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Tissue factor activity in whole blood.
- Source :
-
Blood [Blood] 2005 Apr 01; Vol. 105 (7), pp. 2764-70. Date of Electronic Publication: 2004 Dec 16. - Publication Year :
- 2005
-
Abstract
- Tissue factor (TF) is an integral membrane protein essential for hemostasis. During the past several years, a number of studies have suggested that physiologically active TF circulates in blood at concentrations greater than 30 pM either as a component of blood cells and microparticles or as a soluble plasma protein. In our studies using contact pathway-inhibited blood or plasma containing activated platelets, typically no clot is observed for 20 minutes in the absence of exogenous TF. An inhibitory anti-TF antibody also has no effect on the clotting time in the absence of exogenous TF. The addition of TF to whole blood at a concentration as low as 16 to 20 fM results in pronounced acceleration of clot formation. The presence of potential platelet TF activity was evaluated using ionophore-treated platelets and employing functional and immunoassays. No detectable TF activity or antigen was observed on quiescent or ionophore-stimulated platelets. Similarly, no TF antigen was detected on mononuclear cells in nonstimulated whole blood, whereas in lipopolysaccharide (LPS)-stimulated blood a significant fraction of monocytes express TF. Our data indicate that the concentration of physiologically active TF in non-cytokine-stimulated blood from healthy individuals cannot exceed and is probably lower than 20 fM.
Details
- Language :
- English
- ISSN :
- 0006-4971
- Volume :
- 105
- Issue :
- 7
- Database :
- MEDLINE
- Journal :
- Blood
- Publication Type :
- Academic Journal
- Accession number :
- 15604222
- Full Text :
- https://doi.org/10.1182/blood-2004-09-3567