Abstract

Red blood cells frozen with glycerol can be stored in the frozen state -80 C for a long time. After thawing the red blood cells are washed, the intracellular glycerol is exchanged with water, and the cells can then be transfused. About 90 per cent of the red blood cells that have been frozen have a potential for normal longterm survival after transfusion, but some of them become altered during the preservation procedure and are removed from the recipient's circulation, one possible mechanism for this being trapping of red cells in the spleen due to reduced deformability.

The aim of this study was to investigate the sensitivity of theSt George's filtrometer to detect possible deformability defects in frozen, thawed and deglycerolized red blood cells. The suspension of deglycerolized cells showed a significant reduction in filterability indicating the presence of cells with reduced deformability. IrFR was decreased (p<0.05), RCTT increased (p<0.05) and CP increased (p<0.001). We found a reduction of filterability in these cells roughly corresponding to the presence of 0.01-0.1% glutaraldehyde treated cells. When 10% of the erythrocytes in a blood sample were hemolyzed and thus in ghost form IrFR and RCTT were unaffected, while CP was significantly increased (pt0.05). 1 suitable sampling technique may, however, minimize the influence from ghosts in blood samples used for filtrometry after freezing. Thus, in evaluating different freezing techniques filtrometry with the St George's instrument seems to lave a high capacity to detect and quantify preservation injuries leading to decreased deformability in the red blood cells.