A filtrometric study on red blood cells after storage in frozen form

Abstract

For transfusion purpose, red blood cells can be frozen with glycerol for a long time. After thawing the red cells are washed, the intracellular glycerol is exchanged with water, and then the cells can be transfused. Most 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 the St 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 (p<0.05). A 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 have a high capacity to detect and quantify preservation injuries leading to decreased deformability in the red blood cells.