Hageman factor
Chapter: 2
Also known as clotting factor XII. It was discovered, because of its deficiency in a person with the surname, Hageman. This is a very important plasma protein, that can cause the production of inflammatory mediators and products from several different plasma protein cascades. Thus, to understand why this protein is important, you must think of it in terms of Hageman factor-related systems. For example, it is the protein that initiates the intrinsic (in contrast to the extrinsic) clotting process and fibrinolysis. As a result of Hageman factor's activation, fibrin is produced. Fibrinolysis develops after Hageman factor's activation, because the fibrinolytic proteinase, plasmin, is subsequently produced. Plasmin can also activate C3 and C5 in the complement cascade, producing C3a and C5a, respectively. Both of these activated products are anaphylatoxins, with C5a additionally having powerful chemotactic activity. Hageman factor's activation also leads to kinin production, because the kallikrein/kinin cascade is subsequently triggered.