Figure 6. Aged CD70+ T cells secrete increased levels of inflammatory cytokines that can be reversed by blocking CD70. (A–F) Intracellular staining for TNF-α, IFN-γ, and IL-2 in CD70- and CD70+ T cells from elderly individuals (61-80 years, n = 17) after in vitro anti-CD3/anti-CD28 stimulation. Representative flow data (left) and plots (right) for TNF-α, IFN-γ, and IL-2, respectively. The p-values were obtained by paired t-test (TNF-α, IFN-γ [CD8+ T cells], IL-2 [CD4+ T cells]) or Wilcoxon matched-pairs signed rank test (IFN-γ [CD4+ T cells], IL-2 [CD8+ T cells]). (G–L) Purified CD4+ and CD8+ T cells from healthy individuals (n = 6) were cultured with antagonist anti-CD70 antibody or IgG at a concentration of 10 μg/mL as indicated. After culturing in vitro for 24 h and stimulating with anti-CD3/anti-CD28, the cytokine production was measured by flow cytometry. Representative histogram (left) and plot (right) of TNF-α, IFN-γ, and IL-2 expression in CD4+ and CD8+ T cells. The p-values were obtained by paired t-test. *p < 0.05, **p < 0.01, ***p < 0.001.