g105-specific CTLs can kill γ-globin-positive JMML cells in an HLA-A2-restricted way. (A) g105 peptide-specific CTLs were generated by repeated stimulations of purified CD8⁺ T cells from A2-positive healthy donors with g105 peptide-pulsed aAPCs. Between stimulations, IL-2 and IL-15 were added to the cultures every 3 days. Radiolabeled T2 cells were pulsed with g105 peptide (▴) or control peptide, TAX (▪), and used for a 4-hour cytotoxicity assay. (B) Intracellular flow cytometric analysis of γ-globin expression in A2-positive patient-derived JMML1 and JMML2 cells, and the human T-cell leukemic cell line Jurkat. Histograms represent isotype (filled curves) and γ-globin-specific staining (open curves). (C) A2-positive γ-globin-positive JMML1 cells (▴) and A2-positive γ-globin-negative JMML2 cells (▪) were subjected to 8-hour cytotoxicity assays. (D) A2-positive γ-globin-positive JMML1 cells were subjected 20-hour cytotoxicity assays in the absence (▴) or presence of anti-A2 mAb (•) or isotype control (▪). A2-positive γ-globin-negative JMML2 cells (×) were also included as a target. (A, C-D) Results are expressed as means ± SD.