Antihaemophilic globulin: preparation by an improved cryoprecipitation method and clinical use.

The control of bleeding episodes in haemophilia and the prevention of excessive haemorrhage after surgical procedures depend chiefly on raising the patient's plasma factor VIII concentration to an appropriate haemostatic level, and maintaining this so long as the likelihood of bleeding continues. With whole plasma it is impossible to achieve levels much above 25%, or to maintain values constantly above about 10 % for more than two or three days, without overloading the patient's circulation. In order to overcome this problem antihaemophilic globulin concentrates have been prepared for clinical use by a variety of methods. Most of these require much time and technical skill, and involve considerable loss of activity during the process. The cryoprecipitate method of Pool and her associates, however (Pool et al., 1964 ; Pool and Shannon, 1965), based on their observation (Pool and Robinson, 1959) that when frozen plasma is thawed in the cold most of the factor VIII remains in the cold-insoluble precipitate, provides a simple means of preparation of potent antihaemophilic globulin concentrates , suitable for introduction as a routine blood-banking procedure. We report here 12 months' experience in the preparation and clinical use of cryoprecipitate antihaemophilic globulin, and describe a modification of Pool's original method of preparation, which has resulted in a great improvement of recovery of factor VIII activity in the concentrates. Approximately 500 ml. of blood was taken from each donor into a double pack (Fenwal JD-2) by a clean venepuncture. Continuous gentle agitation ensured thorough mixing of the blood and the acid-citrate-dextrose anticoagulant throughout the bleeding. At the end of the blood donation 5 ml. of well-mixed blood was run back out of the pack for factor VIII assay. The blood pack and assay sample were then rapidly cooled to 2-4' C. in a water-bath containing melting crushed ice, and kept at this temperature until they could be transferred to a precooled centrifuge at 40 C. The pack was then centrifuged for 30 minutes at 1,600 g to obtain the maximum yield of platelet-poor plasma, while the assay sample was centrifuged and assayed immediately for factor VIII. Not more than 280 ml. of plasma, free of red cells and buffy coat, was transferred to the 300-ml. satellite pack, which was placed in a cardboard carton and immersed in a mixture of solid CO2 and ethanol at about-70° C. in a large vacuum flask, leaving the attached main blood pack on …