Comparison and simulation of different levels of erythrocyte aggregation with pig, horse, sheep, calf, and normal human blood.

Erythrocyte aggregation levels in pig, horse, sheep, and calf blood samples were investigated and compared to that of normal human blood. The aggregation kinetics and adhesive forces between red cells, and an index of structure of the aggregates were determined with an erythroaggregameter (Regulest, France) at constant hematocrit (0.40 l/l) and temperature (37 degrees C). The adhesive forces and the index of structure in pig blood were close to those of normal human blood. The results for horse blood showed a very high level of aggregation kinetics and adhesive forces between red cells. For sheep and calf blood, little erythrocyte aggregation was found. To simulate different levels of red cell hyperaggregation in humans, a volume of horse plasma was replaced by isotonic NaCl in different proportions (5 to 40% V/V). The kinetics of rouleaux formation and especially the adhesive forces between erythrocytes were systematically decreased, while the index of structure was raised with increasing concentrations of isotonic NaCl. By replacing the porcine plasma with isotonic NaCl, normal and hypoaggregating levels of human red cells were simulated. The aggregation kinetics and the adhesive forces were reduced and the index of structure was raised when the concentration of isotonic NaCl was increased. In summary, large differences in the aggregation parameters were found between mammals. This study also showed that different human erythrocyte aggregation levels can be simulated by diluting the concentration of plasma proteins in equine and porcine bloods.