Circulating immune complexes in tuberculosis.

Using a polyethylene glycol precipitation method, immune complexes were detected in 56% of patients with active tuberculosis. After antituberculous treatment, 29% remained positive for immune complexes, a frequency similar to that in a group of racially matched clinic controls (35%). In a study of 17 patients whose immune complex levels were determined soon after diagnosis and again when the therapy had ceased, there was a significant decrease in complexed IgM and Clq. Sequential studies of immune complex levels in tuberculosis merit further investigation, their persistence may indicate the continued presence of antigens, and their disappearance from the circulation may be a guide to successful treatment.