Monoclonal antibodies to a 28,000 mol. wt protein antigen of Mycobacterium leprae

Monoclonal antibodies (MoAb) have been used to analyse a protein antigen from Mycobacterium leprae with a subunit mol. wt of 28,000 daltons. Three different patterns of species specificity were observed with two antibodies being specific for M. leprae, two partially specific, and one broadly cross-reactive amongst all mycobacteria. Competitive binding and sandwich assays demonstrated that the specific and partially specific antibodies recognized closely related regions of the molecule while the cross-reactive antibody recognized a spatially separate epitope on the same polypeptide chain. Identification of specific and cross-reactive epitopes on a single antigenic molecule may be of considerable importance for understanding the functioning of the cell-mediated immune system during leprosy infection and the use of MoAb for such analyses is discussed.