RAG1 and colitis: Indeed, Nod2 deletion has been shown to increase mice sensitivity to Toxoplasma gondii infection due to a defect in the induction of Th1-mediated immunity and transfer of naive CD4+CD45RBhigh T cells deficient in Nod2 did not induce colitis in Rag1-/- mice because of a poor helper T cell differentiation and IL-2 production [20].