Serum neopterin--possible immunological marker of myocardial inflammation in patients with dilated heart muscle disease.

Measurement of neopterin in biological fluids is a sensitive and specific tool for detecting activation of the T cell/macrophage system. Serum neopterin level, detected by radioimmunoassay, and data from morphological investigations of myocardium were compared in 29 patients with a clinical diagnosis of dilated heart muscle disease. According to the results of endomyocardial biopsy (22 cases) and autopsy (seven cases), 14 patients had morphological features of myocarditis, 13 dilated cardiomyopathy and two a fibrotic subtype of dilated cardiomyopathy (DCMP). The mean neopterin level in all patients (12 +/- 9 nM l-1) was higher than in the control group (5 +/- 2 nM l-1) (P less than 0.05). Also, the mean neopterin level was significantly higher in patients with myocarditis and fibrotic subtype of DCMP (16 +/- 11 nM l-1) than in patients with a morphological diagnosis of DCMP (9 +/- 6 nM l-1) (P less than 0.05). The highest neopterin levels in both groups were found in those who subsequently died during follow-up (mean level 23 +/- 10 nM l-1). There was a correlation between neopterin and beta 2-microglobulin (r = 0.83, P less than 0.05). Our study suggests that the raised serum neopterin level may be a marker of myocardial inflammation and unfavourable prognosis in patients with a clinical diagnosis of dilated heart muscle disease.