Circulating immune complexes in regularly dialyzed patients with chronic renal failure.

The prevalence of circulating immune complexes (CIC) was investigated using the C1q binding assay (C1q BA) and the conglutinin binding assay (Kg BA) in 200 patients undergoing maintenance hemodialysis. Increased C1q binding was found in 45% (87 of 194) of the patients, and the modified Kg BA gave elevated values in 31% (20 of 65). The prevalence of CIC was similar in American and Swiss patients, and in patients undergoing hemodialysis, self-dialysis or peritoneal dialysis. In patients with 'nonimmunological' renal diseases, CIC were detected with similar frequency. No change in CIC was noted during hemodialysis in 6 additional patients tested. The abnormality was not related to age, sex, duration of dialysis, hepatitis B antigenemia, bacterial infections, or transfusions. Anti-DNA antibodies were absent in all subjects tested and the results of the C1q BA were not changed by DNase digestion of eight sera with high C1q binding. Rheumatoid factor activity (RF) was detected in approximately one-fifth of the patients, and there was a direct correlation between positive C1q binding and RF. There was no correlation between CIC and lymphocytotoxic antibodies. This study demonstrated a high prevalence of CIC in dialyzed uremic patients and established its relationship to other immunological abnormalities.