Abnormal membrane lipid--related properties during maturation of reticulocytes from severely anaemic rats as measured by partition in two-polymer aqueous phases.

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Aqueous solutions of dextran and of polyethylene glycol when mixed give rise to immiscible, liquid two‐phase systems. Such systems are suitable for separating cells by partition and for tracing subtle changes in the cells’membrane surface properties as a function of differentiation, maturation and age. By appropriate manipulation of polymer concentration and ionic composition and concentration one can select certain membrane properties (e.g. charge‐associated, lipid‐related) that will determine the cells’partition coefficient (i.e. the cells’relative affinity for the top or bottom phase or adsorption to the interface). Combining radioisotopic labelling and cell countercurrent distribution techniques we have examined the partition behaviour of reticulocytes from severely anaemic rats (made so through phenylhydrazine‐injection) in two‐polymer phase systems which reflect membrane lipid‐related properties. It was found that such stress reticulocytes are abnormal with respect to their membrane lipid which does not produce the changes in partition coefficients observed with normal reticulocytes during maturation. The mature erythrocytes derived from such stress reticulocytes also have abnormal lipid‐related membrane properties. Together with our earlier results it is clear that red blood cells produced in severe anaemia have and retain abnormal charge‐associated and lipid‐related membrane surface properties during their life‐span and do not undergo the membrane surface changes associated with normal maturation and ageing as discerned by partition in two‐polymer aqueous phase systems.