Figure 5
frBsAb-mediated activation of T cells by antigen-bound bispecific antibody (frBsAb) facilitates specific target cell killing. A. The CD20 cell surface expression (open histograms) on cancer cell lines was detected with biotinylated anti-CD20 mAb rituximab and evaluated by flow cytometry. Numbers represent mean fluorescence intensity (MFI). B. Antigen-specific tumor killing by CD20frBsAb redirected BsAb-IR T-cells. Primary human T-cells transduced to express BsAb-IR-28z or GFP (control) were co-cultured with Cr51-labeled Ramos, and Daudi tumor cells, pretargeted with indicated frBsAb for 4 hrs at the indicated effector to target ratio. Percent specific target cell lysis was calculated as (experimental - spontaneous release) ÷ (maximal - spontaneous release) × 100. Data represent the means ± SD for 3 different experiments. * P = 0.0082 for BsAb-IR-28z T-cells/CD20frBsAB versus IgGfrBsAb redirected BsAb-IRs against Ramos cells. ** P = 0.0166 for BsAb-IR-28z T-cells/CD20frBsAB versus IgGfrBsAb redirected BsAb-IRs against Daudi cells.