Circulating tissue factor positive microparticles in patients with acute recurrent deep venous thrombosis

Introduction: Circulating tissue factor positive microparticles (MPTF) were reported in a wide range of diseases with thrombotic tendency. Though D-dimer assay had a high negative predictive value for deep venous thrombosis (DVT) recurrence, there are currently no reliable positive predictors for recurrent DVT. We therefore quantified MPTF in patients with acute recurrent DVT to determine whether MPTF levels could be used to predict recurrent DVT. Materials and Methods: Microparticles (MPs) were isolated from plasma of initial DVT patients (n = 25), recurrent DVT patients (n = 25) and sex-and age-matched healthy individuals (n = 25), stained with annexin V, cell-specific monoclonal antibodies (MoAbs) and a MoAb directed against tissue factor (TF), and analyzed by flow cytometry. We also determined the plasma procoagulant activity with a Human TF Chromogenic Activity Assay Kit. Results: We found total MPTF to be elevated in recurrent DVT patients versus normal individuals (P=0.001). The number of monocyte-derived MPTF in both initial and recurrent DVT was higher than in normal individuals (P<0.01, respectively). The platelet and endothelial cell derived MPTF in recurrent DVT were significantly increased relative to other MPTF (P<0.05), although there was no difference between initial DVT patients and normal individuals. We demonstrated elevated procoagulant activity of platelet-free plasma in DVT patients relative to normal individuals, and a positive correlation with MPTF. Conclusions: The elevated MPTF could be a potentially predictor for DVT recurrence. Further studies are needed to validate its sensitivity and specificity. (C) 2011 Elsevier Ltd. All rights reserved.