Studies on the procurement of blood coagulation factor VIII
Coagulation factor VIII is needed for the treatment of patients with haemophilia. Requirements for factor VIII are important in determining the numbers of blood donations to be collected in Scotland. The final yield of factor VIII:C in products prepared from blood plasma, when prepared either in the Transfusion Centres or the National Fractionation Centre, is relatively low (30-40%). Improvements in these processes would have major implications for the Transfusion Service. Present technology requires the freezing of plasma from blood donations prior to the preparation of cryoprecipitate; this may then be processed further to produce factor VIII concentrate. In this study, the effects of using different anticoagulants (citrate, heparin), of varying the rate of freezing and the duration of storage on the factor VIII content of plasma and subsequent products have been investigated. The influence of ABO blood group and of drug induced enhancement on levels of factor VIII in starting plasma were also studied. Improvements in the mode of preparing cryoprecipitate from plasma have been made on the basis of the observed effects on processing plasma of different quality (collection procedure, age, etc .) and by various methods. Investigation of the mechanism of cryoprecipitation has led to the development of a high-yield method for the preparation of factor VIII from unfrozen plasma by precipitation with hydrophilic polymers. In the course of this work, methods were developed for the isolation of factor VIII and fibronectin and immunological assays for these and other proteins (fibrinogen), based on immunoprecipitation and immunoradiometric methods, were set up. The immunoradiometric methods were used to follow the recovery and survival of factor VIII components following infusion into patients deficient in this protein. Based on the work described in this thesis, recommendations will be made on the possibilities for improved procurement of factor VIII from blood donations.