Effects of leukotriene C4 on macrophage association with and intracellular fate of Trypanosoma cruzi.

Leukotriene C4 (LTC4) enhanced the association of mouse peritoneal macrophages (MPM) with Trypanosoma cruzi, increasing the proportion of MPM associating with parasites and the number of trypanosomes per MPM. LTC4 affected both cells since pretreatment of either one increased the association. LTC4 also enhanced MPM uptake of killed T. cruzi or latex beads, denoting stimulation of phagocytosis. However, since LTC4 pretreatment of rat heart myoblasts--nonphagocytic cells--also increased the association, host cell membrane alterations induced by LTC4 may also facilitate parasite invasion. Inhibition of MPM guanylate cyclase abrogated the LTC4 effect, suggesting a role for elevated levels of cyclic GMP. LTC4 also increased the rate of intracellular parasite killing by MPM. These results suggest that LTC4, occurring in inflammation such as develops in T. cruzi infection, regulates parasite clearance by MPM by increasing uptake and intracellular destruction.