Ultrastructural localization of mitochondrial and ribosomal antigens by peroxidase-labeled human antibodies.

Immunohistochemical techniques have facilitated the detection of a variety of antibodies to different cells and tissues in patients with chronic active liver disease; however, the ultrastructural localization of the antigenic binding sites, particularly of mitochondrial antibody, has been controversial. Therefore, we have employed direct immunoelectron microscopy to compare the reactivity of mitochondrial antibody with that of ribosomal antibody using gastric and renal tissues as substrates. Mitochondrial antibodies from three patients with primary biliary cirrhosis and from one patient with chronic active hepatitis reacted with the inner membrane and cristae of all mitochondria in different cells, whereas a ribosomal antibody from a patient with ovarian carcinoma bound to the rough endoplasmic reticulum, and possibly free ribosomes and polysomes, of all cells observed. Identification and characterization of these antibodies is needed for the differential diagnosis of chronic active liver disease.