Cytolytic anticardiac membrane antibodies in the pathogenesis of myopericarditis.

Antisarcolemmal (ASAs) and antimyolemmal antibodies (AMLAs) are serological hallmarks of inflammatory heart muscle disease. They occur in a similar incidence in postcardiac injury syndromes, sarcoid heart disease or in dilated and hypertrophic cardiomyopathy. Rarely but still notably they are found with increasing age or in coronary artery disease. We therefore examined whether they are truly pathogenetic or whether they also possess properties of 'natural antibodies'. AMLAs and ASAs, like natural antibodies, have specificity for preserved structures on the membrane; they possess cross-reactivity and increase with age. In contrast to natural antibodies, however, they occur frequently after viral stimulation or other forms of trauma, are more often of the IgG and IgA than of the IgM isotype and fix complement in the acute stage of the disease. They also possess cytolytic and cytotoxic properties when incubated in vitro with isolated heart muscle cells. Antigenic mimicry has been demonstrated to be operative, since they are cross-reactive to viral proteins.