Increase of γδ TCR expression by TCR-β knockout does not enhance the targeting of normal cells by engineered T cells. Normal cells were isolated from peripheral blood of 3 healthy donors (PBMC isolation followed by magnetic pullout of CD19⁺ B cells or CD4⁺ T cells) and incubated with 50 μM zoledronate (where indicated). On the following day after isolation, the cells were coincubated with transduced T cells for 16 hours, followed by quantification of secreted (A) TNFα or (B) IFNγ. The concentration of secreted cytokines was normalized by subtracting the values from T cells incubated alone and target normal cell incubated alone. Leukemia cell line THP1 and myeloma cell line U266 were included as positive controls. Representative data from 2 TCR-transduced donors are shown.