An evaluation of two methods for detection of circulating immune complexes in patients with rheumatoid arthritis.

Immune complexes were detected by Clq-binding activity (Clq-BA) in 58% of 107 patients with seropositive rheumatoid arthritis (RA), and in 24% of 31 patients with seronegative arthritis. The difference is significant. Immune complexes were detected by the anticomplementarity test (AC) in approximately half of the patients without significant inter-group differences. No correlation was observed between the two methods. In 35 randomly selected patients with seropositive RA, a significant correlation was observed between Clq-BA and the functional class and the latex titre for rheumatoid factor. In patients with seronegative RA, the Clq-BA was significantly correlated to the number of joints with impaired mobility. The AC test was correlated to the erythrocyte sedimentation rate and the concentration of hemoglobin and gammaglobulin in patients with seropositive RA. As regards the clinical activity of disease, erythrocyte sedimentation rate and hemoglobin seem better parameters than the Clq-BA and AC tests.