Extended Data Fig. 1: Expression of relevant cell surface antigens on an IL-2 promoter luciferase indicator line, as well as Bcl-xL kinetics and annexin V analysis in primary T cells.

(a) Cell surface expression of CD3, CD28, or CD38 respectively on GloResponse™ IL2-luc2P Jurkat Cells (Promega) was determined by flow cytometry as described in Methods in 1 independent experiment. (b) Induction of pro-survival protein Bcl-xL (left) and annexin V (right) after CD38 trispecific Ab, or indicated mutant Ab, treatment of primary CD3+ cells (n = 3 donors). Cells were isolated as described in Methods and analyzed by flow cytometry targeting CD3, Annexin V, and using a fixable viability dye. The data points and error bars were plotted with mean ± SD.