Autoimmunity to the heart in cardiac disease: Current concepts of the relation of autoimmunity to rheumatic fever, postcardiotomy and postinfarction syndromes and cardiomyopathies

Abstract

Current information on the role of immune mechanisms in rheumatic fever, postcardiotomy and postinfarction syndromes, cardiomyopathies and other cardiac disorders is reviewed. The possible role of autoimmunity is emphasized in view of the evidence that serum autoantibodies to diverse constituents of heart tissue frequently may be detected in these cardiac disorders. In rheumatic fever, experimental and clinical data indicate that autoimmunity to heart tissue may be induced in response to a constituent of group A streptococci, antigenically cross-reactive with heart tissue. Populations of autoantibodies with divergent specificities are present in the sera of patients with rheumatic disease. Certain of these autoantibodies exhibit correlation with the severity of disease and with the presence of carditis. The differentiation of those autoantibodies reactive with streptococcal crossreactive antigen seems essential for further understanding of the possible role of autoimmunity in pathogenesis. Evidence for such a role is provided by immunopathologic findings of bound gamma globulin and complement in postmortem rheumatic hearts and in biopsy specimens of atrial appendage. Circulating autoantibodies to heart tissue occur frequently after cardiotomy and myocardial infarction and are commonly associated with postcardiotomy and postmyocardial infarction syndromes. They may reappear during symptomatic recurrent episodes but are not present in quiescent intervals between attacks. Further efforts should be directed to definition of the specific antigens stimulating such autoantibodies, to the biologic and physicochemical properties of the autoantibodies related to clinical symptoms, as well as to immunopathologic observations in these syndromes. In recurrent acute benign pericarditis and in primary cardiomyopathies, viral infection, complicated by hypersensitivity or autoimmunity, or both, has been proposed as a pathogenetic mechanism. Autoimmune bodies have been described in varying frequency in these conditions, and their possible role in pathogenesis should be investigated further, using combined immunologie, virologie and immunopathologic approaches in the early phases of disease. Abnormal immune mechanisms are strongly suspect in the pathogenesis of the cardiac involvement of rheumatoid arthritis, systemic lupus and polyarteritis, but progress must await further understanding of the cause of the primary lesions in these conditions. In tropical endomyocardial fibrosis, an abnormal autoimmunologic diathesis, presumptively related to malarial infection, has been implicated. Animal models of autoimmune myocarditis have been explored. The available data suggest that experimental cardiac lesions of a focal nature may be produced in a variety of animal species. Their relevance as a model for human cardiac disease is under current study.