RESUMEN
Protective immunity against Schistosoma mansoni infection correlates with increased levels of IgE and blood eosinophilia which are considered as markers of anti-parasitic cell-mediated immunity. IL-5 participates as well in the induction and regulation of IgE and eosinophilia, consequently in the development of acquired immunity. Swiss Webster female mice were subcutaneously injected with either 50 micro g of gamma-irradiated cercarial homogenate [400 Gy] twice weekly for three weeks alone or plus a single dose of IL-12 [0.8 ng/Kg]. The efficiency of immunization regimens were assessed 45 days post infection with 100 live cercariae/mouse by the number of worm burden, ova count, production of IL-5, eosinophils, and IgE levels in the vaccinated groups compared with the non-immunized group. The results demonstrated a significant reduction of ova count in the livers of vaccinated groups [57.19 and 40.13%] and worm couples compared with the non -immunized group. Furthermore, a decrease of IL-5 level as well as eosinopenia was recorded in both vaccinated groups. Scanning electron microscope [SEM] of adult worms recovered from the immunized groups revealed marked damage on the tegumental surface in males rather than females as well as constrictions and intensive corrugation of intertubercles