Mechanistic interaction of CD47 with NK cell SIRPα. (A–E) B2M ^{− / −} CIITA ^{− / −} CD47 tg hiECs engaged with primary NK cells (A) or NK cells from a cell line (B–E) using in vitro impedance assays in the presence or absence of a specific blocking antibody against CD47 (clone B6.H12) or a blocking peptide against SIRPα. Graphs show mean ± SD and three independent replicates per group and time point; three different E:T ratios are shown.