title: Rapid and simple platelet function assay to assess glycoprotein IIb/IIIa receptor blockade.
abstract: BACKGROUND
  The platelet glycoprotein (GP) IIb/IIIa receptor antagonist c7E3 Fab (abciximab; ReoPro) has been approved as an antithrombotic agent, and other GP IIb/IIIa antagonists, including oral agents, are under development. At present, there are no rapid and simple assays to monitor GP IIb/IIIa receptor blockade.
  
  
  RESULTS
  An assay was devised based on the ability of platelets in whole blood to rapidly agglutinate fibrinogen-coated beads when stimulated with a peptide, (iso-S)FLLRN, that activates a platelet thrombin receptor but resists inactivation by plasma aminopeptidase M. Preincubation of normal blood with increasing concentrations of c7E3 Fab led to increasing inhibition of the assay, correlating with increased GP IIb/IIIa receptor blockade. Assay conditions were chosen so that agglutination was inhibited at 2 minutes when > 82% of the receptors were blocked. Similar results were obtained with the use of GP IIb/IIIa antagonists based on the arginine-glycine-aspartic acid (RGD) cell-recognition sequence.
  
  
  CONCLUSIONS
  A simple and rapid assay sensitive to GP IIb/IIIa receptor blockade has been developed that may be helpful in optimizing GP IIb/IIIa antagonist therapy.
authors.affiliation: Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA. BCOLLER@SMTPLINK.MSSM.EDU
authors.forename: B S
authors.initials: BS
authors.lastname: Coller
authors.forename: D
authors.initials: D
authors.lastname: Lang
authors.forename: L E
authors.initials: LE
authors.lastname: Scudder
mesh_terms: D000077284:Abciximab; D000704:Analysis of Variance; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D006384:Hemagglutination / Q000187:drug effects; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology*; D066298:In Vitro Techniques; D051379:Mice; D015588:Observer Variation; D009842:Oligopeptides / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors*; D011993:Recombinant Fusion Proteins; D012016:Reference Values; D013915:Thrombasthenia / Q000097:blood*
chemical_list: D000911:Antibodies, Monoclonal; C090662:GR 144053; D007140:Immunoglobulin Fab Fragments; D009842:Oligopeptides; D010879:Piperazines; D010880:Piperidines; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D011993:Recombinant Fusion Proteins; C084961:arginyl-glycyl-aspartyl-phenylalanine; D000077284:Abciximab