Lipid ratios as a marker for red blood cell storage quality and as a possible explanation for donor gender differences in storage quality

Background and objectives Red blood cells that are stored for transfusions as red cell concentrates (RCCs) undergo changes during the storage period, culminating in the lysis of the cells. The goal of this work is to find markers that are linked to high haemolysis, in order to explain the inter-donor variability that is known to occur in storage quality, and also the known differences between RCCs from male and female donors. Materials and methods The relative amounts of lipids at the end of the storage period were compared for one group of low haemolysis samples (24 units, all <= 0 center dot 15% haemolysis), and one group of high haemolysis samples (26 units, all >= 0 center dot 5% haemolysis). Representative lipids were analysed from different lipid classes, including cholesterol, phosphatidylcholine, phosphatidylethanolamine, sphingomyelin and ceramide. Whole membrane preparations were analysed with one mass spectrometry technique, and lipid extracts were analysed with a second mass spectrometry technique. Results The ratio of palmitoyl-oleoyl phosphatidylcholine (POPC) to sphingomyelin was different for the high and low haemolysis groups (P = 0 center dot 0001) and for the RCCs from male and female donors (P = 0 center dot 0009). The ratio of cholesterol to phospholipids showed only minimal links to haemolysis. Higher relative amounts of sphingomyelin were associated with lower haemolysis, and higher relative amounts of ceramides were associated with increased haemolysis. Conclusion The level of sphingomyelinase activity and the resulting ratio of sphingomyelin to POPC is proposed as a possible marker for RCC storage quality.