Mitochondrial antibodies in primary biliary cirrhosis. V. Ultrastructural localization of the antigen to the inner mitochondrial membrane using a direct peroxidase conjugate.

The IgG fraction of a primary biliary cirrhosis serum with high titre of mitochondrial antibodies was conjugated with peroxidase and applied to 20 μm cryostat sections of various rat tissues (stomach, kidney and liver). Results at the ultrastructural level confirm the localization of the antigen to the inner mitochondrial membrane. It was found that fixation with 1% formaldehyde in 0·1 mol/l phosphate, pH 7·4, containing 0·25 mol/l sucrose for 40 minutes at 4° achieved reasonably good preservation of morphology without undue loss of antigen. Staining variations among mitochondria of different cell types are discussed with regard to antigenic distribution.