Interleukin-10 (IL-10) is essential to maintain intestinal homeostasis. CD4+ T regulatory type 1 (TR1) cells produce large amounts of this cytokine and being therefore currently examined in clinical trials as T-cell therapy in patients with inflammatory bowel disease (IBD). However, factors and molecular signals sustaining TR1 cell regulatory activity still need to be identified in order to optimize the efficiency and to ensure the safety of these trials. We investigated the role of IL-10 signaling in mature TR1 cells in vivo
