1. The Edinburgh and South-East Scotland Blood Transfusion Service Edinburgh, Great Britain
2. The Department of Haematology, Royal Infirmary, Edinburgh, Great Britain
3. The Department of Medicine, Royal Infirmary, Glasgow, Great Britain
4. The MRC/SNBTS Blood Components Assay Group, Forrest Road, Edinburgh, Great Britain
5. The Scottish National Blood Transfusion Service, Headquarters Laboratory, Forrest Road, Edinburgh, Great Britain