Human Neutrophils Activated by Interferon‐γ and Tumour Necrosis Factor‐α Kill Entamoeba histolytica Trophozoites In Vitro

The interaction between cytokine‐activated human neutrophils and Entamoeba histolytica trophozoites was studied as well as the mechanism(s) involved. Treatment of neutrophils with rlFN‐γ alone allowed them to kill 30% of E. histolytica trophozoites; however, rlFN‐γ and rTNF‐α pretreatments in combination increased neutrophil killing to 70%. In the absence of direct contact between neutrophils and amebae, rlFN‐γ‐treated neutrophils were shown to kill 70% of amebae, and rlFN‐γ‐ and rTNF‐α‐treated neutrophils killed 97% of amebae. Neutrophil enhancement of amebicidal activity following cytokine treatments was correlated with Increased neutrophil resistance to amebic contact‐dependent killing and was shown to be 73% H 2 O 2 dependent.