RESUMO
Mycobacterium bovis-BCG was sonified and centrifuged at 90,000g for 2h to obtain pellet (P90) and supernatant (S90), and bacilli broken by chilled X-press were fractionated into cell wall (CW), plasma membrane and cytosol. Rabbits were immunized with P90, S90 and whole sonified-broken BCG. The antigenic make-up of these antisera. These analysed by cross-immunoelectrophoresis using the antisera. These subcellular preparations were also used for detecting circulating antibodies in the sera of 45 leprosy patients by Ouchterlony´s technique and immunoelectrophoresis. Although there were many antigenic determinants common to more than one fraction, some components were found in only one fraction. Furthermore, different leprosy patients showed different patterns of antibody response to the antigens in the different fractions. In addition, these fractions were also used to assess cell-mediated immunity in mice sensitized with lyophilized whole BCG as well as with irradiated Mycobacterium. it was found that BCG, intraperitoneally injected, engedered different specifically antigen-sensitized populations of lymphocytes in the spleen and lymph node. Moreover, a certain degree of antigenic cross-reactivity was observed between BCG and M. leprae, possibly at the T-cell level. In vitro experiments suggested that the CW stimulated B cells, indicating a mitogenic ctivity leading to polyclonal activation. Finally, in vitro priming experiments established that these subcellular fractions could sensitize human peripheral lymphocytes, and upon secondary culture all primed cells were able to respond to homologous preparations but not always to heterologous preparations, thus offering a means to distinguish antigens of interest from those antigenically less complicated fractions at the T-cell level.