ABSTRACT
CD8 T cells can acquire cytokine-secreting phenotypes paralleling cytokine production from Th cells. IL-17-secreting CD8 T cells, termed Tc17 cells, were shown to promote inflammation and mediate immunity to influenza. However, most reports observed a lack of cytotoxic activity by Tc17 cells. In this study, we explored the anti-viral activity of Tc17 cells using a vaccinia virus (VV) infection model. Tc17 cells expanded during VV infection, and TCR transgenic Tc17 cells were capable of clearing recombinant VV infection. In vivo, adoptively transferred Tc17 cells lost the IL-17-secreting phenotype, even in the absence of stimulation, but they did not acquire IFN-gamma-secreting potential unless stimulated with a virus-encoded Ag. However, examination of cells following infection demonstrated that these cells acquired cytotoxic potential in vivo, even in the absence of IFN-gamma. Cytotoxic potential correlated with Fasl expression, and the cytotoxic activity of postinfection Tc17 cells was partially blocked by the addition of anti-FasL. Thus, Tc17 cells mediate VV clearance through expression of specific molecules associated with cytotoxicity but independent of an acquired Tc1 phenotype.
Subject(s)
CD8-Positive T-Lymphocytes/immunology , Immunity/immunology , Interleukin-17/immunology , Vaccinia virus/immunology , Vaccinia/immunology , Animals , CD8-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/metabolism , Cells, Cultured , Cytotoxicity, Immunologic/immunology , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , Interferon-gamma/genetics , Interferon-gamma/immunology , Interferon-gamma/metabolism , Interleukin-12/immunology , Interleukin-12/metabolism , Interleukin-17/metabolism , Mice , Mice, Inbred BALB C , Mice, Inbred C3H , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Receptors, Antigen, T-Cell/genetics , Receptors, Antigen, T-Cell/immunology , Receptors, Antigen, T-Cell/metabolism , STAT4 Transcription Factor/genetics , STAT4 Transcription Factor/immunology , STAT4 Transcription Factor/metabolism , T-Box Domain Proteins/genetics , T-Box Domain Proteins/immunology , T-Box Domain Proteins/metabolism , Vaccinia/virologyABSTRACT
CD4(+) helper T cells acquire effector phenotypes that promote specialized inflammatory responses. We show that the ETS-family transcription factor PU.1 was required for the development of an interleukin 9 (IL-9)-secreting subset of helper T cells. Decreasing PU.1 expression either by conditional deletion in mouse T cells or the use of small interfering RNA in human T cells impaired IL-9 production, whereas ectopic PU.1 expression promoted IL-9 production. Mice with PU.1-deficient T cells developed normal T helper type 2 (T(H)2) responses in vivo but showed attenuated allergic pulmonary inflammation that corresponded to lower expression of Il9 and chemokines in peripheral T cells and in lungs than that of wild-type mice. Together our data suggest a critical role for PU.1 in generating the IL-9-producing (T(H)9) phenotype and in the development of allergic inflammation.
