Immunoglobulins and Complement in Chronic Myocardial Disease

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Abstract
Autoimmune mechanisms were previously suggested to be of significance in chronic myocardial diseases. The frequency and importance of these factors are unknown. In the present study, endomyocardial biopsy specimens from 21 patients with chronic myocardial disease were examined by direct immunofluorescence for the presence of immunoglobulins [Ig] and the 3rd component of complement (C3). Positive staining for Ig and/or C3 was observed in 7 cases. None of the specimens stained for albumin or amyloid. The Ig deposits were located on the surface of the myofiber, and in all but 1 case, C3 was found in the same location. The presence of the C3 together with Ig, and also the lack of albumin, may suggest an immune reaction and not just a passive deposition secondary to heart muscle damage. The localization along the fibers further suggests that the deposits represent an autoimmune reaction to antigens on the fibers and not a trapping of circulating antigen-antibody complexes. It is not known whether the deposits are primary or secondary events, but they may be of importance in initiating or maintaining derangement in heart function.