New monoclonal antibodies specific for the guinea pig line 10 hepatocarcinoma

Monoclonal antibodies reactive to line 10 (L10) hepatocarcinoma cells, but not to L2C leukemia cells, of strain 2 guinea pig were produced and characterized. Complement-mediated cytolysis assay and quantitative absorption analysis revealed that one of the monoclonal antibodies, 3C4 antibody (IgG2a), was highly specific for L10. Neither normal guinea pig tissues including adult and fetal liver, nor other hepatomas of strain 2 guinea pig, line 1 (L1) and Hepatoma III, were reactive with the 3C4 antibody. Another antibody, 2E4 (IgM), was reactive to the liver, kidney and spleen cells but not to the thymocytes, lymph node cells, brain and red blood cells of the guinea pig. The 2E4 antibody reacted to Hepatoma III but not to L1 cells. Therefore, 3C4 antibody is specific to a tumor-associated antigen of L10 hepatoma, and 2E4 antibody is cross-reactive with a certain differentiation antigen of normal tissues. The 3C4 antibody showed antibody-dependent cytotoxicity. Since 3C4 antibody was different in the isotype and the antigen recognized from a monoclonal antibody (D3) which was reported from the NIH in the USA, 3C4 is a new monoclonal antibody reactive with L10 hepatocarcinoma.