Biological Functions of the HNK-1 Carbohydrate Epitope Biological Functions of the HNK-1 Carbohydrate Epitope HNK-1 carbohydrate epitope is recognized by monoclonal antibody HNK-1,which was raised originally to a membrane fraction of human T cell line, HSB-2 (1) The HNK-1 carbohydrate is also recognized by monoclonal antibodies L2, NC-1, 4F4, and M6749, which have specificity similar to that of HNK-1 antibody The epitope is expressed on a subset