Géza Sas

Investigations on Antithrombin III in Normal Plasma and Serum

Summary. Studies on antithrombin III (AT‐III) were made by a modification of the two dimensional crossed immunoelectrophoresis technique and gel filtration. Mixing various quantities of heparin with agarose in the first phase of electro‐phoresis, AT‐III from normal human plasma and serum revealed a heterogeneity which depended on the heparin concentration in the agarose gel. At heparin concentrations higher than 16 u/ml, AT‐III displayed three components with different electrophoretic mobilities. The component with the highest mobility (designated immunoantithrombin III1: IAT‐III1) dominated in plasma. In normal serum, however, the quantity of this component was decreased and the two other peaks with a slower electrophoretic mobility (IAT‐III2 and IAT‐III3) became more evident.

Generation of activated protein C during thrombolysis

The observation that urokinase infusion increases circulating levels of the anticoagulant activated protein C (APC) in baboons implies that APC might be elevated during thrombolytic therapy. Patients undergoing coronary thrombolysis showed an 11-fold increase (means from 6 to 69 micrograms/L) in APC during infusion of streptokinase. Thrombolytic therapy thus generates at least two potent antithrombotic factors in the circulation--the fibrinolytic enzyme, plasmin, and the anticoagulant enzyme, APC. APC may help prevent reocclusion during or after thrombolysis.