Capability of SART3(109-118) peptide to induce cytotoxic T lymphocytes from prostate cancer patients with HLA class I-A11, -A31 and -A33 alleles.

We previously reported the SART3 gene to be a tumor-rejection antigen gene encoding a peptide at positions 109-118 (SART3(109-118)) with the ability to induce HLA-A24-restricted cytotoxic T lymphocytes. In this study, we investigated both humoral and cellular responses to this peptide in cancer patients with alleles other than HLA-A24 to explore the possibility of using this peptide as a cancer vaccine for these patients. IgG reactive to SART3(109-118) peptide was identified in sera of the vast majority of non-cancer subjects (n=50) and all cancer patients (n=50) tested without apparent HLA-A association. Levels of anti-SART3(109-118) peptide antibody in cancer patients were significantly higher than those of non-cancer subjects, but no difference was found between HLA-A24+A2- and HLA-A24-A2+ cancer patients. This peptide induced cancer cell-reactive cytotoxic T lymphocytes from peripheral blood mononuclear cells of both healthy donors and prostate cancer patients with HLA-A11, HLA-A31 and HLA-A33 alleles, but not with HLA-A2. These results suggest that this peptide can be applicable as a cancer vaccine not only for HLA-A24+, but also for HLA-A11+, HLA-A31+ and HLA-A33+ prostate cancer patients.