Effect of Zinc-Treated Entamoeba histolytica on the Human Polymorphonuclear Respiratory Burst

One of the mechanisms that Entamoeba histolytica uses to evade host immune response is inhibition of the polymorphonuclear (PMN) leukocyte respiratory burst. In studies previously conducted in a model used in our laboratory, we observed that when treating trophozoites with different zinc concentrations certain amebic functions are inhibited while significantly limiting development of hepatic abscess in golden hamsters (Mesocricetus aureatus). We carried out an in vitro study using a chemoluminescent method to assess the effect zinc-treated amebic trophozoites exercise on respiratory burst in human PMNs. We measured response of PMNs incubated with E. histolytica trophozoites from cultures with TYI-S33 medium alone and with zinc. Zinc concentrations between 0.1 and 1.0 mM did not affect amebic trophozoite viability, and PMNs in contact with these in a zinc-free medium had an oxidative response similar to that obtained with zymosan and significantly greater (p <0.05) than that generated by cells co-incubated with amebas cultured in TYI-S33 medium alone. These results suggest that zinc alters the amebic mechanism that inhibits the oxidative function of human polymorphonuclear leukocyte.