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Coagulation proteins
See also Individual agents
General information
The major coagulation and fibrinolytic proteins are listed in Table 1 .
Table 1
Proteins involved in coagulation and fibrinolysis
| Protein (synonym) | Function |
|---|---|
| Coagulation proteins | |
| Factor I (fibrinogen) | Activated to fibrin |
| Factor II a (prothrombin) | Activated to thrombin |
| Factor III (tissue thromboplastin) | Extrinsic pathway |
| Factor IV (calcium) | Co-factor |
| Factor V (Ac-globulin; proaccelerin) | Converts prothrombin to thrombin |
| Factor VI (unassigned) | |
| Factor VII a (proconvertin) | Extrinsic pathway |
| Factor VIII (antihemophilic factor) | Intrinsic pathway |
| Factor IX a (Christmas factor) | Intrinsic pathway |
| Factor X a (Stuart-Prower factor) | Extrinsic pathway |
| Factor XI (plasma thromboplastin antecedent) | Intrinsic pathway |
| Factor XII (Hageman factor) | Intrinsic pathway |
| Factor XIII (fibrin stabilizing factor) | Stabilizes fibrin |
| Von Willebrand factor (factor VIII-related antigen; vWF) | |
| High molecular weight kininogen (Fitzgerald factor) | Intrinsic pathway |
| Prekallikrein (Fletcher factor) | Intrinsic pathway |
| Fibrinolytic proteins | |
| Plasminogen | Converted to fibrinolysin |
| Prourokinase | Precursor of urokinase |
| Tissue plasminogen activator | Activates plasminogen |
| Antithrombin III | Inhibits thrombin, IXa, Xa, XIa, XIIa |
| Protein C a | Inhibits factors Va, VIIIa |
| Protein S a | Co-factor for protein C |
| a 2 -Antiplasmin | Inhibits binding of fibrinolysin |
a Vitamin K-dependent factor; the intrinsic and extrinsic pathways converge with the activation of factor X to Xa by factor VIII and IX.
Coagulation protein concentrates became available in the 1970s, a significant step in the prevention and management of bleeding. The factors that are currently available are factor VII, factor VIIa, factor VIII, factor IX, factor XI, and factor XIII. There is also a factor VIII inhibitor bypassing factor, activated prothrombin complex concentrate. Fresh frozen plasma and prothrombin complex concentrate, which contain mixtures of coagulation proteins, are also available.
Two major classes of complications in the use of these proteins have emerged [ ]. First, transfusion-related infections with various blood-borne viruses, such as hepatitis B and C and human immunodeficiency virus (HIV). Secondly, alloimmune antibodies (inhibitors) against the deficient coagulation factors.
Organs and systems
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