ULTRASTRUCTURAL AND IMMUNOHISTOCHEMICAL ANALYSIS OF BIOPSY-PROVEN CHRONIC ACTIVE MYCOCARDITIS WITH NUMEROUS CLUSTERS OF LYMPHOCYTES

A 60-year-old women was admitted to our hospital with deteriorating co ngestive heart failure. Although the diagnosis of active myocarditis w as confirmed by right ventricular endomyocardial biopsy, this patient died of refractory heart failure during corticosteroid treatment. Nume rous lymphocytic clusters were observed microscopically in the heart a t autopsy. Most of the infiltrating cells in the clusters were positiv e for CD 8, HAM 56 or MHC class 2 antigen; few cells were positive for CD 56. Expression of perforin was found in some of the infiltrating c ells. Electron microscopic examination revealed small lymphocytes adhe ring to the surface of injured cardiac myocytes. Close contact of thes e lymphocytes to macrophages was shown in the clusters. ICAM-1 and MHC class 1 antigens were strongly expressed in the cardiac tissue. These results indicate that cytotoxic T lymphocyte-mediated cytotoxicity ha d continued to operate during immunosuppressive therapy. Corticosteroi ds may not be suitable for the treatment of chronic active myocarditis when persistent expression of ICAM-1 is observed.