Intrinsic STING signaling in target AML cells requires priming by effector T-cell–derived cytokines. (A) HL-60 cell lines of the indicated genotypes were treated with IFN-γ or TNF, and pSTAT1 or phosphorylation of IκBα (pIκBα) was assessed by immunoblotting. (B) Flow cytometric analysis of AMG 330–mediated (5 ng/mL) cytotoxicity against HL-60 cell lines of the indicated genotypes (mean of 2 independent knockout clones) in cocultures with human T cells after 72 hours (E:T, 1:10; n = 3). Specific lysis was calculated relative to the c-BiTE condition. The concentration of added cGAMP in cocultures was 40 μg/mL. (C-D) Levels of IFN-α2a (C) and IFN-γ (D) determined after 72 hours by CBA analysis of the supernatants of cocultures of human T cells and HL-60 cells of the indicated genotype in the presence of c-BiTE or AMG 330 ± cGAMP (n = 3). Means ± SEM are presented. Statistical analysis was performed using the 2-way ANOVA with the Tukey comparison. ns, P > .05; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001. E:T, effector-to-target ratio; ns, not significant; WT, wild-type.