Characterization of two monoclonal antibodies obtained after immunization with human liver mitochondrial membrane preparations.

Two monoclonal antibodies have been generated by fusion of mouse myeloma cells with spleen cells from mice immunized with human liver mitochondrial membranes. One antibody, 1H6/C12, an immunoglobulin G2a (IgG2a), binds to the inner membrane of rat hepatocyte mitochondria, and immunoperoxidase staining demonstrates that its epitope has an intracellular particulate distribution within rat and human hepatocytes and human brain neurons. The epitope reactive with 1H6/C12 is partially sensitive to proteinase digestion. The second antibody, 3F12/F2, an IgG1, binds to a contaminating cell type, namely the granulocyte, but it does not bind to monocytes, lymphocytes and red cells in human blood. This antibody reacts with cells in the portal tract and sinusoids of rat and human liver, as shown by immunoperoxidase staining. The epitope for 3F12/F2 is extremely sensitive to proteinase digestion and is only exposed when granulocytes are fixed in acetone, indicating an internal localization.