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Contribution of CD8+ T cells to innate immunity: IFN-γ secretion induced by IL-12 and IL-18

2002; Wiley; Volume: 32; Issue: 10 Linguagem: Inglês

10.1002/1521-4141(2002010)32

1521-4141

Rance E. Berg, C Cordes, James Forman,

Immunotherapy and Immune Responses

The role of CD8+ T cells in adaptive immunity is well documented and involves numerous effector mechanisms including direct cytolysis of targets and secretion of cytokines. The role of CD8+ T cells in innate immunity has not been previously appreciated. Using J774 macrophages infected in vitro with the intracellular bacterium, Listeria monocytogenes (LM), we show that CD8+ T cells isolated from naïve C57BL/6 (B6) mice respond rapidly by secreting IFN-γ. CD8+ T cells secreting IFN-γ can also be found in naïve B6 mice 16 h after infection with LM. This rapid IFN-γ response is TCR-independent and mediated through the actions of IL-12 and IL-18. Cell surface staining and cell sorting experiments indicate that these novel CD8+ T cells express memory markers. In vitro CFSE-labeling experiments show that IFN-γ-secreting CD8+ T cells proliferate rapidly after 2 days in culture andafter 4 days constitute the majority of the CD8+ T cell population. Together, these data suggest an important role for IFN-γ-secreting CD8+ T cells in the innate response to bacterial pathogens.