Immunochemical characterization of Mycobacterium leprae antigens by the SDS-polyacrylamide gel electrophoresis immunoperoxidase technique (SGIP) using patients' sera.

In this study the SDS-polyacrylamide gel electrophoresis immunoperoxidase (SGIP) assay was used for characterizing the antigenic components of Mycobacterium leprae using patients' sera. This technique involved the separation of mycobacterial sonicates on SDS-polyacrylamide gels, longitudinal sectioning of the gels, incubation with patients' sera and visualization of the antigen-antibody complexes by the indirect immunoperoxidase technique. A number of antigens present in M. leprae sonicates were recognized by leprosy patients' sera, some of which were seen in other mycobacteria as well. Antibody binding to a 33 kD antigen, present in both M. leprae and BCG sonicates, was reduced only in the latter after 6 months of multiple drug treatment of one patient. It is suggested that this is a common mycobacterial antigen with one or more M. leprae specific determinants. Several antigens were identified only in M. leprae sonicates, only by leprosy patients: a 12, 22, 28, 36, 41 and 86 kD component. These antigens lost their antigenicity after trypsin treatment, but were heat stable. Such M. leprae specific antigens may be useful for immunodiagnosis.