IL-17+ T cells from mice with established TNBS-induced colitis were rich in CD81+ T cells at 3.7-fold (11.9% versus 3.2%) and 19-fold (3.8% versus 0.2%) compared with CD81− T cells with or without SEB stimulation, respectively (Supplementary Figs. 7 and 9). Here, CD81 is linked to colitis.