The NK cells from young mice preferentially migrate to the D-LN to reduce virus spread and protect aged mice from mousepox. (A) NK^Y and NK^A from B6-CD45.1 mice were transferred into aged or young B6 (CD45.2) mice. The next day, the mice were infected with 3,000 PFU ECTV and the transferred NK cells were determined 2 dpi in the LNs. Data are representative of three experiments. (B) Ratio of NK^Y and NK^A cells that migrate to the D-LN versus the ND-LN in young and aged mice. (C) Aged B6 mice were inoculated with 6–8 × 10⁶ NK^Y cells, T_CD8+Y cells, or NK cell–depleted splenocytes from young mice (NK-^Y) and infected with 50 PFU ECTV. Mice were observed daily for signs of disease and death. Data combines four individual experiments. Statistical analysis was obtained with the Log-Rank test. (D) Aged B6 mice were inoculated with 5 × 10⁶ purified T_CD8+Y cells (white columns) or NK^Y cells (gray columns) and infected with 50 PFU ECTV. Virus titers in these were determined in the indicated organs 5 dpi. Data correspond to the mean ± SD of five individual mice per group.