Circulating immune complexes in patients with rheumatoid arthritis: correlation with disease activity

Abstract

Circulating immune complexes (CIC) have been detected in the majority of patients with rheumatoid arthritis (RA). Their usefulness in monitoring disease activity is still controversial. Thirty-five patients with RA have been studied for the presence of CIC by the C1q binding assay. Abnormally high levels of CIC were detected in 83% of the patients and in 76% of 46 serum samples. Mean C1q binding activity for all serum samples was 27.4 +/- 25 compared to 7.5 /+- 2% in a control group of healthy individuals. A highly significant correlation was observed between C1q binding activity and the following indices of disease activity: the erythrocyte sedimentation rate, the latex and Rose-Waaler tests and a systemic index. The level of CIC in RA patients seems to be a reliable index of disease activity.