Identification of mitochondria in liver biopsies - A study by immunohistochemistry, immunogold and Western blot analysis

Hepatocytes are rich in mitochondria, which play an important role in hepatic metabolism. In certain pathologic conditions (most often alcoholic liver disease) mitochondria became enlarged; nevertheless, even in these conditions they are hardly detectable on light microscopy. Recently an antimitochondrial antibody (mAM), which recognizes a 60-kDa protein, has been characterized. The purpose of the present study was to study immunoreactivity of this antibody in a series of liver biopsies. We studied 146 liver biopsies using an mAM. In 8 cases an ultrastructural study was also done, and in 2 cases Western blot analysis was performed. Cases were divided as follows: alcoholic liver disease (ALD, 31); steatosis (8); nonalcoholic steatohepatitis (NASH, I); hepatitis C virus (HCV)-related hepatitis (83); hepatitis B virus (HBV)-related hepatitis (6); primary biliary cirrhosis (I); sclerosing cholangitis (1); haemosiderosis (1); sarcoidosis (I); alpha-l-antitrypsin deficiency (I); nonspecific findings (12). All the patients were investigated for alcohol or drug abuse, pharmacological treatment, hyperlipidaemia, hypercholesterolaemia and diabetes. Immunoreactivity was diffuse in cases of ALD, NASH and steatosis, and in patients with drug abuse. Electron microscopic immunogold and Western blot analysis confirmed that in the conditions examined the protein recognized by the mAM showed greater expression. Immunohistochemical staining was helpful in demonstrating a toxic or a metabolic insult even in cases in which the histological picture was blurred by viral infection.