KILLING OF SCHISTOSOMA-MANSONI SPOROCYSTS BY BIOMPHALARIA-GLABRATA HEMOLYMPH IN-VITRO - ALTERATION OF HEMOCYTE BEHAVIOR AFTER POLY-L-LYSINETREATMENT OF PLASTIC, AND THE KINETICS OF KILLING BY DIFFERENT HOST STRAINS

Behavior of hemocytes of the gastropod molluse Biomphalaria glabrata w as markedly changed on plastic by treatment of the substrate with 0.1 mg/ml poly-L-lysine compared to behavior on untreated plastic. On lysi ne, the cells showed minimal spreading, moved significantly faster, an d formed aggregates. Cell-mediated cytotoxicity (CMC) assays were set up on the modified and untreated substrates to compare the killing cap acities of B. glabrata hemocytes against Schistosoma mansoni sporocyst s. Hemolymph from 1316-R1 (resistant) snails showed higher killing in lysine-treated wells; no significant difference in sporocyst mortality was observed in MO (susceptible) hemolymph between treated and untrea ted wells. The CMC assays on poly-L-lysine-treated plastic were used t o compare the kinetics of parasite killing in hemolymph from 2 suscept ible (MO, MRLc) and 2 resistant(l316-R1, 10R2) host strains. Marked di fferences could be observed between the two resistant snail strains, s uggesting different mechanisms of parasite recognition, killing, or bo th.