Activated protein C (APC) acts as an "on demand" anticoagulant, reducing thrombin formation. Reduced plasma levels of APC or protein C (PC) are associated with an increased risk of venous thromboembolism. APC also displays cytoprotective functions and its therapeutic use has been evaluated in severe sepsis and is under evaluation in several diseases with an important inflammatory component. In addition, different studies have revealed a potential role of PC/APC in disorders such as obesity, pneumonia, disseminated intravascular coagulation, Alzheimer, stroke, etc. Accordingly, the therapeutic value of different recombinant APC molecules that lack anticoagulant activity but retain the cytoprotective function is being tested in clinical trials for some of these diseases. Therefore, an available method to measure circulating APC in plasma is of great interests. About 16 different methods for the quantification of APC have been reported. Here, we will review the available assays, highlighting their advantages and disadvantages as well as their different stages of implementation and the most appropriate use for each method, including their potential clinical usefulness.
Keywords: Activated protein C; ELISA; Enzyme capture assay; Protein C; Protein C inhibitor; Venous thrombosis.
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