Control and resolution of leishmanial infection depends primarily on T cell-mediated immune mechanisms. The nature of the leishmanial antigens involved in eliciting T cell immunity is unknown. We have examined the pattern of peripheral blood lymphocyte responses in patients with active, healed, or subclinical leishmanial infection to fractionated leishmanial antigens using a T cell immunoblotting method in which nitrocellulose-bound leishmanial antigens, are incorporated into lymphocyte cultures. The proliferative and IFN-γ responses of cells from patients with healed mucosal or cutaneous leishmaniasis were remarkably heterogeneous and occurred to as many as 50-70 distinct antigens. In contrast, responses from subjects with active, nonhealing, diffuse cutaneous leishamniasis were either absent or present to only a small number of antigens. Control and resolution of leishmaniasis, and resistance to reinfection, is therefore associated with a T cell response to a large and diverse pool of parasite antigens. The method of T cell immunoblotting appears to offer a powerful, rapid, and relatively simple approach to the identification of antigens involved in eliciting a T cell response in human leishmaniasis.
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