Anomalies du système immunitaire de la muqueuse au cours des maladies inflammatoires de l'intestin

Abstract

The immunopathology of inflammatory bowel disease consists of a sequence of immunological steps that begin with initial antigen processing events. A major focus has recently been placed on bacterial cell wall products (peptidoglycans, formyl- methionyl-leucyl phenylalanine, lipopolysaccharides). These products nonspecifically induce an intense activation of macrophages, granulocytes, ana lymphocytes. Currently, therefore, the working hypothesis is that in inflammatory bowel disease, ubiquitous and common bacterial cell wall products capable of initiating an inflammatory immune response, in a genetically predisposed individual, activate a sequence of immunologic processes that are not appropriately downregulated. Initiating events then lead to macrophage activation, 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.