Mechanism of Acquired Immunity Induced by “<i>Leptomonas pessoai</i>” against <i>Trypanosoma cruzi</i> in Mice*

Abstract

SYNOPSIS Living culture forms of “ Leptomonas pessoai ” cross protected mice against T. cruzi challenge infection. Circulating antibodies have been detected in the immunized mice by immunodiffusion analysis, passive hemagglutination, complement fixation test and antibody binding assay; these antibodies cross reacted with T. cruzi extracts. A cellular immune response was indicated by leucocyte migration inhibition using L. pessoai and T. cruzi antigens, strongly suggesting a role for cell‐mediated immunity in the mechanism of protection induced by L. pessoai.