IL15 and colitis: In the absence of IL-15, the impaired p-STAT5 signalling could diminish transcription of Foxp3, which stabilizes Treg lineage and suppresses Th17 differentiation30, thus resulting in the lower Treg frequencies observed in the colon of unmanipulated IL-15ko and IL-15Rαko mice and also in IL-15koRAG2ko mice with Th1/Th17-type colitis.