BETA-2 INTEGRIN ICAM EXPRESSION IN CROHNS-DISEASE

We have previously reported on the expression of the beta 2 integrin f amily of adhesion molecules and their ligands, the ICAM molecules, in the normal human intestine. These molecules likely have a role to play in the inflammatory response and, therefore, were studied in a group of patients with Crohn's disease. A comprehensive study was undertaken in both colon (n = 8) and ileum (n = 10) specimens from 15 patients w ho underwent surgical resections. Immunohistochemistry was performed f or CD18, CD11a, CD11b, CD11c, alpha d, ICAM-1, ICAM-2, and ICAM-3. Eac h of the mucosal, submucosal, muscle, and adventitial layers were scor ed for expression. Specimens from normal colon (n = 15), normal ileum (n = 6), and ulcerative colitis (n = 7) were used for comparisons. Com pared with normal, the expression in the colon mucosa and submucosa in Crohn's disease was increased for all beta 2 integrins. Mucosal CD11c expression was significantly greater in Crohn's disease than in ulcer ative colitis. In the colon muscle and adventitial layers the expressi on in Crohn's disease was similar to normal but increased compared wit h ulcerative colitis. In Crohn's disease ileum, the beta 2 integrin mu cosal and submucosal expression was similar to normal; however, muscle and adventitial expression was increased, particularly for CD11c, Col on ICAM-1, ICAM2, and ICAM-3 expression in Crohn's disease was similar to that seen in ulcerative colitis, ICAM-1 was predominantly expresse d on endothelium but in the inflammatory bowel diseases was also evide nt on mucosal mononuclear cells. ICAM-1 and ICAM-2 expression was incr eased in Crohn's disease colon and ileum compared with normals. This w as most notable in ileal mucosa since ICAM-2 is typically absent in no rmal ileal mucosa. In summary, we are reporting a comprehensive immuno histochemical study of the differential expression of beta 2 integrins , including the newly described alpha d molecule, and the ICAM molecul es in all layers of the colon and ileum from patients with Crohn's dis ease. The increased expression of these molecules may have implication s for therapeutic interventions in Crohn's disease. (C) 1998 Academic Press.