HLA-DR4 associated Dw types in rheumatoid arthritis

HLA class II and TNF genes in African Americans from the Southeastern United States: regional differences in allele frequencies

Knowledge of population major histocompatibility complex gene frequencies is important for construction of organ donor pools and for studies of disease association. Human leukocyte antigen DRB1 (HLA-DRB1), HLA-DQB1, and TNFalpha -308 (G-A) promoter genetic typing was performed in 112 healthy, unrelated African Americans (AAs) from the southeastern United States. Allele frequencies were compared with published frequency data from other AA populations. Our AA population had the highest frequency of HLA- DRB1*09 (6.7%) reported in any AA population. The frequency of the TNF alpha -308A polymorphism was also high (14.4%), when compared with published frequencies in AAs. Significant regional differences in the distribution of most HLA-DRB1 and HLA-DQB1 alleles were observed in all AA populations examined. The AA HLA-DRB1 and -DQB1 frequencies also differed from published Caucasian frequencies. This is the first report describing the distribution of TNF alpha promoter alleles in the Southeastern United States. The high DRB1*09 and TNF alpha -308A allele frequencies of our population most resemble the frequencies of these alleles in certain West African populations. These varying major histocompatibility complex gene frequencies may reflect different regional population structures among AAs in the United States, which may be due to differences in ancestral origins, migration, and racial admixture.

Predictors of extra-articular manifestations in rheumatoid arthritis

OBJECTIVE

To identify clinical and genetic risk factors for extra-articular manifestations of rheumatoid arthritis (ExRA).

METHODS

ExRA patients were identified retrospectively using predefined criteria in two hospital-based cohorts of RA patients, and compared to non-extraarticular RA controls from one of the cohorts, matched for disease duration.

RESULTS

Forty-nine living and thirteen deceased cases of ExRA were identified. Extra-articular disease was predicted by the demonstration of antinuclear antibodies (Odds ratio (OR) 3.6; 95% CI: 1.4-9.1) and the presence of rheumatoid nodules within two years from RA diagnosis (OR 3.4; 95%, CI: 1.1-10.9) or at any time before ExRA onset (OR 2.8; 95% CI: 1.1-7.2). Male sex and rheumatoid factor did not affect the risk of ExRA. Although present in the majority of cases as well as controls, the disease associated HLA-DRB1 subtypes were not significant predictors of ExRA.

CONCLUSION

Extra-articular manifestations of rheumatoid arthritis in a hospital based population were predicted by antinuclear antibodies and rheumatoid nodules.

Quantifying the exact role of HLA-DRB1 alleles in susceptibility to inflammatory polyarthritis: results from a large, population-based study

OBJECTIVE

To accurately determine the contributions of HLA-DRB1 alleles in explaining susceptibility to inflammatory polyarthritis in a large, true population-based cohort of new-onset cases.

METHODS

A cohort of 680 consecutive patients with inflammatory polyarthritis, of whom 404 satisfied the American College of Rheumatology (ACR) criteria for rheumatoid arthritis (RA), was recruited from the population-based Norfolk Arthritis Register. All cases were compared with 286 local population controls. A standardized clinical assessment was performed on all patients. HLA-DRB1 phenotypes, including DR4 subtypes, were determined using a semiautomated, reverse dot-blot method. Results were expressed as odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

There was only a modest association (OR 1.8, 95% CI 1.4-2.4) between inflammatory polyarthritis and the presence of any shared epitope (SE) allele; the strongest individual risk was with DRB1*0404 (OR 3.5, 95% CI 1.8-6.8). Comparison of the genotypes demonstrated that the effect of being SE homozygous (OR 2.1, 95% CI 1.5-3.0) was only moderately greater than the effect of being SE heterozygous (OR 1.3, 95% CI 1.1-1.6). The exception to this was genotypic combinations that included HLA-DRB1*0404, which exhibited ORs ranging up to 18.0. There were no differences between either the phenotype or genotype data when the patients were stratified by RA status (defined by the ACR criteria). In contrast, the associations were substantially stronger in patients who were positive for rheumatoid factor.

