ABSTRACT
Tissue factor (TF) is a transmembrane glycoprotein that is essential for hemostasis. It binds coagulation serine protease factor VII/VIIa (FVII/VIIa) to form a bimolecular complex that functions as the primary initiator of coagulation in vivo. The TF/FVIIa complex activates both FX and FIX and leads to the generation of thrombin and fibrin.1 TF is constitutively expressed at high levels in adventitial fibroblasts of the vessel wall, which facilitates rapid activation of the coagulation cascade after injury. In a basal state, smooth muscle cells in the media of the vessel wall and monocytes/macrophages also contain small amounts of TF. TF can be induced in these cells and in endothelial cells of the vessel wall under various pathologic conditions, resulting in a prothrombotic state.2 TF is also expressed in a tissue-specific manner with high levels in a variety of tissues, such as the brain, heart, kidney, and placenta.1
