Platelets in ulcerative colitis and Crohn's disease express functional interleukin‐1 and interleukin‐8 receptors

Tissue and plasma concentrations of several cytokines are increased in patients with inflammatory bowel disease (IBD). Platelets play an important role in inflammation and circulate in an activated state in patients with IBD. This study assesses the expression of IL-8 and IL-1 receptors on the surface of platelets from patients with IBD using phycoerythrin (PE)- labelled recombinant human rhIL-lp and rhIL-8 and flow cytometry. The percentage IL-1R expres- sing platelets (median and interquartile range IQR) in the IBD group was 8.7% (5.5-18.2) compared to 4.2% (2.3-6.1) in controls (P = 0.02). The percen- tage IL-8R expressing platelets in the IBD group was 22.5% (16.5-27.9) and 9.2% (4.3-9.6) in controls (P < 0.001). Furthermore, platelet IL-1R expression in patients with IBD was inversely related to the total daily dose of steroids (r = -0.71, P < 0.01 linear regression analysis). Finally, platelet rich plasma from healthy controls was stimulated with rhIL-lp and rhIL-8 and assessed for activation dependent expression of platelet aGPIIb/IIIa and CD62 (p- selectin, GMP-140). IL-IP and IL-8 in vitro signifi- cantly and specifically activated the platelets. The surface membrane of platelets is able to express functional IL-1R and IL-8R, the expression of which is signficantly increased in IBD. Interleukin- lp and IL-8 modulate platelet activation in vitro indicating a target role for platelet function in inflammation.