Method of Antipasmin Assay in Human Plasma

Abstract

Antiplasmin assay has been substituted for antitrypsin assay in this series. It became, however, evident in the previous experiment that the inhibitors to trypsin are not completely identical with those of plasmin. Therefore, the device of the method of antiplasmin assay has become necessary.
This paper describes the method of antiplasmin assay which is based on the following principles: (1) The total plasmin, caseinolytic activity of streptokinase-activated euglobulin in which most antiplasmin is eliminated, is determined in the first step. (2) In the second step, plasma is preincubated with streptokinase for 2 minutes, and then further incubated with casein. This is the activity influenced by immediately acting antiplasmin in plasma. (3) In the third step, streptokinase-activated euglobulin is preincubated with inhibitor (euglobulin-eliminated supernate) for 2 hours in the presence of ethylamine, a stabilizer of plasmin. Then it is further incubated with casein. This is the activity inhibited by slowly acting antiplasmin. (4) The differences between the values obtained from steps 1 and 2, and 1 and 3 express the immediate and slow antiplasmin of Norman, respectively.