Elevated serum levels of soluble interleukin-2 receptor, neopterin and beta-2-microglobulin in idiopathic dilated cardiomyopathy: relation to diseaseseverity and autoimmune pathogenesis

Background: It has not been assessed whether high levels of soluble interle ukin 2 receptor (sIL-2R), neopterin and beta -2 microglobulin in idiopathic dilated cardiomyopathy reflect heart failure severity and/or an active aut oimmune process. The aim of this study was to relate serum levels of these markers to clinical and autoimmune features.: Methods: We studied 60 patien ts with idiopathic dilated cardiomyopathy, 67 controls with ischemic heart failure and 34 normals. Results: Abnormal levels of sIL-2R, but not of neop terin and beta -2 microglobulin, were more frequent-in idiopathic dilated c ardiomyopathy than in ischemic patients (35% vs. 16%; P = 0.02) or in norma ls (35% vs. 12%, P = 0.01); mean sIL-2R levels were, however, similar in id iopathic dilated cardiomyopathy and ischemic heart failure (842 +/- 75 vs. 762 +/- 93 U/ml, P = NS). In idiopathic dilated cardiomyopathy abnormal lev els of sIL-2R were associated with lower peak oxygen consumption (P = 0.008 ), higher neopterin and HLA class II expression in the myocardium (P = 0.02 ), but were unrelated to cardiac autoantibody status or titer. In addition, abnormal levels of neopterin were associated with adverse prognosis and hi gher beta -2 microglobulin; abnormal levels of beta -2 microglobulin with l ower echocardiographic percent fractional shortening, higher sIL-2R and hig her neopterin. Conclusions: There is no convincing evidence that abnormal s IL-2R, neopterin and/or beta -2 microglobulin are disease-specific markers of idiopathic dilated cardiomyopathy. The lack of association with cardiac autoantibodies suggests that these abnormalities are mainly related to hear t failure severity rather than autoimmune pathogenesis. In keeping with thi s view, high levels of sIL-2R, neopterin and/or beta -2 microglobulin ident ified a subset of idiopathic. dilated cardiomyopathy patients with advanced disease and poor prognosis. (C) 2001 European Society of Cardiology. All r ights reserved.