Functional reactivity of intermediate-avidity PRAME-VLD–specific T-cell clones against targets endogenously overexpressing PRAME. The 7 PRAME-VLD–specific T-cell clones of intermediate avidity were tested against EBV-LCL transduced with the empty vector (mock) or with the vector encoding the full protein sequence of PRAME, MM cell line U266, AML cell line THP-1, and the chronic myeloid leukemia cell line K562 wild-type or transduced with HLA-A*02:01, 6 primary AML samples, and 2 primary ALL samples (2 representative primary samples with relatively high WT1 expression are shown). An allo-HLA-A*02:01–reactive T-cell clone was included as positive control for HLA-A*02:01 expression and costimulatory capacity of the target cells. T2 or K562 transduced with HLA-A*02:01 and loaded with peptide were included as positive control for functional reactivity of clones. The HLA-A*02:01 and TAA expression of the targets is indicated as negative (–) or positive (+) below the x-axis. (A) IFN-γ production was measured by using an ELISA after overnight stimulation (R:S ratio, 1:6). Representative example of 3 experiments is shown. (B) Cytotoxic capacity was measured in a standard ⁵¹chromium-release assay (E:T ratio, 10:1). Mean of triplicates with standard deviation is depicted.