Abstract
The Leishmania major receptor for macrophages is a lipid-containing glycoconjugate that is recognized by the monoclonal antibody WIC-79.3. When L. major promastigotes were incubated with Fab fragments of WIC-79.3 prior to injection into genetically susceptible mice, their infectivity was decreased. Fab fragments from an irrelevant control antibody of the same class had no effect. The L. major glycolipid was purified from detergent-solubilized promastigotes by affinity chromatography on immobilized WIC-79.3 and used to vaccinate mice that are genetically resistant or susceptible to disease. Genetically resistant mice could be protected totally from cutaneous disease with as little as 5 micrograms of glycolipid. A high but not absolute level of resistance was also induced in the susceptible mice, in which the disease is otherwise fatal. No protection was obtained with the carbohydrate fragment of the glycolipid alone or by injection of the glycolipid in the absence of adjuvant. Genetically susceptible mice, immunized and protected from disease as a result of multiple injections of live avirulent cloned promastigotes of L. major, produced antibodies to the glycolipid of L. major. No antibodies were detected in serum from chronically diseased mice. The data suggest that this functionally important antigen of L. major is a candidate vaccine against cutaneous leishmaniasis.