The sarcolemma as antigen in the secondary immunopathogenesis of myopericarditis

The mapping of characteristic moieties of the myolemma, sarcolemma and endothelium is a prerequisite for the definition of heart muscle-specific epitopes which are targets of humoral and cellular effector mechanisms. AMLAs can be demonstrated in perimyocarditis and in most patients with postmyocarditic cardiomyopathy. The microheterogeneity of the membrane antibodies can be defined more clearly by Western blot analysis. There is increasing evidence that in man ASAs and AMLAs have a pathogenetic relevance; they fix various complement components and exert a cytolytic effect on isolated vital heart cells in vitro. These membrane antibodies are cross-reactive to certain viral proteins, indicating that antigenic mimicry may be the biological principle operative in patients with coxsackie B myocarditis. Membrane antibodies in sick sinus syndrome and A–V block may be directed against the sarcolemma and the membrane of the conducting tissue as well. Patients with former myocarditis or rheumatic fever have a many-fold incidence of these antibodies and are a group of patients at risk. Cellular immune reactions which are not HLA restricted are observed only rarely in myocarditis but are found more often in dilated cardiomyopathy and alcoholic heart muscle disease. From these data, a better understanding and a new, immunologically orientated classification of heart muscle disease can be derived.