Summary.A collaborative study on factor VIII related antigen (VIII R: Ag) has been carried out, involving 11 laboratories in the U.K. Samples of two different freeze‐dried plasmas were assayed against participants' own local standards by the Laurell electroimmunoassay method. There was reasonably good agreement on the relative potencies of the two freeze‐dried plasmas, but there were considerable differences in the VIII R: Ag content of the plasma pools used as local standards, with values ranging from 83 to 129 of the mean. All participants agreed on the need for a standard for VIII R: Ag, and that the unit be defined by the mean of the local standards. Accordingly, freeze‐dried plasma 66/355 was established as the 1st British Standard for factor VIII related antigen, with an assigned potency of 1.05 units per am
展开▼
