Patients with myeloproliferative neoplasms Philadelphia chromosome negative (MPNsPh1-) such as Essential thrombocytosis (ET), Polycythemia vera (PV) and Primary Myelofibrosis (PMF) have a higher risk of arterial or deep-vein thrombosis. This is responsible for a significant increase in mortality (up to 31% of increase in thrombosis risk in ET). Cellular inflation and blood hyperviscosity, resulting from these diseases, fail to account for these thromboses, as more than 50% of thrombotic complications happen under adapted antineoplastic drug treatment.

These last years, cellular microparticles (MPs) have been shown to play a major role in thrombogenesis. MPs are generated by apoptosis or the activation of malignant cells, platelets, endothelial cells or monocytes. They are fragments of plasma membrane, smaller than 1 µm, rich in phosphatidylserine, which can express the tissue factor and serve as support for the coagulation factors. Increase in the plasma concentration of procoagulant platelet microparticles has been demonstrated in other thrombotic diseases (acute coronary syndrome, disseminated intravascular coagulation DIC, etc.). The working hypothesis is that platelet microparticles are involved in the hypercoagulability of MPNs patients.

Inclusion Criteria for MNPs patients:

• Age > 18
• Establish MNPs Phi- diagnosis (ET, PV, MFP)
• Consent to participate

Inclusion Criteria for healthy volunteers:

• Healthy volunteers matched in age, sex with the MNPs patients, with a normal complete blood and platelet count
• No personal thromboembolic history
• No known thromboembolic risk factor : thrombophilia, cancers, and other disease associated with a thrombotic risk (Atrial fibrillation, etc.)
• Not pregnant
• Non smoker
• For women, no hormonal contraceptives

Exclusion Criteria for MNPs patients:

• Pregnancy
• Patient unable to give consent

Patients with ET, PV or PMF. Healthy volunteers.