CD8+ T cells are major contributors to cell-mediated immunity to virally infected cells and tumors. Like their helper CD4+ counterparts, these cells rely on the transcriptional regulator T-bet for their correct development. Recently, a second factor called eomesodermin has also been found to control CD8 functions. Intlekofer et al. now find that without both factors, CD8+ T cells fail to develop their normal cell-mediated functions and instead secrete the inflammatory cytokine IL-17, which has been characterized recently in helper T cells. This secretion of IL-17 caused significant pathology in a mouse model of viral infection, which suggests that both transcription factors play a crucial role in maintaining appropriate cell-mediated responses to infection.
A. M. Intlekofer, A. Banerjee, N. Takemoto, S. M. Gordon, C. S. DeJong, H. Shin, C. A. Hunter, E. J. Wherry, T. Lindsten, S. L. Reiner, Anomalous Type 17 response to viral infection by CD8+ T cells lacking T-bet and eomesodermin. Science 321, 408-411 (2008). [Abstract] [Full Text]