The GP IIb/IIIa Inhibitor Abciximab (ReoPro((R))) Decreases Activation and Interaction of Platelets and Leukocytes During In Vitro Cardiopulmonary Bypass Simulation

Objective: Cardiopulmonary bypass (CPB) induces a systemic inflammatory response and increases expression of the platelet activation marker P-selectin which mediates binding of platelets to leukocytes. Inhibition of the platelet GP IIb/IIIa receptor during CPB has been shown to protect platelets without increasing bleeding complications and is assumed to reduce the inflammatory response. The aim of this study was to investigate the effect of the GP IIb/IIIa inhibitor abciximab (ReoPro((R))) on the function and interaction of platelets and leukocytes during experimental CPB.

Methods: Heparinized (3U/ml) fresh whole blood of healthy volunteers was treated before continuous in vitro circulation in a well established CPB model with 3.2mug/ml abciximab (n=6) or left untreated as control (n=6). Measurements were made before (baseline) and after 30 and 60min of circulation and comprised: percentage of platelets expressing P-selectin and percentage of platelet-bound leukocytes (flow cytometry), release of the leukocyte activation marker PMN-elastase (ELISA), and platelet and leukocyte counts.

Results: Abciximab almost completely prevented a CPB-induced increase of platelet P-selectin and platelet-leukocyte binding after 30 and 60min of circulation, and significantly inhibited release of PMN-elastase after 30min of circulation. Furthermore, abciximab significantly inhibited a CPB-induced decrease of platelet and leukocyte counts.

Conclusions: Abciximab inhibits CPB-induced activation, interaction and consumption of platelets and leukocytes in vitro. GP IIb/IIIa inhibition should be considered as a promising approach not only to conserve platelet function but also to inhibit pro-inflammatory events during CPB in vivo.