Effects of cellular factors on the aggregation behavior of human,rat and bovine erythrocytes

The present study was designed to extend our prior observations of RBC aggregation (Clinical Hemorheology 7, 93–108, 1987) in order to examine the electrokinetic behavior of age-separated RBC in various media, aggregation behavior of rat and bovine RBC in plasma, dextran and PVP, and donor-specific differences in human RBC aggregation. Our results indicate: 1) age-separated human RBC exhibit identical mobilities in PBS or in albumin, whereas older RBC have significantly (p<0.02) greater mobilities than younger cells in plasma or serum; 2) extracellular calcium reduces equally the mobility of young and old human RBC and increases equally the aggregation of both cell populations; 3) markedly reduced aggregation for unfractionated rat RBC in dextran T70, greater aggregation for old rat RBC in T70 yet a more negative mobility for these old cells, and no aggregation for bovine RBC in plasma, dextran (T70, T500, T2000) or PVP-360. Of particular interest were donor-specific differences for thrice-washed human RBC suspended in dextran T70; 1) cells exhibit a > two-fold range of aggregation between donors unrelated to ABO blood group or cell volume; 2) significant (p<0.05) correlations were observed between RBC aggregation behavior in autologous plasma and T70, thus suggesting possible in vivo conditioning of the cells. In overview, our current results further emphasize the importance of erythrocyte factors in RBC aggregation and suggest that when evaluating situations associated with abnormal aggregation, possible contributions of cellular as well as suspending media factors need to be considered.