Fate of Mycobacterium tuberculosis within murine dendritic cells

The interaction of microbes with dendritic cells (DCs) is likely to have an enormous impact on the initiation of the immune response against a pathoge n. In this study, we compared the interaction of Mycobacterium tuberculosis with murine bone marrow-derived DCs and macrophages (M phi) in vitro, M. t uberculosis grew equally well within nonactivated DCs and M phi. Activation of DCs and M phi with gamma interferon and lipopolysaccharide inhibited th e growth of the intracellular bacteria in a nitric oxide synthase-dependent fashion. However, while this activation enabled M phi to kill the intracel lular bacteria, the nl, tuberculosis bacilli within activated DCs were not killed. Thus, DCs could restrict the growth of the intracellular mycobacter ia but were less efficient than M phi at eliminating the infection. These r esults may have implications for priming immune responses to M. tuberculosi s, In addition, they suggest that DCs may serve as a reservoir for nl, tube rculosis in tissues, including the lymph nodes and lungs.