Lack of cross-reactivity of lytic antibodies with bloodstream forms of Trypanosoma cruzi zymodemes generated in a mouse experimental model.

Immune sera from mice infected with specific Zymodemes of Trypanosoma cruzi parasites displayed preferential in vitro complement-mediated trypanolytic activity with homologous or genetically related bloodstream trypomastigotes. Culture-derived and metacyclic trypomastigotes were more susceptible to lytic antibodies than bloodstream trypomastigote forms when the same serum panel was tested. Different levels of maximal trypanolytic reaction were observed when several parasites and sera were tested, suggesting that T. cruzi stocks are dissimilar in their efficiency to evade the lytic reaction, probably by capping and shedding mechanisms. A discussion based on the heterogeneity of surface antigens able to elicit the lytic response among different T. cruzi populations is presented.