HLA-DR antigens in rheumatoid arthritis. A Swiss collaborative study. Swiss Federal Commission for the Rheumatic Diseases, Subcommission for Research.

In a Swiss multicenter study, a significant increase of HLA-DR4 was found in patients with rheumatoid arthritis when compared with normal controls (P less than 0.01). This increase was limited to patients with rheumatoid factors; it was strongest in patients with high titers. Similarly, the frequency of HLA-DR4 was higher in patients with larger amounts of circulating immune complexes when compared with patients with low amounts. No correlation with the presence of antinuclear antibodies was found. HLA-DR1 was more frequent in patients with rheumatoid arthritis than in controls (N.S.). This was due to an increase of HLA-DR1 in patients without rheumatoid factors (P less than 0.05), low amounts of circulating immune complexes (N.S.) and without antinuclear antibodies (P less than 0.05).