SEPARATION AND CHARACTERIZATION OF RED-BLOOD-CELLS WITH DIFFERENT MEMBRANE DEFORMABILITY USING STERIC FIELD-FLOW FRACTIONATION

Human red blood cells were treated in different ways to alter their me mbrane deformability, and the hydrodynamic behavior of these altered c ells was studied using the steric field-flow fractionation (FFF) techn ique. The relationships between cell retention in the FFF channel, flo w-rate of the carrier fluid and the applied field strength were studie d for normal and glutaraldehyde-fixed human red cells, and separation conditions were optimized. The effect of flow-induced hydrodynamic lif t forces on red cell retention in the steric FFF channel was studied, and the results suggest that the membrane deformability of the red cel l is an important factor contributing to the lift force, besides other previously described effects due to density and flow velocity. Using steric FFF, a mixture of normal and glutaraldehyde-fixed human red cel ls was completely separated with a resolution twice that found in publ ished data from gel permeation, another hydrodynamic separation techni que. Partial loss of membrane deformability, induced by different degr ees of glutaraldehyde-fixation, by diamide, or by a thermal treatment, has also been studied. Steric FFF is thus shown to have potential for rapid separation and differentiation of red cells with different dens ity and membrane deformability, conditions known to be associated with , e.g., cell senescence and certain hematological diseases.