A ONE-STEP ENZYME-IMMUNOASSAY FOR TOTAL PLASMINOGEN-ACTIVATOR INHIBITOR-1 ANTIGEN IN HUMAN PLASMA

A one-step enzyme immunoassay (EIA) has been developed for plasminogen activator inhibitor-1 (PAI-1) antigen. The assay is based on polyclon al antibodies, which were found to be slightly more reactive with tiss ue-type plasminogen activator (t-PA)/PAI-1 complexes and latent PAI-1 than with active PAI-1. To correct this, active PAI-1 is converted to t-PA/PAI-1 complexes. Latent PAI-1 and t-PA/PAI-1 complexes were equal ly reactive. The EIA is specific (PAI-2 and PAI-3 are not detected), p recise (CVs range from 1.8% to 11.1%, depending on the PAI-1 concentra tion), fast (assay time less than 3 h), and easy to perform. It is com patible with the use of Stabilyte(R) plasma. The assay is calibrated a gainst the putative international standard of the National Institute o f Biological Standards and Control (NIBSC; lot 87/512). The normal ran ges found with this EIA were 13.2-88 ng/ml; one apparently normal dono r had a value of 100 ng/ml.