relative risk for RA (RR = 5.31). Relative risk was also associated with DR1.1, the common white DR1 (Dw1) type, which has a third hypervariable region amino acid sequence similar to some forms of DR4 and has glycine at position 86. Variants of DR1 (DR1.2) or DR4 (Dw13.1, Dw14.1) with valine at position 86 appeared less able to confer risk for RA. Substitution of residues in the third hypervariable region of the first domain of DRB1 appeared to correlate with relative risk for RA. Among subjects having 0-1 amino acid substitutions, RA developed in 53%, whereas in subjects with 2-4 amino acid changes, RA was present in only 17.4% (P less than 0.00001). DQw7 (formerly DQw3.1) was slightly increased in DR4+ RA patients compared with controls, but a striking excess of Dw4,DQw7 homozygous patients was observed. The results suggest that DQw7 may have an additional effect, possibly with a recessive mechanism, since it was observed only in DR4 homozygous patients.

HLA-DR antigens and HLA-DQ beta chain polymorphism in susceptibility to rheumatoid arthritis

Forty four patients with rheumatoid arthritis (RA) were studied for HLA-DR antigens and for HLA-DQ beta chain gene restriction fragment length polymorphism using DNA hybridisation. A significant increase in the prevalence of the DR4 antigen and a tendency towards an increase of DR1 was found in patients with RA. No allelic form of HLA-DQ restriction fragment length polymorphism patterns was increased, but the prevalence of an allele characterised by a combination of 7.5 and 3 kb fragments was decreased among patients with RA. The DQw8 subtype represented by a 12 kb fragment was the most common DR4 associated allele, and a 3.7 kb fragment related to DQw7 was found in only 5/25 (20%) DR4 positive patients and 2/12 (17%) controls. The results support the hypothesis that RA susceptibility factors are primarily located within HLA-DR genes but HLA-DQ genes may have a role in protection from the disease.

Immunogenetic heterogeneity of seronegative rheumatoid arthritis and the antiperinuclear factor

HLA typing was carried out in 132 patients with rheumatoid arthritis (RA) with long term follow up, and special attention was focused on rheumatoid factor negative patients. The patients were divided into four groups: 55 patients with a seropositive RA and a positive antiperinuclear factor (group A); 39 seropositive patients but a negative antiperinuclear factor (group B); 14 patients consistently seronegative for 3-28 years (mean 11.8 years) but positive for antiperinuclear factor (group C); patients consistently negative for 3-28 years (mean 11.8) and also negative for antiperinuclear factor (group D). The prevalence of HLA-DR4 was 31/55 (56%), 29/39 (74%), 10/14 (71%), and 9/24 (37%) for groups A, B, C, and D respectively, and in all groups was significantly higher than in 277 healthy controls (55/277, 20%). No significant difference was found between seropositive (groups A and B) and seronegative (groups C and D) patients, but groups A, B, and C had higher prevalences than group D. It is concluded that in seronegative RA HLA-DR4 is preferentially associated with the antiperinuclear factor positive group.

Susceptibility epitope on HLA-DR beta chain for rheumatoid arthritis and the effect of the positivity on the clinical features

A highly significant association of an amino acid sequence, '70Q71R72R73A74A' located on the DR beta-1 chain, with rheumatoid arthritis (RA) was confirmed in Japanese patients using polymerase chain reaction. The '70QRRA74A' is the most plausible candidate of susceptibility epitope in Japanese RA patients. The patients carrying the sequence showed slightly higher but not significant familial incidence. The positivity of the 'QRRAA' showed no effect on the positivity of the rheumatoid factor, rheumatoid nodules, and extra-articular signs. Also no significant differences in other clinical parameters (ESR, CRP, Hb, A/G) and age at onset were observed regarding the positivity. The risk that the 'QRRAA' positive subjects would suffer from RA was estimated to be about 1.3% which meant 7.2 times easier to get RA than those without 'QRRAA'.

