Urokinase plasminogen activator (uPA), along with its receptor uPAR, is a serine protease that activates plasminogen to plasmin in the blood fibrinolytic system. It is also implicated in events related to cell invasion and migration. Clinical studies have indicated that high uPA levels may elevate the risk for tumor invasion and metastasis. Increased expression and activity can exert potent arthritogenic properties in rheumatoid arthritis patients. Increased uPA activity may be an implication for the pathophysiology of endometriosis. The sensitive quantitative measurement of functionally active human uPA in plasma and other biological fluids is easily performed with this 96 well strip format ELISA kit. The mean value of uPA in healthy donors was found to be 1.1 ng/ml. The assay measures active uPA in the 0.1-50 ng/ml range. Samples giving human uPA levels above 50 ng/ml should be diluted in blocking buffer before use. Samples of human plasma in citrate or EDTA may be assayed with this kit. Plasma in heparin is not recommended. It is important to ensure a platelet free preparation as platelets can release PAI-1, which in turn could potentially form a complex with active uPA. Serum and cell culture media at neutral pH may also be used. Functionally active uPA will form a covalent complex with the biotinylated human PAI-1 which is bound to the avidin on the plate. Inactive or complexed uPA will not bind to the PAI-1 and will not be detected by the assay. This kit does not cross react with mouse uPA. After appropriate washing steps, anti-human uPA primary antibody binds to the captured enzyme. Excess antibody is washed away, and bound antibody is reacted with the secondary antibody conjugated to HRP. Following an additional washing step, TMB substrate is used for color development at 450 nm. Color development is proportional to the concentration of active uPA in the samples. A standard calibration curve is prepared using dilutions of purified uPA and is measured along with the test samples. All reagents and standards are provided in these ELISA kits.

This assay uses an exclusive enzyme capture technology to only detect functionally active protein.

Suggested additional reagents: 10X Wash Buffer, TMB Substrate, Avidin Plate, Secondary Antibody