Two Novel Squamous Cell Carcinoma Antigen-Derived Hla-A*0201-Binding Peptides Induce In Vitro And In Vivo Cd8(+) Cytotoxic T Lymphocyte Responses

Squamous cell carcinoma antigen (SCCA) is over-expressed in many squamous cell cancers and SCCA-derived peptide-specific CD8(+) cytotoxic T lymphocytes can display cytotoxicity against tumor cells. In the present study, we screened the SCCA amino acid sequence for potential HLA-A*0201-binding CD8(+) T-cell epitopes using two predictive computational algorithms. Seven epitope candidates were selected of which SCCA(246-254)(LLPNEIDGL), SCCA(223-231)(SLEDVQAKV), SCCA(328-336)(VLHKAFVEV) and SCCA(324-332)(VLSGVLHKA) significantly stabilized HLA-A*0201 molecules on T2 cells. Both SCCA(328-336) and SCCA(324-332) induced CD8(+) IFN-gamma(+) T-cell responses in HLA-A*0201-positive peripheral blood mononuclear cells as assessed by intracellular cytokine staining. Consistent with this, immunization with either SCCA(328-336) or SCCA(324-332) effectively elicited CD8(+) IFN-gamma(+) T cells in HLA-A*0201 transgenic mice as visualized by IFN-gamma ELISPOT assay and intracellular cytokine staining. Furthermore, CD8(+) T cells induced in vitro or in vivo by SCCA(328-336) or SCCA(324-332) demonstrated in vitro cytotoxicity against peptide-pulsed T2 cells and splenocytes, respectively. These novel SCCA-derived CD8(+) T-cell epitopes described, herein, may be potentially important components for diagnostic reagents and immunotherapeutic vaccines for the treatment of squamous cell carcinomas.