Transduced chA21-28z chimeric antigen receptor T cells secrete interferon γ and interleukin 2 in response to tumor cells. (A) Breast and ovarian cancer cell lines were stained with a monoclonal antibody specific for the HER2 antigen and analyzed by flow cytometry. HER2 expression was evident in the majority of cell lines after staining with an anti-HER2 monoclonal antibody (thick lines) compared to staining with control antibody (dashed lines). MDA-MB-468 and TC-1 were used as negative controls. (B) and (C) Antigen-specific interferon γ (IFN-γ) and interleukin 2 (IL-2) secretion by chA21-28z chimeric antigen receptor (CAR)–transduced T cells, but not nontransduced (NT) T cells, following overnight incubation with HER2+ cancer cell lines. Mean IFN-γ and IL-2 concentrations ± SEM (in pg/ml) from triplicate cultures are shown.