Immune responses during human schistosomiasis mansoni. XVI. Idiotypic differences in antibody preparations from patients with different clinical forms of infection.

Antibodies were purified from pooled sera from patients with different clinical forms of schistosomiasis mansoni on immunoaffinity columns of schistosome soluble egg Ag (SEA). As previously reported, T lymphocytes in PBMC preparations from schistosomiasis patients (but not control subjects who have never been infected) proliferate when cultured in the presence of certain of these anti-SEA purified antibodies. We now show that PBMC from most patients with chronic schistosomiasis, regardless of the clinical form of their infection, respond to anti-SEA antibodies from sera of asymptomatic (intestinal) or hepatointestinal patients. In stark contrast, none responds to anti-SEA antibodies purified from sera of acute or hepatosplenic patients. All of these multiclonal anti-SEA antibody preparations were active in anti-SEA ELISA assays and gave comparable patterns of reactivity with SEA upon immunoblotting analysis. Immunization of rabbits with some of these anti-SEA antibody preparations, followed by absorption of the rabbit antisera on absorbents of normal Ig, produced specific anti-Id reagents. Use of these reagents in competitive ELISA systems demonstrated that the Id in stimulatory and nonstimulatory anti-SEA antibody preparations differ with regard to the proportion of the serologically defined Id expressed by each. It appears possible to screen patients' plasmas for the presence of shared Id by use of suitable Id/anti-Id competitive ELISA assays. Taken together these data indicate that only certain Id-positive preparations are stimulatory to patients' PBMC, and the expression of these T cell stimulatory, immunoregulatory Id on anti-SEA antibodies correlates with the clinical form of a patient's infection.