Seronegative rheumatoid arthritis, rheumatoid factor cross reactive idiotype expression, and hidden rheumatoid factors

The major rheumatoid factor cross reactive idiotype (RCRI), defined by prototypic monoclonal rheumatoid factors (RFs), is expressed as a dominant idiotype by pokeweed mitogen induced plasma cells obtained from seropositive (RF+) patients with rheumatoid arthritis (RA). Some patients who meet clinical diagnostic criteria for RA set by the American Rheumatism Association fail to express RFs at any time during their clinical course. To determine if seronegative (RF-) patients with RA, so designated by the latex fixation, Rose-Waaler classic binding assays, or a RF enzyme linked immunosorbent assay (ELISA), express the RCRI in the absence of detectable RFs we examined pokeweed mitogen plasma cells from these patients by indirect immunofluorescence. In addition, we used an inhibition ELISA to detect RCRI bearing molecules in the sera of RF- patients with RA. Five of 10 RF- patients with RA had a high prevalence of RCRI+ plasma cells (16-49% of total pokeweed mitogen plasma cells in culture). Six of 20 RF- patients with RA had high serum concentrations of molecules marked by the RCRI, equivalent to 21-110 micrograms/ml of RCRI+ reference monoclonal IgM RF. Four of five patients who expressed the RCRI in high prevalence in pokeweed mitogen plasma cells, also demonstrated high concentrations of RCRI in their sera detected by inhibition ELISA. There was significant concordance of RCRI expression determined by the two different assays. Four RF- patients with RA who expressed RCRI in their whole sera had hidden RFs detected in their 19S and, in one case, 7S serum fraction. Detection of RF related molecules in whole sera by the expression of RCRI in RF- patients with RA identifies a subgroup of RF- patients with RA who possess hidden RFs. Some RF- patients with RA can express the major RCRI in pokeweed mitogen plasma cells and in their sera and therefore are related to patients with prototypic Waldenstrom's macroglobulinaemia, who produce RCRI+ 19S IgM monoclonal RFs.

HLA class III haplotypes in multicase rheumatoid arthritis families

The class III complement proteins (C2, BF, C4A, and C4B) were studied in 57 multicase rheumatoid arthritis (RA) families. When the gene frequencies for RA probands were compared to a normal control panel (162 haplotypes), a significantly higher frequency of the rare variant C4B*3 was observed (p less than 0.05). No significant differences were seen for the other C2, BF, C4A, or C4B alleles. The most common haplotype found in the probands was HLA-Cw5,B44,C2*C,BF*S,C4A*3,C4B*3,DR4, occurring with a frequency of 0.088. Haplotypes containing HLA-DR4 and Bw62 were found to carry either C4A*3,C4B*3; C4A*3,C4B*1; or C4A*4,C4B*2. When only haplotypes containing DR4 were compared between probands and controls, the frequency of the C4B*3-bearing haplotype remained higher in the probands. It is concluded that Bw62,C4A*3,C4B*3DR4 is a haplotype which is especially associated with RA. The low frequency in the RA population of this haplotype indicates that C4B*3 has a minor role in overall RA susceptibility.

HLA DQ alpha and DQ beta restriction fragment length polymorphisms associated with Felty's syndrome and DR4-positive rheumatoid arthritis

HLA DQ alpha and DQ beta cDNA probes were used to study TaqI generated restriction fragment length polymorphisms (RFLPs) in DR4-positive patients with Felty's syndrome (FS), seropositive rheumatoid arthritis (RA), and in HLA-DR4 positive controls. The results of this analysis revealed two DQ beta RFLP patterns (DQ beta 3a and DQ beta 3b) associated with DR4, of which DQ beta 3b was found at significantly higher frequency in patients with FS (73%) or with RA (52%) than in DR4 controls (29%). Hind III generated RFLPs provide evidence that DQ beta 3b is in strong linkage disequilibrium with the gene encoding the serologically recognized epitope TA10. Results obtained using a DQ alpha chain probe revealed polymorphic differences between DQ alpha chain genes associated with different DR types, thereby providing a possible explanation for the lack of association between RA and other DR haplotypes in linkage disequilibrium with TA10. We conclude that both DQ alpha and DQ beta genes may be important in determining HLA-linked susceptibility to severe forms of RA.

HLA haplotypes in non-familial rheumatoid arthritis

The frequencies of HLA-A, B, C, DR, and BF haplotypes in 44 unrelated Caucasian patients with definite seropositive rheumatoid arthritis (RA) were compared with haplotype frequencies in controls. Overall, the patients had an increased risk for HLA-DR4, DR3, and DR2 antigens, but frequencies of certain DR4 or DR3 haplotypes were not increased, suggesting the importance of other HLA loci for the evaluation of risk. The presence of DR4 alone was not found to produce an increased risk for RA since the frequencies of certain DR4 haplotypes were similar in patients and controls. Increased frequencies of HLA-B18, DR4, HLA-B15, DR4, and HLA-A1, B8, Cw7, DR3 haplotypes were found in patients. RA susceptibility has been found to be associated with the last two haplotypes in some studies of multiple case families, suggesting that similar genetic mechanisms may underlie the disease in familial and sporadic forms.

