IMMUNOCHEMICAL STUDIES ON BLOOD GROUPS LXtI Fractionation of Hog and Human A, H, and AH Blood Group Active Substance on Insoluble Immunoadsorbents of Dolichos

The fucose-binding lectins from Lotus tetragonolobus have been purified (1-3), characterized, and shown to be specific for oligosaccharides containing fucosyl residues on C-2 of DGalfll--~4DGlcNAc I (type 2 chains) but not for DGalfll-->3DGlcNAc (type 1 chains) similarly substituted (3, 4). In addition, the Lo~us lectin precipitated with H, A2 and Le a, but failed to interact with A1 or B blood group substances (3, 4). The purified lectin from Dolichos biflorus did not precipitate with H or B blood group glycoproteins, but reacted with A~ and A2 substances (5). Because of their blood group specificities and since these two lectins can easily be purified in good yields using polyleucyl hog blood group A + H substances as immunoadsorbents (6, 7), they represent important potential tools in purification and for structural studies of blood group substances and their oligosaccharides. Indeed, lectins have already proven invaluable in the elucidation of the structures of blood group oligosaccharides isolated from human ovarian cysts, hog and horse gastric mucins, as well as from malignant cells and tissues (8-13). The hog gastric mucin blood group substances are known to have A, H, or AH serological activities (14, 15). In addition, a new determinant consisting of terminal nonreducing DGlcNAc~I---~4DGal has been identified in blood group glycoproteins from hog and human stomachs. This determinant is antigenic in man (16) and goat (17), and is responsible for Con A reactivity (9, 18). The commercial preparation of hog gastric mucin (Wilson) is a mixture obtained by pooling hog stomachs and therefore has A molecules and H molecules and contains individual molecules having both A and H activities. The usual fractionation procedures using phenol extraction and fractional ethanol precipitation (19) yielded products possessing both activities, while precipitation with Con A resulted in two fractions with similar blood group activities but differing in Con A reactivity (18, 20). However, a blood group A active material was separated from H by precipitation of hog mucin with A hemagglutinin from Vicia cracca, dissolution of the precipitate with 0.1 M sodium acetate pH 5.0, and gel filtration on Sepharose 2B (21).