Fig. 6. Stem-like CD8 T cells that have received cycle 1 PD-1 therapy can robustly proliferate in response to viral challenge.

(A) Stem-like (PD-1⁺Tim-3⁻CD73⁺) and Tim-3⁺ (PD-1⁺Tim-3⁺CD73⁻) CD8 T cells were each sorted from isotype or cycle 1 αPD-1-treated CD45.2⁺ donor mice. These subsets were transferred into naïve CD45.1⁺ recipients that were challenged with LCMV Clone 13 (2 × 10⁶ pfu, i.v.) the next day. Donor CD8 T cell responses were analyzed on day 14 post-challenge. (B) Expansion of donor cells among PBMC at day 14 post-challenge. Dotted line indicates the limit of detection based on 5% estimated take of donor cells within the recipient. (C) Frequency of donor (CD45.2⁺) and recipient (CD45.1⁺) CD8 T cells in the spleen. Treatment of the donor cells prior to transfer is shown above each plot. Frequency (D-F) or absolute number (G-I) of donor CD8 T cells within the spleen, liver, or lung. (J) Phenotype of donor CD8 T cells based on Tim-3 and TCF-1 expression. Colored arrows indicate the direction of differentiation. Two independent transfer experiments were performed, each with n=2-4 mice per group. In all plots, individual data points represent individual mice; bars represent mean ± SEM. Two-way Statistical significance was determined by ANOVA with Sidak’s test for multiple comparisons (B) or one-way ANOVA with Tukey’s test for multiple comparisons (D-I); *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****; P ≤ 0.0001; ns, non-significant.