Introduction Paroxysmal nocturnal hemoglobinuria (PNH) is a disease characterized by the susceptibility of blood cells to attack by the complement system, inducing extracellular vesicle (EV) production. Thromboembolism is the leading cause of death in this condition. Eculizumab, a humanized monoclonal antibody which inhibits the C5 protein of the complement, reduces the thrombotic risk in PNH. Materials and method We conducted a pilot, prospective, open-label, longitudinal clinical study with six PNH patients treated with eculizumab. The aim was to measure, by flow cytometry, the EVs’ production in the patients’ platelet-free plasma (PFP) before and during the treatment. We also assessed the procoagulant activity in PFP using STA®-Procoag-PPL and thrombin generation assays (TGA). A high-sensitive version of TGA was also used to study the procoagulant profile induced by the EVs using EVs pelleted from PFP. Results We observed a decrease in platelet EV count with eculizumab treatment (p < 0.05). STA®-Procoag-PPL assay showed a decrease of the procoagulant profile induced by procoagulant phospholipids (PL) during treatment. These results were not confirmed by TGA on PFP, due to a lack of sensitivity. Thus, we used a high-sensitive version of TGA that enabled us to observe variation in the procoagulant profile induced by the EVs with eculizumab (p < 0.05). Conclusions Eculizumab has an impact on the extent of EV production and on the procoagulant profile induced by the procoagulant PL and the EVs. One factor in the antithrombotic action of eculizumab is its ability to decrease EV production and the procoagulant profile induced by PL and EVs.

Original languageEnglish
Pages (from-to)142-148
Number of pages7
JournalThrombosis Research
Early online date2017
Publication statusPublished - 1 Aug 2017


  • Eculizumab
  • Extracellular vesicles
  • Paroxysmal nocturnal hemoglobinuria
  • Thrombosis

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  • Student Theses

    Study of the potential role of extracellular vesicles in thrombosis associated with paroxysmal nocturnal hemoglobinuria and red blood cell concentrates transfusions

    Author: Wannez, A., 12 Sep 2018

    Supervisor: Dogne, J. (Supervisor), Mullier, F. (Supervisor), Masereel, B. (President), Brichard, S. (External person) (President), Chatelain, C. (External person) (Jury), Chatelain, B. (Jury), Van Den Neste, E. (External person) (Jury), Delettre, F. (External person) (Jury) & Gerotziafas , G. (External person) (Jury)

    Student thesis: Doc typesDoctor of Biomedical and Pharmaceutical Sciences

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