Resistance to Infection with Schistosoma Mansoni after Immunization with Worm Extracts or Live Cercariae: Role of Cytotoxic Antibody in Mice and Guinea Pigs

Abstract

Mice and guinea pigs were immunized with adult and cercarial extracts prepared in different ways. Most animals responded by producing moderate to high levels of cytotoxic antibody; but no correlation with resistance to infection could be detected. Initial experiments with a 3M KC1 extract and with cercarial exoantigen produced partial resistance; several attempts to reproduce these results tailed. Mice immunized either by live or attenuated cercariae, while developing very low levels of cytotoxic antibody, were highly resistant to challenge infection. These results are discussed in terms of a failure to induce a cooperative immune mechanism required for the action of cytotoxic antibody. It is suggested that homocytotropic antibodies may play a gatekeeper role by initiating a reaction that promotes the transloction of serum cytotoxic antibodies and cells into the tissue surrounding the migrating schistosomules.