A2-SL9–specific TCRs are able to redirect human CD4 Teff responses. (A) RNA encoding each of the A2-SL9–specific TCRs was transfected into resting primary human CD4 T cells and, after overnight culture, the ability to bind SL9 tetramer was measured by flow cytometry. (B) K562 cells were transduced with lentiviral vectors expressing HLA-A2, dsRED-SL9 minigene encoding, and full-length NYESO-1 linked to green fluorescent protein (GFP) via an internal ribosome entry site (IRES). (C) Cells described in panel A were mixed at a 1:1 ratio with aAPCs described in panel B. IFNγ and IL-2 production were measured by intracellular cytokine staining after 5 hours. As a positive control, T cells were also stimulated with 3 μg/mL of phorbol 12-myristate 13-acetate and 1 μg/mL of ionomycin (P/I). Data presented is representative of at least 3 independent experiments.