['T cells in peripheral blood reflect the systemic inflammatory response in patients with heart failure (HF). In a rat model of HF, osteopontin is dramatically increased in the left ventricular myocardium, so the association between osteopontin and HF was examined in the present study.', "Peripheral blood was collected from 93 patients with heart disease and 38 controls. Left ventricular ejection fraction (LVEF) was calculated using a modified Simpson's rule. The 93 patients were classified into 3 classes according to the New York Heart Association (NYHA) functional classification. Osteopontin-expressing CD4+ T cells were quantified by flow cytometry. Plasma osteopontin levels (ng/ml) and the frequencies of osteopontin-expressing CD4+ T cells (%) were higher in patients with HF than in controls (800+/-554, 575+/-229, p=0.016 and 27.3+/-12.2, 16.7+/-10.0, p<0.001). Furthermore, the plasma osteopontin levels and the frequencies of osteopontin-expressing CD4+ T cells increased in proportion to the severity of the NYHA functional class. The frequencies of osteopontin-expressing CD4+ T cells were significantly correlated with LVEF (r=-0.336, p=0.0048) and log plasma brain natriuretic peptide levels (r=0.305, p=0.0025)."] Are osteopontin expression of circulating T cells and plasma osteopontin levels increased in relation to severity of heart failure?