CONCLUSION

Previous studies had not been able to clarify whether the influence of HLA-DRB1 on RA was related to disease susceptibility or to disease severity and progression. These data on a unique population-based incident cohort suggest only weak effects on susceptibility, with the exception of the clearly distinct influence of HLA-DRB1*0404.

Influence of the major histocompatibility complex on age at onset of chronic lymphoid leukaemia

The major histocompatibility complex is one of the interactive factors in the multifactorial model of carcinogenesis. Its main influence in experimental models is on the age at onset of malignancies. We have previously shown a similar effect of homozygosity for HLA-DR53 in CML. In the present study, we investigated 79 patients with CLL and 329 local controls from Germany. In addition to full serotyping, all patients and 116 of controls were also typed by HLA-DRB PCR analysis. The homozygosity rates for DR53 in patients under and over the median age (60 years) were 18.6% and 2.9%, respectively (p = 0.03). Eight of the 9 homozygous patients were under the median age. The sex ratio in the DR53 homozygous group was reversed in favour of females. The homozygosity rates for DR53 were different in the overall groups of patients and controls, yielding a relative risk (RR) of 2.4 (p = 0.03). This association was stronger in the early-onset group compared to age-matched controls (RR = 4.4; p = 0.008) and for females with an early onset compared to age- and sex-matched controls (RR = 17.9; p = 0.0008). The simultaneous occurrence of the alleles of the haplotype A2B62DR4 showed a strong association with CLL (RR = 4.1; p = 0.002). This was probably the reason behind the association with HLA-DRB1*0401 (RR = 2.4; p = 0.009). Compared to the accelerating effect of HLA-DR53, HLA-DR52 showed a significant delaying effect on the onset of CLL. These findings confirmed the influence of the HLA complex on the development of another leukaemia.

Anti-neutrophil cytoplasm antibodies (ANCA) in rheumatoid arthritis: relationship to HLA-DR phenotypes, rheumatoid factor, anti-nuclear antibodies and disease severity

To investigate a possible relationship between the presence of anti-neutrophil cytoplasm antibodies (ANCA), rheumatoid factors (RF), anti-nuclear antibodies (ANA), disease severity and HLA-DR phenotypes, 46 consecutive ANCA+ and 48 ANCA-, clinically well-documented RA patients were studied for RF, ANA and HLA-DR phenotypes. The 46 ANCA+ patients showed predominantly an atypical perinuclear staining pattern (89%). ANCA positivity was associated with higher RF titres (P < 0.005) and advanced functional Steinbrocker grades III/IV (P < 0.015). ANCA+ patients were also more often positive for ANA than ANCA- patients (P < 0.008). There was no correlation between ANCA positivity and certain HLA-DR phenotypes although the frequency of DR4+ (67% vs 52%) and, in particular, of DR4+ blanks (phenotypically homozygous) was increased in ANCA+ as compared to ANCA- patients (20% vs 8%). DR4-DR1-RA patients were twice as frequent in the ANCA- than in the ANCA+ group (22.9% vs 8.7%). Correspondingly, the DR4+DR1- phenotype was increased among ANCA+ RA patients. Regarding functional Steinbrocker grades, the DR4+ phenotypes were slightly but not significantly increased in grades III and IV whereas ANCA positivity was significantly associated with severe functional Steinbrocker grades III/IV (66% ANCA+ vs 39% ANCA-, P < 0.015). ANCA positivity identified a population of RA patients with a long-standing and severe clinical course of the disease. There was no correlation between ANCA positivity and certain HLA-DR phenotypes.

HLA-DRB1 typing of Vogt-Koyanagi-Harada's disease by PCR-RFLP and the strong association with DRB1*0405 and DRB1*0410

Vogt-Koyanagi-Harada's (VKH) disease is reported to be closely associated with the HLA class II antigen, HLA-DR4. Serologically defined DR4 is further divided into 11 alleles by molecular HLA genotyping. However, no study of HLA-DNA typing of VKH patients has been reported. To clarify molecular genetic mechanism underlying the susceptibility/resistance to VKH disease, HLA-DNA typing of DR antigens (DRB1 genotyping) by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was performed. It was found that DRB1*0405 showed a significant association with VKH disease compared with the healthy controls (corrected p value < 1 x 10(-5)) and that all the patients had DRB1*0405 and/or DRB1*0410. The specific amino acid residue shared only by these two alleles is Ser at position 57 which is located in the antigen binding groove and may influence the immunological function as an antigen-presenting molecule, suggesting that Ser at position 57 plays an important role in the susceptibility to VKH disease, although the possibility that the involvement of the HLA-DQ molecule, DQ4, in strong linkage disequilibrium with DRB1*0405 and DRB1*0410, cannot be excluded.

