PLATELETS CIRCULATE IN AN ACTIVATED STATE IN INFLAMMATORY BOWEL-DISEASE

Background/Aims: Platelets show proinflammatory as well as prothrombot ic properties. Patients with inflammatory bowel disease are at increas ed risk of systemic thromboembolism, and multifocal microvascular infa rction has been proposed as a pathogenetic mechanism in Crohn's diseas e. The aim of this study was to determine if inflammatory bowel diseas e is associated with abnormal platelet behavior. Methods: Platelet act ivation and aggregability were assessed using flow cytometry, Born agg regometry, and the modified method of Wu and Hoak. Serum beta-thrombog lobulin was measured in patients with Crohn's disease and ulcerative c olitis and, as controls, in healthy volunteers and patients with activ e rheumatoid arthritis. Results: Platelet surface expression of P-sele ctin and GP53 (markers of activation) were increased in Crohn's diseas e (13 of 30 patients abnormal for P-selectin; 9 of 28 abnormal for GP5 3) (P < 0.01) and ulcerative colitis (9 of 21 for P-selectin; 10 of 21 for GP53) (P < 0.01) compared with healthy controls. Increased circul ating platelet aggregates (15 of 24 patients with Crohn's disease and 8 of 16 with ulcerative colitis) (P < 0.01), platelet aggregability in vitro, and serum beta-thromboglobulin were detected in active inflamm atory bowel disease compared with healthy controls. Platelet behavior in active rheumatoid arthritis resembled that in healthy controls. Con clusions: Increased platelet activation and aggregation are features o f inflammatory bowel disease and may contribute to the risk of systemi c thromboembolism and the pathogenesis of mucosal inflammation. Theref ore, antiplatelet agents may be valuable in the management of inflamma tory bowel disease.