title: Underlying mechanism and specific prevention of hemolysis-induced platelet activation.
abstract: Thromboembolic complications significantly impair the outcome of hemolytic disorders. We hypothesized that red cell adenosine diphosphate (ADP) release results in significant platelet activation in hemolysis and that this prothrombotic state can be prevented by inhibition of the ADP P2Y12receptor. In the current study, we therefore sought to investigate the mechanism and inhibition of hemolysis-induced platelet activation. The expression of activated integrin αIIbß3 was determined by flow cytometry, and platelet aggregation was assessed by multiple electrode platelet aggregometry. We demonstrate platelet activation and increased platelet aggregation by adding hemolytic blood (lysates) to whole blood, similarly to that achieved by the platelet agonist ADP. Enhanced platelet activation and reactivity in the presence of hemolytic blood were significantly abolished by apyrase, which catalyzes ADP degradation, and inhibited by blockade of the platelet ADP P2Y12receptor with cangrelor. Platelets from patients treated with the ADP P2Y12receptor antagonist clopidogrel showed a reduced response to lysates compared to platelets from healthy controls without antiplatelet treatment. Further, in vitro blood group ABO incompatibility induced hemolysis and led to increased platelet activation. Finally, "spontaneous" platelet aggregation seen in patients with cold agglutinin disease was completely abolished by cangrelor. In conclusion, hemolysis is associated with increased platelet activation and aggregation due to red cell derived ADP, which can be prevented by ADP receptor blockade.
authors.affiliation: a Department of Internal Medicine II , Medical University of Vienna , Vienna , Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gremmel
authors.affiliation: b Department of Blood Group Serology and Transfusion Medicine , Medical University of Vienna , Vienna , Austria.
authors.forename: Simone
authors.initials: S
authors.lastname: Fedrizzi
authors.affiliation: c Central Institute for Medical and Chemical Laboratory Diagnostics , Medical University of Innsbruck , Innsbruck , Austria.
authors.forename: Günter
authors.initials: G
authors.lastname: Weigel
authors.affiliation: b Department of Blood Group Serology and Transfusion Medicine , Medical University of Vienna , Vienna , Austria.
authors.forename: Beate
authors.initials: B
authors.lastname: Eichelberger
authors.affiliation: b Department of Blood Group Serology and Transfusion Medicine , Medical University of Vienna , Vienna , Austria.
authors.forename: Simon
authors.initials: S
authors.lastname: Panzer
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000328:Adult; D000368:Aged; D001081:Apyrase / Q000494:pharmacology; D001787:Blood Group Incompatibility / Q000378:metabolism* / Q000473:pathology; D001792:Blood Platelets / Q000378:metabolism* / Q000473:pathology; D000077144:Clopidogrel; D005260:Female; D006461:Hemolysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D058925:Receptors, Purinergic P2Y12 / Q000378:metabolism*; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C548576:P2RY12 protein, human; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D058925:Receptors, Purinergic P2Y12; D000244:Adenosine Diphosphate; D000077144:Clopidogrel; D001081:Apyrase; D013988:Ticlopidine
keywords: ADP; P2Y12inhibitors; hemolysis; platelet activation