CD20-specific effector activity of transduced T cells in vitro.

<p>(<b>A</b>) Transduced T cells exhibit CD20-specific cytolytic activity in vitro. iC9-CD20CAR-Δ19 T cells transduced with CD20-CAR (CD20-CAR T), or non-transduced (mock) T cells were co-cultured with EL4, Daudi, and Granta in various effector to target (E:T) ratios. Mean percent killing (± SD of triplicate culture) was determined by 4-hour standard ⁵¹C release assay. (<b>B</b>) Anti-tumor effect of the transduced T cells. Mock or iC9-CD20CAR-Δ19 transduced T cells were co-cultured with CD20⁺ Ramos cells in various Effector to Target ratios (E:T) for 48 hours. Cells were then stained with antibodies recognizing CD22 and CD3. Flow cytometric analysis was used to determine the presence of Ramos cells (CD22⁺CD3⁻) and T cells (CD22⁻CD3⁺). Similar results were obtained with three independent experiments. (<b>C</b>) Cytokine production. Expanded T cells secreted IL2, IFN-γ and TNF-α after co-culture with CD20-expressing Ramos target cells for 48 hours (mean ± SD of triplicate samples). There were negligible levels of cytokine production when the expanded T cells were cultured alone with no target cells. Results are representative of three independent experiments.