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.

Identification of HLA-Dw14 genes in DR4+ rheumatoid arthritis

Genes of the major histocompatibility complex, HLA, are associated with susceptibility to rheumatoid arthritis (RA), but the aetiology of this chronic inflammatory disease is not known. Synthetic oligonucleotide DNA probes were constructed to distinguish between two closely related but distinct alleles encoding the HLA-DR4 specificity in patients with RA. With these allele-specific oligonucleotide probes an uncommon DR4 genetic variant, Dw14, was identified in 6 of 7 RA patients homozygous for HLA-DR4. This allele may play an important part in susceptibility to RA.

HLA and rheumatoid arthritis: a combined analysis of 440 British patients

Four hundred and forty unrelated British Caucasoid patients with rheumatoid arthritis (RA) have been HLA typed for class I and class II antigens. Analyses of HLA antigen associations were performed on the overall group and in patient subsets selected according to particular disease parameters or sex, or both. The results confirm previously reported positive associations of HLA-DR4, Dw4, and DRw53 and negative associations of HLA-DR2 and DR7 with RA. Patients subsets with severe erosions, seropositivity, and features of extra-articular disease showed a stronger association, also confirming earlier reports. The link between HLA and disease severity was emphasised by a significant trend of increased Dw4 frequency with increasing severity of radiological erosions. In addition, a positive association of RA with HLA-A2 was observed and a strong negative association with DR3. The frequency of HLA-B27 was significantly increased in patients with subluxation of the spine. Differences were observed between male and female patients in relation to the HLA association. In men an increase in the frequency of the haplotype HLA/Dw4/DR4/Bw62/Cw3/A2 was observed. This showed no relationship with parameters of disease severity other than extra-articular disease. In women only class II antigens (DRw53/Dw4/DR4) showed an increased frequency. This increase was strongly associated with disease severity. A significant decrease of this class II association was observed with increasing age of disease onset; this was not seen in men.

Association of different HLA antigens with various toxic effects of gold salts in rheumatoid arthritis

An association of gold induced proteinuria with HLA-D(R)3 has been reported. To investigate other possible relationships between gold toxicity and HLA antigens we studied 85 patients with rheumatoid arthritis (RA) divided into four subgroups: patients with gold induced interstitial pneumonitis, mucocutaneous lesions, proteinuria, and patients without gold toxicity. The HLA frequencies in patient groups and 283 healthy controls were compared in different pairwise combinations. Gold induced pneumonitis was associated with HLA-B40 and Dw1. An association between gold induced proteinuria and HLA-Dw3 was also seen. The increased prevalence of Dw4 in RA was observed only in the control patient group without gold induced side effects. The frequencies of HLA-B7 and Dw2 were decreased in all patient groups compared with the control population. These results further support the view of the heterogeneity of RA as manifested by the unique HLA associations with resistance and susceptibility to gold induced side effects characterising different subgroups.

HLA antigen associations with extra-articular rheumatoid arthritis

Seventy-seven patients with rheumatoid arthritis were investigated to examine the frequency of HLA antigens and their relationship to clinical and serological manifestations of extra-articular disease. The phenotype frequencies of DR4, DRw53, Bw62 and Cw3 were significantly increased, compared to normal controls, and there were negative associations with DR2 and DR7. The HLA antigen in strongest association with rheumatoid arthritis was DR4 (73.6%) and the relationship with DRw53 appeared to be secondary. The frequency of DR4 rose to 92% in seropositive patients with extra-articular disease manifestations whose serum contained immune complexes. A high frequency of DR4 was also seen in male patients (86%), reaching 100% in the small group of seropositive male patients with immune complexes. It is suggested that extra-articular disease represents a manifestation of severe classical rheumatoid arthritis and is not an 'overlap' syndrome. We propose that the HLA haplotype Cw3-Bw62-Dw4-DR4-DRw53 makes a greater genetic contribution to disease susceptibility in both extra-articular and male rheumatoid arthritis patients than in other subsets of RA.

