The international standard for platelet-derived growth factor-BB: Comparison of candidate preparations by in vitro bioassays and immunoassays

In an international collaborative study, four preparations of recombinant, human sequence, platelet-derived growth factor-BE (PDGF-BB), two glycosylat ed and two nonglycosylated, were evaluated, using in vitro bioassays and im munoassays, by seven laboratories in three countries, for their suitability to serve as the international standard (IS) for PDGF-BB. The study shows t hat interlaboratory variation in estimates of PDGF-BE potency is reduced by use of a common standard. The bioassays, using various types of fibroblast , detected PDGF-BB and PDGF-AB as equally potent, while immunoassays discri minated between the two isoforms. On the basis of the results reported here , the World Health Organization (WHO) established the preparation coded 94/ 728 as the first IS for PDGF-EB, with an assigned unitage of 3000 Internati onal Units per ampoule. The IS maybe obtained by writing to NIBSC, PO Box 1 193, Potters Bar, EN6 3QH, UK, or through web site http:\\wmw.nibsc.ac.uk.