Abstract

The cellular and humoral immune responses of CF1 and C57BL/6 mice with schistosomiasis mansoni were evaluated before and after chemotherapeutic cure of their infections by praziquantel. Mice were infected for either 10 or 20 weeks prior to treatment and followed until 10 weeks after treatment. Peripheral blood eosinophilia, without concomitant general leukocytosis, was observed within 3 days of treatment and persisted for up to 4 weeks. By 6 and 10 weeks after treatment schistosomal-associated hepatosplenomegaly had greatly decreased. Delayed-type hypersensitivity to a soluble adult worm extract (SWAP) was modulated over 20 weeks of infection, and in C57BL/6 mice this modulation was alleviated by cure. In parallel studies of pulmonary egg granuloma formation, granuloma modulation was not effectively reversed. Antibodies against egg (SEA), cercarial (CAP) and adult worm (SWAP) extracts generally decreased by 10 weeks after chemotherapy of mice that were previously infected for 10 weeks. Mice infected for 20 weeks and then treated, generated increased levels of antibodies to SWAP and CAP by 10 weeks after treatment. Immunoglobulin isotypic analyses largely reflected the results of total antibody studies. These data demonstrate that the duration of infection prior to treatment is a determining factor in subsequent expression of immune reactivity, and provide the immunological background for experiments on resistance following chemotherapy of experimental murine schistosomiasis mansoni.