Variation in interleukin-2 (IL-2) receptor expression in different forms of leprosy and leishmaniasis
Lymphoma, Large B-Cell, Diffuse
Leprosy and leishmaniasis may occur in two polar forms: a) high resistance tuberculoid leprosy (TT) and oriental sore (OS), characterized by vigorous host reaction to the parasites, and b) low resistance forms: lepromatous leprosy (LL) and diffuse cutaneous leishmaniasis (DCL) which show decreased ability to respond. Peripheral blood mononuclear cells of LL patients have defective in vitro proliferative responses to parasite specific antigens. This defect is repaired in vitro by T-cell growth factor which contains IL-2. To investigate the ability of cells in granulomas to respond to IL-2 we used the avidin-biotin-peroxidase complex technique with anti-Tac, a monoclonal antibody reacting with the IL-2 receptor. We examined frozen sections of lesional tissue from 24 leprosy patients and 4 leishmaniasis patients. We detected Tac antigen on surface membranes of many lymphocytes in lesions of OS, DCL and TT, as well as in hypersensitivity ('reversal') and erythema nodosum leprosum type reactions in leprosy patients. Tac (+) cells were rare in non-reactional LL. We conclude 1) Tac (+) cells are present in some granulomatous lesions, 2) The pathophysiologic mechanisms of parasite resistance are different in leprosy and leishmaniasis and 3) the defect in the lepromatous immune response occurs at or prior to IL-2 induced clonal proliferation. To our knowledge this represents the first demonstration of Tac (+) cells in tissue. Supported in part by the Heiser Program. Anti Tac supplied by Dr. T. Waldman.