Specific IFN-γ production and cytotoxic activity of HM1.24-specific CTL lines against human neoplastic cell lines. Purified CD8⁺ T cells from a healthy donor (HLA-A2⁺, A24^-) were cultured with autologous DCs pulsed with HM1.24-126 or HM1.24-165 peptides, and then CTL lines were established as described in “Patients, materials, and methods.” (A) Specific recognition of target cells by HM1.24 peptide–induced CTL lines. Each CTL (1 × 10⁴ cells) was cultured with target cell lines (1 × 10⁴ cells) for 24 hours and IFN-γ production was measured by ELISPOT assay. (B) Cytotoxic activity of these CTLs against ARH-77 cells. Cytotoxicity (%) was determined by ⁵¹Cr-release assay at different E/T ratios. (C) Cytotoxic activity of these CTLs against several tumor cell lines expressing HM1.24 at different levels. Cytotoxicity (%) was determined by ⁵¹Cr-release assay at an E/T ratio of 20. Values indicate the mean ± SD of triplicate experiments.