The prevalence of inflammation is high among patients with chronic heart failure (CHF). Reduced ejection fraction was associated with frequency of CD4(+) T cells of leukocytes. Therefore, we investigated inflammatory cytokines of expression markers in CD4(+) T cells in patients with CHF. Blood samples were obtained from 103 patients with CHF, from 83 patients with stable angina (SA), and from 57 controls. Interferon-gamma (IFN-gamma)-positive CD4(+) T cells and interleukin-4 (IL-4)-positive CD4(+) T cells were analyzed using 3-color flow cytometry. The frequency (%) of IFN-gamma-positive CD4(+) T cells increased in patients with CHF compared with those with SA and controls (CHF: 28.3 +/- 13.8, SA: 23.50 +/- 10.38, controls: 19.00 +/- 7.45, P < 0.001). There was no significant difference in the frequency of IL-4-positive CD4(+) T cells among the three groups. The frequencies of CD4(+) T cells that stained for IFN-gamma decreased from 32.37% +/- 16.40% on admission to 26.91% +/- 12.53% after 2 weeks in 26 patients with CHF. B-type natriuretic peptide (pg/ml) and high-sensitivity C-reactive protein (mg/dl) levels decreased from 251.7 +/- 150.4 and 0.64 +/- 0.78 on admission to 208.2 +/- 166.4 and 0.36 +/- 0.34 after 2 weeks in the 26 patients with CHF. We have demonstrated expression of IFN-gamma production of CD4(+) T cells during CHF. Prevention of unwanted T cell activation could represent a new target in the treatment of CHF.