Identification of platelet glycoprotein IIb/IIIa as the major binding site
for released platelet-von Willebrand factor [published erratum appears in
Blood 1987 Jun;69(6):1789]
RI Parker and HR Gralnick
We studied the effects(s) of two monoclonal antibodies, 6D1 and 10E5
(directed against platelet glycoprotein Ib [GPIb] and the GPIIb/IIIa
complex, respectively), and purified human plasma fibrinogen on the binding
of released platelet-von Willebrand factor (vWf) to the platelet surface.
Neither of the monoclonal antibodies nor fibrinogen had any effect on the
amount of platelet-vWf expressed on unstimulated platelets or on the amount
expressed on platelets stimulated in the absence of extracellular Ca++.
However, the antibody directed against GPIIb/IIIa inhibited 72% of the
thrombin-induced increase in the platelet-vWf bound to the platelet surface
when platelets were stimulated in the presence of 5 mmol/L Ca++. The
antibody against GPIb did not inhibit the surface expression of
platelet-vWf on stimulated platelets in the presence of Ca++. Purified
normal human fibrinogen inhibited the surface binding of platelet-vWf to
thrombin-stimulated platelets to a degree similar to that observed with the
monoclonal antibody directed against the GPIIb/IIIa complex. These data
indicate that platelet-vWf released from platelets binds primarily to the
GPIIb/IIIa complex at or near the plasma fibrinogen binding site.
Volume 68,
Issue 3,
pp. 732-736,
09/01/1986
Copyright © 1986 by The American Society of Hematology
