title: Platelet VASP phosphorylation assessment in clopidogrel-treated patients: lack of agreement between Western blot and flow cytometry.
abstract: Vasodilator-stimulated phosphoprotein (VASP) 239 phosphorylation flow cytometric assessment has been reported as a tool to evaluate the responsiveness to clopidogrel in coronary heart disease (CHD) patients. We report for the first time the comparison between flow cytometry and two challenger assays, aggregometry and Western blot. We studied 21clopidogrel-treated CHD patients, and 28 healthy volunteers. Aggregometry showed platelet function inhibition inpatients. VASP 239 phosphorylation was assessed using flow cytometry and Western blot. ADP receptor response index (RI) were calculated using the formula (PGE1) - (PGE1 + ADP)/(PGE1) x 100. Flow cytometry was not able to detect clopidogrel intake, as RI were 99 +/- 10% [68-130] in healthy volunteers, and 91 +/- 17% [66-127] in treated patients (ns). On the contrary, RI mean in Western blot was 91 + 8% [76-127] in healthy volunteers, and 37 i 25% [4-80] in patients (p<0.05). The extreme values in Western blot revealed inter-individual variability in response to treatment. The comparison between both tests showed a total lack of agreement. Flow cytometric VASP 239 phosphorylation assay lacks sensitivity to detect clopidogrel intake, contrary to Western blot and aggregometry. Caution is required before classifying patients as 'low-responders' to thienopyridines using such method.
authors.affiliation: Laboratory of Haematology, CHU Rober Debré, Reims, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Hezard
authors.forename: Damien
authors.initials: D
authors.lastname: Metz
authors.forename: Roselyne
authors.initials: R
authors.lastname: Garnotel
authors.forename: Gerard
authors.initials: G
authors.lastname: Simon
authors.forename: Catherine
authors.initials: C
authors.lastname: Mace
authors.forename: Pascale
authors.initials: P
authors.lastname: Koebel
authors.forename: Philippe
authors.initials: P
authors.lastname: Nguyen
mesh_terms: D000368:Aged; D001792:Blood Platelets / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western / Q000379:methods; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D000077144:Clopidogrel; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism*; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000188:drug therapy / Q000401:mortality*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D000098662:Vasodilator-Stimulated Phosphoprotein; D000077144:Clopidogrel; D013988:Ticlopidine