Studies of the recovery and the cost of low-glycerol cryopreserved human red blood cells.

Red blood cells were equilibrated with 28 per cent (v/v) glycerol and 3 per cent mannitol in 0.65 g/100 ml sodium chloride. The units were frozen by immersion into liquid nitrogen and stored at -160 C. After thawing, they were reconstituted and washed using the IBM 2991 Blood Cell Processor. Freeze-thaw rate curves, the effect of thawing techniques, the effect of varying postthaw washing and processing techniques, estimates of red blood cell losses because of hemolysis, and in vitro recovery were determined. In vivo recovery was determined by 51Cr techniques 24 hours after infusion and Ashby survivals and subsequent life span were measured. Metabolic, scanning electronmicroscopy, cost estimates and quality control studies were done on the reconsituted red blood cells. Recipients were evaluated before and after transfusion for metabolic erythrocyte characteristics and for evidence of hemolysis. The modified method requires less wash solution and less technician time than does the standard low-glycerol method. Two units for the same recipient could be passed through the IBM software with no alteration of cell survival or loss. Revision of the IBM 2991 processing procedure provided excellent recovery of viable previously frozen red blood cells at probably a lower cost.