Heterogeneous expansion of CD4+ tumor-infiltrating T-lymphocytes in clear cell renal cell carcinomas.

Aberrant expression of tumor-associated antigens (TAAs) mediates the effective mounting of adaptive immunity in human solid tumors. The foundations of this tumor-host interaction strongly depend on specific recognition via TAA-cognate-receptors in T-cell repertoires. Previous studies focused on the phenotypic and functional properties of CD4+/CD8+ tumor-infiltrating T-lymphocytes (TILs), but the detailed composition of T-cell repertoires of these fundamental subsets remains largely unknown. This study recruited 10 clear cell renal cell carcinoma (ccRCC) patients and obtained samples from various tissues, including tumors, adjacent healthy renal tissue and peripheral blood. We utilized deep sequencing of T-cell receptor beta chains (TCRB), which serve as a unique identifier for each T clonotype, to characterize the CD4+/CD8+ TIL repertoire in ccRCC patients, assess the diversity and clonality of infiltrated T-cells in distinct tissues from patients and depict the clonal expansion events that occur in anti-tumor immune responses. We found that the CD4+ TIL repertoire exhibited signatures of heterogeneous T-cell expansion, which were characterized by divergent TRBV/J usage and an enrichment of expanded dominant clones. Taken together, our findings provide additional evidence of CD4+ T-cell-mediated anti-tumor immunity. The identification of the underlying molecular mechanisms of this process may provide novel avenues for targeted immunotherapeutic interventions.