Figure 4.

CXCR6 deficiency prevents CD8⁺ T-cell–TAMC interactions and increases CD8⁺ T-cell activity and survival. (A) CD8⁺ T cells from control or CXCR6 KO mice were isolated, activated in vitro, labeled with a fluorescent-tracker dye, and then cocultured at a 1:1 ratio with tumor-associated myeloid cells (TAMCs). After 90 minutes, the slides were washed and analyzed via epifluorescence microscopy. The data shown in (A, B) are from 4 replicates, and two images per slide were analyzed. A paired Student’s t test was performed, and p<0.001 = **. (C) Tumors were isolated on the 19th day after the adoptive transfer experiment, and the data in (D) show the CD45.1 and CD45.2 ratios in tumors without and after transfer, as analyzed by flow cytometry. In (G–I), flow cytometry analysis of the coexpression of CD44 with CD62L, PD1, GzmB, INF-γ, and TNF-α in CD45.1⁺ or CD45.2⁺ CD8⁺ T cells is shown. The CXCR6 knockout group treated with PD-1 blockade achieved 50% survival. (J). Median survival: control = 24 days, control + PD-1 blockade = 36.5 days, CXCR6 KO = 30 days, CXCR6 KO + PD-1 blockade = 65 days; p= 0.002 = ** Log-rank test). (K) Surviving mice were rechallenged via tumor implantation. Tumor rejection in both groups represented the generation of immunologic memory against tumor antigens. Significance in (D–I) was analyzed by paired Student’s t test; *p<=0.05, **p<=0.01, ***p<=0.001.