Plasmin effect on platelet glycoprotein Ib-von Willebrand factor interactions

Blood. 1985 Jan;65(1):32-40.


We have studied the effect of streptokinase on platelets in platelet-rich plasma (PRP) and of plasmin on washed platelets. By three and one-half minutes after the addition of 50,000 IU/mL streptokinase to PRP, the maximum rate of ristocetin-induced platelet agglutination declined 40%, and by 60 minutes, it declined 70%. During the same time interval, the thrombin time increased from 20 seconds to over 120 seconds. At a concentration as low as 50 IU/mL, streptokinase reduced the maximum rate of ristocetin-induced platelet agglutination by 50% and prolonged the thrombin time to 1.5 times control value. Streptokinase added to PRP also caused inhibition of platelet aggregation following stimulation by 2.9 mumol/L adenosine diphosphate, 0.25 U/mL thrombin, and 0.025 mg/mL collagen. Plasmin, 0.05 to 1.0 CU/mL, reduced ristocetin-mediated agglutination of washed platelets in the presence of von Willebrand factor (vWF) from 66% of control to 2% of control, following a one-hour incubation. Autoradiograms produced following sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE) of plasmin-treated 125I-surface-labeled platelets demonstrated progressive loss of a protein with a molecular weight (mol wt) of 180,000; simultaneously, a protein with mol wt 135,000 appeared on autoradiograms produced following SDS-PAGE of the surrounding platelet medium. These proteins are similar in molecular weight to glycoprotein (gp) Ib, a platelet surface receptor for vWF, and glycocalicin, a proteolytic fragment of gpIb. By use of an enzyme-linked immunosorbent assay (ELISA) based immunoinhibition assay for glycocalicin, we were able to demonstrate that plasmin treatment of washed platelets released a glycocalicin-related antigen into the surrounding medium and that appearance of this material corresponding to loss of vWF-dependent, ristocetin-induced agglutination.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Blood Coagulation Factors / metabolism*
  • Drug Interactions
  • Fibrinolysin / pharmacology*
  • Formaldehyde / pharmacology
  • Glycoproteins / analysis
  • Glycoproteins / metabolism*
  • Humans
  • In Vitro Techniques
  • Isoantigens / analysis
  • Membrane Proteins / analysis
  • Membrane Proteins / metabolism*
  • Molecular Weight
  • Platelet Aggregation / drug effects
  • Platelet Glycoprotein GPIb-IX Complex*
  • Platelet Membrane Glycoproteins
  • Ristocetin / metabolism
  • Streptokinase / pharmacology
  • von Willebrand Factor / metabolism*


  • Blood Coagulation Factors
  • Glycoproteins
  • Isoantigens
  • Membrane Proteins
  • Platelet Glycoprotein GPIb-IX Complex
  • Platelet Membrane Glycoproteins
  • glycocalicin
  • von Willebrand Factor
  • Ristocetin
  • Formaldehyde
  • Streptokinase
  • Fibrinolysin