RESPONSE TO CHEMOTHERAPY IN EXPERIMENTAL VISCERAL LEISHMANIASIS - T-CELL-DEPENDENT BUT INTERFERON-GAMMA-INDEPENDENT AND INTERLEUKIN-2-INDEPENDENT

The capacity of Leishmania donovani-infected BALB/c mice to respond to conventional chemotherapy with pentavalent antimony (Sb) is T cell dependent and, in nude mice, can be restored in part by treatment with the T cell lymphokines, interferon-gamma (IFN-gamma) or interleukin-2 (IL-2). To document the presumed role of endogenous IFN-gamma and IL-2 in responsiveness to antileishmanial chemotherapy in the T cell-intact host, L. donovani-infected euthymic BALB/c mice were treated with anti-IFN-gamma or anti-IL-2 monoclonal antibodies (MAbs) before and after Sb administration. Treatment with MAbs exacerbated visceral infection but did not inhibit the in vivo efficacy of Sb. Thus, while combination therapy of Sb plus IFN-gamma or IL-2 may prove beneficial in T cell-deficient hosts with visceral leishmaniasis, T cell activities other than or in addition to IFN-gamma or IL-2 production may mediate in vivo responsiveness to antileishmanial chemotherapy in the euthymic host.