The Increase of IFN-γ Production through Aging Correlates with the Expanded CD8+highCD28−CD57+ Subpopulation

The use of flow cytometry to detect intracellular cytokines at the single cell level has the potential to quantify cytokine production together with the possibility of phenotypic identification of the cell population concerned. The unbalanced presence of intracellular cytokines produced by T cells has been recognized in some pathological conditions. To better address this issue, we studied the production of IFN-γ and IL-4 in CD4+ and CD8+high T cells in healthy donors of a broad range of age (17–62 years). Given that an increase of IFN-γ and IL-4 with aging had been reported by some authors in healthy controls, we have performed a multivariate analysis to assess the intrinsic role of aging or of other external factors, such as chronic antigenic exposures (i.e., viruses), over the cytokine production of phenotypically characterized T cells. In this respect we show that, mainly in CD8+high T cells, the production of IFN-γ is directly correlated with age. Besides, the cytokine production correlates with the CD8+highCD28−CD57+ T-cell population, which we have recently reported elevated in aged individuals. Perhaps this T-cell subpopulation plays a regulatory role as a Tc1 response in aging individuals.