Antileukemic reactivity of HA-2 TCR-modified T-cell clones. HA-2 TCR-modified T-cell clones were tested in a (A) liquid hematopoietic progenitor cell inhibition assay (PIA) and in a (B) cytotoxicity assay against HLA-A2-positive HA-2-positive CML cells (CML-T), HLA-A2-positive HA-2-negative CML cells (CML-Z), and HLA-A2-negative HA-2-positive CML cells (CML-B). As positive controls, the original HA-2-specific T-cell clone HA2.27 and the allo-HLA-A2-specific T-cell clone MBM13 were used. Between parentheses the MFI of HA-2/HLA-A2 tetramer staining is indicated. In the cytotoxicity assay HLA-A2-positive HA-2-positive EBV-LCLs (EBV-RZ) and HLA-A2-positive HA-2-negative EBV-LCLs (EBV-Z) were included. The effector T cells were tested in the PIA at an E/T ratio of 1:1 and in the cytotoxicity assay at an E/T ratio of 7:1. The cytotoxicity assay was performed for 18 hours.