TRYPANOSOMA-CRUZI - PARTICIPATION OF INTRACELLULAR CA2-MACROPHAGE INTERACTION( DURING METACYCLIC TRYPOMASTIGOTE)

The interaction between Trypanosoma cruzi, the protozoan causative of Chagas's disease, and its host cell is a complex process in which mult iple signals including those of Ca2+ are involved. Macrophage cytosoli c Ca2+ levels were studied during the interaction of these cells with metacyclic trypomastigotes of T. cruzi, since this event is an initial step in the natural infection. In this model we detected an increase in the macrophage cytosolic Ca2+ concentration after infection, or inc ubation with a metacyclic lysate or with isolated membranes, suggestin g that these increments could be necessary for parasite invasion. This fact was confirmed by treating macrophages with a Ca2+ chelator or a Ca2+ channel antagonist which decreased the infection percentages whil e parasitization levels increased after treatment with a Ca2+ channel agonist. (C) 1996 Academic Press, Inc.