Complete association of the HLA-DRB1*04 and -DQB1*04 alleles with Vogt-Koyanagi-Harada's disease

VKH disease is a bilateral panuveitis and has been known to be closely associated with the particular HLA class II antigens HLA-DR4 and -DQ4, defined by serologic typing. In this study, 63 Japanese VKH patients were analyzed for HLA class II alleles at the DNA level using the PCR-RFLP method. The DRB1*04 alleles encoding the serologic specificity DR4 were found in 100% of the VKH patients carrying DRB1*0405 or DRB1*0410. By statistical analysis, only DRB1*0405 was found to be significantly increased as compared to the healthy controls (RR = 46.7 and pc < 1 x 10(-5)). As to the DQB1 locus, all the patients carried DQB1*0401 or DQB1*0402 expressing the serologic DQ4 specificity, which is in a strong linkage disequilibrium with DRB1*0405 or DRB1*0410 in a Japanese population, respectively. Only DQB1*0401 showed a statistically significant increase as compared to the healthy controls (RR = 41.3 and pc < 1 x 10(-5)). Comparison of the amino acid sequences of these DRB1 and DQB1 alleles indicates that Ser at position 57 of DRB1 and/or Glu at position 70 and Asp at position 71 of DQB1 plays a crucial role in determining the susceptibility to VKH disease.

Analysis of the HLA-DR gene frequencies in Japanese cases of juveniles rheumatoid arthritis and rheumatoid arthritis by oligonucleotide DNA typing

HLA-DR gene frequencies in 59 Japanese children with juvenile rheumatoid arthritis (JRA) and 62 Japanese adults with rheumatoid arthritis (RA) were analyzed by oligonucleotide DNA typing. As in other studies, the frequency of DRB1*0405 in RA patients was significantly higher than in the Japanese controls. In a comparison of non-classified JRA patients with Japanese controls, no significant differences were observed in the frequency of DR types. However, when the JRA patients were classified into four clinical types, i.e., a rheumatoid factor-positive [RF(+)] polyarticular type, a rheumatoid factor-negative [RF(-)] polyarticular type, a pauciarticular type, and a systemic onset type, DRB1*0405 was found to be significantly higher in the RF(+) polyarticular JRA patients than in the controls (P < 0.05). Thus, the RF(+) polyarticular type of JRA had the same HLA association as RA. This result is consistent with the fact that both RF(+) polyarticular JRA and RA cases have a similar clinical course.

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.

HLA and disease

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.

Diversity in HLA-DR4-related DR,DQ haplotypes in Australia, Oceania, and China

The relative distributions of 12 HLA-DR4-related DRB1 alleles in indigenous populations of Australia, Melanesia, Micronesia, Polynesia, and northern and southern China have been determined by analysis of oligonucleotide hybridization patterns of 406 examples of HLA-DR4. DRB1*0405 and DRB1*0410 were common DR4 alleles in Australian aborigines and in Melanesians, while DRB1*0403 was the predominant DR4 allele in coastal Melanesians, Micronesians, and Polynesians; DRB1*0406 was confined to Chinese. A novel DR4 allele, found in 30% of DR4-positive Australian aborigines but exclusive to one aboriginal population, was a combination of DRB1*04 and 0803 nucleotide sequences and was carried on a haplotype with DR4-like DQ linkage arrangements. DQA1 and DQB1 typing generated 12 DR4-related haplotypes; the population distributions of these reflected the ancestral affinities of aborigines and Melanesians, the overlaying of coastal Melanesia with pre-Polynesian DR4 alleles and the colonization of Micronesia by an independent, non-Polynesian group. DR4-related autoimmune disorders such as rheumatoid arthritis (RA) and insulin-dependent diabetes mellitus (IDDM) are virtually unknown in indigenous populations of Australia and Oceania and this study confirmed that high-risk RA determinants, Dw4 and Dw14, occurred rarely. However, the DQw8 allele, thought particularly to predispose to IDDM, was present in the majority of DR4-positive Polynesians and Micronesians.

