title: Comparison of the in vitro characteristics of von Willebrand factor in British and commercial factor VIII concentrates.
abstract: Qualitative/quantitative analysis of von Willebrand factor antigen (vWf:Ag) in either heat or solvent/detergent treated factor VIII concentrates, used for haemophilia replacement therapy, was undertaken to assess their suitability for the treatment of vWD. For the first time immunoaffinity purified vWf:Ag (Monoclate by-product) was also evaluated by in vitro assessment. Potencies of vWf:Ag varied considerably but were consistently higher (28.9-420.5 iu/ml) than factor VIII:C (one-stage) activity (8.13-42.44 iu/ml). The functional activity of vWf was assessed by either Ristocetin Cofactor (vWf:RCo) or collagen binding methods (vWf:CBA) with typical vWf:RCo/vWf:Ag ratios ranging from 0.08 to 0.94. Multimeric analysis confirmed that in vitro biological activity was dependent on the presence of the high molecular weight forms of vWf:Ag. A significant correlation (r = 0.95) between vWf:RCo activity and collagen binding was observed in all of the concentrates with the exception of the immunopurified product. The data suggest that either NHS 8Y (mean vWfRCo/vWf:Ag = 0.94), Haemate P (mean vWf:RCo/vWf:Ag = 0.69) and high purity Octapharma V.I (vWf:RCo/vWf:Ag = 0.82) which contain medium/high MW vWf:Ag multimers are likely to be most cost-effective in the treatment of symptomatic severe vWD patients than other currently available concentrates.
authors.affiliation: Coagulation Research Unit, Rayne Institute, St Thomas' Hospital, London.
authors.forename: A S
authors.initials: AS
authors.lastname: Lawrie
authors.forename: P
authors.initials: P
authors.lastname: Harrison
authors.forename: A L
authors.initials: AL
authors.lastname: Armstrong
authors.forename: B R
authors.initials: BR
authors.lastname: Wilbourn
authors.forename: R G
authors.initials: RG
authors.lastname: Dalton
authors.forename: G F
authors.initials: GF
authors.lastname: Savidge
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003094:Collagen; D003902:Detergents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005169:Factor VIII; D006358:Hot Temperature; D006801:Humans; D012997:Solvents / Q000494:pharmacology; D014842:von Willebrand Diseases / Q000188:drug therapy; D014841:von Willebrand Factor / Q000627:therapeutic use
chemical_list: D003902:Detergents; D012997:Solvents; D014841:von Willebrand Factor; D005169:Factor VIII; D003094:Collagen