CD4 and inflammatory bowel disease: Although some studies have indicated that human T cells can induce FOXP3 expression transiently upon activation without gaining suppressive function,29,30 further data show that even transient FOXP3 expression can promote suppressive function in CD4+ T cells.31–33 Paradoxically, patients with IBD show elevated numbers of Treg in the intestinal mucosa that can suppress proliferation of CD4+ T cells in vitro.