We found that the Rag1−/− mice that received TNFR1−/− naive CD4+ T cells slowly gained weight and only caused slight colitis (Fig. 2b), while TNFR2−/− naive CD4+ T cells caused the most severe weight loss, and H&E staining showed the most severe inflammatory cells infiltration, ulcer, edema, and bowel wall thickening among the three groups (Fig. 2c, d). Here, CD4 is linked to colitis.