Contact activation of the Hageman factor

The Hageman factor (contact factor, or clotting factor XII), first discovered by Ratnoff and Kololi in 1955, has long been considered responsible for the primary activation of the coagulation cascade through the internal thrombin pathway. It is well known that the formation of active factor XII occurs upon contact with negatively charged surfaces: celite, glass, kaolin in vitro, collagen, damaged vascular endothelium and basement membrane in vivo. Further studies have shown that several plasma proteins are involved in the contact activation process: factor XII, factor XI or plasma thromboplastin precursor, precallikrein, high molecular weight kininogen. Currently, knowledge about the "trigger" mechanism of the contact phase, which leads to the activation of coagulation systems, kinin formation and fibrinolysis, has been significantly expanded.