Epidemiological study of HLA and GM in rheumatoid arthritis and related symptoms in an open Dutch population

This report deals with the question of whether or not the established association of HLA-DR4 with rheumatoid arthritis (RA) can also be detected in cases of RA as diagnosed in a population survey. For this purpose 6584 persons older than 19 years living in a single community in The Netherlands were investigated for the presence of rheumatoid arthritis and related abnormalities. After five years 83 patients with RA, 30 with only erosive abnormalities on radiological examination (Rad), and 48 with only rheumatoid factor (RF) were reinvestigated and typed for HLA and allotypes of immunoglobulin G heavy chain (GM). On the classification of the initial survey no significant association of HLA-DR4 or GM could be detected in any of the three categories. When the information of the follow-up investigation was taken into account, a reappraisal of the classification resulted in 53 cases with RA, 18 with Rad only, and 35 with RF only. The frequencies of HLA-DR4 and GM in the three categories were also about the same as those in normal controls. However, an increase in the frequency of HLA-DR4 was observed in cases of RA positive for Rad, RF, or both. We found no evidence for an interaction between HLA-DR4 and GM. Our results suggest that rheumatoid arthritis is a heterogeneous disorder, only a fraction of which is associated with HLA-DR4. At present no single determinant of RA such as Rad or RF can characterise the HLA-DR4-associated, and most probably more severe, type of RA.

[HLA-A, B, C, and DR typing in rheumatoid polyarthritis]

HLA-A, B, C typing were performed in 72 caucasians with rheumatoid arthritis. HLA-DR typing were accomplished in 40 patients among these 72 subjects. DR4 was clearly increased with a frequency of 55 p. 100 versus 18 p. 100 in controls. We did not find an association between DR4 and the presence of rheumatoid factor. Clinical and biological signs are similar in rheumatoid arthritis with and without DR4. Two other HLA antigens, B40 and Cw3, were increased and their frequency was twice as high in patients as compared with controls. A synthesis of six studies published in the world confirms the elevation of B40 in this disease and later on suggests the elevation of Cw3 which is often linked with B40. The association of rheumatoid arthritis with B40 and Cw3 can be explained by a linkage disequilibrium between DR4 and B40 on the one hand, between DR4 and Cw3 on the other hand.

Extended haplotypes of chromosome 6 in adult rheumatoid arthritis

In 46 patients with rheumatoid arthritis (RA) the allele C4B*3 occurred in 6 patients, while among 350 normal controls, it occurred 6 times (P less than 0.00002). Among 9 white and 1 black families, each of which had 2 or more members with RA, there were 36 haplotypes associated with RA. An extended haplotype (specific HLA-B, DR, complotype haplotypes in significant linkage disequilibrium) containing C4B*3: HLA-B15, DR4, BF*S, C2*C, C4A*3, C4B*3, was found twice (P less than 0.001) among whites with the disease-associated chromosomes.

HLA DR antigens and disease expression in rheumatoid arthritis

Ninety-four patients with rheumatoid arthritis who possessed one or more of the HLA DR alloantigens 2, 3, or 4 were studied to investigate the genetic influence on disease severity and prognosis. In those with a disease duration of less than 10 years radiological damage was less in patients with DR2 than in those without this antigen. When current joint scores were compared, patients with this antigen had less evidence of disease than patients with DR3 or 4, DR3 patients having the highest scores. The presence of nodules and Sjögren's syndrome were less common in the DR2 patients. Variability in response to disease modifying drugs according to the patient's HLA DR antigen status may explain these differences. It is concluded, however, that possession of HLA DR2 may be an indicator of good prognosis in patients with rheumatoid arthritis.

Rheumatoid arthritis: relationship with HLA-D

Understanding of the genetic component of rheumatoid arthritis has been greatly enhanced by the discovery of the association of risk for development of this disease with certain histocompatibility antigens. The HLA-D region, at the centromeric end of the HLA gene complex, on the short arm of chromosome number 6, is concerned with important functions in the regulation of the immune response. The products of the HLA-D region (DR, SB, MT, and the like) function as "restriction elements" for antigen presentation, mediators of immune response and immune suppressor genes, stimulators of graft rejection, and of other allogenic effects. Rheumatoid arthritis is associated with Dw4 and DR4 in Caucasians. The association with DR4 has been observed also in Blacks and Orientals. HLA-DR4 is associated with more severe, rheumatoid factor-positive disease. Clinical and genetic heterogeneity has been revealed by studies of patients with juvenile arthritis. Conditions often associated with rheumatoid arthritis and also thought to have an immunologic basis, such as Sjögren's syndrome, Felty's syndrome, and rheumatoid vasculitis, and reactions to medications, such as gold and penicillamine, reveal an interesting spectrum of immunogenetic relationships. Thus, HLA studies have shed light on the classification of patients with rheumatoid diseases. In view of the role of HLA-D in the immune response, these studies are expected to further our understanding of the mechanism underlying predisposition for development of rheumatoid arthritis and related conditions.

