Figure 5. CD80-acquired memory CD8⁺ T cells exhibit a reduced in vivo expansion and a decreased IL-2 production during recall responses. (A) Experimental scheme for comparison of in vivo recall responses between CD80-acquired and CD80-deficient Tmem cells. CD80-acquired and CD80-deficient memory T cells were adoptively transferred together into CD80-KO recipient mice. One day after the adoptive transfer, mice were intraperitoneally infected with 2×10⁵ PFUs LCMV Arm. (B) Representative FACS plots showing the ratio between donor memory T cells and expression of CD80 on each memory T cell before transfer. (C) Frequency of donor memory T cells gated on Thy1.1⁺ T cells from the PBMCs at day 8 and 15 post-infection. (D) Frequency of donor memory T cells gated on Thy1.1⁺ T cells from the SP at day 17 post-infection. (E) Frequency of IFN-γ⁺, TNF-α⁺, and IL-2⁺ cells among CD80-acquired and CD80-deficient memory T cells obtained from SP after re-stimulation with GP33 peptide. Data are representative of 2 independent experiments (n=3−5 mice per group). Results represent mean±SEM and statistical significance was determined by 2-tailed unpaired Student's t-test.

NS, not significant; MFI, mean fluorescence intensity; Tmem, memory T.

^***p<0.001.