For instance, in an adoptive transfer colitis model when Treg-depleted memory/effector CD4+CD45RBlo T cells were transferred into RAG-1-/- mice, IL-22 derived from these memory/effector T cells is pathogenic, whereas IL-22 is protective when CD4+CD45RBhi naïve T cells were transferred (84). The gene discussed is RAG1; the disease is colitis.