Blood-group A and B isoantigens of sphingoglycolipid nature with a single carbohydrate chain have been isolated from human erythrocytes. Three polymorphic types of A-active glycolipids from A1 cells, two types of A-active glycolipids from A2 cells, and two types of B-active glycolipids from B cells have been separated. One of the A-active polymorphic types found in A1 cells was not found in A2 cells. One glycolipid fraction isolated from O cells was found to be H active as well as Leb active. None of the Lea-active glycolipid was found in normal human erythrocytes. All of the glycolipids that carry ABH and Leb specificities were found to have a high content of fucose. Ceramide pentasaccharide, which consists of 1 mole each of glucose, glucosamine, and fucose and 2 moles of galactose, constitutes the fundamental common skeleton of blood-group ABH and Lewis glycolipids. The fatty acid compositions of these glycolipids are almost identical irrespective of blood type. Thus, the carbohydrate composition of the blood-group glycolipids is very similar to that of a Lea-active, fucose-containing glycolipid (“tumor glycolipid”) accumulating in human adenocarcinoma (Hakomori, S., and Jeanloz, R. W. (1964), J. Biol. Chem. 239, pc 3606; Hakomori, S., Koscielak, J., Bloch, K. J., and Jeanloz, R. W. (1967), J. Immunol. 98, 31). © 1968, American Chemical Society. All rights reserved.
