Figure 5. Dampened proliferative recall response in mice primed with strong TCR signaling.

(A–D) Splenocytes from 5C.C7αβ TCR transgenic mice were adoptively transferred into congenic mice. The recipient mice were s.c. immunized with PCC_88–104 or PCC_103K peptides, challenged 7 days later with WSN-MCC_88–104 influenza virus, and analyzed on day 4 postinfection. (A–C) Frequency of KLRG1⁺ (A), Ki67⁺ (B), or BrdU⁺ (C) 5C.C7 cells in lung. (D) Frequency of BrdU⁺ 5C.C7 cells in MLN. (E–F) B10.BR mice were s.c. immunized with PCC_88–104 or PCC_103K peptides. After 7 days, mice were infected with WSN-MCC_88–104 influenza virus and analyzed on day 4 postinfection. Frequency of Ki67⁺ (E) or CD69⁺ (F) Ag-specific CD4 T cells (Dapi⁻B220⁻CD8a⁻CD11b⁻Vα11⁺Vβ3⁺CD44^hi) in MLN. Means ± SEM for at least three animals are shown. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001 (unpaired Student t test). Data shown are derived from at least three independent experiments (n ≥ 3 mice per group).