Cutting edge:: Antilisterial activity of CD8+ T cells derived from TNF-deficient and TNF/perforin double-deficient mice

The mechanisms by which CD8(+) T cells mediate immunity against bacterial pathogens remain largely unknown. Perforin-dependent cytolysis plays a role, but is not required for CD8(+) T cell-mediated immunity against Listeria monocytogenes. TNF is essential for CD8(+) T cell immunity to L. monocytogenes, but the cellular source of TNF is undefined. TNF-deficient and TNF/perforin double-deficient mice were used to generate CD8(+) T cells specific for an L. monocytogenes-derived Ag, Wild-type and TNF-deficient CD8(+) T cells mediated antilisterial immunity in wild-type but not TNF-deficient host mice, revealing that CD8(+) T cell-derived TNF is not required for CD8(+) T cell-mediated antilisterial immunity, but demonstrating a role for TNF derived from other cell types. TNF/perforin double-deficient CD8(+) T cells mediated antilisterial immunity in the liver, but not in the spleen, of wild-type recipient mice, suggesting that perforin-independent immunity in the spleen requires CD8(+) T cell derived TNF.