Structural characterization of blood group A glycosphingolipids recognized by the antibody 3G9-A

In this study, the antibody 3G9-A was assayed for activity against human erythrocyte glycosphingolipids. The antibody was found to recognize glycosphingolipid components from blood group A erythrocytes but not glycosphingolipids from blood group B or O erythrocytes. Subsequent investigation revealed that the glycosphingolipid components recognized by the antibody were also recognized by a blood group A specific monoclonal antibody. The structures of two of the isolated active glycosphingolipid components were structurally characterized using proteon nuclear magnetic resonance (¹H NMR) and gas chromatography-mass spectrometry (GC-MS) techniques and were found to consist of two blood group A glycosphingolipids; the type 2 chain A^b and type 3 chain A^a glycosphingolipids. Subsequent analysis of the remaining active components by GC-MS and immunostaining techniques revealed that all of the active components were blood group A glycosphingolipids. Furthermore, structural studies of the active components suggested that the epitope of the antibody consisted of the group A trisaccharide, GalNAc1,3(Fuc1,2)Gal.Abbreviations GC-MS gas chromatography-mass spectrometry - ¹H NMR proton nuclear magnetic resonance - Gal d-galactose - Glc d-glucose - Fuc l-fucose - GalNAc N-acetylgalactosamine - GlcNAc N-acetylglucosamine - Cer ceramide - mAb monoclonal antibody - BSA bovine serum albumin - PBS phosphate buffered saline - FID free induction decay - PMAA partially methylated alditol acetates