title: Retention of coagulation factors in plasma frozen after extended holding at 1-6 degrees C.
abstract: OBJECTIVE
  The ability to use plasma, isolated from units of whole blood and frozen within 24 h of phlebotomy, as a substitute for plasma frozen within 8 h of phlebotomy would have several advantages for blood centers. It should provide increased flexibility pertaining to the freezing of plasma for clinical use. We have conducted studies to assess the influence of an extended holding time for separated plasma, prior to freezing, on the retention of coagulation factor activity.
  
  
  METHODS
  Freshly harvested plasma from each of 10 units of CPD-whole blood was divided into four equal aliquots. These aliquots were held in plastic packs at 1-6 degrees C for a total of 0, 8, 15 and 24 h. Subsequently, the plasma aliquots were frozen rapidly and stored at -20 degrees C for 4 months. The thawed plasma was tested for coagulant factors V and IX, factor VIII coagulant activity (factor VIII:C), von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor of von Willebrand factor.
  
  
  RESULTS
  The levels of factor V, factor vWF:Ag, factor IX and ristocetin cofactor were not influenced by holding the plasma for up to 24 h prior to freezing. Factor VIII:C activity was reduced with extended holding at 1-6 degrees C; the percentage at time zero activity was 75.9+/-2.4% for samples frozen immediately after a 24-hour period.
  
  
  CONCLUSIONS
  The data indicate that coagulation factor properties of harvested plasma are retained except for factor VIII for at least 24 h prior to freezing.
authors.affiliation: American Red Cross Blood Services, Greater Chesapeake and Potomac Region, Baltimore, MD 21215, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Smith
authors.forename: P M
authors.initials: PM
authors.lastname: Ness
authors.forename: G
authors.initials: G
authors.lastname: Moroff
authors.forename: N L
authors.initials: NL
authors.lastname: Luban
mesh_terms: D000941:Antigens / Q000097:blood; D001779:Blood Coagulation Factors / Q000378:metabolism*; D001793:Blood Preservation / Q000379:methods / Q000592:standards*; D015925:Cryopreservation / Q000379:methods / Q000592:standards*; D005164:Factor IX / Q000378:metabolism; D005165:Factor V / Q000378:metabolism; D005169:Factor VIII / Q000378:metabolism; D006801:Humans; D010949:Plasma / Q000737:chemistry / Q000378:metabolism; D012310:Ristocetin / Q000378:metabolism; D013997:Time Factors; D014841:von Willebrand Factor / Q000276:immunology / Q000378:metabolism
chemical_list: D000941:Antigens; D001779:Blood Coagulation Factors; D014841:von Willebrand Factor; D012310:Ristocetin; D005165:Factor V; D005169:Factor VIII; D005164:Factor IX