Effect of recombinant tumor necrosis factor alpha on in vitro amoebicidal activity of murine Kupffer cells.

The present study was undertaken to determine whether recombinant tumor necrosis factor alpha (TNF) could induce Kupffer cells to kill Entamoeba histolytica parasite in vitro. C57BL/6 mice were used in this study. The liver was perfused and Kupffer cells harvested and treated with TNF for 6 h. It was found that Kupffer cells treated with TNF are able to kill amoebic trophozoites in vitro. These results further show that amoebicidal activity of TNF-activated Kupffer cells is dependent on the ratio of Kupffer cells to amoebic trophozoites. The maximum amoebicidal activity of Kupffer cells was observed with the ratio of one Kupffer cell to five amoebae. This study also shows that the optimal concentration of TNF is required in the induction of amoebicidal activity in Kupffer cells (10(5) units). It seems that both oxidative-dependent and -independent mechanisms are important for the killing of amoebae by the TNF-treated Kupffer cells. It is likely that TNF-treated Kupffer cells produce endogenous TNF or other cytotoxic molecules which are capable of mediating the parasite killing. Our results indicate that the immunologic production of TNF is important in the activation of Kupffer cells to kill amoebic trophozoites.