To test this, we tried to induce colitis in mice colonized with a HD microbiota by transferring naive CD4+ T cells isolated from FoxP3-cre × Rorcfl/fl (RorcΔTreg) mice, from which no RORγt+ Treg cells can develop, but in which RORγt+ effector Th17 cells are preserved (42). Here, CD4 is linked to colitis.