Cytotoxicity mediated by WT1-siTCR–transduced CTLs against autologous leukemia cells and hematopoietic progenitor cells. (A) Cytotoxic activities of WT1-siTCR–transduced CTLs against autologous leukemia cells and autologous normal hematopoietic progenitor cells were examined by 5-hour ⁵¹Cr-release assays. WT1-siTCR–transduced CTLs were generated from peripheral blood CD8⁺ T cells from a patient with acute lymphoblastic leukemia (ALL) in complete remission, 2 patients with blastic crisis of chronic myelogenous leukemia (CML-BC) in chronic phase after chemotherapy, and cord blood CD8⁺ T cells from 3 donors. Their cytotoxicity against autologous freshly isolated leukemia cells or autologous hCB-CD34⁺ cells was examined by standard ⁵¹Cr-release assays at various E/T ratios. The relative expression levels of WT1 mRNA in target cells are shown. N.D. indicates not detectable. (B) Cytotoxicity mediated by WT1-siTCR–transduced CTLs generated from cord blood CD8⁺ T cells against C1R-A*24:02 cells with or without loaded WT1 peptide, K562-A*24:02 cells, and K562 cells was examined by 5-hour ⁵¹Cr-release assays at various E/T ratios. Each number of effector cells (#1, #2, and #3) corresponds to that of the hCB-CD34⁺ cell sample shown in Figure 4A, respectively.