Tissue factor expression in blood cells

Thromb Res. 2010 Apr;125 Suppl 1:S31-4. doi: 10.1016/j.thromres.2010.01.032. Epub 2010 Feb 10.

Abstract

The popular concept of TF serving predominantly as a hemostatic envelope encapsulating the vascular bed, has recently been challenged by the observation that blood of healthy individuals may form TF-induced thrombus under conditions entailing shear stress and activated platelets, corroborating the notion of blood borne TF. Accordingly, small amounts of TF activity is detected in calcium ionophore-stimulated monocytes, whereas it is questionable whether neutrophils and eosinophils express TF. Still there are contradicting reports on TF synthesis and expression in activated platelets, but when using a very sensitive and specific assay for TF activity measurements, we fail to detect TF activity associated with platelets activated with various agonists. However, activated platelets may play a role in decrypting monocyte TF activity in a process entailing transfer of TF to activated platelets in a P-selectin-PSGL-1 reaction whereby inactive TF (encrypted) becomes active through the availability of clusters of phosphatidylserine. Microparticles from plasma of healthy subjects possess weak TF-like activity which is not inactivated by anti-TF antibody. Endothelial cells are well documented to synthesize TF by several agonists in vitro. In contrast, there is little evidence that these cells are capable of synthesizing TF in vivo, and a recent report fails to show that TF on the endothelium may play any role in thrombin generation in a murine endotoxemia model. It may be concluded that monocytes are the only blood cells that synthesize and express TF and which may be the only source for TF-induced thrombosis when the endothelium is intact.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Blood Platelets / cytology
  • Blood Platelets / metabolism
  • Endothelial Cells / cytology
  • Endotoxemia / metabolism
  • Eosinophils / cytology
  • Humans
  • Mice
  • Monocytes / cytology
  • Monocytes / metabolism
  • Neutrophils / cytology
  • Neutrophils / metabolism
  • P-Selectin / metabolism
  • Phosphatidylserines / metabolism
  • Platelet Activation
  • Thrombin / metabolism
  • Thromboplastin / metabolism*
  • Thrombosis / metabolism
  • Thrombosis / pathology

Substances

  • P-Selectin
  • Phosphatidylserines
  • Thromboplastin
  • Thrombin