Cutting edge: The Ets1 transcription factor is required for the development of NK T cells in mice

Ets1-deficient mice develop B and T cells but display a severe defect in th e development of the NK cell lineage. Ire this report, we demonstrate that Ets1 is also required for the development of NK1.1(+) T (NK T) cells. We ob served significantly decreased numbers of NK T cells in the thymus, spleen, and liver of Ets1-deficient mice. These organs also contained markedly de; creased levels of the canonical V(alpha)14-J(alpha)281 TCR alpha transcrip t seen in NK T cells. Unlike wild-type NK T cells, Ets1-deficient thymocyte s failed to produce detectable levels of IL-4 following anti-CD3 stimulatio n. The absence of NK T cells in the Ets1-deficient mice was not associated with defective expression of CD1, an MHC class I molecule required for NK T cell development, We conclude that Ets1 defines a novel transcriptional re gulatory pathway that is required for the development of both the NK and NK T cell lineages.