title: Specificity clusters of MUC1-reactive mouse monoclonal antibodies.
abstract: The ISOBM TD-4 Workshop antibodies 122-177 were grouped according to their reactivity with: (a) monomeric MUC1 peptide (TAP25); (b) the pentameric tandem repeat peptide (TR-5), both unglycosylated or as their GalNAc-substituted derivatives, and (c) the lactation or tumor-associated glycoforms of MUC1. The antibodies were grouped into nine clusters: Clusters 1-4 comprise those antibodies that bind to MUC1 tandem repeat peptide (monomeric) and define sequential epitopes differentially affected by glycosylation (GalNAc substitution) in the peptide motifs VTSA and GSTA. The ISOBM-163 antibody in cluster 5 defines Tn antigen as a site-specific glycotope within the tandem repeat peptide. The antibodies in clusters 6 and 7A recognize peptide epitopes within the tandem repeats, although these seem to be conformationally dependent on complex glycosylation or on oligomeric peptide repetition. Antibodies in clusters 7B bind to a conformational epitope not related to the tandem repeat peptide or to a carbohydrate epitope (cluster 7BC). Antibodies in cluster 8 showed a high selective binding to tumor-associated epitopes on MUC1 from mammary carcinoma cells. Cluster 9 antibodies were not reactive on any of the tested antigens and may be argued to lack MUC1 specificity. Alternatively, these antibodies could have a carbohydrate specificity not expressed by the MUC1 glycoforms tested in our studies.
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Cologne, Germany. akd10@rs1.rrz.uni-koeln.de
authors.forename: F G
authors.initials: FG
authors.lastname: Hanisch
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis*; D000918:Antibody Specificity / Q000276:immunology*; D018604:Epitope Mapping; D005260:Female; D006020:Glycopeptides / Q000276:immunology*; D006801:Humans; D051379:Mice; D018396:Mucin-1 / Q000276:immunology*; D009077:Mucins / Q000276:immunology; D012091:Repetitive Sequences, Nucleic Acid; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D006020:Glycopeptides; D018396:Mucin-1; D009077:Mucins