[Immunosorption method of urokinase determination].

An immunosorption procedure is developed for quantitative estimation of plasminogen activator of the urokinase type in human blood serum. The procedure involved sorption of urokinase from blood serum using polyclonal antibodies to the enzyme as a sorbent at the first step of the assay. Concentration of the immunoreactive urokinase in a preparation correlated with the absorbed fraction of standard urokinase added into the sample at the second step after washing of the sorbent. The residual fibrinolytic activity of the standard dose was detected in fibrin-agar gel. Results of the assay were not altered in presence of high molecular (bovine blood serum, soy bean inhibitor of trypsin) and low molecular inhibitors of urokinase (benzamidine, arginine, epsilon-aminocapronic acid). Sensitivity of the assay constituted 0.05 IU/sample (2.5 IU/ml, 0.25 ng/sample) and might be increased by a decimal order after addition of plasminogen into fibrin-agar gel. Content of urokinase in blood serum of healthy men (21-48 years old) was equal to 166 +/- 8.9 IU/ml with individual variations from 107 to 260 IU/ml.