Preservation of red cell concentrates. Dependence on storage time of IgG binding, osmotic fragility, MCV, and surface area index.

In a comparative study of red cells from concentrates preserved in SAG medium without and with 30 mM sucrose, mannitol or sorbitol, resp., we determined the variation of IgG binding, osmotic fragility, MCV and the surface area index with storage time. IgG binding gave no conclusive results. Osmotic fragility turned out to be increased in simple SAG in comparison to the sugar-supplemented media. From measurements of microhematocrit and pH, the mean cellular volume (MCV), standardized to the initial pH value, turned out to decrease in all the media tested by not more than about 5 per cent after 3 weeks, and 10 per cent after 6 weeks. This is in advantageous contrast to the strong decrease in microhematocrit formerly observed in red cell concentrates in CDS-AG medium. Cells resuspended in simple SAG medium exhibited the smallest decrease in MCV. However, as inferred from data on hemolysis and vesiculation (D. Stibenz, accompanying paper), in these cells the loss of surface area proved to be maximal.