One unit of donor blood may be used to treat several patients. Each recipient is given the appropriate blood component. Proper component therapy is more effective and less hazardous than whole blood transfusion. In addition, valuable human blood is conserved.

Transfusion services require facilities to process fresh blood and separate otherwise labile components such as cryoglobulin precipitate and platelet concentrates. The production of large amounts of these components and of fractions such as plasma protein solution is facilitated by the clinical use of concentrated red cells rather than whole blood. Recurrent shortages of fresh donor blood are inevitable. Components which can be preserved for long periods should be stockpiled.

Plasmapheresis, plateletpheresis and leukapheresis allow the frequent collection of selected components from individual donors. Some of these donors may be hyperimmunised by the injection of an appropriate immunogen, and a specific immunoglobulin IgG can be prepared from the donated plasma. Hazards such as wrong identification and protein depletion must be avoided by individual attention to plasmapheresis donors.

Automation and modern transportation may increase the availability of blood. The importance of the blood donor to the health service and to the community should be fully recognised.