T-bet in the spot light: roles in distinct T-cell fate determination.

The transcription factor T-bet was originally described to be important for the differentiation of the CD4(+) Th1 subset. More recent investigations implicate T-bet in the lineage commitment of a variety of innate immune cells also. The T-bet appears to have a dual role in the immune system. Under certain conditions T-bet provides a beneficial role, whereas the exaggerated expression of T-bet in certain innate lymphoid cells can be detrimental to the host. Therefore, this transcription factor needs to be carefully regulated. The feedback control and the epigenetic mechanisms involved in the expression of T-bet remain to be fully elucidated.