Monoclonal antibodies specific for Leishmania tropica. I. Characterization of antigens associated with stage- and species-specific determinants

Four monoclonal antibodies (T-1 through T-4), which were produced to membrane-enriched preparations of Leishmania tropica major promastigotes, reacted specifically with the members of L. tropica complex. The antibodies T-1 and T-4 react exclusively with L. t. major and L. t. minor. The remaining two monoclonal antibodies bind, in addition, to L. t. aethiopica and weakly to L. mexicana amazonensis. No significant cross-reactivity was observed with L. donovani, L. braziliensis braziliensis, and Trypanosoma cruzi. Antibodies T-1, T-2, and T-4 were found to be specific for the promastigote stage (insect) of L. tropica. Antibody T-3 reacts with both the amastigote and promastigote stages of the parasite. All of the monoclonal antibodies react with cell surface components on intact promastigotes. The protein antigens containing the species-specific determinants recognized by each of the four antibodies were identified by radioimmunoprecipitation of solubilized ¹²⁵I-labeled L. t. major promastigotes. A single 50 kilodalton protein is recognized by clone T-4. T-1 recognized two high m.w. proteins (100 and 200 kilo-daltons). These two antigens plus an additional protein of lower m.w. (70 kilodaltons) are also immunoprecipitated by the antibodies T-2 and T-3, demonstrating that species-specific determinants are present on several different cell surface proteins of L. t. major.