DICHOTOMY OF THE HUMAN T-CELL RESPONSE TO LEISHMANIA ANTIGENS .1. TH1-LIKE RESPONSE TO LEISHMANIA-MAJOR PROMASTIGOTE ANTIGENS IN INDIVIDUALS RECOVERED FROM CUTANEOUS LEISHMANIASIS

The T cell response to antigens from Leishmania major promastigotes wa s investigated in peripheral blood mononuclear cells from Sudanese ind ividuals with a history of cutaneous leishmaniasis (CL), Sudanese indi viduals with positive DTH reaction in the leishmanin skin test but wit h no history of skin lesions, and in Danes without known exposure to L eishmania parasites. Proliferation and production of interferon-gamma (IFN-gamma) and IL-4 in antigen-stimulated cultures was measured. Lymp hocytes from individuals with a history of CL proliferated vigorously and produced IFN-gamma after stimulation with either a crude preparati on of L. major antigens or the major surface protease gp63. These cult ures produced no or only little IL-4. Also cells from leishmanin skin test-positive donors with no history of CL produced IFN-gamma and no I L-4 in response to L. major antigens. Cells from the unexposed Danes w ere not activated by gp63. The cells from Danish donors produced eithe r IFN-gamma or IL-4, but not both cytokines after incubation with the crude preparation of L. major antigens. The data show that the T cell response to Leishmania antigens in humans who have had uncomplicated C L or subclinical L. major infection is an IFN-gamma-producing Th1-like response.