The association between rheumatoid arthritis and the HLA antigen DR4

One hundred and forty-two patients with 'definite' or 'classical' rheumatoid arthritis (RA) were studied for the frequency and possible prognostic significance of HLA DR4. Of these, 122 were seropositive, while 20 were negative for rheumatoid factor (RF) in serum. The HLA antigen DR4 was significantly increased in the seropositive group (65%) as well as in the seronegative group (55%) in comparison with a frequency of 27% in 116 healthy controls. Among seropositive patients a higher frequency of DR4 was found in females (73%) than in males (50%), the difference being statistically significant (p less than 0.01). DR4 was more frequent among patients with a family history of RA (74%) than among patients without affected relatives (57%). DR4 appeared to be associated with an early onset of RA. No significant differences in general disease activity or functional capacity between DR4-positive and DR4-negative RA patients were found. Patients without the HLA antigen DR4 had a significantly (p less than 0.05) higher mean titre of RF than those with the antigen.

Dermatologic conditions reported in patients with rheumatoid arthritis

Dermatologists, while becoming increasingly involved in the diagnosis and management of patients with connective tissue diseases, have left rheumatoid arthritis relatively unexplored. An increased awareness of possible pathomechanisms of rheumatoid arthritis may allow for generalizations that lead to increased understanding of other connective tissue disorders. The types of cutaneous disorders that occur in association with rheumatoid arthritis include: vasoreactive dermatoses (e.g., various forms of vasculitis), which may occur secondary to the circulating immune complexes present in rheumatoid arthritis; autoimmune bullous disorders, which may occur in the setting of a suppressor T cell defect in rheumatoid arthritis; and various miscellaneous cutaneous associations. Hopefully, this review will lead to an increased understanding of both rheumatoid arthritis and the wide array of cutaneous associations of rheumatoid arthritis.

HLA-DR antigens and disease patterns of rheumatoid arthritis

HLA-DR antigens were determined in 111 patients with classic or definite rheumatoid arthritis. HLA-DR4 was significantly (P corr. less than 10(-6] increased in patients with rheumatoid arthritis (54%) compared with controls (23.2%). HLA-DR 5 was decreased in rheumatoid arthritis (12.6% vs 26.4% of controls); however, the corrected P value was not significant. There were no significant differences with regard to various clinical, radiological and serological parameters between HLA-DR 4 positive and negative patients. However, a milder course of rheumatoid arthritis was observed in DR 7 positive patients: Patients with this antigen were associated significantly with seronegativity and low titers of IgM-rheumatoid factor. Despite a similar disease duration patients with DR 7 had a significantly lower number of joints with inflammatory arthritis (synovitic swelling with limitation of movement) and developed less frequently severe radiological changes as joint ankylosis than DR 7 negative patients. In addition to the well known association between rheumatoid arthritis and HLA-DR 4, our data indicate that HLA-DR 7 may have a protective effect on the course of rheumatoid arthritis.

HLA DR antigens in rheumatoid arthritis

The prevalence and possible prognostic significance of HLA-DR antigens have been studied in 129 patients with seropositive (RF-positive) classical rheumatoid arthritis (RA). HLA-DR4 was increased in RA, whilst HLA-DR2 was decreased, though it was not associated with either low titres of RF or with good prognosis. HLA-DR3-positive patients had the highest prevalence of antibodies to nuclear antigens, and the antigen correlated negatively to the presence of subcutaneous nodules, bony erosions and familial RA. RA patients possessing DR3 thus had some of the characteristics of SLE. HLA-DR5 was not present in male RA patients. An absence of familial RA was observed among DRw8-positive patients.

