Hageman (contact) factor

Last reviewed 01/2018

Factor XII, Hageman factor, is a plasma protein at the centre of a number of plasma protease cascades involved in inflammation. It is part of the beta-globulin fraction of plasma proteins.

It is activated by:

  • exposed collagen
  • basement membrane
  • endotoxin
  • negatively-charged surfaces
  • glass
  • endogenous substances e.g. kallikrein

It stimulates:

  • directly, the intrinsic pathway of blood coagulation
  • indirectly, the extrinsic pathway of blood coagulation
  • the kallikrein-kinin system
  • the plasmin fibrinolysis system
  • indirectly via kallikrein and plasmin, the complement cascade