Fig. 3

Anti-4-1BB preferentially drives the expansion of CD73-negative CD8⁺ T cell subset. Percentage of 4-1BB⁺ cells (a), or CD73⁺ cells (b) among infiltrating CD4⁺ and CD8⁺ T cells in B16-SIY tumor-bearing mice treated as indicated was determined by flow cytometry (5 mice per group). c Percentage of CD73⁺ cells among tumor-infiltrating B220⁺ cells or Gr1⁺CD11b⁺ MDSCs in B16-SIY-bearing mice treated as indicated. d The absolute number of CD73⁺ versus CD73⁻ subsets from tumor-infiltrating CD8⁺ T cells were calculated in B16-SIY-bearing mice treated with control IgG or anti-4-1BB. e Percentage of T_EM (CD62L^-CD44⁺), or T_CM (CD62L⁺CD44⁺) in CD73⁺ versus CD73^- subsets from B16-SIY-infiltrating CD8⁺ T cells treated with anti-4-1BB. Purified CD8⁺ T cells from naïve mice were treated with control IgG or anti-4-1BB in the presence of anti-CD3/anti-CD28 in vitro. The expression levels of CD73 or Ki67 in CD8⁺ T cells were evaluated by flow cytometry. f The representative dot plots are depicted. g The absolute number of CD73⁺ versus CD73^- subsets from cultured CD8⁺ T cells was also counted. h The representative dot plots showed the percentage of IFN-γ⁺ cells in CD73⁺ versus CD73^- subsets from CD8⁺ T cells. i The fold changes of IFN-γ⁺ cells in CD73⁺ versus CD73^- subsets were calculated. *p < 0.05, **p < 0.01, ***p < 0.001. Unpaired and paired Student’s two-tailed t test were used. Data (mean ± SEM) are representative of 2 independent experiments with 5 independently analyzed mice/group