[Autoantibodies against cardiac myosin in patients with myocarditis and dilated cardiomyopathy].

Evidence accumulated in recent years indicates that autoimmunologic mechanisms may play an important role in the pathogenesis of myocarditis and dilated cardiomyopathy. In animal studies with Coxsackie B3-virus-induced murine myocarditis circulating autoantibodies against cardiac myosin have been detected. The present study investigates whether in patients with myocarditis and dilated cardiomyopathy antimyosin-autoantibodies can be detected. Patients with other cardiac diseases and healthy blood donors were used as controls. In 30 of 62 (48.4%) patients with myocarditis antimyosin-antibodies could be detected, whereas in patients with dilated cardiomyopathy only 10 of 41 (24.4%) sera contained antimyosin-antibodies (p < 0.05). In patients with other cardiac diseases, 9 of 43 (21%) sera showed antimyosin-autoantibodies (p < 0.05 vs myocarditis, not significant vs DCM). In healthy blood donors, antimyosin-autoantibodies could only be detected in 1 of 39 (2.5%) sera. In Western-blot tests, the antimyosin-antibodies in patients with myocarditis bound to the myosin heavy chain. Protein A-Sepharose chromatography showed that the antimyosin-autoantibodies are of the IgG-type. No organ-specificity of the antibodies for cardiac myosin could be detected, and the antimyosin-autoantibodies bind equally to myosin prepared from either cardiac or skeletal muscle, respectively.