Figure 1.

 Protocol of the modified CTL response index of the peptide (CRI-p) culture method. On the first day of blood sampling, 5×10⁶ peripheral blood mononuclear cells (PBMCs) in complete medium in triplicate cultures in a six well flat bottomed plate (Nunc, Roskilde, Denmark) with a mixture of the panel of peptides to be tested (each 1 μg/ml), 1 μg/ml recombinant hepatitis B core antigen (rHBcAg)³², and 20 U/ml recombinant human interleukin 2 (rhIL-2) were incubated at 37°C in a humidified 5% CO₂ incubator. On days 3, 5, 7, 9,11, and 13, the culture medium was refreshed with 20 U/ml of rhIL-2. Usually, the total number of cells could proliferate up to 3∼5×10⁷ cells on day 13, and sometimes to 10⁸ cells by day 14. Cells harvested on days 14–15 were used for cell lytic assays and phenotypic study, with surface staining of MHC-A2-peptide tetrameric complexes. CTL, cytotoxic T lymphocyte; TCR, T cell receptor.