It has been declared that naive CD4 + T cells differentiate into Th17 cells in the presence of IL-6, IL-21 or TGF-β; however, in the absence of pro-inflammatory cytokines, naive CD4 + T cells differentiate into Treg cells.[60] If this balance is disturbed, autoimmune diseases can be expected, including IBD. This evidence concerns the gene CD4 and inflammatory bowel disease.