Distinct effects of T-bet in TH1 lineage commitment and IFN-γ production in CD4 and CD8 T cells

T-bet is a member of the T-box family of transcription factors that appears to regulate lineage commitment in CD4 T helper (T-H) lymphocytes in part by activating the hallmark T(H)1 cytokine, interferon-gamma (IFN-gamma), IFN-gamma is aLso produced by natural killer (NK) cells and most prominently by CD8 cytotoxic T cells, and is vital. for the control of microbial pathogens. Although T-bet is expressed in all these cell types, it is required for control of IFN-gamma production in CD4 and NK cells, but not in CD8 cells. This difference is aLso apparent in the function of these cell subsets. Thus, the regulation of a single cytokine, IFN-gamma, is controlled by distinct transcriptional mechanisms within the T cell lineage.