Mallory bodies--immunohistochemical detection by antisera to unique non-prekeratin components

Mallory bodies (MBs) were prepared in 95% pure form from a case of human chronic alcoholic liver disease. A protein referred to as Mallory body protein (MBP), was isolated from MB by reduction and alkylation which gave one band an SDS-polyacrylamide electrophoresis. Antisera were raised to both purified MBs and MBP in rabbits and a goat. Both antisera, after absorption with spleen cells, specifically reacted immunohistochemically with MBs in frozen sections from patients with alcoholic liver disease. They also reacted with small granular structures in hepatocytes which are interpreted as a precursor or degradation product of MBs. The anti-MB serum also stained MBs in trypsinised paraffin sections in the immunoperoxidase procedure. Neither antisera reacted with normal liver or skin, and the reactivity of anti-MB and MBP sera for MBs was not abolished by absorption with prekeratin; these results indicate that MBs contain unique antigenic determinants not present in prekeratin. It is concluded that MBs are not simply composed of intermediate filament proteins.