i.p.-primed memory CD8⁺ T cells are not activated by cognate residual antigen in the lung-draining LNs. (A and B) Mice were infected either i.p. or i.n. with Sendai virus and rested for 30 d. (A) Tetramer⁺ cells in the MLN of i.n.-primed or i.p.-primed mice were analyzed for the expression of CD69, CD49a, and CD103 on day 30 after infection. (B) Mean fluorescence intensity (MFI) of CD49a and CD103 on resting (CD69⁻) or activated (CD69⁺) cells in the spleen and MLN on i.n.-primed and i.p.-primed tetramer⁺CD8⁺ cells. The data are from 10–20 mice (mean ± SD). (C and D) Donor mice (CD45.1⁺CD90.2⁺ and CD45.2⁺CD90.2⁺) were infected either i.p. or i.n. with Sendai virus and rested for 30 d. After 30 d, CD8⁺ enriched splenocytes from each donor population were combined such that the number of Sendai NP_324-332/K^b+ cells derived from each donor was equivalent and intravenously transferred into recipient mice (CD45.2⁺CD90.1⁺) that had been infected with either Sendai virus (C) or influenza x31 virus (D) 30 d before donor cell transfer. 7 d after transfer, cells were isolated from the MLN and spleen and stained with anti-CD8, congenic marker, and Sendai NP_324-332/K^b tetramer. The data show the frequency of CD69⁺ cells among CD8⁺tetramer⁺ cells in each tissue on day 7 after transfer. The parentheses indicate the manner by which the donor cells were originally primed. The data are representative of two independent experiments. Error bars indicate SD.