Redirected antibody-dependent cytotoxicity assay against P815. (A) CD3⁻CD7⁺CD56⁺ NK cells were stimulated with IL-2 for 72 h, and SIRPα expression was assessed by flow cytometry (representative histogram of two independent experiments). (B and C) CD3⁻CD7⁺CD56⁺ NK cells were added to Fluc⁺ target P815 cells (green bar), or NK cells were added together with activating antibodies against CD16 (B) or NKG2D (C). The effect of anti-SIRPα to offset the activating signals was assessed. An antibody against CD56 served as control (mean ± SD, three independent experiments per group, ANOVA with Bonferroni’s post hoc test).