Simultaneous influence of erythrocyte deformability and macromolecules in the medium on erythrocyte aggregation: a kinetic study by a laser scattering technique.

The aggregation and sedimentation kinetics of human erythrocytes was studied by modifying the cellular properties and medium compositions simultaneously. Dextrans of average molecular weight 70400 and 494000 were used to provide suspending medium modifications, while diamide (diazene dicarboxylic acid bis(N,N-dimethylamide)) was used to alter the membrane structural properties. Laser scattering method was employed for this study, and it was compared with a kinetic method combined with a low-shear rheoscope and an image analyzer. From scattered light intensity profiles continuously obtained during aggregation of erythrocytes and sedimentation of the aggregates, characteristic kinetic parameters were computed. Kinetic parameters obtained from a phase of the one-dimensional aggregate formation and sedimentation corresponded well to the velocity of rouleaux formation obtained by the low-shear rheoscope technique. Dextrans accelerated the erythrocyte aggregation and the sedimentation, and diamide treatment suppressed the process by decreasing the erythrocyte deformability. The aggregating force by dextrans overcame the disaggregating force by the decreased deformability. However, the arrangement of erythrocytes as expressed in specific units for aggregates (i.e., rouleaux) became irregular by decreasing the erythrocyte deformability. In conclusion, the progression of erythrocyte aggregation and the structure of the aggregates were dependent on both erythrocyte properties and macromolecules in the medium.