EWS/FLI-l peptide-pulsed dendritic cells induces the antitumor immunity in a murine Ewing's sarcoma cell model

An increasing number of T-cell epitopes derived from various tumor-associated antigens have been reported, and they proved to play significant roles for tumor rejection both in vivo and in vitro. Over 85% of Ewing's sarcoma family of tumors (ESFTs) express tumor-specific chimeric protein EWS/FLI-1, making it an attractive target for therapeutic cytotoxic T-lymphocyte responses. Here, we identified a novel peptide epitope derived from the EWS/FLI-1 protein and demonstrated that effectors induced by the peptide could specifically secrete IFN-γ and lyse the tumor cell line of EWS/FLI-1-positive and HLA-matched cells. In addition, mice treated with dendritic cells pulsed with the EWS/FLI-1 epitope were able to reject a lethal tumor inoculation of the Ewing's sarcoma A673 cells. Therefore, these data provide evidence for the use of the EWS/FLI-l peptide epitope in T cell-based immunotherapeutic concepts against Ewing's sarcoma cell in vitro and in vivo.