Clotting/fibrinolytic system
Chapter: 2
One of the three "cascades" of plasma proteins that result in the production of proinflammatory mediators. The initiating protein in the clotting/fibrinolytic system is Hageman factor (clotting factor XII). One product of the cascade, kallikrein, is a strong activator of Hageman factor, resulting in the development of an autocatalytic amplification loop (i.e., activation of Hageman factor leads to the production of kallikrein, which causes the activation of more Hageman factor, etc.). This is also the cascade that leads to the production of fibrin from plasma fibrinogen. Another of the products is plasmin, which is a proteinase that cleaves fibrin (and produces fibrin-split products in the process). However, plasmin is also important as an activator of other proinflammatory systems, such as the complement cascade (where it cleaves C3 to C3a and C5 to C5a).