IN-VITRO MIMICRY OF CAMBR1 TUMOR-ASSOCIATED ANTIGEN BY SYNTHETIC OLIGOSACCHARIDES

The murine monoclonal antibody (Mab) MBr1, raised against the breast c ancer cell line MCF7, recognizes a saccharidic epitope overexpressed o n a high percentage of human breast, ovary, and lung carcinomas, This antigen was originally identified on the immunogen as a globe-series g lycosphingolipid with an II-like determinant at its terminus (globe-II ), We report here the biological characterization of the entire globe- II hexasaccharide and five synthetic oligosaccharides representing fra gments of the entire structure and/or different anomeric configuration s, Using competitive binding assays on live cells, we identified the r esidues and the linkages essential for mimicry of the cellular antigen s recognized by Mab MBr1 on the breast carcinoma cell line MCF7 and sm all cell lung cancer cell line POVD, The terminal tetrasaccharidic fra gment of globe-a is the oligosaccharide that most resembles the MBr1-d efined epitope both on glycolipids and on glycoproteins, This informat ion will help in the rational design of a highly specific reagent for active specific immunotherapy of carcinomas overexpressing the MBr1-de fined antigen.