Antigen-specific T Cell precursor frequency influences the proliferation of stem-like T Cells in tumor-draining lymph nodes and anti-tumor immune responses.

Background: While immune checkpoint blockade has transformed the landscape of cancer therapy, variability in patient responses constrains its therapeutic potential. Tumor-specific stem-like T (TSL) cells sustain durable immunity through self-renewal and differentiation. However, upstream regulators of TSL cells generation remain elusive, and direct evidence is still lacking regarding whether naïve tumor-specific T cell precursor frequency influences TSL cells pool establishment and immunotherapy response. This study aims to clarify the direct causal relationship between this precursor frequency and the number of TSL cells in tumor-draining lymph nodes, as well as the efficacy of anti-PD-L1 therapy. Methods: We initially constructed a novel bone marrow cell chimeric model. Specifically, recipient mice of the wild-type C57BL/6 strain were subjected to lethal irradiation, after which they received intravenous adoptive transfer of a cell suspension (5 × 10 Results: The results of the bone marrow chimeric model demonstrated that: different precursor frequencies of antigen-specific T cell s significantly affect the abundance of stem-like T cells in the TDLNs of tumor-bearing mice. A higher precursor frequency of antigen-specific T cell could significantly suppress tumor growth and prolong the survival time of the mice. In the group with a higher precursor frequency, anti-PD-1 therapy effectively inhibited tumor growth, leading to long-term survival of the mice. Conclusion: Our study provides the first direct