Frequency and specificity of antiheart antibodies in patients with dilated cardiomyopathy detected using SDS-PAGE and western blotting

AbstractObjectives. This study was designed to investigate the organ and disease specificity of antiheart antibodies in patients with dilated cardiomyopathy.Background. Autoimmune disease is characterized by the presence of circulating autoantibodies, and autoimmune mechanisms may play a role in the pathogenesis of dilated cardiomyopathy.Methods. An SDS-PAGE (sodium dodecylsulfate polyacrylamide gel electrophoresis) procedure followed by Western blotting was used to screen serum samples for antiheart antibodies of two immunoglobulin classes, IgM and IgG, from 52 patients with dilated cardiomyopathy and 48 patients with ischemic heart disease as control subjects. Use of two-dimensional gel electrophoresis followed by Western blotting and protein sequencing enabled us to identify the protein bands against which antiheart antibodies were produced in both groups of patients.Results. Strong IgG antiheart antibodies against myocardial proteins, cross-reacting with skeletal muscle proteins, were detected in significantly more patients with dilated cardiomyopathy (n = 24 [46%]) than with ischemic heart disease (n = 8 [17%]) (p = 0.001). Patients with dilated cardiomyopathy showed a significantly greater frequency and reactivity of IgG antiheart antibodies against six myocardial proteins (molecular weight 30, 35, 40, 60, 85 and 200 kD) than did patients with ischemic hrart disease. These were identified as myosin light chain 1, tropomyosin, actin, heat shock protein (HSP)-60, an unidentified protein and myosin heavy chain, respectively.Conclusions. We detected strong IgG antiheart antibodies in significantly more patients with dilated cardiomyopathy than with ischemic heart disease. The most immunogenic band was that corresponding to HSF-60. Antibodies against HSP-60 were found in 85% and 42% of patients with diluted cardiomyopathy and ischemic heart disease, respectively, confirming our hypothesis of an immune involvement in dilated cardiomyopathy