Figure 4.

Pretreatment with platinum compounds increased both peripheral blood, draining lymph node and intratumoral PD-1-positive CD8 T cells. A. The MC38 tumor model was established and treated with 10 mg/kg Oxa on day 6. Then, the tissues were harvested, and blood was drawn on the indicated day. B. Tumor-infiltrating lymphocytes (TILs) were isolated on days 6 (d0), 9 (d3), and 13 (d7). The frequencies of CD4 T cells, CD8 T cells and PD-1-positive T cells in tumor sites were analyzed by flow cytometry (n = 4). C. The frequencies of CD4 and CD8 T cells (gated on lymphocytes) in the draining lymph node (DLN), spleen (SP), and peripheral blood (PB) and within the TIL population were analyzed in MC38 tumor-bearing mice on day 3 after Oxa treatment (n = 4). D. The frequencies of CD4⁺PD-1⁺ and CD8⁺PD-1⁺ T cells (gated on lymphocytes) in TILs, DLN, SP and PB of Oxa-treated and untreated mice. E. The frequencies of CD45^-PD-L1⁺ and CD45⁺PD-L1⁺ cells (gated on living cells) in Oxa-treated and untreated tumors. F. Oxa-treated and untreated tumor tissues were harvested for TUNEL staining (left graph) and immunohistochemical staining with an anti-CD8 antibody (right graph) (n = 3). Scale bar, 200, 50 μm. Con: untreated mice; Oxa: Oxa-treated mice; Nor: normal mice. Representative data are shown from at least two experiments conducted using 4 mice per group. Error bars, SEM. *, P < 0.05; **, P < 0.01; ****, P < 0.0001 compared with untreated mice.