title: comparison of clot-based vs chromogenic factor Xa procoagulant phospholipid activity assays.
abstract: We compared 2 commercial plasma procoagulant phospholipid activity (PPA) assays, chromogenic, using bound annexin V to capture phosphatidylserine-containing microparticles, and clot-based. In both, anionic phospholipids accelerated activation of prothrombin by factor Xa. PPA levels were lower in the chromogenic vs the clot-based assay, with poor correlation between methods: normal samples, mean ± SD, 27 ± 17 vs 590 ± 414 nmol/L (n = 24; r(2) = 0.29) and patient samples, mean ± SD, 45 ± 44 vs 401 ± 330 nmol/L (n = 51; r(2) = 0.26). Recovery of phosphatidylserine added to normal, heparinized, and warfarin plasma samples averaged 109% ± 39% using the chromogenic assay but was higher and more varied (mean ± SD, 176% ± 59%) in the clot-based assay. Lupus anticoagulants caused low recovery in both assays. Removal of microparticles by 0.22-μm filtration reduced PPA by 91% in the clot-based and 65% in the chromogenic assay. The clot-based assay showed higher correlation (r(2) = 0.82 vs 0.23) with flow cytometric platelet microparticle counts. The 2 assays measure different aspects of PPA in plasma, with the chromogenic assay primarily measuring smaller microparticles.
authors.affiliation: Methodist Pathology Associates, 6565 Fannin, Houston, TX 77030, USA.
authors.forename: Sandra D
authors.initials: SD
authors.lastname: Bohling
authors.forename: Monica B
authors.initials: MB
authors.lastname: Pagano
authors.forename: Maria R
authors.initials: MR
authors.lastname: Stitzel
authors.forename: Chris
authors.initials: C
authors.lastname: Ferrell
authors.forename: Wandy
authors.initials: W
authors.lastname: Yeung
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Chandler
mesh_terms: D000328:Adult; D017304:Annexin A5 / Q000737:chemistry / Q000378:metabolism; D001777:Blood Coagulation; D001780:Blood Coagulation Tests / Q000379:methods*; D055252:Cell-Derived Microparticles / Q000737:chemistry; D002863:Chromogenic Compounds; D015951:Factor Xa / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000097:blood*; D012016:Reference Values; D014947:Wounds and Injuries / Q000097:blood
chemical_list: D017304:Annexin A5; D002863:Chromogenic Compounds; D010718:Phosphatidylserines; D010743:Phospholipids; D015951:Factor Xa