Whereas Crohn’s disease is believed to be more Th1-mediated and characterized by increased production of IFN-γ, a Th2-bias has been reported in ulcerative colitis despite evidence indicating that T cells from ulcerative colitis patients do not produce IL-4, the signature cytokine of the Th2 response [37]; however, increased production of IL-5, another Th2 cytokine, has been reported [38]. This evidence concerns the gene IL5 and Crohn disease.