We have characterized a murine IgG monoclonal antibody, OP-G2, specific for platelet glycoprotein (GP) IIb-IIIa (alpha IIb beta 3). OP-G2 Fab fragments inhibit fibrinogen-mediated platelet aggregation and competitively inhibit adenosine diphosphate-induced binding of 125I-fibrinogen to washed platelets. OP-G2 binding to GPIIb-IIIa is specifically inhibited by RGD-containing peptides but not the...

An infant with severe neonatal alloimmune thrombocytopenia is described in whom an antibody directed at a new platelet-specific alloantigen, Ca (HPA-6b), is implicated. The new alloantigen is of low frequency in the population and was localized to platelet glycoprotein (GP) IIIa. Immunoprecipitation studies using murine monoclonal antibodies specific for the GP complex IIb-IIIa and GPIIIa alone...

BACKGROUND Some studies have suggested reduced activity of clopidogrel on platelet activation and adherence in patients using statins. OBJECTIVE To assess whether platelet activation and aggregation decrease with clopidogrel, and whether there is a reduction of the action of clopidogrel when associated with atorvastatin or simvastatin. METHODS This prospective study included 68 patients wit...

Previous studies have indicated that activated blood platelets interact with fibronectin through binding of fibronectin to the glycoprotein IIb-IIIa complex (GPIIb-IIIa). The cell attachment site of fibronectin with its crucial arg-gly-asp(-ser) [RGD(S)]sequence is involved in these bindings. We studied the importance of these interactions for the fibronectin dependence of platelet adhesion und...

Vitronectin (Vn) is a multifunctional 75-kD glycoprotein that is present in plasma and the extracellular matrix. Vn functions as a complement regulatory protein in plasma, and promotes the growth and attachment of cells in tissue culture. Recent cDNA cloning reveals that like other adhesive proteins, Vn contains the sequence Arg-Gly-Asp and binds to some members of the integrin class of adhesiv...

BACKGROUND The glycoprotein (GP) IIb/IIIa receptor antagonist abciximab is approved for use in high-risk percutaneous coronary interventions. The purpose of the present study was to establish the pharmacodynamic profile and platelet-bound life span of abciximab. METHODS AND RESULTS The pharmacodynamics of abciximab (inhibition of ex vivo platelet aggregation and GP IIb/IIIa receptor blockade)...

Platelets from two afibrinogenemic patients were used to determine whether fibrinogen is essential for platelet aggregation and to examine whether released fibrinogen contributes to the stabilization of platelet aggregates when platelets have been induced to aggregate and release their granule contents by stimulation with thrombin. The addition of adenosine diphosphate (ADP) to platelet-rich pl...

BACKGROUND Platelet deposition at the site of injury caused by balloon angioplasty is associated with acute closure and restenosis. METHODS AND RESULTS In a new ex vivo whole artery angioplasty model, we examined the roles of thrombin inhibition with D-Phe-Pro-ArgCH2Cl (PPACK) and inhibition of the platelet membrane fibrinogen receptor glycoprotein IIb/IIIa (GPIIb/IIIa) with monoclonal antibo...

OBJECTIVES We examined the lytic effects of anti-glycoprotein (GP) IIb/IIIa agents on platelet thrombi formed on the collagen surface under blood flow conditions. BACKGROUND Anti-GP IIb/IIIa agents may influence platelet thrombi already formed. METHODS Blood samples were anticoagulated either by the specific antithrombin Argatroban (100 microM) or by unfractionated heparin (0.1 U/ml). After...

BACKGROUND The optimal level of platelet inhibition with a glycoprotein (GP) IIb/IIIa antagonist necessary to minimize thrombotic complications in patients undergoing a percutaneous coronary intervention (PCI) is currently unknown. METHODS AND RESULTS Five hundred patients undergoing a PCI with the planned use of a GP IIb/IIIa inhibitor had platelet inhibition measured at 10 minutes, 1 hour, ...