Comparison of the cytoplasmic antigens of leprosy-derived corynebacteria and some mycobacteria.

The immunological relationship between leprosy-derived corynebacteria (LDC) and reference mycobacteria was analysed by crossed immunoelectrophoresis with intermediate gel. For this purpose, three reference systems (LDC15/anti-LDC15, LDC18/anti-LDC8, and LDC8/anti-LDC8) were developed. They showed 15 to 20 distinct antigenic components in LDC cytoplasm. Extensive cross-reactivity was observed among different LDC isolates, affecting 3 to 17 components. Moreover, several components were shown to cross-react with mycobacteria when anti-bacillus Calmette-Guérin (BCG), anti-Mycobacterium leprae, other antisera and lepromatous leprosy sera were incorporated in the intermediate gel. The major cross-reactive component, antigen M, was present in all LDC isolates and cross-reacted with antigen 7 of M. leprae and antigen 60 of M. bovis BCG. The thermostability of these antigens and the specificity of the cross-reacting antigens were assessed. The data underline the degree of immunochemical homogeneity within the LDC group of micro-organisms and relatedness with M. leprae and other mycobacteria.