Figure 2: Vaccine-induced numbers of NP-specific CD8+ T cells in the blood, spleen, and lung. Groups of young and aged mice were vaccinated with 1010 vp of AdC68NP, given IM. A portion of these primed mice, along with age-matched groups of naïve mice, were subsequently boosted at 2 months after priming with 0.8 × 105 TCID50 of A/X31, given IN. 2 months after the boost, cohorts were euthanized before or after challenge with 3LD50 A/PR8. Lymphocytes were harvested from the blood, spleen, and lungs of these mice and underwent tetramer and CD8 staining to determine the total number of tetramer+CD8+ cells in each compartment. Graphs show numbers of NP-specific CD8+ T cells over 107 live PBMCs (upper row) or per all live mononuclear cells from spleens (middle rows) or lungs (low rows). The bars reflect group averages ± SD; gray bars represent young mice and black bars represent aged mice. Asterisks indicate significant differences between groups at the level.