TRANSFERRIN-BINDING CAPACITY AS A MARKER OF DIFFERENTIATION AND MATURATION OF RAT ERYTHROID-CELLS FRACTIONATED BY COUNTER CURRENT DISTRIBUTION IN AQUEOUS POLYMER 2-PHASE SYSTEMS

Rat bone marrow cell populations, containing different proportions of erythroid cells, have been fractionated by counter-current distributio n in the non-charge-sensitive dextran/polyethyleneglycol two-phase sys tems on the basis of hydrophobic cell surface properties. Cell fractio ns with a low distribution coefficient, which contain non-erythroid ce lls and early erythoblasts, showed a low transferrin binding capacity and a low haemoglobin/cell ratio whereas cell fractions with a high di stribution coefficient, which contain intermediate-late erythroblasts and mature red cells, showed an elevated transferrin binding capacity and the highest haemoglobin/cell ratio. These results support transfer rin binding capacity as a good marker parameter for the erythroid bone marrow cell differentiation and maturation processes.