Clq binding in serum in juvenile rheumatoid arthritis.

The Clq assay for antigen-antibody complexes was performed on 79 blood samples from 43 patients with juvenile rheumatoid arthritis (JRA). The results were compared with assays for the activation products of C3 (C3c,d), for the concentration of C3, for rheumatoid factor, and for antinuclear antibodies. A statistically significant association was found between Clq binding and positive tests for latex fixation and C3c,d in systemic and polyarticular JRA, but positive results of each assay were found independently. These 3 assays were usually negative in pauciarticular JRA. No relationship was found between Clq binding and C3 concentration or antinuclear antibodies.