Specificity of human natural antibodies referred to as anti-Tn

Publication date: April 2020Source: Molecular Immunology, Volume 120Author(s): Kira Dobrochaeva, Nailya Khasbiullina, Nadezhda Shilova, Nadezhda Antipova, Polina Obukhova, Tatiana Ovchinnikova, Oxana Galanina, Ola Blixt, Horst Kunz, Alexander Filatov, Yuriy Knirel, Jacques LePendu, Sergey Khaidukov, Nicolai BovinAbstractTo understand the role of human natural IgM known as antibodies against the carbohydrate epitope Tn, the antibodies were isolated using GalNAcα−Sepharose affinity chromatography, and their specificity was profiled using microarrays (a glycan array printed with oligosaccharides and bacterial polysaccharides, as well as a glycopeptide array), flow cytometry, and inhibition ELISA. The antibodies bound a restricted number of GalNAcα-terminated oligosaccharides better than the parent monosaccharide, e.g., 6-O-Su-GalNAcα and GalNAcα1−3Galβ1−3(4)GlcNAcβ. The binding with several bacterial polysaccharides that have no structural resemblance to the affinity ligand GalNAcα was quite unexpected. Given that GalNAcα is considered the key fragment of the Tn antigen, it is surprising that these antibodies bind weakly GalNAcα−OSer and do not bind a wide variety of GalNAcα−OSer/Thr-containing mucin glycopeptides. At the same time, we have observed specific binding to cells having Tn-positive glycoproteins containing similar glycopeptide motifs in a conformationally rigid macromolecule. Thus, specific recognition of the Tn antigen apparently requires that th...
Source: Molecular Immunology - Category: Allergy & Immunology Source Type: research