Their molecular weights were confirmed by electrospray ionization-mass spectrometry (ESI-MS). The IAb-restricted HBV core antigen-derived T helper epitope (sequence 128–140: TPPAYRPPNAPIL) was used in the in vivo assay. Peptides were dissolved in DMSO at a concentration of 100 mm and stored at −20 °C.

Blood samples and cell line.  Peripheral blood samples were obtained from six HLA-A*02+ healthy donors. The sample collection was approved by the ethics committee of Zhengzhou University. The human Olaparib TAP-deficient T2 cell line (HLA-A*0201-positive) was a generous gift from professor Yu-zhang Wu (Third Military Medical University, China). The human oesophageal carcinoma cell line EC-9706 (HLA-A2-positive, COX-2-positive [15]) was maintained in our laboratory, human oesophageal carcinoma cell line KYSE-140 (HLA-A2-positive, COX-2-negative) was a gift from professor Qiao-zhen Kang (Zhengzhou University, China), human colon cancer cell line HT-29 (HLA-A2-negative, COX-2-positive) was purchased from American Type Culture Collection (ATCC, selleck chemical Rockville, MD, USA). T2 cells and cancer cells were cultured in RPMI 1640 medium (Invitrogen, Grand island, NY, USA) supplemented with 100 units/ml penicillin, 100 units/ml streptomycin, 2 mm L-glutamine, and 10% foetal bovine serum (FBS, Hyclone).

All cells mentioned above were kept at 37 °C in a humidified for atmosphere containing 5% CO2. Mice.  HLA-A2.1/Kb transgenic mice, 8–12 weeks old, which express a chimeric heavy chain of the MHC-I molecule (α1 and α2 fragments of human HLA-A*0201, and transmembrane and intracytoplasmic domains of mouse H-2Kb), were kindly provided by professor Xue-tao Cao (Second Military Medical University, China). Mice were bred and maintained in a specific pathogen-free (SPF) facility. Peptide-binding assay.  To determine whether the synthetic peptides could bind to HLA-A*0201 molecule, peptide-induced

HLA-A*0201 upregulation on T2 cells was examined according to a protocol described previously [21, 22]. Briefly, T2 cells (1 × 106 cells/ml) were incubated with various concentrations of the candidate peptides and 3 μg/ml human β2-microglobulin (β2-M, Merck, Germany) in serum-free RPMI 1640 medium for 18 h at 37 °C in a 5% CO2 atmosphere. Then, cells were washed twice and incubated with the anti-HLA-A2 mAb, BB7.2 (Santa Cruz, USA), followed by treatment with FITC-labelled goat IgG anti-mouse immunoglobulin (Bioss, China). Cells were harvested and analysed by flow cytometry (FACSCalibur, Becton Dickinson, USA). The fluorescence index (FI) was calculated as follows: FI = [(mean fluorescence intensity (MFI) of the peptide – background) − (MFI of the PBS control group – background)]/[MFI of the PBS control group − background], the MFI value of the cells which were not incubated with peptides or antibodies was used as background.