Differential regulation of CD8+T cell differentiation states in the tumor immune microenvironment by Batf3 gene deficiency versus cDC1-specific deficiency.

Objective BATF3 and TRIM33 are both critical regulators of cDC1 development. This study comparatively investigates the impact of cDC1 deficiency induced by either global Batf3 knockout (Batf3-/-) or conditional Trim33 knockout in cDC1 (Xcr1CreTrim33f/f) on antitumor immune responses. The aim is to dissect, in the context of Batf3 deficiency, which effects on intratumoral CD8+T cells are specifically mediated by cDC1 deficiency, and which arise from Batf3-dependent alterations in other immune cell populations.Methods Under steady-state conditions, the proportion and number of cDC1 were compared in the lungs and spleens of Trim33f/f（Ctrl）, Batf3-/-，and Xcr1CreTrim33f/f mice. A Lewis lung carcinoma (LLC) tumor model was established to monitor tumor growth and analyze the phenotypes of tumor-infiltrating DC and CD8+T cell. Intratumoral CD8+T cells were sorted for bulk RNA sequencing to characterize transcriptional differences.Results Under steady-state conditions，both Batf3-/-and Xcr1CreTrim33f/f mice exhibited a comparable and significant reduction in cDC1 proportion and number in lung and spleen compared with Ctrl，and compared with Ctrl and Xcr1CreTrim33f/f mice, Batf3-/-mice showed exhibited higher proportion and number of central memory CD8+T cells (CD44+CD62L+) in the lymph nodes. Following lung cancer cell line，LLC implantation，tumor growth was significantly accelerated in both Batf3-/-and Xcr1CreTrim33f/f mice compared with the Ctrl mice，with no statistically significant difference between Batf3-/-and Xcr1CreTrim33f/f groups. However, within intratumoral CD8+T cells, Batf3-/- mice exhibited a reduction in effector CD8+T cells (CD44+), whereas the number of central memory CD8+T cells remains unchanged; however, CD62L expression on these cells was significantly upregulated; in contrast, Xcr1CreTrim33f/f mice showed no significant deviation from Ctrl mice in this regard. Transcriptomic analysis revealed that, compared with Ctrl mice, both Batf3-/- and Xcr1CreTrim33f/f mice shared downregulated differentially expressed genes (DEGs) enriched in functional pathwaysin CD8+T cell , In addition, DEGs uniquely altered in Batf3-/- mice included downregulation of exhaustion-associated genes (e.g., Tox, Havcr2) and upregulation of memory-associated genes (e.g., Sell/Cd62L).Conclusion BATF3 governs antitumor CD8+T cell immunity through a dual mechanism: (1) a cDC1-dependent axis—where cDC1-mediated antigen presentation is essential for CD8+T cell priming and effector differentiation; and (2) a cDC1-independent axis—where BATF3 intrinsically constrains T cell exhaustion and fosters memory-like differentiation within the tumor microenvironment.