Different sequences of expression of band 3, spectrin, and ankyrin during normal erythropoiesis and erythroleukemia.

Expression of the erythrocyte anion exchanger band 3, and ankyrin and spectrin, two cytoskeletal proteins of the red blood cell membrane, was studied by immunofluorescence using: 1) smears of human bone marrow from healthy donors and from a patient with erythroleukemia, 2) human red blood cell precursors grown in cell culture, and 3) murine erythroleukemia cells grown in cell culture. Double immunostaining with antibodies to band 3 in combination with spectrin or ankyrin revealed that these proteins become expressed synchronously during normal human erythropoiesis. In contrast, both murine erythroleukemia cells (induced by fibronectin and dimethyl sulfoxide to differentiate in vitro) and erythroblasts from a patient suffering from erythroleukemia displayed distinct asynchronicity in expression of these proteins, ie, ankyrin and spectrin were synthesized first, followed by band 3 at a later stage of erythroid development. After the onset of band 3 expression in human erythroleukemia cells, an increase of membrane-associated fluorescence was detectable for both ankyrin and spectrin, supporting the general view that band 3 promotes assembly of the membrane cytoskeleton. These findings indicate that the current concept of a sequential expression of spectrin/ankyrin and band 3 is valid only for erythroleukemia cells or transformed erythropoietic cell lines but does not occur in normal erythropoiesis, during which these proteins become expressed simultaneously.