The impact of activated blood and endothelial cells on the thrombosis in myeloproliferative neoplasms (MPN) has not yet been clarified. We prospectively analyzed correlation between circulating leukocyte‐platelet aggregates and soluble selectins to thrombosis occurrence in MPN, in the context of standard and cardiovascular risk factors, and different clinical and biological characteristics.

Flow cytometric analysis of neutrophil‐platelet (Neu‐Plt) and monocyte‐platelet (Mo‐Plt) aggregates in peripheral blood, as well as quantification of soluble E‐/L‐/P‐selectins by enzyme immunoassay, was performed on 95 newly diagnosed MPN patients.

During the follow‐up, thrombosis occurred in 12.6% MPN patients (arterial 9.4%, venous 3.2%), with a mean time of 39 months. The overall incidence rate of main thrombotic events was 4.36 per 100 patient‐years. The incidence of arterial hypertension (HTA) was significantly higher in patients with thrombosis, compared to those without thrombosis (P < .05). The level of soluble P‐selectin was significantly higher in patients with thrombosis compared to those without thrombosis (346.89 ng/mL vs 286.39 ng/mL, P = .034). The mean level of Neu‐Plt (26.7% vs 22.4%) and Mo‐Plt (17.8% vs 12.3%) aggregates did not differ significantly between the groups with and without thrombosis. A multivariate COX proportional hazard regression model confirmed an independent predictive significance of Mo‐Plt aggregates (HR = 1.561, 95% CI: 1.007‐2.420, P = .046), as well as the cumulative effect of Mo‐Plt aggregates and HTA (HR = 1.975, 95%CI: 1.215‐3.212, P = .006) for thrombosis occurrence.

Monocyte‐platelet aggregates represent an independent risk factor for thrombosis occurrence, further on supported by HTA.