CXCL13-CXCR5 Signaling in CD8⁺ T Cell Recruitment and Lymphoid Immune Organization in Clear Cell Renal Cell Carcinoma

ABSTRACT Clear cell renal cell carcinoma (ccRCC) exhibits heterogeneity in immune infiltration and clinical outcomes, but the mechanisms governing recruitment and organization of tumor-reactive CD8⁺ T cells remain incompletely defined. We investigated the role of the CXCL13–CXCR5 axis in shaping CD8⁺ T cell recruitment, differentiation, and immune organization in high-risk, non-metastatic ccRCC. Human tumor, plasma, and matched adjacent kidney specimens were analyzed using ELISA, quantitative PCR, migration assays, multiplex immunofluorescence, single-cell RNA sequencing, spatial transcriptomics, and a syngeneic mouse model. CXCL13 was among the most upregulated chemokines in ccRCC relative to matched normal kidney and was embedded within a CD8⁺ T cell-associated inflammatory transcriptional program. In transwell and microphysiological system (MPS) assays, CXCL13 promoted CD8⁺ T cell migration, enriched CXCR5⁺ cells among migrating CD8⁺ T cells and showed reduced migration after CXCL13 or CXCR5 blockade. Single-cell analyses identified CXCR5 expression within stem-like CD8⁺ T cell states associated with TCF7 and IL7R, whereas CXCL13 associated with later cytotoxic/exhausted states along a continuous differentiation landscape. Spatial transcriptomics demonstrated that stem-like CD8⁺ T cells localized within structured lymphoid aggregates enriched for B cells, coordinated CXCL13/CXCR5 expression, and signaling programs. In vivo, tumor-derived CXCL13 suppressed tumor growth, increased intratumoral CD8⁺ T cell infiltration, and enriched CXCR5⁺TCF1⁺CD8⁺ stem-like T cells. In human tumors, higher CXCL13 expression correlated with increased CXCR5⁺CD8⁺ T cell infiltration and improved recurrence-free survival. These findings identify CXCL13 as a regulator of immune recruitment and niche organization and support the CXCL13–CXCR5 axis as a biomarker and possible therapeutic target in ccRCC. Competing Interest Statement Pavlos Msaouel has received honoraria for service on a Scientific Advisory Board for Mirati Therapeutics, Bristol Myers Squibb, and Exelixis; consulting for Axiom Healthcare Strategies; non-branded educational programs supported by DAVA Oncology, Exelixis and Pfizer; and research funding for clinical trials from Regeneron Pharmaceuticals, Summit Therapeutics, Merck, Takeda, Bristol Myers Squibb, Mirati Therapeutics, Gateway for Cancer Research, and the University of Texas MD Anderson Cancer Center. David J. Beebe holds equity in Bellbrook Labs LLC, Salus Discovery LLC, Lynx Biosciences Inc., Stacks to the Future LLC, Flambeau Diagnostics LLC, Navitro Biosciences LLC, Eolas Diagnostics, Inc., and Onexio Biosystems LLC. The remaining authors have no relevant financial interests to disclose.