Prediction and peptide binding assay of HLA-A2.1-restricted CTL epitope from heparanase

Objective To predict and identify the HLA-A2.1-restricted cytotoxic T lymphocyte (CTL) epitopes in heparanase (Hpa), a new tumor associated antigen. Methods Supermotif and quantitative motif methods were used to predict the CTL epitopes. Then the prediction was evaluated by T2 binding test. Results Five predicted highest score candidate epitopes were Hpa(525-533), Hpa(353-361), Hpa(277-285), Hpa(400-408) and Hpa(405-413). The results of molecular simulations showed that the 5 candidate peptides could effectively bind with HLA-A2.1. Further peptide binding assay demonstrated that these 5 candidate peptides bound to HLA-A2.1 with high affinity. Hpa (525-533), Hpa(277-285) and Hpa(405- 413) induced heparanase-specific immune responses against KATO-Ⅲ gastric tumor cells, which was both positive for heparanase and HLA-A2. Conclusion Hpa(525-533), Hpa(277-285) and Hpa(405-413) might be the HLA-A2.1- restricted epitope of Hpa.