FIGURE 2.

DON inhibited CD4⁺ T‐cell immunity age specifically in vitro and in vivo. (a) IL‐2 production of young and old naïve CD4⁺ T cells was measured 24 h after unspecific activation (10 µg/ml anti‐CD3 and 2 µg/ml anti‐CD28). (b) Naïve CD4⁺ T cells were isolated from young and old C57BL/6 mice and labeled with CFSE. Proliferation of naïve CD4⁺ T cells was measured by the dilution of CFSE, after 72 h in co‐cultures with DBA‐derived splenocytes. (c) IFN‐γ was measured by ELISA in cultural supernatants. (d) OT‐II mice‐derived CD4⁺ T cells were adoptively transferred into wild‐type C57BL/6 mice. Recipients were then stimulated with 500 μg OVA. Proliferation and function of OT‐II CD4⁺ T cells were measured by flow cytometry (day 3). Column plots display individual data points and mean ± SD, n = 5/group. The results are representative of at least three independent experiments