title: Circulating microparticles in carriers of factor V Leiden with and without a history of venous thrombosis.
abstract: Although factor V Leiden (FVL) is a major determinant of thrombotic risk, the reason why less than 10% of carriers eventually develop venous thromboembolic (VTE) events is unknown. Recent observations suggest that circulating levels of microparticles (MP) may contribute to the thrombogenic profile of FVL carriers. We measured the plasma level of annexin V-MP (AMP) platelet-MP (PMP), endothelial-MP (EMP), leukocyte-MP (LMP) and tissue factor-bearing MP (TF(+)MP), and the MP procoagulant activity (PPL) in 142 carriers of FVL (of these 30 homozygous and 49 with prior VTE), and in 142 age and gender-matched healthy individuals. The mean (± SD) level of AMP was 2,802 ± 853 MP/μl in carriers and 1,682 ± 897 in controls (p<0.0001). A statistically significant difference between homozygous and heterozygous carriers of FVL was seen in the level of PMP, EMP and LMP, but not in that of the remaining parameters. When the analysis was confined to carriers with and without a VTE history, the mean level of AMP was 3,110 ± 791 MP/μl in the former, and 2,615 ± 839 MP/μl in the latter (p<0.005). The mean level of all subtypes of circulating MP showed a similar pattern. The PPL clotting time was 39 ± 9 seconds (sec) in carriers, and 52 ± 15 sec in controls (p=0.003); and was 35 ± 8 sec in carriers with prior thrombosis, and 41 ± 10 sec in thrombosis-free carriers (p<0.005). Our study results suggest that circulating MP may contribute to the development of thrombosis in carriers of FVL mutation.
authors: Department of Cardiologic, Thoracic, and Vascular Sciences, 2nd Chair of Internal Medicine, University of Padua Medical School, Padua, Italy.
authors: Elena
authors: E
authors: Campello
authors: Luca
authors: L
authors: Spiezia
authors: Claudia M
authors: CM
authors: Radu
authors: Maria
authors: M
authors: Bon
authors: Sabrina
authors: S
authors: Gavasso
authors: Patrizia
authors: P
authors: Zerbinati
authors: Barry
authors: B
authors: Woodhams
authors: Daniela
authors: D
authors: Tormene
authors: Paolo
authors: P
authors: Prandoni
authors: Paolo
authors: P
authors: Simioni
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000473:pathology*; D015331:Cohort Studies; D005165:Factor V / Q000235:genetics*; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020246:Venous Thrombosis / Q000097:blood* / Q000209:etiology / Q000235:genetics*
chemical_list: C095381:factor V Leiden; D005165:Factor V