Cohen M, Hurtado-Ziola N, Varki A
ABO blood group glycans modulate sialic acid recognition on erythrocytes. [JOURNAL ARTICLE]
Blood 2009 Aug 24.
ABH(O) blood group polymorphisms are based on well-known intra-species variations in structures of neutral blood cell surface glycans in humans and other primates. While natural antibodies against these glycans can act as barriers to blood transfusion and transplantation, the normal functions of this long-standing evolutionary polymorphism remain largely unknown. Although microbial interactions have been suggested as a selective force, direct binding of lethal pathogens to ABH antigens has not been reported. We show here that ABH antigens found on human erythrocytes modulate the specific interactions of three sialic-acid recognizing proteins (human Siglec-2, 1918SC influenza hemagglutinin and Sambucus nigra agglutinin) with sialylated glycans on the same cell surface. Using specific glycosidases that convert A and B glycans to the underlying H(O) structure, we show ABH antigens stabilize sialylated glycan clusters on erythrocyte membranes uniquely for each blood type, generating differential interactions of the three sialic acid binding proteins with erythrocytes from each blood type. We further show that by stabilizing such structures ABH antigens can also modulate sialic acid-mediated interaction of pathogens such as Plasmodium falciparum malarial parasite. Thus, ABH antigens can non-covalently alter the presentation of other cell surface glycans to cognate binding proteins, without themselves being a direct ligand.
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