Potential role of platelet-leukocyte aggregation in trauma-induced coagulopathy: ex vivo findings.

Background: Platelet dysfunction has been identified as an important contributor of trauma-induced coagulopathy (TIC) but the underlying mechanism still remains to be elucidated. Trauma-associated pro-inflammatory stimuli strongly activate leukocytes, which in turn bind activated platelets. Therefore, we investigated the role of platelet-leukocyte aggregation (PLA) as a potential feature of trauma-induced platelet dysfunction. Methods: Whole blood from 10 healthy donors was exposed to selective and collective platelet and leukocyte agonists in order to simulate differential states of activation. PLA formation and CD11b expression as a measure of leukocyte activation were determined by flow cytometry. Platelet-mediated hemostatic function was measured by thromboelastometry (ROTEM(R)) and impedance aggregometry (Multiplate(R)). Results: Activation of platelets and leukocytes was associated with diminished platelet-mediated hemostatic potential. Aggregation of platelets with monocytes rather than granulocytes resulted in a reduction of hemostatic function, as indicated by an impaired responsiveness in platelet aggregometry and a reduction of thromboelastometric maximum clot firmness. This finding was irrespective of CD11b expression and was not paralleled by a reduction of measurable platelet counts. Conclusion: PLA formation occurs primarily between monocytes and activated platelets and is associated with impaired platelet-mediated hemostatic function. PLA formation was not paralleled by a reduction in platelet complete blood counts. (C) 2017 Lippincott Williams & Wilkins, Inc.

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