Mycobacterial antigens in antibody responses of leprosy patients.

A reference system for M. smegmatis antigens in crossed immunoelectrophoresis was used to study antibody activities in serum samples of 91 leprosy patients. All polar and borderline lepromatous patients were positive. Mean numbers out of 14 M. smegmatis antigens involved were 4.3 and 3.5, respectively. Precipitins against antigen no. 1 were seen in all lepromatous cases. Antibodies against this antigen were detected in 50% of tuberculoid (polar, subpolar and borderline) cases. Antibody activity against M. avium and M. duvalii antigens was also detected using a staphylococcal radio-immuno-assay. Borderline and polar lepromatous cases showed elevated levels. Antigenic comparisons were made between four slow growing mycobacteria, fourteen fast growing mycobacteria and the leprosy bacillus using lepromatous serum pools as antibody reagents. Four of the antigens detected in M. leprae were also found in slow growing as well as fast growing species indicating a common occurrence among mycobacteria. Antigen no. 1 of M. duvalii, with an apparent molecular weight of 290,000, showed nonprotein characteristics. Further analysis of antigen no. 21, using lepromatous serum pools as antibody reagents, indicated the existence of at least two groups of antigenic determinants. In addition to determinants shared by all mycobacteria, there were antigenic structures apparently unique to M. leprae.