AssayPro—Human PAI-1/tPA ELISA

Introduction
Type I plasminogen activator inhibitor (PAI-1) is a 50 kDa serpin family member that inhibits tissue- and urokinase-type plasminogen activators (t-PA, u-PA). Whereas tPA is a 68 kDa serine protease that converts the plasminogen into plasmin and facilitates the digestion of fibrin clots (1 - 2). In plasma, half or more of PAI-1 and most tPA present in the circulation is in an inhibited complex (3). In the resting state in healthy individuals, typically less than 20% of tPA is present in its free form in the plasma. In normal individuals, as well as in patients with recurrent venous thrombosis, high PAI-1 plasma concentration is usually associated with high tPA antigen (but not with free tPA) levels (4). PAI-1/tPA complex, a novel fibrinolytic marker, increases during the pregnancy-associated hypercoagulable state, atherosclerosis, and vascular spasm (5). Determination of PAI-1/tPA complex may provide valuable prognostic information with respect to breast cancer patients (6) and myocardial infarction in patients with manifest coronary heart disease (7).

Principle of the Assay
The AssayMax Human PAI-1/tPA ELISA kit is designed for detection of PAI-1/tPA in human plasma, serum, milk, tissue extracts, and cell culture supernatants. This assay employs a quantitative sandwich enzyme immunoassay technique that measures PAI-1/tPA in less than 4 hours. A polyclonal antibody specific for PAI-1 has been pre-coated onto a microplate. PAI-1/tPA complex in standards and samples is sandwiched by the immobilized antibody against PAI-1 and a biotinylated polyclonal antibody against tPA, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.