title: Qualitative thrombelastographic detection of tissue factor in human plasma.
abstract: BACKGROUND
  Tissue factor (TF) is the principal in vivo initiator of coagulation, with normal circulating TF concentrations reported to be approximately 23-158 pg/mL. However, patients with atherosclerosis or cancer have been reported to have TF concentrations ranging between 800 and 9000 pg/mL. Of interest, thrombelastographic (TEG)-based measures of clot initiation and propagation have demonstrated hypercoagulability in such patients at risk for thromboembolic events. Thus, our goal in the present investigation was to establish a concentration-response relationship of the effect of TF on TEG variables, and determine specificity of TF-mediated events with a monoclonal TF antibody.
  
  
  METHODS
  Thrombelastography was performed on normal human plasma exposed to 0, 500, 1000, or 2000 pg/mL TF. Additional experiments with plasma exposed to 0 or 750 pg/mL TF in the presence or absence of a monoclonal TF antibody (1:360 dilution, 10 min incubation) were also performed. Clot initiation time (R) and the speed of clot propagation (MRTG, maximum rate of thrombus generation) were determined.
  
  
  RESULTS
  The addition of TF to normal plasma resulted in a significant, concentration-dependent decrease in R and increase MRTG values. The addition of TF antibody to samples with TF significantly increased R and decreased MRTG values compared to samples with TF addition.
  
  
  CONCLUSIONS
  In conclusion, changes in TEG variables in conjunction with use of a TF antibody can detect pathological concentrations of TF in human plasma in vitro. Further investigation is warranted to determine if TEG(R)-based monitoring could assist in the detection and prevention of TF-initiated thromboembolic events.
authors.affiliation: Department of Anesthesiology, The University of Alabama at Birmingham, Birmingham, Alabama 35249-6810, USA. vnielsen@uab.edu
authors.forename: Vance G
authors.initials: VG
authors.lastname: Nielsen
authors.forename: Paul
authors.initials: P
authors.lastname: Audu
authors.forename: Lana
authors.initials: L
authors.lastname: Cankovic
authors.forename: Ralph T
authors.initials: RT
authors.lastname: Lyerly
authors.forename: Brad L
authors.initials: BL
authors.lastname: Steenwyk
authors.forename: Valerie
authors.initials: V
authors.lastname: Armstead
authors.forename: Garry
authors.initials: G
authors.lastname: Powell
mesh_terms: D001777:Blood Coagulation / Q000187:drug effects; D005175:Factor XII Deficiency / Q000097:blood*; D006487:Hemostasis; D006801:Humans; D012016:Reference Values; D013916:Thrombelastography / Q000379:methods*; D013925:Thromboplastin / Q000032:analysis* / Q000494:pharmacology
chemical_list: D013925:Thromboplastin