Purification and Localization of Colon Antigen Recognized by Tissue Bound IgG of Ulcerative Colitis and Its Significance as a Ttarget Molecule for ADCC

The role of colon associated antigen for the cytopathic effect of colonic mucosa in ulcerative colitis was evaluated. （1） A glycoprotein recognized by colitis colon associated IgG （CCA-IgG） was purified by the combination of DEAE Affi-gel Blue column chromatography and Phenyl Sepharose column chromatography. The protein obtained was electrophoretically pure and migrated to the position of 40,000 daltons by SDS polyacrylamide gel electrophoresis. （2） Murine monoclonal antibodies and a monospecific polyclonal rabbit antibody specifically reacted with this protein have been developed. （3） By using one of the 18 monoclonal antibodies, 7 E12H12, an indirect immunoperoxidase method was performed in order to elucidate the tissue localization of this protein. The significant stain was observed in the basolateral and apical aspects of the colonic epithelial cells lining the lumen as well as in the crypts. There was no significant stain within the cytoplasm of epithelial cells. （4） The F（ab'）2 of rabbit polyclonal antibody blocked the antibody dependent cell mediated cytotoxicity of the colonic tumor cell line by sera of patients with ulcerative colitis, suggesting that the antigen recognized by this F（ab'）2 is a target molecule of the antibody for ADCC of colonic mucosal cells.departmental bulletin pape