INCREASED PRODUCTION OF TGF-BETA AND IL-6 BY AGED SPLEEN-CELLS

Aging is accompanied by a progressive decline in immunity in every spe cies that has been studied. Despite its ubiquity, the causes of immuno senescence are unknown. Transforming growth factor beta (TGF-beta) is a cytokine with potent, immunosuppressive properties. Cells from aged mice produce increased levels of TGF-beta in vitro along with similar increases in interleukin 6 (Il-6), a cytokine which is immunosuppressi ve at elevated concentrations. Il-6 does not upregulate TGF-beta produ ction, but high concentrations of Il-6 increase the percentage of cell s expressing the TGF-beta receptor. Increased TGF-beta production and Il-6-induced upregulation of the TGF-beta receptor may be factors cont ributing to age-associated immunosuppression.