Definition of species specific and cross-reactive antigenic determinants of Mycobacterium leprae using monoclonal antibodies.

Four soluble antigens of Mycobacterium leprae have been identified using 12 murine monoclonal antibodies. Their specificity, taxonomic distribution and molecular nature were analysed by radioimmunoassays and by immunoblotting from polyacrylamide electrophoresis gels. A protein antigen MY1 (12K) reacted with one antibody (ML06) without demonstrable cross-reactivity for any of the other 20 tested species of mycobacteria. Another four antibodies which identified antigen MY2 revealed only a marginal degree of cross-reactivity with three other species of mycobacteria. Two antigens shared by several other mycobacteria species were: MY3 represented by five protein bands (35-70K) and a subtilisin resistant molecule MY4 (40-50K) with two distinct determinants and presumably of polysaccharide nature. The described monoclonal antibodies may represent novel valuable diagnostic reagents as well as tools for the purification of antigens which could be explored towards prophylactic or therapeutic immunization against leprosy.