Circulating immune complexes and rheumatoid factor in schistosomiasis and visceral leishmaniasis.

Circulating immune complexes, measured by the C1q binding and Raji cell radioimmunoassays, were detected in 16 of 25 (64%) patients with schistosomiasis alone, in all 13 patients (100%) with schistosomiasis infection associated with prolonged bacteremia by salmonella organisms, and in 15 of 18 (83%) patients with visceral leishmaniasis. The C3 levels in the serum of patients with schistosomiasis, with and without prolonged salmonella bacteremia, were significantly lower in those with renal disease. Further, in patients with schistosomiasis alone, the absence of renal involvement was positively associated with C1q binding within the normal range (P = 0.