Figure 6. Blockade of PD-1 pathway in T cells from old mice did not improve T cell proliferation or survival, but improved cytokine production by PD-1⁻ CD4⁺ and CD8⁺ T cells.

Splenic cells from young (3-month old; N=6) and aged (12-month old; N=6) mice were stained with CFSE and stimulated for 5 days with or without 5 μg/ml of anti-CD3 alone or with 10 μg/ml of antibody blocking PD-1/PD-Ls pathway. The proliferation of CD4⁺ and CD8⁺ T cells in young (bottom) and aged (top) mice was analyzed by flow cytometry and the percentage of cells which divided at least once is summarized (A). The production of IFN-γ, IL-13 and IL-10 was analyzed by ELISA (B). The percentage of 7-AAD⁺ T cells in PD-1⁺CD4⁺ or CD8⁺ and PD-1⁻CD4⁺ or CD8⁺ was analyzed by flow cytometry (C).