Figure 5.

Induction of Leukemia Antigen-Specific CTLs By CD40L^high CD4⁺ iPS-T Cells

(A) Proliferative response of CD8⁺ T cells. Indicated iPS-T cells (5 × 10³) and DCs (1 × 10⁴) ± b3a2 peptide (5 μM) were initially co-cultured for 5 hr to mature the DCs, after which DCs and iPS-T cells were irradiated and cultured with autologous CD8⁺ T cells (5 × 10⁴) in the presence of WT1 peptide (5 μM). The proliferative response (day 7) was measured as the amount of [³H]thymidine incorporated. Data shown are the means ± SD of triplicate cultures and are representative of two independent experiments.

(B) Left panels: frequency of WT1/HLA-A24 tetramer-positive CD8⁺ T cells primed by CD40L^high CD4⁺ iPS-T cell-conditioned DCs. CD40L^high CD4⁺ iPS-T cells (5 × 10³) and DCs (1 × 10⁴) prepulsed with b3a2 peptide (5 μM) were initially co-cultured for 5 hr to mature the DCs, after which DCs and CD4⁺ iPS-T cells were irradiated and cultured with autologous CD8⁺ T cells (5 × 10⁴) in the presence of WT1 peptide (5 μM). Tetramer staining at day 10 after stimulation is shown. Center panel: frequency of WT1/HLA-A24 tetramer-positive CD8⁺ T cells after a third stimulation with WT1 peptide. Representative flow cytometry profiles of two independent experiments. HIV-env/HLA-A24 tetramer was used as a control. Right panel: cytotoxic activities of expanded WT1-specific CD8⁺ T cells against K562-A24 loaded with vehicle or WT1 peptide. Cytotoxicity was measured by ⁵¹Cr-release assay for 4 hr at the indicated E:T ratios. Data are representative of two independent triplicate experiments.