A new murine monoclonal antibody against human hepatoma.

A murine monoclonal antibody (MAb 336) reactive with human hepatocellular carcinoma has been raised after immunizing BALB/c mice with whole HepG2 cells. MAb 336 (IgG1) was reactive with HepG2 (whole cells and membrane fractions), but not normal liver or peripheral blood cells. Immunohistological studies indicated that 12/16 hepatocellular carcinoma and 6/11 cirrhotic livers expressed MAb 336-associated antigen, and most normal human tissues and tissues derived from other cancers were unstained. Direct and competitive binding assays ruled out the possibility that this MAb reacts with alpha-fetoprotein, carcinoembryonic antigen, or ferritin. Western blot analysis indicated that MAb 336 reacts with an antigen of approximately 30,000 daltons. This MAb may be potentially useful for studying antigenic expression in hepatocellular carcinoma and as a targeting agent for radioimmunodetection and immunoconjugate therapy.