Immunologic Studies of Heart Tissue

Reactions of normal and pathologic sera with heart tissue have been investigated by the immunofluorescent method, with particular reference to presumptive autoantibodies to heart and their differentiation from blood group isoantibodies and Wassermann antibody. In the heart, blood group substances A and B were found distributed in capillary walls, vascular endothelium, and interstitial connective tissue. In surveys of randomly selected sera, isoimmune reactions against tissue blood group substances A and B were noted infrequently. This finding was considered related to the limited sensitivity of fluorescent antibody methods. Heart tissue from blood group O individuals was used for screening of pathologic sera for presence of tissue-reactive factors. Wassermann antibody was found reactive with constituents of myocardial sarcoplasm, of which the major reactant was cardiolipin. Wassermann-positive sera absorbed with beef cardiolipin gave evidence of reaction with other constituents of myofiber sarcoplasm. Sera of patients with rheumatic fever, rheumatic heart disease, rheumatoid arthritis, disseminated lupus, and liver disease frequently showed a marked reactivity with constituents of myofiber sarcoplasm. These serum factors were differentiated from Wassermann antibody. At least three patterns of immunofluorescent staining could be differentiated by the distribution of reactants in the myofiber sarcoplasm. These reactants were extractable with ethanol and methanol but not by acetone. Sera found reactive by immunofluorescence frequently gave positive flocculation and complement-fixation tests with alcohol extracts of human heart. Immunofluorescent tests were best correlated with flocculation reactions. Sarcoplasmic-reactive factors were associated in some sera with 19S gamma globulin as demonstrated by the use of fluorescent anti-19S gamma globulin. Serologic reactions with homologous or autologous heart were observed particularly frequently with sera from rheumatic patients approximately 2 weeks following cardiac surgery, as well as in some non-rheumatic patients following cardiac or thoracic surgery or acute myocardial infarction. The pathogenetic significance of these presumptive autoantibodies to heart is unknown. As yet, no definite conclusions may be drawn regarding their relationship to bound gamma globulin in rheumatic hearts or to the postcardiotomy and post-infarction syndromes.