Temperature-dependence of red cell aggregation.

To investigate the temperature-dependence of red cell aggregation 20 blood samples of normal donors and 20 blood samples of patients with venous ulcers of the leg were examined by photometric aggregometry at 3 degrees C, 10 degrees C, 20 degrees C, 30 degrees C and 37 degrees C. With decreasing temperature red cell aggregates become more resistant to hydrodynamic dispersion and they become more prone to growing under low shear stress. It is concluded that a decrease in temperature causes an increase in adsorptive energy of red cell aggregation, which is most likely due to an increase in molecular adsorption stress. Red cell aggregate formation as an overall process is retarded by a decrease in temperature, which is primarily due to an increase in plasma viscosity causing increased damping of aggregate formation. Accordingly the rate constant of aggregate formation corrected for plasma viscosity increases with decreasing temperature. The temperature-dependence of the kinetic parameters can be explained by a theoretical model that suggests the increase in contact area between aggregating red blood cells as the rate-limiting step of red cell aggregation. As a whole red cell aggregation is favoured by lowering of temperature.