Posttransfusion survival of red cells frozen for 8 weeks after 42-day liquid storage in AS-3

Current standards recommend that red cells (RBCs) should be frozen within 6 days of donation. There are situations, however, in which it is desirable to freeze RBCs that are older than 6 days, such as for the salvage of rare or autologous units. To determine the therapeutic efficacy of RBCs frozen after prolonged liquid storage, standard units were drawn from nine normal donors and stored at 4 degrees C for 42 days in a nutrient-additive solution, AS-3. 51CrRBC survival assays were performed (24-hour survival: 78.2 +/- 12.4%; n = 8) and the units were frozen at -80 degrees C in glycerol for 8 weeks. After deglycerolization, the mean RBC recovery was 81.0 +/- 4.1 percent and the mean 24-hour 51Cr survival was 78.0 +/- 9.1 percent. The index of therapeutic effectiveness (ITE) was determined by multiplying the postdeglycerolization 24-hour 51Cr survival by the mean RBC recovery (63.3 +/- 9.2). ITE values greater than 60 percent (75% 51Cr survival x 80% RBC recovery) were considered acceptable. Mean adenosine triphosphate levels declined from an initial 3.81 +/- 0.56 micromol per g of hemoglobin to 2.33 +/- 0.55 micromol per g after frozen storage. These findings show that an acceptable percentage of RBCs survives frozen storage after maximum liquid storage (mean ITE greater than 60%). If necessary, RBCs stored in AS-3 can be frozen at any time before 42 days.