Fig 1. Effect of aging on the induction of CTL response.
(A and B) Young and old C57BL/6 mice were immunized with a single intravenous injection of 2.5x109 OVA-beads in 100 μg polyU/DO. Additional young and old mice were injected with saline as control. Seven days later, CTL response was determined by an in vivo killing assay. (A) Data show the percentage of specific in vivo killing of each individual mouse and the bars indicate the mean of each group. (B) IFN-γ content in culture supernatants of splenocytes from immunized mice determined by ELISA. Spleen cells were recovered and cultured for 72 hours in the presence of OVA or OVA257–264. (C and D) cDCs purified from the spleen of young and old C57BL/6 mice were incubated with 20 mg/mL OVA in 20 μg/mL polyU/DO, or with RPMI alone (control) for 90 minutes and then washed twice. One million cDCs per age group were intravenously injected into young C57BL/6 mice. Seven days later, CTL was determined by in vivo killing assay. (C) Representative flow cytometry histograms gated on CFSE+ cells are shown. (D) Data show the percentage of specific in vivo killing values, expressed as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001. Results are representative of 3 independent experiments (4 mice/age group/experiment). In all cases, young and old control groups gave similar results, and only the results of the young control group are depicted.