Immunological studies in human schistosomiasis. II. Antibodies cytotoxic for Schistosoma mansoni schistosomules.

Complement dependent cytotoxic antibodies for Schistosoma mansoni schistosomules were studied in a Brazilian population. The sera of S. mansoni-infected patients gave a high percentage of cytotoxicity (63.4%) compared with sera from persons not infected (8.7%). The IgG class and the specificity of these cytotoxic antibodies are defined. The index of lethality appeared to be independent of the titers of other specific anti-S. mansoni antibodies. A statistical correlation was found between the index of lethality and both the severity of the disease and delayed hypersensitivity to S. mansoni antigen. The significance of cytotoxic antibodies in human schistosomiasis and their relevance to immunity in man are discussed.