Immunohistochemical characterization of a monoclonal antibody to hyperplastic nodules induced in rat liver by chemical carcinogens.

To investigate the specific phenotype of hyperplastic nodules (HPN) in rat liver, we produced a monoclonal antibody (HAM-6). HAM-6 was a member of the mouse IgG1 class and was specific for hyperplastic nodules, as shown by cellular radioimmunoassay and immunohistochemical studies. The antigen recognized by HAM-6 was located in the rat HPN cell membrane. HAM-6 was also slightly reactive to rat hepatocellular carcinoma, but not to normal or fetal rat liver, other normal rat organs, human hepatocellular carcinoma, or human liver cirrhosis. That is, the antigen recognized by HAM-6 appeared to be differentiated and to occur during chemical carcinogenesis. HAM-6 may be a useful marker for the investigation of premalignant states in chemical carcinogenesis.