title: A collaborative study to establish the 1st International Standard for factor XIII plasma.
abstract: BACKGROUND
  An international collaborative study, involving 23 laboratories, was carried out, under the auspices of the FXIII Standardization Working Party (SWP), to calibrate the 1st International Standard (IS) for factor XIII (FXIII) plasma.
  
  
  METHODS
  Potency estimates for the proposed candidate FXIII plasma (preparation Y: NIBSC code 02/206) were calculated relative to locally collected normal plasma pools (pool N), for both FXIII activity and antigen levels.
  
  
  RESULTS
  Estimates of FXIII activity potency for preparation Y showed good agreement between laboratories, with an interlaboratory geometric coefficient of variation (GCV) of 11.5% and a mean value of 0.91 U mL(-1). Furthermore, there was a negligible difference in potencies by two commercially available methods, the potencies differing only by approximately 1%. Estimates of FXIII antigen (A(2)B(2) complex) potency for preparation Y showed good agreement between laboratories, with an interlaboratory GCV of 16.3% and a mean value of 0.93 U mL(-1). Accelerated degradation studies showed that the proposed standard is very stable, with a predicted loss of activity (and antigen) per year of< 0.06% at the recommended storage temperature of -20 degrees C.
  
  
  CONCLUSIONS
  The suitability and potency of preparation Y were considered by the participants, members of the ISTH/SSC FXIII Subcommittee, the Scientific and Standardization Committee and the SWP. Following their approval, preparation Y was proposed to and accepted by the Expert Committee on Biological Standardization of the World Health Organization to be the 1st IS for FXIII plasma with an activity potency of 0.91 IU per ampoule and an antigen potency of 0.93 IU per ampoule.
authors.affiliation: Division of Haematology, National Institute for Biological Standards and Control, Potters Bar, UK. sraut@nibsc.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Raut
authors.forename: R E
authors.initials: RE
authors.lastname: Merton
authors.forename: P
authors.initials: P
authors.lastname: Rigsby
authors.forename: L
authors.initials: L
authors.lastname: Muszbek
authors.forename: R
authors.initials: R
authors.lastname: Seitz
authors.forename: R A S
authors.initials: RA
authors.lastname: Ariëns
authors.forename: T W
authors.initials: TW
authors.lastname: Barrowcliffe
authors.forename: A
authors.initials: A
authors.lastname: Ichinose
mesh_terms: D003299:Cooperative Behavior; D005176:Factor XIII / Q000276:immunology / Q000592:standards*; D006801:Humans; D007753:Laboratories; D010949:Plasma; D015203:Reproducibility of Results
chemical_list: D005176:Factor XIII