title: Monocytes and plasma tissue factor levels in normal individuals and patients with deep venous thrombosis of the lower limbs: potential diagnostic tools?
abstract: BACKGROUND
  Tissue factor (TF) is the main physiological initiator of blood coagulation; it is membrane-bound on monocytes (mTF) and free in plasma (pTF). Abnormal expression of TF by monocytes has been implicated in various diseases. We therefore quantified monocytes expressing TF and pTF levels in patients with lower-limb deep venous thrombosis (DVT).
  
  
  METHODS
  DVT was confirmed by Duplex Scan. Blood mTF levels under resting condition (baseline), after incubation without (unstimulated) and with (stimulated) lipopolysaccharide (LPS), and total mTF levels were determined by flow cytometry using two analytical methods (Histogram and Quadrant-Statistics). Plasma TF levels were measured using an enzyme-linked immunoabsorbent assay (ELISA). Results were compared with age-matched controls.
  
  
  RESULTS
  Histogram analysis in patients with DVT showed significantly elevated mTF levels for baseline, unstimulated and total mTF over controls. For Quadrant-Statistics, DVT patients also showed significantly raised baseline, unstimulated, stimulated and total mTF. Similarly, pTF levels were significantly raised in subjects with DVT compared to controls. Baseline mTF levels correlated with pTF levels by Histogram and Quadrant-Statistics analysis. Using the relative operating characteristic (ROC) curve, baseline mTF and pTF assays displayed sensitivity and specificity in detecting DVT. Quadrant-Statistics baseline mTF and pTF gave the best discrimination.
  
  
  CONCLUSIONS
  The TF assays used in this study showed acceptable sensitivity and specificity and are cost-effective and practical. Therefore, they should be considered in patients with, or at risk of, DVT.
authors.affiliation: Faculty of Pharmacy - Federal University of Minas Gerais, Brazil.
authors.forename: Lauro M
authors.initials: LM
authors.lastname: Vieira
authors.forename: Luci M S
authors.initials: LM
authors.lastname: Dusse
authors.forename: Ana P
authors.initials: AP
authors.lastname: Fernandes
authors.forename: Olindo A
authors.initials: OA
authors.lastname: Martins-Filho
authors.forename: Marcos
authors.initials: M
authors.lastname: de Bastos
authors.forename: Mônica F R
authors.initials: MF
authors.lastname: Ferreira
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Cooper
authors.forename: Bashir A
authors.initials: BA
authors.lastname: Lwaleed
authors.forename: Maria G
authors.initials: MG
authors.lastname: Carvalho
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D035002:Lower Extremity / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000737:chemistry* / Q000166:cytology; D010949:Plasma / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013925:Thromboplastin / Q000032:analysis*; D020246:Venous Thrombosis / Q000175:diagnosis*
chemical_list: D008070:Lipopolysaccharides; D013925:Thromboplastin