CD176
CD176 designates the sialyl-Tn carbohydrate antigen, the Neu5Acα2-6GalNAc determinant carried on O-glycans of mucins and other glycoproteins. In healthy adults the epitope is nearly absent, appearing only on a subset of erythrocytes and some secretory epithelia, but it is abundantly expressed on many breast, colon, gastric, and ovarian carcinomas. Its aberrant presence stems from blocked O-glycan elongation, which leaves short sialylated Tn structures on mucin backbones. Owing to this tumor-restricted distribution, sialyl-Tn is a classic tumor-associated carbohydrate antigen studied for vaccine development, antibody-based targeting, and epithelial cancer monitoring. The CD176 assignment rests on monoclonal antibodies raised against this determinant.
