• J Zipperle, M Ponschab, C J Schlimp, A Islam, P Dungel, C Penzenstadler, S Bahrami, H Redl, and H Schöchl.
• 1Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria 2Departments of Anaesthesiology and Intensive Care Medicine, AUVA Trauma Centers, Austria 3Faculty of Health Sciences, Linköping University, Linköping, Sweden.
• Shock. 2015 Oct 1;44 Suppl 2:3.

IntroductionLeukocyte-platelet aggregates (LPA) are associated with atherosclerosis, SIRS and sepsis. Severely injured patients often develop granulocytosis and present with coagulopathy with prolonged clotting times, impaired clot stability and fibrinolytic activation. Following major trauma, 'capture' of functional platelets on activated granulocytes might exacerbate trauma-induced coagulopathy. This study investigated whether the prevalence of activated granulocytes and/or platelets could impair the functional clot firmness in a viscoelastic test (ROTEM).MethodsBlood of 8 healthy donors was stimulated with different leukocyte and platelet activators such as bacterial peptides (fMLP), protein kinase C activator (phorbol-myristate-acetate, PMA) and thrombin receptor activating peptide 6 (TRAP6) and was examined for changes in maximum clot firmness (MCF). Leukocyte-platelet aggregation was defined as the presence of platelet antigens on activated granulocytes and was assessed by flow cytometry. Complete blood cell count (CBC) was performed to investigate changes in available platelet numbers.ResultsStimulation of whole blood with fMLP and PMA resulted in an up-regulation of the phagocytosis marker CD11b on granulocytes. In the PMA samples, the increased presence of platelet antigens on granulocytes was observed. Formation of LPA after PMA stimulation was associated with a reduction of MCF, an effect that was absent when platelet function was inhibited with Cytochalasin D.ConclusionOur data obtained in an ex vivo assay indicate that the formation of LPA is associated with a diminished platelet count and a consecutive reduction in MCF.

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