Objective: To investigate plasma tumor necrosis factor (TNF)alpha, tumor necrosis factor alpha Soluble receptor I, interleukin-1 beta and neopterin concentrations as markers of monocyte activation in patients with heart failure. Study design: The group consisted of patients with heart failure due to dilated cardiomyopathy (n=19) and coronary artery disease (n=11). Patients without cardiac failure served as controls (n=10). Results: TNF alpha concentrations were elevated only in heart failure patients with coronary artery disease (2.9+/-0.3 pg/ml versus 1.7+/-0.3 pg/ml; P<0.05). When the patients were grouped according to acute and chronic failure, TNF alpha concentrations were significantly elevated in acute failure (3.1+/-0.4 pg/ml, n=6 versus 1.7+/-0.2 pg/ml, n=8; P<0.05). TNF alpha concentrations were elevated in patients with coronary artery disease and chronic heart failure compared to coronary artery disease patients without failure (2.0+/-0.4 pg/ml, n=6 versus 1.8+/-0.3 pg/ml, n=7; P<0.05). A higher proportion of patients with myocardial insufficiency showed increased lipopolysaccharide-inducible TNF alpha concentrations (10/30 versus 0/9, P<0.05). Conclusions: TNF alpha is elevated in patients with acute cardiac decompensation. Among patients with chronic heart failure only those with coronary artery disease exhibit increased levels. Cytokine concentrations are similar in heart failure due to dilated cardiomyopathy and coronary artery disease. Monocytes of patients suffering from cardiac insufficiency show an increased sensitivity towards stimuli such as lipopolysaccharides. (C) 1998 Elsevier Science Ireland Ltd.