Studies on immune complexes in rheumatoid arthritis.

Sera and synovial fluids of patients with rheumatoid arthritis were studied for immune complexes by means of the anti-antibody inhibition test; approximately 40% of these specimens were shown to contain immune complexes. To study the nature of antigens participating in the formation of complexes under investigation, the anti-antibody inhibition test was repeated after addition of various soluble antigens to the complex-positive rheumatoid arthritis sera. This resulted in conversion of some sera from inhibitory to noninhibitory. It was found that of 15 positive rheumatoid arthritis sera, 7 had complexes formed by heterophile, Hanganutziu-Deicher antigen and of 12 positive sera tested, 2 had complexes formed by human IgG.