[Class II HLA antigens and rheumatoid factors in rheumatoid polyarthritis. Inverse influence of DR4 and DR7 antigens?].

A linkage disequilibrium was searched for between HLA-DR antigens and rheumatoid factor level both measured using latex agglutination and a solid phase immuno-enzymic assay (FR-PAP) among 251 sera from patients suffering from classical rheumatoid arthritis for at least 5 years, recorded in the Cooperative Swiss Study on Rheumatoid Arthritis. An association between the presence of HLA-DR7 and low levels of rheumatoid factor was found. This association was stronger when the DR4, 7 heterozygous subjects were excluded. The comparison of the DR7, not equal to 4 and DR not equal to 4, not equal to 7 subjects demonstrated that the DR7 effect was independent of DR4. Although the association between DR4 and high levels of rheumatoid factor was not statistically significant in this study, these data suggested an opposite influence of DR4 and DR7 on rheumatoid factor level among rheumatoid arthritis suffering patients. The influence of DR4 appeared to be dominant among heterozygous DR4, 7 patients.