Although the mechanisms how DFAT cells attenuate the experimental colitis have not been clarified, our in vitro data suggest that the transplanted DFAT cells exhibited therapeutic effect by suppressing T cell activity through an increased secretion of immunomodulatory factors such as TRAIL, IDO1, and PGE2 under inflammatory conditions with high concentrations of TNFα and IFNγ. The gene discussed is IDO1; the disease is colitis.