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Expression of blood group A antigens in human bone marrow cells.

We have studied the appearance of blood group A-activity during hematopoiesis in human bone marrow cells by the use of the blood group A-specific lectin from Vicia cracca. Cells that bound the lectin were identified using antiserum against the lectin followed by rosetting with protein A-containing Staphylococcus aureus cells. Only cells of the erythroid lineage from blood group A individuals formed staphylococcal rosettes. A-activity occurred in basophilic normoblasts and later stages of erythropoiesis, whereas pronormoblasts were negative. The appearance of blood group A-activity coincided roughly with the onset of hemoglobin synthesis and slightly later than the expression of the major sialoglycoprotein of erythrocytes, glycophorin A. Glycophorin A did not, however, contain blood group A-activity when analyzed by immunoprecipitation and gel electrophoresis.