Schistosoma mansoni: ability of con A to protect in vitro mechanically transformed schistosomula against the lethal effect of immune serum plus complement.

Concanavalin A added to a defined culture medium renders schistosomula more resistant to the lethal effect of antibody plus complement. The Con A dose-dependent acquisition of protection reached a plateau at a concentration of 4 micrograms Con A/ml. alpha-Methylmannoside was not able to reverse the Con A-induced protection but excess methylmannoside, added to the incubation medium together with Con A partially prevented the effect of the lectin. Binding of anti-parasite antibody to the schistosomula surface did not change after pre-incubation with Con A. In the presence of puromycin (100 micrograms/ml) Con A is still able to confer protection. Incorporation of labelled amino acid into the tegumental proteins was not affected by Con A. Furthermore, a progressive reduction of protection was observed as the time of culture preceding Con A addition increased.