Prostate‐specific antigen‐derived epitopes capable of inducing cellular and humoral responses in HLA‐A24+ prostate cancer patients

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Abstract
BACKGROUND We tried to identify prostate-specific antigen (PSA)-derived epitopes immunogenic in HLA-A24+ prostate cancer patients. METHODS Peripheral blood mononuclear cells (PBMCs) were in vitro stimulated with each of four different PSA peptides carrying the HLA-A24 binding motif, and their HLA-A24-restricted anti-tumor responses were examined using a parental HLA-A24-negative prostate cancer cell line (PC93) and its HLA-A24-expressing transfectant line (PC93-A24). Serum levels of immunoglobulin G (IgG) against PSA peptides were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS PBMCs, which were in vitro stimulated with either the PSA152–160 or PSA248–257 peptide, showed higher levels of IFN-γ production and cytotoxicity against the PC93-A24 than against the PC93. IgG against the PSA248–257 peptide was detected in half of the prostate cancer patients tested. CONCLUSIONS The PSA152–160 and PSA248–257 peptides could be appropriate target molecules in use for specific immunotherapy of HLA-A24+ prostate cancer patients. Prostate 57: 152–159, 2003.