Carbohydrate side chains of Muc-1 peptide interfere with cytotoxic activity of CTL which recognize Muc-1

Mucin is high-polymer glycoprotein that is widely distributed in various organs. Its immunogenicity is protected by long carbohydrate side chains coating the core protein. In certain types of cancer, such coating does not form normally, and the core protein is manifest, presumably showing immunogenicity. Conversely, abnormal chains may often be expressed. As a result of investigation into how much the chains are affected by cytotoxicity to the Muc-1 core proteins, it was found that the cytotoxicity of the lymphocytes recognizing the core protein portion are impeded by the carbohydrate side chains incorporating Sialyl-Tn.