Localisation of heparin in mast cells

Heparin is localised in mast cells as an activator of the contact system. The potent anticoagulant properties of heparin confine this activation to the top half of the intrinsic pathway, and coagulation is prevented. Certain mast cells contain chondroitin sulphate E, which can also activate the contact system but is a weak inhibitor of coagulation. The localisation of these mast cells to the intestine suggests that coagulation is required for effective inflammatory response in the intestinal wall.