Monoclonal antibodies VIB-E3, IB5 and HB9 to the leucocyte/epithelial antigen CD24 resemble BA-1 in recognizing sialic acid-dependent epitope(s). Evidence that VIB-E3 recognizes NeuAc alpha 2-6GalNAc and NeuAc alpha 2-6Gal sequences.
The specificities of seven monoclonal antibodies to the human B cell differentiation marker CD24 have been investigated with respect to sialic acid containing carbohydrates. These are antibodies HB8, HB9, VIB-C5, VIB-E3, AL1a, LC66 and IB5, which are known to bind to polydisperse sialoglycoprotein(s) on Nalm-6 B lymphoblastoid cells. Three of the antibodies, HB9, VIB-E3 and IB5, have been found to resemble the first described antibody in this series, BA-1, in binding also to bovine submaxillary mucin. As with BA-1, the binding of the antibodies is abolished or reduced markedly after desialylation of the epithelial glycoprotein, and the binding to neuraminidase-treated Nalm-6 cells is also reduced. There is evidence for the involvement of of non-O-acetylated sialic acid in the determinants recognized by these antibodies, since there is a substantially enhanced binding following mild-alkali treatment of the epithelial mucin which removes O-acetyl groups. One of the antibodies, VIB-E3, is deduced to recognize the oligosaccharide sequences NeuAc alpha 2-6GalNAc and NeuAc alpha 2-6Gal as part of larger antigenic structures. This conclusion has been reached from the results of inhibition-of-binding experiments using a series of structurally defined sialo-oligosaccharides and direct binding experiments using oligosaccharides chemically linked to lipid (neoglycolipids).
Larkin
M
M
Glycoconjugates Section, MRC Clinical Research Centre, Harrow, England, UK.
Knapp
W
W
Stoll
M S
MS
Mehmet
H
H
Feizi
T
T
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D015703:Antigens, CD / Q000276:immunology*; D051927:CD24 Antigen; D002240:Carbohydrate Sequence; D002417:Cattle; D000939:Epitopes / Q000276:immunology; D006017:Glycolipids / Q000378:metabolism; D006020:Glycopeptides / Q000494:pharmacology; D006801:Humans; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid; D009844:Oligosaccharides / Q000276:immunology / Q000494:pharmacology; D011485:Protein Binding; D012794:Sialic Acids / Q000494:pharmacology*; D012795:Sialoglycoproteins / Q000378:metabolism; D013363:Submandibular Gland
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D051927:CD24 Antigen; C497889:CD24 protein, human; D000939:Epitopes; D006017:Glycolipids; D006020:Glycopeptides; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D012794:Sialic Acids; D012795:Sialoglycoproteins; D019158:N-Acetylneuraminic Acid