Autoantibodies in hypertrophic cardiomyopathy and their clinical significance.

Data concerning autoantibodies in hypertrophic cardiomyopathy are rare and controversial and only the results of indirect immunofluorescence methods are available in the literature. The aim of this study was to determine the frequency and clinical significance of autoantibodies in hypertrophic cardiomyopathy by means of the Western blot which is a highly sensitive immunological technique. Sera from twelve (48.0%) of the whole group of 25 patients with hypertrophic cardiomyopathy reacted with actin from the HeLa extract. The incidence of anti-actin antibodies in sera from 23 ischaemic heart disease patients was 13.0% (P less than 0.025) and in 37 apparently healthy subjects was 8.1% (P less than 0.001). When samples were assayed on the actomyosin prepared from Xenopus laevis muscle, sera of 14 (56.0%) of the patients exhibited actin positivity while the positivity in ischaemic heart disease and in healthy subjects was found to be 13.0 and 13.5%, respectively (P less than 0.001). Presence of anti-actin antibodies was related to the functional and clinical status and the progression of the disease. Anti-actin antibodies were found more frequently in medically treated patients. These data suggest that anti-actin antibodies are probably not directly involved in the pathogenesis of hypertrophic cardiomyopathy, but their detection might be useful as an additional marker of disease severity.