A Case of Superior Vena Cava Syndrome with Down-Regulation of Platelet Glycoprotien Ib/IX by Thrombolytic Therapy

A 51-year-old male patient with Behcet syndrome was found by venography to be complicated with superior vena cava syndrome. Flow cytometrical analysis revealed that the patient's platelet surface glycoprotein (GP) Ib and GPIX were decreased by 40 and 10%, respectively, after administration of 80, 000 U/body weight kg of urokinase. The decrease in the total platelet GPIb was confirmed by quantitative immunoblotting. The patient's plasma concentration of glycocalicin increased after administration of urokinase. In contrast, the patient's platelet surface GPIIb/IIIa were not changed after urokinase therapy. These results suggest that administration of urokinase caused proteolysis of the circulating platelet surface GPIb/IX molecules.