Figure 4. The extrinsic acquisition of CD80 does not affect the ability of Ag-specific memory CD8⁺ T cells to produce effector cytokines. (A) Experimental scheme for comparison of cytokine productions between CD80-acquired and CD80-deficient memory T cells after in vitro peptide stimulation. CD80-KO P14 CD8⁺ T cells were adoptively transferred into WT or CD80-KO recipient mice. One day after the adoptive transfer, mice were intraperitoneally infected with 2×10⁵ PFUs LCMV Arm. The LG and SP were obtained from WT and CD80-KO mice at day 60 post-infection and were re-stimulated with GP33 peptide. (B) Representative FACS plots showing production of IFN-γ, TNF-α, and IL-2 versus their CD80 expression in CD80-KO P14 CD8⁺ T cells obtained from the LG and SP of WT or CD80-KO mice. (C) Frequency and number of IFN-γ⁺, TNF-α⁺, and IL-2⁺ cells and expression levels of IFN-γ, TNF-α, and IL-2 among donor CD80-KO P14 CD8⁺ T cells obtained from the LG and SP in WT or CD80-KO recipient mice. (D) Representative flow cytometric analysis of production of TNF-α and IL-2 versus IFN-γ in CD80-KO P14 CD8⁺ T cells obtained from the LG and SP of WT and CD80-KO mice. (E) Frequency and number of TNF-α- and IL-2-producing cells among IFN-γ⁺CD8⁺ T cells. MFI of TNF-α and IL-2 among IFN-γ⁺CD8⁺ T cells. Data are representative of 3 independent experiments (n=3−4 mice per group). Results represent mean±SEM and statistical significance was determined by 2-tailed unpaired Student's t-test.

MFI, mean fluorescence intensity.