Microenvironment and Immunology Distinctive Features of the Differentiated Phenotype and Infiltration of Tumor-Reactive Lymphocytes in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (RCC) is considered an immunogenic tumor, but it has been difficult to identify tumor-infiltrating lymphocytes (TIL) that show in vitro tumor recognition. We compared the characteristics of fresh RCC TIL to peripheral blood lymphocytes (PBL) or melanoma TIL. Our results showed that RCC TIL contained fewer CD27þT cells, and fewer na€ ve and centralmemory (CM) T cells, butmore effectormemory (EM) T cells than melanoma TIL or renal PBL. We hypothesized that factors in the RCC microenvironment were skewing TIL phenotype toward EM. One possibility was the expression of CD70 on nearly all humanRCCs, but not melanomas. Differentiation of na€ ve T cells to EM cells only occurred from CD70 costimulation in concert with T-cell receptor (TCR) stimulation (signal one), suggesting that EM TIL responding to CD70 would be enriched for T cells reactive with local antigens, including those associated with RCC. Clonotypic analysis of TCRs in fresh RCCs showed that EM T cells were more clonally expanded than CM or na€ ve T cells, and the clonal expansion occurred at the tumor site as oligoclonal TCRs were distinct from PBL TCRs from the same patient. In addition, we found that 2 TCRs from the highly represented EM TIL clones, when reexpressed in fresh PBL, recognized an MHC-class II or MHC-class I–restricted antigens shared by multiple RCC lines. Our results suggest that RCCreactive TIL do exist in situ, but may be difficult to recover and study because of proliferative exhaustion, driven by tumor-expressed CD70. Cancer Res; 72(23); 1–11. 2012 AACR.