INTERLEUKIN-12 RESTORES INTERFERON-GAMMA PRODUCTION AND CYTOTOXIC RESPONSES IN VISCERAL LEISHMANIASIS

American visceral leishmaniasis (AVL) is associated with the absence o f lymphocyte proliferative responses and interleukin (IL)-2 and interf eron-gamma (IFN-gamma) production upon stimulation with Leishmania ant igen. In contrast, cure of AVL is associated with restoration of these T cell functions. In the present study, the ability of IL-12, a cytok ine that acts on NK and T cells to restore cellular immune responses i n AVL, was evaluated. Participants of the study included 12 patients w ith AVL and 7 subjects cured of AVL. The [H-3]thymidine uptake and IFN -gamma production in cultures of peripheral blood mononuclear cells (f rom AVL patients) stimulated with Leishmania chagasi antigen were 882 +/- 1393 cpm and zero, respectively. Addition of IL-12 enhanced the pr oliferative response to 5097 +/- 6429 cpm (P < .001) and IFN-gamma pro duction to 305 +/- 325 pg/mL (P < .01), IL-12 also restored cytotoxic activity against the K562 cell line. These results indicate that IL-12 has an important role in the regulation of the cellular immune respon se in human leishmaniasis.