Natural killer cell activity in visceral leishmaniasis

Natural killer (NK) cell activity has received little attention in human visceral leishmaniasis (VL). We have recently shown an imbalance of endogenous cytokine production in VL resulting in predominance of interleukin 4 over IFN- gamma . We therefore tested NK activity in VL with and without exogenous IFN- gamma . NK activity by pbmnc of 3/6 VL patients did not differ appreciably from control cells tested on the same day. However, severe impairment of NK activity was observed in the 3 patients. Whereas, in controls, the addition of 0 multiplied by 1-10 units/ml rIFN- gamma linearly augmented K562 lysis by 10-20%, a markedly dose-dependent enhancement of NK activity was noted in the 2 patients in whom NK activity was not detectable in the absence of exogenous IFN- gamma . In the last patient, 10 units/ml of IFN- gamma more than doubled NK activity.