Figure 2. ATR redirect T cells to CD19⁺ tumor cells antigen-specific and variation of effector cell:target cell signal ratio increases ATR function.

Redirected killing in CD19⁺ tumor cells (Raji) by ATR was determined by ⁵¹Cr release assay. A. Antigen-specific engagement of 2C T cells with cognate ATR (^SIY−K^b-Ig/CD19) and non-cognate ATR (^OVA−K^b-Ig/CD19) was analyzed. B. 2C T cells mediated redirected lysis of CD19⁺ tumor cells (Raji) through ATR (1B2/CD19). To control for specific TCR engagement effects on 2C T cells in redirection cultures beads coated with 1B2 and isotype control mAb were used (control). C. Schematic of a 1:10 and a 1:1 ATR. D. Staining control of 1:1 and 1:10 ATR. Effector cells (2C T cells, upper panel) and target cells (Raji tumor cells, lower panel) were stained with ATR at 4°C for 15 minutes, washed and co-stained with anti-IgG1. E. 2C T cells mediated redirected lysis of CD19⁺ tumor cells (Raji) through 1:10 ATR (1B2/CD19). To control for specific TCR engagement effects on 2C T cells in redirection cultures, beads coated with 1x 1B2 and 10x isotype control mAb were used (control). All data displayed represents background subtracted (cells only) specific lysis of tumor cells, derived from triplicates of the same experiment.