On the mechanism of killing ofTrypanosoma cruzi by human polymorphonuclear leukocytes

Summary The temperature-dependence of some processes involved in the killing of sensitizedT. cruzi epimastigotes by human polymorphonuclear leukocytes (PMN) was determined. The rate of the reactions was related to the temperature of incubation according to the Arrhenius equation and the apparent energies of activation (Ea) were calculated. The Ea values separated these complex reactions into two groups: one with Ea of about 10 kcal/mol for the phagocytosis of the parasites and the release of lysosomal enzymes by PMN, and the other with Ea of about 22 kcal/mol for the cytotoxicity against sensitizedT. cruzi, the rate of oxygen consumption by PMN, and the lysis of the parasites with added hydrogen peroxide.This work was supported by research grants from CONICET and SUBCYT, Argentina, and UNDP/Word Bank/WHO Special Programme for Research and Training in Tropical Diseases. The author wish to thank Dr I. Reisin, Dr. A. Boveris and Dr M.M.E. de Bracco for their helpful discussion.