Control of Effector CD8⁺ T Cell Function by the Transcription Factor Eomesodermin

Activated CD8⁺ T cells play a critical role in host defense against viruses, intracellular microbes, and tumors. It is not clear if a key regulatory transcription factor unites the effector functions of CD8 ⁺ T cells. We now show that Eomesodermin (Eomes), a paralogue of T-bet, is induced in effector CD8⁺ T cells in vitro and in vivo. Ectopic expression of Eomes was sufficient to invoke attributes of effector CD8⁺ T cells, including interferon-γ (IFN-γ), perforin, and granzyme B. Loss-f-function analysis suggests Eomes may also be necessary for full effector differentiation of CD8⁺ T cells. We suggest that Eomesodermin is likely to complement the actions of T-bet and act as a key regulatory gene in the development of cell-mediated immunity.