Background: Ageing is associated with an altered immune response. Elevated plasma levels of tumour necrosis factor-alpha (TNF-alpha) are present in patients with advanced chronic heart failure (CHF). However, the relationship between age and the immune response in CHF is unknown.
Methods: We investigated the relationship between age and the TNF-alpha generating capacity of lipopolysaccharide (LPS) stimulated peripheral blood mononuclear cells (PBMC) in nine healthy control subjects (mean age 51.6+/-3.6 years, age range 39-75 years) and 22 stable patients with CHF (mean age 68.3+/-1.5 years, age range 52-78 years, NYHA class 3.0+/-0.2). We also tested the TNF-alpha generating capacity of all control subjects and 18 CHF patients in whole blood cultures.
Results: Subjects were subgrouped according to baseline TNF-alpha secretion in PBMC cultures into low- and high-responders, with the latter producing TNF-alpha even without LPS stimulation. High-responders produced more TNF-alpha than low-responders at all LPS doses (0.001-10 ng/ml, P<0.0001, repeated measures ANOVA), and high-responders were significantly older than low-responders (controls: 65.8+/-9.2 vs. 47.5+/-2.5 years; patients: 71.9+/-1.9 vs. 65.9+/-1.9 years, both P<0.05). Age correlated with TNF-alpha production in both patients and controls. This effect was independent of NYHA class.
Conclusions: LPS-responsiveness appears to relate to age in both healthy controls and CHF patients. When assessing the immune status of CHF patients, age should therefore be considered an important confounding factor. In whole blood these findings could only be confirmed at the highest LPS concentration used, thus suggesting that certain factors in the blood may be able to abolish LPS activity at lower concentrations.