Summary
A simple plasminogen determination method is presented. It is based upon the conversion
of plasminogen into activator by large and constant amounts of streptokinase. The
activator contained in a standard coagulum consisting of bovine fibrin, streptokinase,
and a 1:40 dilution of human plasma converts the plasminogen adsorbed on bovine fibrin
into plasmin. Lysis of the test coagulum is hereby induced. The speed of such lysis
is limited by the concentration of the activator incorporated in the test coagulum.
The variable component of the activator being human plasminogen, the speed of lysis
is directly dependent upon the concentration of human plasminogen in the standard
coagulum. Using the thromboelastograph according to Hartert in recording the test
clot lysis times, this method of plasminogen determination was shown to be a simple
and quick procedure. The standard deviation ranged from ± 13.2 to 68 %, depending
upon the plasminogen value to be measured (lower rates of error were attached to high,
and higher rates of error to low, plasminogen concentrations). The biological variation
of plasminogen values in a group of 26 men aged from 40 to 65 years was calculated
to be ±21 %. Both plasminogen and plasmin, its activated form, were exchangeable in
the test, i.e. plasminogen determinations performed by activator assay did not differentiate
between plasminogen and plasmin. There was no influence by varying anti-SK titers
in the plasma up to a circulating antibody content of 2 million. Furthermore, plasma
antiplasmins did not affect the plasminogen measuring system. Plasminogen tested by
activator assay displayed values closely related to those achieved by immunochemical
methods. Plasminogen measurements were performed in patients undergoing streptokinase
and urokinase infusion treatment. 5,000 u streptokinase per hour, as well as 270,000
CTA-u urokinase per hour, infused over a period of 2 days produced a fall in plasminogen
down to 30-60% of normal. In contrast, 100,000 u streptokinase per hour lowered the
plasminogen concentration down to values of below 1%. The foregoing data indicate
that plasminogen measurement, according to the principles outlined here (activator
assay), may be regarded as a valuable and rehable method for the routine control of
streptokinase and urokinase therapy.