Association between HLA and Japanese patients with rheumatoid arthritis

Japanese patients with rheumatoid arthritis (RA) were observed to have a statistical association with HLA-DR4, MT3. Strong association between the clinical severity of RA and HLA was also observed. Male patients had a stronger association with HLA than female patients. Males are more resistant to RA than females. This suggested that the threshold of liability for RA is higher in males than in females. Japanese patients with RA with systemic vasculitis were negative for HLA-Bw44 and had antilymphocytotoxic autoantibody, indicating that RA with systemic vasculitis is different in etiology from RA without systemic vasculitis.

Seronegative rheumatoid arthritis. A distinct immunogenetic disease?

Measurement of serum rheumatoid factor (RF) by conventional methods in patients with rheumatoid arthritis (RA) has repeatedly identified a subpopulation of patients without detectable RF. Previous investigators have consistently confirmed the association of HLA-DR4 with seropositive RA, but studies of seronegative RA have been limited and contradictory. We studied 140 randomly selected patients from Alabama, all of whom had either classic or definite RA, and we were able to complete HLA typing for 110 of these individuals. Eighty were consistently seropositive (on at least 2 separate occasions) and 30 were consistently seronegative (on at least 3 separate determinations). There was no statistically significant difference between the seronegative RA patients and 123 control subjects in the distribution of DR antigens. In seropositive RA, there was a significant increase in DR4 (P less than 0.001; relative risk = 8.02; attributable risk = 49.2%) and a significant decrease in DR3 (P less than 0.001; relative risk = 0.14) and DR7 (0.01 greater than P greater than 0.001; relative risk = 0.33). The clinical data also distinguished between seropositive RA and seronegative RA; subcutaneous nodules (37.5%) and vasculitis (6.3%) were present only in seropositive RA. DR4 positively did not correlate with any of the clinical variables measured in the seropositive RA group. In contrast, DR4 in the seronegative RA group was associated with more destructive disease. The data suggest that seronegative RA represents a disease entity clinically and immunogenetically distinct from seropositive RA. Moreover, our results indicate that DR4 may be a previously undisclosed marker for disease severity in seronegative RA.

HLA and rheumatoid arthritis. A study of five families

Five families with two or more members ill with rheumatoid arthritis were investigated clinically. Tissue typing for HLA A, B, C and D/DR antigens was performed. We could not define may HLA haplotype associated with disease within these families. However, the prevalence of the haplotypes containing HLA-DR4 was high, suggesting a direct relationship between DR4 and increased risk of contracting rheumatoid arthritis.

Genetic aspects of rheumatoid arthritis

Studies on the population of patients with rheumatoid arthritis and families with multiple cases of rheumatoid arthritis have provided definite evidence that susceptibility to the disease is determined both by genetic factors associated with alleles of the major histocompatibility complex as well as environmental factors. The development of seropositive, but not seronegative rheumatoid arthritis is associated with the presence in an individual of the Ia alloantigen HLA-DR4. This association is common to all major ethnic groups. Some evidence exists that this association is stronger in patients that have more severe disease but this fact requires further study. The fraction of the seropositive patients with rheumatoid arthritis that lack HLA-DR4 has not been well characterized. The occurrence of certain untoward side effects of therapy is influenced by the presence of HLA-DR2 or HLA-DR3. Family studies emphasize the association with HLA-DR4, and indicate that the disease has a dominant mode of inheritance with partial penetrance. The inheritance of susceptibility appeared, at least in some families, to be primarily associated with the inheritance of HLA-DR4 itself and not well explained by a hypothetical disease susceptibility gene present at low frequency and associated in linkage disequilibrium with a HLA-DR4 marker. However, in others different mechanisms appeared more likely. A model of two MHC genes involved in influencing disease susceptibility is postulated. Speculations concerning the primary disease mechanism are presented involving abnormalities of IR genes, general immune regulation, and factors outside of the immune system.

HLA DR4 and rheumatoid arthritis in Japanese people

Eighty-eight Japanese patients with rheumatoid arthritis and 104 normal Japanese persons were typed for HLA A, B, C, and DR antigens. The frequency of HLA DR4 was 70.5% in patients compared with 46.1% in normal controls (P less than 0.001). However, a sex difference in the frequency of HLA DR4 in patients was noted. HLA DR4 was found in 80.6% of male patients, which was highly significant compared with controls (P less than 0.0005), while only a borderline increase of 60.5% was found in female patients (P less than 0.05). In addition, the frequency of HLA DR2 was remarkably low in male patients. These suggest the possible heterogeneity of rheumatoid arthritis in Japanese.