A Lipopeptide Facilitate Induction of Mycobacterium leprae Killing in Host Cells

Little is known of the direct microbicidal activity of T cells in leprosy, so a lipopeptide consisting of the N-terminal 13 amino acids lipopeptide (LipoK) of a 33-kD lipoprotein of Mycobacterium leprae , was synthesized. LipoK activated M. leprae infected human dendritic cells (DCs) to induce the production of IL-12. These activated DCs stimulated autologous CD4 + or CD8 + T cells towards type 1 immune response by inducing interferon-gamma secretion. T cell proliferation was also evident from the CFSE labeling of target CD4 + or CD8 + T cells. The direct microbicidal activity of T cells in the control of M. leprae multiplication is not well understood. The present study showed significant production of granulysin, granzyme B and perforin from these activated CD4 + and CD8 + T cells when stimulated with LipoK activated, M. leprae infected DCs. Assessment of the viability of M. leprae in DCs indicated LipoK mediated T cell-dependent killing of M. leprae . Remarkably, granulysin as well as granzyme B could directly kill M. leprae in vitro . Our results provide evidence that LipoK could facilitate M. leprae killing through the production of effector molecules granulysin and granzyme B in T cells.