Factor VIII collection by pheresis.

A new blood donation procedure for obtaining selectively the proteins in cryoprecipitate consists of sequential automated plasma exchanges, in which the donor's fresh plasma is replaced with the autologous cryoprecipitated supernatant from the previous exchange donation. Fresh plasma is processed into cryoprecipitate and supernatant, both of which are frozen and stored. Six donors have undergone a total of twenty-six exchange donations of 1.5 to 2 litres. No adverse effects have been encountered. The yield of factor VIII per unit of plasma processed decreases during a donation but remains substantial in the last unit of plasma obtained from a 2 litre exchange. The average total yield of factor VIII from a donation was 730 U. The increased yield of factor VIII per donor may reduce the donor exposure, and hence the hepatitis risk, associated with factor VIII replacement therapy.