FIGURE 3.

DON dampens alloimmune responses in vivo in an age‐specific manner. Skin allografts from young DBA mice were transplanted onto young and old C57BL/6 mice. Recipients were treated with 1.6 mg/kg DON q.o.d or PBS starting on the day of transplantation. (a) Frequencies of CD4⁺ and CD8⁺ T cells and (b) frequencies and absolute numbers of Tregs in the spleen were assessed after 7 days by flow cytometry gating on single cells. (c) Recipient mice received a single intraperitoneal injection of BrdU prior to skin engraftment; animals were then treated with DON or PBS. 7 days after transplantation, splenic frequencies of BrdU⁺ cells were analyzed by flow cytometry. (d) Splenocytes from young and old C57BL/6 recipients of DBA skin allografts were collected 7 days after transplantation. Recipient mice received DON or PBS. Splenocytes were co‐cultured with anergic DBA splenocytes. By 48 h, cytokine secretion was measured by ELISA. Column plots display individual data points and mean ± SD, n = 5/group. The results are representative of at least three independent experiments