Assay for In Vivo Activated Protein C (APC) Activity

In the area of clinical coagulation research, much attention is focused on the molecular eventswhich occur before, during, and after anticoagulant and antithrombotic therapies. For purposes ofmonitoring the safety, efficacy and long-term effects of such therapies, there exist a number ofcommercially available assays to assess the progression of the procoagulant and fibrinolytic responses.For example, to monitor the procoagulant response, there exists: a) an assay for fragment 1-2 ofprothrombin to monitor prothrombinase activity; and b) an assay for fibrinopeptide-A to monitor thrombinactivity. The same holds true for the fibrinolytic response where assays for D-Dimer and FDP fragmentsof fibrin and fibrinogen respectively may be used to monitor the activity of plasmin. Unfortunately, ananalogous assay to measure the progression of the anti-anticoagulant response does not exist. Webelieve that an assay to measure the in vivo activity of APC, by measuring the APC catalyzedinactivation of factor Va will provide a direct measure of the anticoagulant response. In this proposalwe plan to develop an ELISA assay which may be used to quantitatively measure the APC catalyzedconversion of factor Va to factor Vai (inactivated factor Va).