[Effects of cytokine-activated macrophages on intracellular leishmania].

The effects of activated macrophages on Leishmania donovani amastigotes and nitrite (NO2-) release were determined by in vitro inducement of macrophage activation with recombinant IFN-r, TNF-alpha, and rIL-3. The results indicated that rIFN-r or rTNF-alpha at 40,000U/L was able to induce a significant but modest level of macrophage activity, and synergistic effect of rIFN-r and rTNF-alpha was apparent in the induction of macrophage activation. 48 hours after macrophages were induced with both rIFN-r and rTNF-alpha, the percentage of the macrophages infected by Leishmania donovani was 16%, and the mean number of the parasite per infected macrophage was 1.2 +/- 0.04. There was a strikingly significant difference in comparison with the control group, in which the infection rate of macrophages was 62% and the mean number of the parasite per infected macrophage was 6.8 +/- 0.10. However, no significant difference was noted between rIL-3 at 1/100 concentration, alone or combined with rIFN-r, and the control in leishmanicidal activity of macrophages. An increase of NO2- in the culture supernatants was paralleled by the ability of various cytokine-activated macrophages to kill the intracellular parasites.