Human dendritic cells transfected with renal tumor RNA stimulate polyclonal T-cell responses against antigens expressed by primary and metastatic tumors.
Although renal cell carcinoma has been shown to respond to immunotherapy, renal cell carcinoma-specific rejection antigens and their corresponding CTL epitopes have rarely been described. The use of dendritic cells (DCs) transfected with mRNA isolated from tumor cells may allow specific immunotherapy even in cancers for which potent rejection antigens have not been identified. Here we show that DCs transfected with RNA isolated from renal cancer tissue are remarkably effective in stimulating tumor-specific T-cell response in vitro but do not cross-react with normal tissue antigens including antigens expressed by renal parenchyma. In contrast, the tumor-specific CTLs lysed allogeneic tumor but not allogeneic normal tissue targets, suggesting the presence of shared albeit unidentified antigens among renal carcinomas. CTL responses against telomerase reverse transcriptase (TERT) accounted in part for the reactivities against allogeneic tumors because renal tumor RNA-transfected DCs stimulated polyclonal CTL responses, which encompassed as a subcomponent a response against TERT. Nonetheless, the tumor-specific CTLs were consistently superior to the CTLs stimulated with TERT RNA-transfected DCs in recognizing and lysing tumor targets, suggesting that tumor-specific CTLs represent a polyclonal response providing more effective antitumor activity than T-cell responses directed against a single antigen in the form of TERT. Tumor RNA-transfected DCs were capable of stimulating T-cell reactivities not only against the primary tumor but also against metastatic tumors, although discrete differences in the antigenic repertoire expressed by these tissues were apparent. Thus, total tumor RNA-transfected DCs may represent a broadly applicable vaccine strategy to induce polyclonal and potentially therapeutic T-cell responses in renal cancer patients.