Autoantibodies against human ventricular myosin in sera of patients with acute and chronic myocarditis.

OBJECTIVES: The present study investigated the presence of antimyosin autoantibodies in sera of patients with myocarditis and in three control groups: healthy blood donors, patients with alcoholic cardiomyopathy and patients with other cardiac diseases.
BACKGROUND: An increasing body of evidence indicates that in the course of myocarditis, autoimmunologic mechanisms may play a pathogenetic role. Animal studies with Coxsackie B3 virus-induced murine myocarditis could demonstrate the appearance of circulating autoantibodies against cardiac myosin.
METHODS: Sera were analyzed by enzyme-linked immunosorbent assay (ELISA) and Western blot with human left ventricular myosin as antigen.
RESULTS: Seventeen (42%) of 40 serum samples from patients with myocarditis showed antibody-binding against myosin, whereas only 1 (2.5%) of 39 samples from healthy blood donors and 9 (21%) of 43 samples from patients with other cardiac diseases showed autoantibodies against myosin (p < 0.05 vs. myocarditis). In sera from patients with alcoholic cardiomyopathy (n = 12), no antibodies against human ventricular myosin could be detected. In Western blots, the antimyosin antibodies in patients with myocarditis bound to the myosin heavy chain. Using protein-A sepharose chromatography, it could be shown that the antimyosin autoantibodies are of the immunoglobulin G (IgG) type. In ELISA, the antimyosin autoantibodies bind equally to myosin prepared from either cardiac or skeletal muscle, respectively.
CONCLUSIONS: These results demonstrate the presence of autoantibodies against human ventricular myosin in patients with myocarditis. The prevalence of these autoantibodies is significantly higher in patients with myocarditis than in patients with other cardiac diseases. No organ specificity of the autoantibodies could be detected.