Overexpression of Xcl1 in CD8 ⁺ T cells enhances antitumor immunity. (A) Frequency plots of indicated endogenous cell type following B16 inoculation (left) and RNA expression of Xcl1 in Id3^hi and Id3^lo subsets from Milner et al. (2020). n = 4 per time point. (B) Experimental schematic where congenically distinct P14 T cells were transduced with empty vector (CD8^EV) or Xcl1 (CD8^Xcl1) encoding retrovirus and transferred into tumor-bearing mice (B16-GP_33–41) (left) and frequency of XCR1⁺ cDC1 in indicated tissue (right), n = 8 (CD8^EV) and n = 12 (CD8^Xcl1). (C) Representative flow cytometry plots of KI67, TCF1, and TIM3 in intratumoral P14 T cells and corresponding quantification, n = 10 (CD8^EV) and n = 13 (CD8^Xcl1). (D) Kaplan-Meier curve of mouse survival in indicated tumor type with log-rank (Mantel-Cox) test. Tumor area was monitored every 2–3 days, n = 5 (no T cells), n = 10 (CD8^EV), and n = 13 (CD8^Xcl1). (E) scRNA-seq clusters (top) derived from pan-cancer atlas (Zheng et al., 2021), subset labels shown. XCL1 and XCL2 expression (bottom) within cluster UMAP. (F) TCGA melanoma (SKCM) patient survival curve (left) based on XCL1/XCL2 expression and correlation with functional cDC1 signature (Meiser et al., 2023). Data representative (B, C, G, and H) or pooled (D–F) from at least two independent studies. P values shown. Two-way ANOVA (B), unpaired t test (C), log-rank Mantel-Cox test (D).