Demonstration of organ specific antibodies against heart mitochondria (anti-M7) in sera from patients with some forms of heart diseases.

Using submitochondrial particles (SMP) from beef heart, pig kidney and rat liver in the ELISA, we detected partial organ specific anti-mitochondrial antibodies (AMA) against heart and kidney SMP in sera from patients with different forms of cardiomyopathies. Serum samples from 50 of 159 patients with congestive or hypertrophic cardiomyopathy (31%) and from two of 15 patients with acute myocarditis (13%) were AMA positive. These AMA could be clearly differentiated from other known AMA (anti-M1-M6) and were therefore named anti-M7. Thirteen of the 52 sera (25%) reacted only with heart SMP (type a) and 39 showed a cross-reaction with kidney, lung and pancreas mitochondria (type b). However, using liver SMP, no positive reaction was found. The anti-M7 type a and b activity was abolished completely by absorption with heart SMP. The anti-M7 antibodies were directed against an antigen which co-purified with the inner mitochondrial membrane and had a molecular weight of 67,000-72,000. They seem to be confined to some forms of cardiomyopathies and myocarditis of unknown aetiology and were not detected in sera from patients with other diseases.