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IL‐12 induced STAT‐4 signaling is increased in CD8 T cells from aged mice
Author(s) -
Turner Joanne
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.675.25
Subject(s) - stat4 , cd8 , cytotoxic t cell , biology , immunology , microbiology and biotechnology , immune system , phosphorylation , stat , in vitro , biochemistry , stat3
Old mice express an early resistance to infection with Mycobacterium tuberculosis (M.tb) which is associated with CD8 T cells and IFN‐γ production. CD8 T cells from old mice are also capable of secreting IFN‐γ in an antigen independent manner in response to TH1 cytokines. In this study we sought to determine whether CD8 T cells from old mice were more responsive to IL‐12. Using flow cytometric analysis of phosphorylated STAT4 we found that old mice possessed more CD8 T cells that could respond directly to IL‐12 than young mice. Furthermore, on an individual cell basis, CD8 T cells from old mice could phosphorylate more STAT4 than similar cells from young mice. This increased phosphorylation was independent of STAT4, as STAT4 levels in CD8 T cells were equivalent between young and old mice. These data indicate that CD8 T cells from old mice have enhanced IL‐12 signaling, which ultimately leads to the secretion of more IFN‐γ. The presence of increased levels of IL‐12 and IFN‐γ within the lungs of old mice early after infection with M.tb provides additional evidence that CD8 T cells contribute to the expression of early resistance to infection. This work was supported by R01‐AG21097.