title: Tissue Factor Expression on Platelet Surface during Preparation and Storage of Platelet Concentrates.
abstract: BACKGROUND
  Tissue factor (TF), the main activator of blood coagulation, is expressed on platelet surface and, together with procoagulant phospholipids, contributes to the global coagulation potential of these blood components. The present study evaluated, for the first time, the expression of TF on platelet surface during preparation and storage of platelet concentrates (PC) for transfusional use.
  
  
  METHODS
  Platelet TF was measured by flow cytometry in healthy donor whole blood (WB) and in pooled buffy-coat-derived PC on the day of preparation and up to 4 days of storage in parallel with classical markers of platelet activation, i.e., fibrinogen, P-selectin, and glycoprotein GPIIb. Data were analyzed according to donor age and blood ABO group.
  
  
  RESULTS
  TF was detected on whole blood platelets and was found highest in O donors. Compared to whole blood, platelet surface TF was higher upon PC preparation and further increased during storage. The rise in TF levels positively correlated with the elevations of the other platelet markers.
  
  
  CONCLUSIONS
  Our findings show that platelet surface TF is maintained in PC obtained by the pooled buffy coat method. Further studies are warranted to investigate a possible correlation between TF levels and the hemostatic response of the platelet transfusion recipient.
authors: Division of Immunohematology and Transfusion Medicine, Azienda Ospedaliera Papa Giovanni XXIII, Bergamo, Italy.
authors: Alfonso
authors: A
authors: Vignoli
authors: Cinzia
authors: C
authors: Giaccherini
authors: Marina
authors: M
authors: Marchetti
authors: Cristina
authors: C
authors: Verzeroli
authors: Chiara
authors: C
authors: Gargantini
authors: Luca
authors: L
authors: Da Prada
authors: Barbara
authors: B
authors: Giussani
authors: Anna
authors: A
authors: Falanga
keywords: Fibrinogen; Flow cytometry; P-selectin; Platelet concentrates; Tissue factor
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