Immunological analysis of auto-antibodies against the adenine nucleotide translocator in dilated cardiomyopathy

We have previously identified the adenine nucleotide translocator (ANT), an intrinsic protein of the inner mitochondrial membrane, as an auto-antigen in dilated cardiomyopathy (DCM). Further immunochemical characterization by crossed immunoelectrophoresis, indirect solid phase radioimmunoassay and immunoadsorption studies on the isolated translocator protein and mitochondria from heart, kidney and liver showed the existence of organ-specific antigenic determinants although partial crossreactivity between the three proteins was observed. Sera from 18 patients with histologically proven dilated cardiomyopathy were studied for their capacity to bind to the translocator protein. Seventeen of 18 patients showed significant binding, while in the sera of patients with coronary heart disease, suspected alcoholic heart disease or healthy blood donors, no anti-ANT antibodies were observed. Further studies showed organ-specific and functionally active autoantibodies, which decreased the ADP/ATP exchange rate from heart mitochondria. A close correlation was found between the antibody-titer and the hemodynamic function. These results give new evidence for autoimmunological events in dilated cardiomyopathy.