ALTERATIONS OF THE MUCOSAL IMMUNE-SYSTEM IN INFLAMMATORY BOWEL-DISEASE

The immunopathology of inflammatory bowel disease consists of a sequen ce of immunological steps that begin with initial antigen processing e vents. A major focus has recently been placed on bacterial cell wall p roducts (peptidoglycans, formyl-methionyl-leucyl phenylalanine, lipopo lysaccharides). These products nonspecifically induce an intense activ ation of macrophages, granulocytes, ana lymphocytes. Currently, theref ore, the working hypothesis is that in inflammatory bowel disease, ubi quitous and common bacterial cell wall products capable of initiating an inflammatory immune response, in a genetically predisposed individu al, activate a sequence of immunologic processes that are not appropri ately downregulated. Initiating events then lead to macrophage activat ion, with the resultant production of large amounts of IL1, 116, 118, and TNF-alpha. Subsequent cell-mediated immunologic events involve the mucosal immune system, and lead to the chronic intestinal destruction associated with inflammatory bowel disease.