Mononuclear cell subpopulations and cytokine levels in human visceral leishmaniasis before and after chemotherapy.

Serum cytokine levels and mononuclear cell subpopulations in the spleen and peripheral blood of patients with visceral leishmaniasis before and after antimony therapy were analyzed. The percentages of activated monocytes/macrophages, T cells, and possibly B cells; of gamma/delta T cell receptor (TCR)-bearing T cells; of CD4- CD8- alpha/beta TCR-bearing T cells; and serum levels of tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN-gamma), and interleukin-6 (IL-6) were high in patients with active visceral leishmaniasis. The proportion of both helper and suppressor CD4+ cells and of cells with NK and cytotoxic T phenotypes were depressed. Successful chemotherapy normalized these parameters with the exception of activated monocytes. Thus, the impaired cell-mediated immunity in human Leishmania donovani infection is primarily due to a decrease in the proportion and possibly the activity of helper CD4+ cells, while suppressor cells do not seem to play a relevant role. TNF alpha, IL-6, and IFN-gamma may prove to be useful markers for monitoring response to therapy.