title: A comparative in vitro evaluation of six von Willebrand factor concentrates.
abstract: The efficacy of von Willebrand factor (VWF) concentrates for treatment of von Willebrand disease (VWD) is dependent on their content of VWF and factor VIII (FVIII).
  
  
  OBJECTIVE
  To measure the content and quality of VWF and FVIII in six VWF concentrates: Haemate-P (Aventis Behring), Immunate (Baxter Bioscience), Koate (Bayer Corp.), 8Y (BPL), Innobrand (LFB) and Facteur Willebrand (LFB).
  
  
  METHODS
  The VWF antigen content (VWF:Ag), ristocetin cofactor activity (VWF:RCo), collagen-binding activity (VWF:CB), VWF multimers with electrophoresis and densitometry, FVIII activity and total protein content.
  
  
  RESULTS
  Specific activity (VWF:RCo/total protein) varied considerably (4.7-129.5 IU mg(-1)). Activity measures, VWF:RCo and VWF:CB, correlated well, but we found no correlation between any of these and VWF:Ag. The content of high-molecular weight multimer (HMWM) was normal or close to normal in Haemate-P, Innobrand and Facteur Willebrand, moderately reduced in Koate and 8Y, and significantly reduced in Immunate. The HMWM content correlated significantly with the VWF:RCo/VWF:Ag ratio. Only Haemate-P, Innobrand and Facteur Willebrand had VWF:RCo/VWF:Ag ratios >0.7. We found large differences in the content of FVIII and in the FVIII/VWF:RCo ratio. Facteur Willebrand had the lowest (0.02) and Immunate the highest (6.00) ratio.
  
  
  CONCLUSIONS
  Treating physicians must be aware of the large differences between different VWF concentrates and the potential clinical implications. Concentrates lacking HMWM are probably less efficient for mucosal bleedings. FVIII is most important for surgical bleedings, but concentrates with high FVIII/VWF-ratio may induce very high FVIII levels with increased risk of thrombosis. A low FVIII content may be preferable except in case of acute surgery.
authors.affiliation: Department of Coagulation Disorders, Malmo University Hospital, Lund University, Malmo, Sweden. stefan.lethagen@medforsk.mas.lu.se
authors.forename: S
authors.initials: S
authors.lastname: Lethagen
authors.forename: M
authors.initials: M
authors.lastname: Carlson
authors.forename: A
authors.initials: A
authors.lastname: Hillarp
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D005169:Factor VIII / Q000032:analysis / Q000737:chemistry / Q000592:standards*; D006487:Hemostasis; D006801:Humans; D014842:von Willebrand Diseases / Q000188:drug therapy*; D014841:von Willebrand Factor / Q000737:chemistry / Q000592:standards*
chemical_list: D014841:von Willebrand Factor; D005169:Factor VIII