TNF and irritable bowel syndrome: We chose to concentrate on TNFα, IL-6, and IL-10 since previous reports have demonstrated evidence for the existence of TNFα, IL-6 and IL-10 gene polymorphisms in IBS21,22, and these cytokines have been well studied in the serum2,3,10,12,17,18 and peripheral blood mononuclear (PBMC) populations16,23–28 in IBS.