[Identification of an immunodominant antigen of Mycobacterium leprae and its application for the development of protective measures].

Host defense against Mycobacterium leprae (M. leprae) is chiefly conducted by cellular immunity. The adaptive immunity plays an important role, and T cells are activated through recognition of some immunodominant antigens of M. leprae. A search for an immunodominant antigen was carried out using human peripheral monocytes-derived dendritic cells and M. leprae-derived cell membrane fraction which is the most antigenic fraction of the bacteria, and Major Membrane Protein (MMP)-II was found as one of the immunodoninant antigens. The MMP-II highly stimulated both dendritic cells and macrophages to produce various cytokines. Further, MMP-II was recognized by T cells in vivo in patients infected with M. leprae. Then, we constructed a recombinant BCG secreting MMP-II. The recombinant BCG strongly stimulated both naive CD4+ and naive CD8+ T cells, and seemed to be a useful immunostimulatory agent.