Multicentre collaborative study to calibrate IGF-II by bioassay and immunoassay: establishment of the First WHO Reference Reagent.
A preparation of recombinant insulin-like growth factor-II (IGF-II) (NIBSC code 96/538) was compared with local standards in bioassays and immunoassays by eight laboratories in four countries to assess its suitability for use as a World Health Organisation (WHO) reference reagent. Estimates of relative potencies for the bioassays gave a geometric mean of 1.04 (0.94--1.16) microg of local standard per microg of 96/538. Estimates of relative immunological activities by immunoassay gave a geometric mean of 1.15 (0.94--1.38) microg of local standard per microg of 96/538. The study provided evidence that a common standard for rhIGF-II would be helpful and that 96/538 was sufficiently stable to serve as a reference reagent. Accordingly 96/538 was established as the First WHO Reference Reagent for IGF-II, human, recombinant, and assigned a unitage of 5000 units per ampoule and on the basis of the immunoassay results a nominal mass content of 5 microg per ampoule.
Rafferty
B
B
Division of Endocrinology, National Institute for Biological Standards and Controls, South Mims, Potters Bar, Herts, UK. brafferty@nibsc.ac.uk
Rigsby
P
P
Gaines-Das
R E
RE
D001671:Biochemistry / Q000592:standards; D001681:Biological Assay / Q000379:methods*; D004275:DNA, Ribosomal / Q000378:metabolism; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007335:Insulin-Like Growth Factor II / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry; D012015:Reference Standards; D015203:Reproducibility of Results; D013696:Temperature; D014944:World Health Organization
D004275:DNA, Ribosomal; D011994:Recombinant Proteins; D007335:Insulin-Like Growth Factor II