Circulating immune complexes in onchocerciasis.

Circulating immune complexes were detected in sera of patients with both localized and generalized onchocerciasis by a 125I-Clq binding assay but not by the IgG latex agglutination inhibition method. Gel filtration of sera demonstrated high molecular weight Clq-reactive material(greater than 2 x 10(6) Daltons) which contained IgM but no IgG. Antibody titres to Onchocerca volvulus antigen were higher in patients with generalized disease than in those with the localized form. The lack of correlation between antibody titres and levels of immune complexes suggests that these immune complexes contain antigens other than those derived exclusively from the parasite. Although few of the symptoms of this disease are likely to be due to deposition of circulating immune complexes, the depression of delayed hypersensitivity reactions to the parasite found in patients with generalized onchocerciasis may be due to IgM immune complexes exerting an immuno-regulatory role on T cell function.