Guest guest Posted May 29, 2006 Report Share Posted May 29, 2006 http://www.jimmunol.org/cgi/content/full/169/9/5202 Studies in animal models of intracellular bacterial infections support our hypothesis that the importance of perforin-mediated cytolysis in protective immunity is related to the ability of bacteria to directly spread from cell to cell. Rickettsia sp. are intracytoplasmic bacteria capable of direct cell-cell spread. In agreement with a prediction of our model, protective immunity against Rickettsia depends on perforin-mediated CD8 T cell cytotoxicity (29). Although CD8 T cells have been established to participate in defense against the intracellular pathogens Chlamydia pneumoniae and Mycobacterium tuberculosis, perforin has been shown to play a minimal role in controlling infections with these bacteria (30, 31). Unlike Lm and Rickettsia, which are intracytoplasmic pathogens, these bacteria reside within vacuolar compartments, which may influence the contribution of perforin. However, perforin- mediated cytolysis should release and expose both cytosolic and vacuolar bacteria to macrophage and Ab-mediated immune mechanisms. An alternative interpretation suggested by our model is that perforin-independent control of Chlamydia and Mycobacterium relates to their inability to spread directly from cell to cell without host cell lysis. Quote Link to comment Share on other sites More sharing options...
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