Lower serum concentrations of cytokines in elderly patients with pneumonia and the impaired production of cytokines by peripheral blood monocytes in the elderly.

It has been well documented that the immune function declines with age; however, little is known about the monocyte/macrophage function of age. In the present study, we measured the concentrations of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), IL-8 and monocyte inflammatory protein-1 alpha (MIP-1 alpha) in sera from 15 elderly patients and 22 young patients with pneumonia, in the acute phase and after recovery, by ELISA. In addition, we measured the concentrations of these cytokines in culture supernatants from lipopolysaccharide (LPS)-stimulated peripheral blood monocytes from normal healthy elderly subjects and young subjects in order to clarify the ability of the elderly to produce these cytokines. The concentrations of these cytokines in sera from old patients and in those from young patients obtained in the acute phase were higher than those in sera obtained after recovery phase. However, the concentrations of these cytokines in the acute phase were lower in elderly patients compared with those in young patients. Serum concentrations of cytokines did not appear to be associated with clinical outcome. In the production of these cytokines by monocytes, LPS-stimulated monocytes from healthy normal elderly subjects produced smaller amounts of G-CSF, GM-CSF, IL-1 beta, TNF-alpha, IL-8 and MIP-1 alpha than those from healthy normal young subjects. These results with the impaired production of these cytokines in the elderly may prove, at least in part, the characteristic features of host defence mechanisms of the elderly.