Separate antigenic determinants on cell wall associated carbohydrate antigens of Mycobacterium leprae defined with monoclonal antibodies.

Monoclonal antibodies (Mabs) raised against Mycobacterium leprae sonicate defined two different determinants on related, cell-wall-associated, carbohydrate antigens common to M. leprae, M. bovis (BCG), and M. tuberculosis. Antigen inhibition ELISA and antigen capture assays demonstrated that the two antigens were present in a cell-wall fraction, M. leprae resonicate. There was species variation in the distribution of the antigens; the 4.5-6 kD antigen was more abundant in M. tuberculosis and M. bovis, while the 30-40 kD antigen was more concentrated in M. leprae preparations. Although both were present in the cell wall, only determinants on the 30-40 kD antigen were accessible on intact bacilli. The results from capture assays and Mab affinity chromatography with both L9 and L4 indicated that the 4.5-6 kD antigen was probably a fragment of the larger molecule. Both antigens are significant immunogens in the human B-cell response to M. leprae.