Peripheral blood mononuclear cells from leprosy patients underwent spontaneous apoptosis upon culture for 24 h. The apoptosis was inhibited by anti-TNF alpha antibodies and to a certain extent by anti-IL-1 alpha and IL-6, thus showing that T(H)2-type cytokines (mainly TNF alpha) are responsible for inducing apoptosis. This cytokine-mediated apoptosis could be inhibited by ionomycin and zinc, thereby suggesting that these metal ions can be used to decrease the levels of these inflammatory cytokines in various diseases. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.