A morphological study of the interaction between Trypanosoma cruzi and rat eosinophils, neutrophils and macrophages in vitro.

The interaction between trypomastigotes of T. cruzi and purified rat eosinophils, neutrophils and macrophages has been studied. Macrophages induced by dextran, became infected and the parasites multiplied as amastigotes, eventually being released as trypomastigotes into the medium. Eosinophils show an antibody-dependent phagocytosis, while neutrophil phagocytosis is enhanced by antibody. Electron microscopy showed that once inside the granulocyte phagosome, the trypomastigotes transform to amastigotes as a prelude to degeneration. This occurs as material apparently of granule origin accumulates in the phagosome. Eosinophils have the capacity to eject incompletely degenerated amastigotes into the medium. This phenomenon is discussed in relation to previous time-lapse cinematography studies of the lysis of chick erythrocytes by eosinophils, and reports that eosinophils release granule contents by means of a secretory vesicle.