title: Patients with acute coronary syndromes have low tissue factor activity and microparticle count, but normal concentration of tissue factor antigen in platelet free plasma: a pilot study.
abstract: OBJECTIVE
  Tissue factor (TF) is a main initiator of coagulation cascade. Its determination in conditions of acute coronary syndrome is logistically difficult. Hence, in our study, the activity and the concentration of TF and the count of microparticles in the platelet free plasma (PFP) were determined.
  
  
  METHODS
  Blood was drawn from both coronary sinus and femoral vein circulation in a cohort of 40 patients. TF activity was measured by activation of factor X in the presence of factor VIIa, whereas microparticles were detected using flow cytometry. TF antigen concentrations were determined using the ELISA test.
  
  
  RESULTS
  TF activity in the stable angina subgroup was not significantly different from the control group (18.12 +/- 3.35 mOD/min vs. 17.72 +/- 4.05 mOD/min, respectively), but it was significantly lower in the unstable angina (7.62 +/- 4.19 mOD/min) and myocardial infarction (MI) (3.56 +/- 3.85 mOD/min) subgroups (P < 0.05). Results from the coronary sinus and femoral vein circulations were not significantly different. The count of microparticles decreased according to the severity of the acute coronary syndrome: control group, 520 +/- 172; stable angina subgroup, 532 +/- 167; unstable angina subgroup, 392 +/- 142; and MI subgroup, 165 +/- 30 (P < 0.05). There were no significant differences in concentrations of TF antigen in four subgroups.
  
  
  CONCLUSIONS
  These results suggest that the procoagulant TF-bearing microparticles could be recruited from PFP by interaction with platelets and blood cells in the conditions of acute coronary syndrome.
authors.affiliation: Department of Cardiology, University Hospital Motol, 1st Medical Faculty, Prague, Czech Republic. martin.maly@fnmotol.cz
authors.forename: Martin
authors.initials: M
authors.lastname: Maly
authors.forename: Ingrid
authors.initials: I
authors.lastname: Hrachovinova
authors.forename: Pavol
authors.initials: P
authors.lastname: Tomasov
authors.forename: Peter
authors.initials: P
authors.lastname: Salaj
authors.forename: Petr
authors.initials: P
authors.lastname: Hajek
authors.forename: Josef
authors.initials: J
authors.lastname: Veselka
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood*; D000368:Aged; D001324:Autoantigens / Q000097:blood*; D001792:Blood Platelets; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D013925:Thromboplastin / Q000032:analysis* / Q000276:immunology
chemical_list: D001324:Autoantigens; D013925:Thromboplastin