 There was a prevailing view that Crohn's disease is a primary T cell autoimmune disorder; however, a newer theory hypothesizes that Crohn's results from an impaired innate immunity.The later hypothesis describes impaired cytokine secretion by macrophages, which contributes to impaired innate immunity and leads to a sustained microbial-induced inflammatory response in the colon, where the bacterial load is high.Another theory is that the inflammation of Crohn's was caused by an overactive Th1 and Th17 cytokine response.