DR, C4, and Bf allotypes in juvenile rheumatoid arthritis.

HLA-DR, C4, and Bf typing was performed in 99 patients with juvenile rheumatoid arthritis (JRA). DR1 was found with higher frequency in patients with polyarticular JRA than in controls (P less than 0.05). DR3 was more common in patients with fever and/or rash than in those without these manifestations (P less than 0.05). A significant negative association between JRA and C4A6 (P less than 0.05), C4BQ0 (P less than 0.0005), and BfF1 (P less than 0.05) was found. It is possible that a disequilibrium between DR and C4/Bf genes plays a role in the pathogenesis of JRA.