Effect of delayed blood processing on the yield of factor VIII in cryoprecipitate and factor VIII concentrate

Current standards for the preparation of factor VIII (FVIII) concentrates from human plasma recommend separation of plasma from red cells (RBCs) within 6 hours of blood donation, thereby reducing the volume of plasma from donated whole blood available for processing to FVIII concentrate. The decay of FVIII clotting activity (FVIII:C) in whole blood and plasma stored at 22 and 4°C and the recovery of FVIII:C in cryoprecipitate and FVIII concentrate prepared from plasma separated from whole blood stored overnight at 4°C were investigated. In whole blood stored at 22°C and plasma stored at either 4 or 22°C, 90 percent of the original FVIII:C was present at 6 hours, 80 percent at 12 hours, and 65 to 70 percent at 18 hours. At these times lower levels of FVIII:C were recovered from whole blood stored at 4°C, that is, 84, 68, and 56 percent, respectively. In cryoprecipitates prepared from plasma separated from RBCs after 18 hours' storage at 4°C (18‐hour plasma), 43 percent of FVIII:C activity was recovered, as compared with 61 percent recovered from standard plasma separated within 6 hours of donation (6‐ hour plasma), p < 0.05. With large‐scale preparation of FVIII concentrates, however, the yield of FVIII:C was similar whether 18‐ or 6‐hour plasma was used. Thus FVIII concentrates‐but not cryoprecipitates‐can be prepared from plasma separated from whole blood stored at 4°C for up to 18 hours without undue loss of potency.