CD4 and colitis: However, TCR-Tg CD4+ T cells, i.e., Flagellin-specific CD4+ Tg (Cbir) T cells, induce experimental colitis upon the transfer into lymphopenic mice, while the administration of Treg-inducing Bifidobacterium bifidum ameliorates the colitis by inducing the generation of Cbir Treg cells (Verma et al., 2018).