In contrast to studies suggesting that ILC1 promote colitis, we have reported previously that T-bet expression can also protect from colitis, as Rag2-/- mice with germline deletion of Tbx21 can develop spontaneous colitis if Helicobacter thyphlonius is present in the gut (13–15, 17, 19, 20). The gene discussed is TBX21; the disease is colitis.