A human-specific mitochondrial antibody its importance in the identification of organ-specific reactions.

A previously unrecognized autoantibody, detected by immunofluorescence, reacted with all human organs but gave negative results on tissues from rat, mouse, rabbit, guinea-pig, calf and chicken. From its predilection for mitochondria-rich cells (oncocytes) and its selective absorption with human but not animal mitochondria, it was identified as an anti-human mitochondrial antibody and named AHMA. The antibody is found in about 1% of normal subjects and is mostly of IgG class and of low titres. Its prevalence is increased in primary biliary cirrhosis where it may be associated with the standard non-species-specific AMA used for the differential diagnosis of this disease. The importance of AHMA is mainly in possible confusion with organ-specific reactions in submaxillary duct, parathyroid oxyphil cells and in trying to identify new endocrine cells such as those producing pancreatic polypeptide (HPP) in human tissues. Animals immunized with human hormones develop reactions to human mitochondria and thus produce misleading immunofluorescence reactions when used in low dilutions.