Killing of Trypanosoma cruzi and Leishmania mexicana, and survival of Toxoplasma gondii, in chicken macrophages in vitro.

Abstract

The interaction between trypomastigotes of Trypanosoma cruzi, amastigotes of Leishmania mexicana mexicana and tachyzoites of Toxoplasma gondii with chicken macrophages, obtained by cultivation of blood monocytes, was studied. Mouse macrophages were used for comparative purposes. All three protozoa are ingested by chicken macrophages. However, only T. gondii survives within cytoplasmic vacuoles. Trypomastigotes of T. cruzi and amastigotes of L. mexicana are destroyed within endocytic vacuoles of chicken macrophages, independently of the temperature of incubation (33 or 37 degrees C), while multiply within mouse macrophages. By use of horseradish peroxidase labeling of the chicken macrophage lysosomes we show that fusion of lysosomes with phagocytic vacuoles containing T. cruzi occurs. We also show, using ultrastructural cytochemistry, the presence of H2O2 within endocytic vacuoles containing T. cruzi. These results suggest that cellular mechanisms, besides the well known effect of complement, play some role in the refractiveness of birds to trypanosomatids.