Trypanosoma cruzi: immunological consequences of parasite modification of host cells.

Parasite antigens released from Trypanosoma cruzi-infected cells were adsorbed to infected and uninfected mammalian cells thus rendering them susceptible to immune lysis by antibody and cell-mediated immunity directed against the parasite. BALB/c mice infected with T. cruzi for 15 days developed cytotoxic T lymphocytes specific for parasite antigens. At 60 days post infection, however, the mice developed an additional population of cytotoxic T lymphocytes that were able to kill normal syngeneic muscle or neuronederived cell lines in vitro. These '60-day" T lymphocytes did not kill HeLa cells unless they were coated with T. cruzi antigens suggesting that the population of atuoaggressive T lymphocytes was not an artefact due to an increase in natural killer cells.