Development and Characterization of a Novel Anti‐fucosylated Antigen Monoclonal Antibody YB‐2 and Its Usefulness in the Immunohistochemical Diagnosis of Colorectal Cancer

A novel monoclonal antibody, YB‐2 was obtained after immunization of mice with fucosylated antigens isolated from human saliva. The antibody was demonstrated to react with Y (Fucα1→2Gal‐ β1→4[Fucα1→3]GlcNAcβ),Le(b)(Fucα1→2Galβ1→3[Fucα→4]GlcNAcβ)andHtype2 (Fucα→2Gal‐βl→4GlcNAcβ) antigens, but not with H type 1 (Fucα→2Galβ1→3GlcNAcβ), Le(→) (Galβ1→3[Fucα1→4]GlcNAcβ), X (Galβ1→4[Fucα1→3]GlcNAcβ) or with non‐fucosylated antigens. Inhibition assays of YB‐2 antibody with such reactive antigens showed that YB‐2 antibody preferentially reacted with Y antigen. Formalin‐fixed and paraffin‐embedded sections prepared from normal and malignant colorectal tissues were examined immunohistochemically with YB‐2. The positive rates of staining with YB‐2 antibody were 88.6% in malignant and 12.0% in normal tissues. The expression of fucosylated antigens detected by YB‐2 antibody seemed to be correlated with survival among patients with primary colorectal cancer. Therefore, YB‐2 antibody could be useful as an immunochemical tool for diagnosis and evaluation of the prognosis of colorectal cancer.