Circulating immune complexes in rheumatic fever.

We measured the circulating immune complex levels in patients with rheumatic fever using the following three methods: the C1q binding test, the conglutinin binding test and Raji cell radioimmunoassay. Thirty-four samples from 21 patients with rheumatic fever were examined, and circulating immune complexes were detected in 47.6% of the patients by one or more of these methods. Especially by the C1q binding test, the sera obtained in the acute phase were found to contain the circulating immune complexes with higher frequency than those obtained in the post-acute phase. Therefore, the C1q binding test was more likely to be useful in the acute phase of this disease. The present study suggests that the circulating immune complexes are related to the pathogenesis of rheumatic fever.