Natural killer activity in experimental cutaneous leishmaniasis.

Studies were performed to determine the role of natural killer (NK) cell cytotoxicity in experimental cutaneous leishmaniasis. Analysis of a possible correlation between in vitro NK cell activity and in vivo susceptibility to Leishmania mexicana infection showed that there is no relationship between the degree of NK reactivity to YAC-1 lymphoma cells and in vivo leishmania growth. It was also observed that spleen lymphoid cells from mice with high NK activity did not cause an increase in isotope release by the macrophage permanent cell line J774G8-1 previously infected with the parasite and supporting its growth. Mice infected with L. mexicana manifested an increased NK activity to YAC-1 cells but not to leishmania-infected J774G8-1 tumor macrophages. The lack of effect of NK cell activity is discussed with regard to the role of NK cells in immune mechanisms to intracellular parasites.