Characterization of monoclonal antibodies to novikoff hepatoma cytokeratin antigen p39.

Three stable monoclonal antibody-producing mouse hybridoma lines have been developed which produce high-titer, immunoglobulin M antibodies specific for the Novikoff ascites hepatoma (NAH) Mr 39,000 cytokeratin antigen (p39). Immunotransfer assays of cytoskeletal protein-enriched fractions indicated p39 to be present in a range of rat tissues, including colon, breast, lung, and uterus. Two-dimensional gel immunoblots confirmed that immunoreactivity in the latter tissues was for polypeptides with similar isoelectric points to those of NAH p39; however, reactivity in the colon contained a wide range of additional isomeric forms. Immunohistochemical localization studies with these antibodies revealed enrichment of p39 in the simple epithelia or ductular structures of organs containing this antigen. In all sections examined, glandular epithelia were observed to be only weakly immunoreactive. Additional immunoblot and immunocytochemical analyses with the monoclonal antibodies and polyspecific antisera to NAH cytokeratin suggest the human Mr 40,000 cytokeratin to be similar to but not identical to NAH p39.