Evidence of in situ cytotoxicity in American cutaneous leishmaniasis.

The role of cytotoxicity in the defense mechanisms or pathogenesis of human cutaneous leishmaniasis is not yet well known. In the present work we assessed the presence of NK, CD8+ and CD45RO+ T cells, as well as the expression of a molecule associated with cytotoxic properties (TIA-1) in the lesions of cutaneous leishmaniasis. CD8+ T cells, NK and activated T cells were found within the dermal cell infiltrate. We found a heterogeneous but usually strong expression of TIA-1, a marker of cytotoxic granules of T and NK cells, in human cutaneous leishmaniasis lesions. These data suggest that cytotoxic activity occurs in situ in American cutaneous leishmaniasis and that both NK cells and activated CD8+ T cells are involved in this reaction.