Polymorphonuclear neutrophil leucocytes in childhood Crohn's disease: a morphological study.

Light and electron microscopy was applied to surgical resections and endoscopic biopsies from the ileum and colon of 15 children with Crohn's disease in order to investigate the involvement of neutrophils in the disease process. Clear evidence was found of neutrophil infiltration of the lamina propria and epithelium, neutrophil migration into the gut lumen through epithelial breaks and intact epithelium, neutrophil phagocytosis of luminal and lamina propria bacteria, and the presence of intracellular neutrophils in enterocytes. Similar findings were seen in 5 of 6 children with ulcerative colitis and in a case of an E. coli colitis, but not in 8 controls. The observations demonstrate the involvement of neutrophils in Crohn's disease in childhood and suggest that the response is directed, in part, against luminal enterobacteria and enterocytes.