Deficiency of β1‐6 N‐Acetylglucosaminyltransferase Involved in the Biosynthesis of Blood Group I Antigen in the Liver of LEC Rats

The activities of the β1‐6 and β1–3 N‐acetylglucosaminyltransferases, which synthesize blood group I and i antigens, respectively, were measured in various tissues of hepatitis‐ and hepatoma‐predisposed rats (LEC rats). In LEC rats the β1‐6 N‐acetylglucosaminyltransferase activity was barely detectable in the liver, while substantial enzyme activity was found in other tissues. In the control LEA rats the enzyme was expressed in most tissues, including the liver. Immunochemical studies using a monoclonal antibody which recognizes I antigen indicated that the expression of I antigen was less prominent in hepatocytes of LEC rats than in hepatocytes of LEA rats. The level of β1–3 N‐acetylglucosaminyltransferase activity was constant in most of the tissues during the development. These results indicate that the biosynthesis of I antigen does not occur in the livers of the LEC rats.