[Significance of immunologic effector mechanisms in infectious endocarditis].

Whereas a number of investigations deals with extracardiac manifestations of immune reactions in infective endocarditis (e.g. circulating immune complexes), immunological effector mechanisms directed against the heart itself have not yet been analyzed. In 72 patients with infective endocarditis (41 patients with defined pathogen, 31 no pathogen isolated) humoral und cellular immunological effector mechanisms were investigated. Antibodies directed against the cytoskeleton of myocardial cells and against the endocardium were demonstrated in 60% to 100% depending on the infective pathogen and the clinical course. Whereas the antibodies were found in subacute and chronic courses regularly, they were found less frequently in acute lethal cases. Antibodies directed against connective tissue, endocardium and sarcolemma were indicative of, but not specific for the endocardial affection. Those antibodies which were directed against the inner parts of the sarcolemma, the myolemma, appear to be indicators of an additional myocardial affection, if they are cytolytic against vital cardiocytes in vitro. Circulating immune complexes are non-specific markers of an increased immunoreactivity. They were detected in 35 out of 41 patients with defined bacterial pathogen in the early phase of the disease. Both, their incidence and serum concentrations decreased significantly after antibiotic treatment. Cellular immune reactions directed against vital heart cells (e.g. cytotoxic reactions) can most likely be attributed to K- or NK-lymphocytes and were found in 48% of patients. Serum factors such as circulating immune complexes and/or antimyolemmal antibodies may enhance or block this cytotoxic reaction.