Survival of the fittest?--survival of stored red blood cells after transfusion.

During the last 90 years many developments have taken place in the world of blood transfusion. Several anticoagulants and storage solutions have been developed. Also the blood processing has undergone many changes. At the moment, in The Netherlands, red blood cell (RBC) concentrates (prepared from a whole blood donation and leukocyte-depleted by filtration) are stored for a maximum of 35 days at 4 degrees C in saline adenine glucose mannitol (SAGM). Most relevant studies show that approximately 20% of the RBCs is lost in the first 24 hr after transfusion. Even more remarkable is that the average life span is 94 days after a storage period of 42-49 days. Such observations create the need for a parameter to measure the biological age of RBCs as a possible predictor of the fate of RBCs after transfusion. The binding of IgG to RBCs can lead to recognition and subsequent phagocytosis by macrophages. This occurs during the final stages of the RBC life span in vivo. We determined the quantity of cell-bound IgG during storage, and found considerable variation between RBCs, but no significant storage-related change in the quantity of cell-bound IgG. The significance of this finding for predicting the survival of transfused RBCs in vivo remains to be established. Hereto we developed a flow cytometric determination with a sensitivity of 0.1% for the measurement of survival in vivo based on antigenic differences. This technique has various advantages compared with the 'classical' 51Cr survival method.

Quantification of loss of haemoglobin components from the circulating red blood cell in vivo.

Previous studies have shown that a considerable amount of haemoglobin is lost from the intact red cell during its lifespan. The aim of this study was to determine the relative contribution of all the haemoglobin components to this process. Therefore, the relative amount of haemoglobins A0, A2, F and the glycated haemoglobins were determined in 24 fractions of different cell age. These fractions were obtained by the combination of counterflow and density centrifugation. When the absolute amount of all haemoglobin components were calculated using the MCH-values of each fraction, it appeared that the mean red cell loss of haemoglobins A0, A2, F, an unknown X and "rest" comprised, respectively, 440, 23, 1, 4 and 1 amol per cell, while the mean gain of the glycated haemoglobins was 84 amol per cell. This resulted in a net loss of 385 amol of haemoglobin per cell. One of the glycated haemoglobins (HbA1e2) turned out to be the product of further carbamylation. It was concluded that in the first half of the red cell lifespan HbA0 and HbA2 decreased by glycation and carbamylation and that in the second half some of the HbA0 and HbA2 but also some of the glycated and carbamylated haemoglobin components leave the red cell. The total loss amounted to about 20%.

Determinants of red blood cell deformability in relation to cell age.

Red blood cell (RBC) deformability was determined with an ektacytometer in fractions separated on the basis of differences in cell volume or density. Deformability was measured with ektacytometry (rpm-scan and osmo-scan). We studied three groups of RBC fractions:1. By counterflow centrifugation we obtained fractions of different cell age which showed a slight decrease in mean corpuscular haemoglobin concentration (MCHC) and an increase in surface-to-volume (S/V) ratio in fractions with older cells. 2. By Percoll fractionation fractions were obtained which showed a pronounced increase in (MCHC) but no change in S/V ratio. 3. By a combination of both fractionation techniques, fractions were obtained which showed an increased MCHC and an increase in S/V ratio. Deformability in group 1,2 and 3 showed respectively no change, a moderate decrease and a pronounced decrease in fractions of older cells. A decline in deformability occurs during the aging process of the red blood cell. This decline in deformability in old red cells is greater than originally thought. This decline is the result of an increase in haemoglobin concentration and a second factor, probably a decrease in membrane elasticity.

Characteristics of red blood cell populations fractionated with a combination of counterflow centrifugation and Percoll separation.

Red blood cell (RBC) fractions were studied after separation of whole blood by means of counterflow centrifugation, Percoll column (Pharmacia, Uppsala, Sweden), and a combination of both separation techniques. Mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and hemoglobin A1c (HbA1c) were measured in each fraction. From the results it was obvious that the combination of both techniques was the best separation technique of these three. MCV had a good correlation with cell age as measured with HbA1c concentration gradient; MCH and MCHC less so. MCV and MCH decreased in parallel to an increase in HbA1c. MCHC increased with increasing HbA1c. From these data it is concluded that there is a steadily ongoing loss of cellular hemoglobin and proportionally more cellular water during the life of the RBC.