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Histones induce phosphatidylserine exposure and a procoagulant phenotype in human red blood cells
Author(s) -
Semeraro F.,
Ammollo C. T.,
Esmon N. L.,
Esmon C. T.
Publication year - 2014
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.12677
Subject(s) - phosphatidylserine , histone , prothrombinase , chemistry , flow cytometry , microbiology and biotechnology , biochemistry , biology , platelet , thrombin , immunology , phospholipid , membrane , gene
Summary Background Extracellular histones exert part of their prothrombotic activity through the stimulation of blood cells. Besides platelets, histones can bind to red blood cells ( RBC s), which are important contributors to thrombogenesis, but little is known about the functional consequences of this interaction. Objectives To evaluate the effect of histones on the procoagulant potential of human RBC s with particular regard to the expression of surface phosphatidylserine ( PS ). Methods PS exposure on human RBC s treated with a natural mixture of histones or recombinant individual histones was evaluated with fluorescein isothiocyanate–annexin‐V binding and measured with flow cytometry. Calcium influx in RBC s loaded with the calcium‐sensitive fluorophore Fluo‐4 AM was assessed with flow cytometry. The procoagulant potential of histone‐treated RBC s was evaluated with a purified prothrombinase assay and a one‐stage plasma recalcification clotting test. Results Natural histones induced PS exposure on RBC s in a dose‐dependent manner, and neutralization or cleavage of histones by heparin or activated protein C, respectively, abolished PS externalization. H4 was mainly responsible for the stimulating activity of histones, whereas the other subtypes were almost ineffective. Similarly, natural histones and H4 induced influx of calcium into RBC s, whereas the other individual histones did not. Histone‐induced exposure of PS on RBC s translated into increased prothrombinase complex‐mediated prothrombin activation and accelerated fibrin formation in plasma. Conclusions Histones induce RBC s to express a procoagulant phenotype through the externalization of PS . This finding provides new insights into the prothrombotic activity of extracellular histones.