TNF-alpha, leptin, and lymphocyte function in human aging

Aging is associated with increased inflammatory activity and concomitant de creased T cell mediated immune responses. Leptin may provide a link between inflammation and T cell function in aging. The aim of the study was to inv estigate if plasma levels of tumor necrosis factor (TNF)-alpha were associa ted with leptin, circulating interleukin-2 receptors (sIL-2R), and phytohae magglutinin (PHA) induced IL-2 production in whole blood in elderly humans. Circulating levels of TNF-alpha and sIL-2R were higher in elderly humans ( N=42) compared to a young control group (N=37) whereas there was no differe nce with regard to IL-2 production. Furthermore, there were no age-related differences in serum levels of leptin, However, women had higher levels tha n men. In the elderly people, serum levels of leptin were correlated with T NF-alpha in univariate regression analysis and in a multiple linear regress ion analysis adjusting for the effect of gender and body mass index. Furthe rmore, TNF-alpha, but not leptin, was positively correlated to sIL-2R and n egatively correlated to IL-2 production. In conclusion, increased plasma le vels of TNF-alpha in aging is associated with poor IL-2 production ex vivo and lymphocyte activation in vivo. These associations do not seem to involv e leptin. (C) 2000 Elsevier Science Inc. All rights reserved.