Analysis of the antigenic profile of Mycobacterium leprae: cross-reactive and unique specificities of human and rabbit antibodies

Thirty-two mycobacterial components were detected by antibodies contained in leprosy patients' sera across the clinical spectrum and rabbit anti-M. leprae hyperimmune sera by western blot analysis of armadillo-derived M. leprae antigen preparations. Sera of borderline tuberculoid patients were found to contain antibodies recognizing 18 M. leprae components. While the reactivity of the sera on the lepromatous pole seemed to be distributed over the entire molecular weight range, most of the reactivity in the borderline tuberculoid patients was directed at higher molecular weight components (greater than 70,000). Identification of a series of previously unrecognized M. leprae components offers new possibilities in regard to the potential use of these antigens as targets for immunodiagnosis. Antibodies contained in the rabbit anti-M. leprae sera reacted with 19 M. leprae components. Antigens migrating at 64,000, 38,000, and 22,000 were detected by the rabbit sera only. Evidence of extensive cross-reactivity between M. leprae and BCG organisms emphasizes the need to use well-characterized antibody probes to determine the specificity of select mycobacterial antigens. The potential usefulness of rabbit monospecific hyperimmune sera to select M. leprae fractions in immunodiagnosis, in immune regulation studies, or as a tool to screen for mycobacterial products in lambda gt11 phage lysates of E. coli is discussed. Select M. leprae components were partially purified and their recovery assessed through SDS-PAGE analysis of Coomassie blue-stained gels.