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In a survey of 210 young haemophiliacs living in South-east England it was recently shown that, by modern standards, under 20% received adequate treatment (Dormandy et al., 1967 (Bennett and Dormandy, 1966). A total of 1,304 pints (in 500 ml. units) of blood were used. The 914 pints which were collected by the plastic-bag method and processed at the haemophilia centre yielded 2,019 blood components, which were used separately. Supernatant plasma left after the separation of cryoprecipitate was given to three patients with Christmas disease (factor IX deficiency) and to one patient with plasma thromboplastin antecedent (factor XI) deficiency. Specific assays for factor IX and factor XI activity were carried out on these preparations. Plasma PreparationsDonors were bled either at the hospital or at regular bloodtransfusion sessions. Of the hospital donors, 70 underwent single plasmapheresis-that is, the separated red cells from the pint (500 ml.) of blood donated were immediately returned to the donor (Kliman and Schwab, 1961). By means of this procedure donors could be bled at intervals of one to two weeks.Cryoprecipitate.-Donors were bled into Fenwal JD-2 double plastic bags, consisting of a primary blood pack connected to a satellite bag. 500 ml. of blood was collected in not more than 10 minutes. The blood was spun within two and a half hours of taking (often immediately) at 4,600 g for 20 minutes at 40 C. and the plasma separated. The satellite bag containing the plasma, which was not severed from the primary blood pack, was frozen in a C,-ice-alcohol mixture. minutes at 40 C., and the supernatant plasma was run back into the primary blood pack. Alternatively, the supernatant plasma was collected into a third bag, and the packed red cells in the primary blood pack were issued as such. (A triple-bag system allows this transfer to be carried out without opening the closed system.) In either case 10-15 ml. of plasma was left with the cryoprecipitate in the satellite bag, which was stored at -30°C. On use the thawed cryoprecipitate from up to five satellite bags could be collected into a single 50-ml. syringe for injection. Washing out the series of satellite bags with 10 ml. of saline permitted the collection of the residual cryoprecipitate (equivalent to the factor VIII activity of up to one extra bag of cryoprecipitate).Supernatant Plasma.-When this was not used for the reconstitution of the red-cell mass, the supernatant plasma separated from the cryoprecipitate was used in the treatment of coagulation defects in patients with a deficiency of either factor IX or factor XI.Fresh-frozen Plasma in Plastic Bags.-The first stages in the preparation of fresh-frozen plasma were as above, with the exception that the plasma in the satellite bag was severed from the primary blood pack. (1962). Assays, which were all done in the hospital laboratory, were carried out as follows: (1) on the plasma at the time of donationj; (2) on the plasma or cryoprecipitate at the time of thawing for therapeutic use ; (3) on the supern...

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