Serological classification of chronic cholestatic liver disease by the use of two different types of antimitochondrial antibodies.

Clinical and morphological features in fifteen patients with chronic cholestatic liver disease (mixed form) who had two different types of complement-fixing antimitochondrial antibodies were compared with those found in twenty-five patients with classic primary biliary cirrhosis (PBC). PBC-specific antimitochondrial antibody (M2) directed against an antigen of the inner mitochondrial membrane was always present in both groups. However, mixed-form cases had a second antimitochondrial antibody (M4) which fixed complement with a trypsin insensitive antigen probably located on the outer membrane. Histological lesions typical of chronic active hepatitis, often associated with granulomata formation and bileduct proliferation, and simultaneous increases in IgM and IgG were predominant features, indicating that these mixed-form cases may represent a separate clinical entity.