Immunization against Schistosoma mansoni in rhesus monkeys and the requirement of activation of both cell-mediated and humoral mechanisms.

When groups of rhesus monkeys were pretreated with BCG plus hyperimmune serum from monkeys with chronic schistosomiasis or with dialyzable transfer factor from uninfected monkeys plus hyperimmune serum and were challenged with 1,500 cercariae of Schistosoma mansoni, the mean worm burdens were significantly lower than that of untreated controls. Pretreatment with neither BCG alone nor Corynebacterium parvum plus a membrane antigen of adult worms of S. mansoni affected susceptibility. Neither lymphocyte proliferation in the presence of mitogens or schistosome antigen nor serological responsiveness (as measured by gel diffusion, Cercarienhüllenreaktion, circumoval precipitation, or enzyme-linked immunoabsorbent assay) correlated with the degree of resistance of the animals to S. mansoni. The pretreatment procedures used did not cause any abnormal histopathological responses and did not alter the characteristic host response to schistosome eggs in the lungs, liver, mesenteric lymph nodes, and colon.