Immune response of guinea pigs to Schistosoma mansoni. I. In vitro effects of antibody and neutrophils, eosinophils and macrophages on schistosomula.

Schistosomula of Schistosoma mansoni were rapidly killed in vitro by IgG2 antibodies from serum of schistosome-infected guinea pigs and heat-labile factors present in normal serum. Addition of polymorphonuclear neutrophilic leukocytes greatly increased the rate and degree of killing. Eosinophils and macrophages did not increase the level of killing, though they did react with schistosomula already damaged or killed by antiserum. Neutrophils and eosinophils reacted with schistosomula only in the presence of specific antibody, while macrophages nonspecifically attacked dead schistosomula. Serum antibody levels reached a plateau at approximately 6 weeks after a single infection. Attempts to precoat schistosomula with antibody prior to exposure to complement were largely unsuccessful.