Neutrophil expression and infiltration into Crohn's intestine.

Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) of unknown etiology. The main pathological feature of IBD is transmural infiltration of polymorphonuclear neutrophils (PMN) and mononuclear cells associated with smooth muscle cell proliferation, accumulation of collagen, thickening and stenosis. While the etiology of Crohn's disease remains unknown, increased levels of proinflammatory cytokines, such as IL-1, IL-6, IL-8 and TNF in the inflamed bowel probably play a major role in the tissue injury and fibrosis that ensue. PMNs infiltrate into tissue in response to chemotactic signals produced by the tissue, such as a-chemokines (IL-8). Although, the initial infiltration of neutrophils is beneficial to kill foreign particles and bacteria, persistent infiltration causes tissue damage. This review shows some evidence of neutrophil expression in Crohn's bowel and the process of neutrophil infiltration into the inflamed tissue.