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EI Peerschke
Department of Pathology, State University of New York at Stony Brook
11794-7300.
The platelet-membrane glycoprotein IIb-IIIa (GPIIb-IIIa) complex is
essential for platelet aggregation and is involved in the attachment of
platelets to thrombogenic surfaces. This study shows the retention of GPIIb
and GPIIIa on immobilized fibrinogen after Triton X-100 (Sigma Chemical Co,
St Louis, MO) lysis of adherent platelets. Glycoproteins were detected
using subunit specific monoclonal antibodies in a modified enzyme-linked
immunosorbent assay procedure. GPIIb-IIIa retention was judged to be
specific relative to GPIb recovery, and was modulated by platelet
activation. Platelet exposure to adenosine diphosphate or thrombin, but not
A23187 or chymotrypsin, markedly enhanced GPIIb and GPIIIa recovery
relative to that observed with unstimulated platelets, or prostaglandin
E1-treated platelets. Moreover, lysis of adherent platelets in the presence
of 10 mmol/L EDTA, under conditions promoting GPIIb-IIIa complex
dissociation (pH 8.1, 60 minutes, 37 degrees C), had no effect on GPIIb or
GPIIIa subunit recovery. Platelet activation with Zn+2 also enhanced GPIIb
and GPIIIa recovery on fibrinogen-coated surfaces over that observed with
unstimulated platelets, but GPIIb and IIIa retention was EDTA sensitive.
This correlated with the EDTA-reversible nature of Zn+2- activated platelet
adhesion to fibrinogen-coated surfaces. The data (1) show that platelet
adhesion to fibrinogen is accompanied by the induction of high-affinity
interactions between GPIIb-IIIa and immobilized fibrinogen that are
EDTA-resistant and enhanced by platelet activation with some but not all
agonists, and (2) implicate these interactions in stabilizing platelet
contacts with fibrinogen-coated surfaces.
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| Copyright © 1993 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||