Expression of the SART3 tumor-rejection antigen in brain tumors and induction of cytotoxic T lymphocytes by its peptides.

The authors recently reported on the SART3 tumor-rejection antigen, which possesses epitopes that can induce cytotoxic T lymphocytes (CTLs) in patients with epithelial cancer. To explore a new modality for treatment of patients with brain tumors, this study investigated the expression of the SART3 antigen in patients with brain tumors and the ability of SART3 peptides to induce CTLs from peripheral blood mononuclear cells (PBMCs) of these patients. The SART3 antigen was detected in the cytoplasmic fraction of all 18 glioma cell lines examined and in the majority (31 of 34; 91%) of brain tumor tissues irrespective of their histologies. It was also expressed in the nuclear fraction of all 18 glioma cell lines and in the majority (26 of 34; 76%) of brain tumor tissues. In contrast, the SART3 was not expressed in nontumorous brain tissues. Cytotoxic T lymphocytes were induced in patients with glioma by stimulation with two epitope peptides of SART3. These CTLs could eliminate glioma cells in a HLA-A24-restricted manner. Therefore, the SART3 peptides may be appropriate molecules for use in peptide-based specific immunotherapy of HLA-A24+ patients with brain tumors.