RT Journal Article SR Electronic T1 Determination of cell-derived microparticles in patients with pulmonary hypertension and connective-tissue diseases using flow cytometry JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP p3345 VO 38 IS Suppl 55 A1 Xhylsime Kqiku A1 Gabor Kovacs A1 Eva Rohde A1 Dirk Strunk A1 Horst Olschewski YR 2011 UL http://erj.ersjournals.com/content/38/Suppl_55/p3345.abstract AB Background: Microparticles (MPs) are small plasma membrane vesicles released from different cell types during activation or apoptosis.Increased MPs levels have been associated with cardiovascular diseases,thrombotic disorders and systemic inflammatory conditions.In pulmonary hypertension (PH) the role of MPs is poorly understood.Aims and objectives: The aim of this study was to analyze the MPs fractions in PH-and connective-tissue disease (CTD) patients which represent a risk factor for PH development.Patients and methods: Plasma samples derived from PH and CTD patients were tested using flow cytometry (FC). Circulating MPs from platelets (CD61+), endothelial cells (CD31+) as well as Annexin V+ were measured by FC in 28 PH patients,36 CTD patients and 41 healthy controls.The levels of MPs were compared in these three groups.Results: The overall fraction of MPs was higher in PH patients (57±26% of total events) and CTD patients (51±21%)as compared to controls (42±18%) (p<0,05). Platelet derived CD61+ MPs were tendentially increased in PH patients comparing to controls (p=0,096) whereas CD31 expression was not found to be different on MPs from patients and controls.The expression of Annexin V on MPs from PH patients were significantly higher as compared with controls (mean fluorescence intensities: 56±26%vs.38±17%,p=0,003).There were no significant differences between Annexin V expression levels on MPs in PH vs. CTD patients (p=0,384) and not between CTD vs.controls (p=0,179).Conclusions: According to these preliminary data, the plasma levels of AnnexinV+MPs are increased in PH patients and may be related to an activated pro-coagulatory and inflammatory vascular status.