Serum kynurenine and neopterin concentrations in patients with cardiomyopathy.

Serum kynurenine and neopterin concentrations were determined in patients with hypertrophic (n = 22) and dilated (n = 23) cardiomyopathy. Significantly increased kynurenine and neopterin levels have been observed in cases of dilated cardiomyopathy. In these patients we found a positive correlation between serum kynurenine and neopterin levels (RS = 0.52, P less than 0.001). There existed several associations between the laboratory parameters neopterin and kynurenine and clinical findings, such as left ventricle (LV) systolic volume and LV circumferential fiber shortening velocity in patients with dilated cardiomyopathy (all P less than 0.05). In vitro, interferon-gamma induces the formation of neopterin in human monocytes/macrophages. Also the degradation of tryptophan via the kynurenine pathway is induced by interferon-gamma. Our data show that increased kynurenine as well as neopterin accumulation in serum are associated with severity of dilated cardiomyopathy. Thus, the data point to a role of immune activation in the pathogenesis of the disease.