Summary
Host defense requires the specification of CD4+ helper T (Th) cells into distinct fates including Th1 cells that preferentially produce interferon-γ(IFN-γ) IFN-γ, a member of a large family of anti-pathogenic and anti-tumor IFNs, induces T-bet, a lineage defining transcription factor for Th1 cells, which in turn supports IFN-γ production in a feed-forward manner. Herein, we showed a cell intrinsic role of T-bet to influence how T cells perceive their secreted product in the environment. In the absence of T-bet, IFN-γ aberrantly induced a type I IFN transcriptomic program. T-bet preferentially repressed genes and pathways ordinarily activated by type I IFNs to ensure that its transcriptional response does not evoke an aberrant amplification of type I IFN signaling circuitry otherwise triggered by its own product. Thus, in addition to promoting Th1 effector commitment, T-bet acts as a repressor in differentiated Th1 cells to prevent abberant autocrine type I IFN and downstream signaling.