Soluble Interleukin-2 Receptor Levels in Patients With Dilated Cardiomyopathy

Abstract

Background There is evidence that autoimmunity plays an important role in the initiation and progression of myocardial injury in dilated cardiomyopathy. Abnormalities of both cellular and humoral immunity have been described in this disease. Soluble interleukin-2 receptor (sIL-2R) levels in the serum reflect activation of T lymphocytes in the periphery or in tissues. The present study explored the possibility that activation of cellular immunity is frequent in patients with idiopathic dilated cardiomyopathy and may have functional consequences. Methods and Results Serum sIL-2R levels were determined with an enzyme-linked immunosorbent assay in 50 dilated cardiomyopathy patients, 30 patients with ischemic heart disease, and 22 normal control subjects. In addition, the presence of anti–β-receptor and antimyosin antibodies was sought in the serum of cardiomyopathy patients. High sIL-2R levels (>1400 pg/mL) were found in 38% of the dilated cardiomyopathy patients but only 6% of the ischemic heart disease patients. The group of sIL-2R–positive patients was characterized by higher average age, a higher percentage of women, and more severe disease (lower ejection fraction, higher left ventricular filling pressures, and lower cardiac output). Although the prevalence of cardiac autoantibodies did not correlate with the presence of high sIL-2R levels, higher titers of autoantibodies were found predominantly in the sIL-2R–positive group. Conclusions T-lymphocyte activation, as reflected in elevated sIL-2R levels, is frequent in patients with dilated cardiomyopathy and is associated with more severe disease. Cellular and humoral immune activation may correlate with progression of the disease process.