Action of Glycosyl Transferases upon "Bombay" (Oh) Erythrocytes. Conversion to Cells Showing Blood-Group H and A Specificities

Abstract

Individuals of the rare “Bombay” (O_h) blood-group phenotype are lacking, due to a genetic defect, the α(1—2)fucosyl transferase, which is responsible for converting blood-group H precursor substances to H-specific structures. Treatment with GDP-fucose and β(1—2)fucosyl transferase prepared from gastric mucosa of O individuals failed to transform native or ficin-treated “Bombay” erythrocytes into cells phenotypically resembling O cells. The transformation was achieved, however, after prior incubation of the “Bombay” erythrocytes with neuraminidase, indicating that blood-group H precursor molecules on the surface of these cells are masked by sialyl residues. Blood-group A specificity was conferred upon neuraminidase-treated “Bombay” cells by enzymatic transfer of α-N-acetylgalactosamine residues, in addition to α-fucose residues.