In support of our aGVHD findings, we observed that both Fli1fl/WTCre+ and Fli1fl/flCre+ naive CD4+ T cells had a reduced ability to induce colitis, in which Fli1fl/WTCre+ CD4+ T cells showed the least pathogenicity in colitis development (Supplemental Figure 4A). Here, CD4 is linked to colitis.