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.

A variant of HLA-DR4 determines susceptibility to rheumatoid arthritis in a subset of Israeli Jews

HLA-DR4 is associated with risk for developing rheumatoid arthritis (RA) in most populations. In Israeli Jews, in whom the Dw10 subtype of DR4 predominates, no association of RA with DR4 has been found. The inability to detect an association could be due to the high frequency of DR4-Dw10. We used DNA typing with amplification by the polymerase chain reaction and dot-blotting with allele-specific oligonucleotides to determine DR4 variants in 131 Jewish RA patients living in Israel and 134 controls. In both Ashkenazi Jews and non-Ashkenazi Jews, the rare variant Dw15 (previously identified in Japanese populations and in Japanese patients with RA) was found to be the main allele associated with the risk of developing RA (relative risk = 9.2, corrected P less than 0.001). However, this low-frequency allele could be responsible for susceptibility in only 11.5% of the patients. Susceptibility for rheumatoid factor-positive RA was associated with Dw4 and Dw15; the risk for rheumatoid factor-negative RA was associated only with Dw14. The distribution of the HLA-DQ alleles associated with DR4 showed that more than half of the RA patients with Dw15 also had HLA-DQw2. The frequencies of DQw7 and DQw8 were not different in RA patients compared with controls. The results suggest that, as in other populations, susceptibility for the development of RA in Israeli Jews is associated with DRB1 locus alleles of the DR4 group.

Is rheumatoid arthritis in Indians associated with HLA antigens sharing a DR beta 1 epitope?

HLA class II antigens were identified in a group of 44 patients with rheumatoid arthritis (RA) originating largely from the north or northeast of the Indian subcontinent and resident now in east London. Compared with 67 locally typed east London Asian controls, the prevalence of three HLA-DR antigens was raised in the patients: DR1 18.2% v 6.0% chi 2 = 3.99, DR4 20.5% v 11.9% chi 2 = 1.48, and DRw10 27.3% v 8.9% chi 2 = 6.56. These differences were also found when the patients with RA were compared with a larger control group of 110 northern Indians: DR1 18.2% v 7.2% chi 2 = 4.02, DR4 20.5% v 7.2% chi 2 = 5.56, and DRw10 27.3% v 8.1% chi 2 = 9.7. Twenty five (57%) of the patients expressed at least one of these antigens. All patients were also characterised for HLA-Dw types by mixed lymphocyte culture typing. The prevalence of the HLA-DR4 associated Dw types in the patients was: Dw4 2.3%, Dw10 0%, Dw14 11.4%, and Dw15 6.8%. The DR beta 1 chains of DR1 and DRw10 together with the Dw types of DR4 other than Dw10 share amino acid residues in a region of the third hypervariable region considered to be critical in antigen presentation. It is concluded that RA in Indians is associated with these HLA antigens, and data from this study support the hypothesis of a cross reactive epitope common to HLA specificities associated with RA.

HLA-DR1 and DRw6 association in DR4-negative rheumatoid arthritis patients

This study of 110 seropositive rheumatoid arthritis (RA) patients confirms the significant association of susceptibility to RA with HLA-DR4 specificity (P less than 0.001). The DR1 frequency is elevated in the entire seropositive patient group, reaching marginal significance (P less than 0.025). The DR4-negative patients, however, have a much higher prevalence of DR1 (P less than 0.001). Surprisingly, the DRw6 specificity is significantly increased in the remaining DR4- and DR1-negative patients (P less than 0.01). These results demonstrate that RA is not associated with a single HLA-specificity, but to various degrees with DR4, DR1, and DRw6. These findings, and particularly the newly recognized association with DRw6, support the hypothesis that functionally equivalent shared epitopes or conformations on otherwise distinct MHC molecules may confer risk for developing RA.