HLA and disease manifestations in rheumatoid arthritis--a Canadian experience.

Forty-eight Canadian patients with rheumatoid arthritis (RA) were tissue typed for class 1 (HLA-A, B, and C) and class 2 (HLA-DR and DQ) antigens in an attempt to identify HLA associations and to relate them to disease manifestations and drug toxicity. HLA-DR4 was found with a significantly higher frequency among patients with RA than in the control population. DR4 correlated with presence of rheumatoid nodules and pulmonary manifestations, and was more frequent among patients who had vasculitis. All 4 patients who died were DR4 positive. DR2 and DR7 were less frequent in our patients. There was no association between the presence of DR3 or DR4 and drug toxicity.