Increased circulating platelet-neutrophil, platelet-monocyte complexes, and platelet activation in patients with ulcerative colitis: a comparative study

It is reported that the incidence of thromboembolism is increased in ulcerative colitis (UC), and hypercoagulability persists even when patients are in remission. We evaluated the association of inflammatory response parameters with UC activity, and activation parameters of the platelets, endothelium, and the coagulation system in UC. Eighteen UC patients and 19 healthy subjects were included in the study. The patients' clinical features were recorded down; whole blood counts and acute phase parameters were evaluated. UC patients were divided into two as active (9 patients) and inactive (9 patients) according to combined clinical activity index (CAI) and endoscopic activity index (EAI) scores. In all subjects, platelet CD62P expression, platelet-monocyte complexes (PMC), platelet-neutrophil complexes (PNC), and platelet microparticles (PMP) were determined by flow cytometry. E-selectin, thrombin-antithrombin complex (TAT) levels in plasma, and sCD40L levels in serum were determined by ELISA. In both active and inactive UC patients, platelet CD62P expression, the percentages of PMC, and PNC were significantly higher than those in the control group (P< 0.01). PMP level was higher in the control group than in inactive UC patients (P = 0.001). sCD40L level was significantly higher in active UC group than in the control group (P < 0.01). EAI score correlated significantly with PMP (r = 0.5, P = 0.04) and sCD40L (r = 0.48, P = 0.044); CAI score had a negative correlation (r = -0.68, P = 0.002) with sE-selectin level. In addition to increased CD62P expression and sCD40L, increased formation of PMC and PNC suggests a role for platelet-leukocyte complex formation together with platelet activation in thromboembolic events observed in UC.