Despite recent advances, the pathogenesis and therapy of various forms of chronic inflammatory diseases of the gastrointestinal tract remains problematical. Especially threatening is the possible complication of the development of a malignant growth, but the role of the chronic inflammatory process in this is not known. Three examples are: H. pylori-induced gastritis is associated with gastric lymphomas and carcinomas; there is an increased incidence of intestinal T-cell lymphomas in tropical sprue; and chronic inflammatory bowel diseases, particularly ulcerative colitis,...