Assessment of red blood cell aggregation with dextran by ultrasonic interferometry

Aggregation of human red blood cells (RBCs) induced by dextrans of various molecular weight has been studied by using a new ultrasonic interferometry method. This method, based on A-mode echography, allowed for the measurement of the accumulation rate of particles on a solid plate which is related to their sedimentation rate (i.e., to their mean size). The initial aggregation process, the mean and the maximum sedimentation rate of aggregates and the packing of the sedimented RBCs have been investigated. Effects of hematocrit, molecular weight of dextrans and inhibition by dextran 40 on the RBC aggregation induced by dextran of higher molecular weight have been determined by analysing variations of the aggregate size. Results obtained confirm the aggregation effect of dextrans of molecular weights equal or higher than 70,000 dalton and disaggregation effect of dextran 40,000 dalton on aggregation by dextrans of higher molecular weight.