Specificityof Antigen Assays of Plasminogen Activator Inhibitor in Plasma: Innotest PAl-i Immunoassay Evaluated

We evaluate a new commercial enzyme immunoassay (EIA) of plasminogen activator inhibitor-i (PAl-i) in plasma, the lnnotest PAl-i. Because we wanted to mea-sure PAl-i in blood samples, we developed a procedure for evaluating the specificity of the assay for dtfferent PAl-i forms in their natural environment. All molecular forms were prepared from a plasma that contained only active PAl-i. The recovery of the different molecular forms of PAl-i, relative to active PAl-i (100%), was 99% ± 7 % for PAl-i complexed with recombinant tissue-type plasminogen activator (t-PA), 104 % ± 4 % for PAl-i com-plexed with melanoma t-PA, 94 % ± 11 % for PAl-i com-plexed with high-Mr urokinase, and 113 % ± 3 % for latent PAl-i. The parallelism between the calibration curve of the EIA and the serial dilutionsof the different PAl-i form