HMAs can sensitize AML cells to NK cell–mediated killing. (A) Experimental design: THP-1 and KG1a cells were cultured in the presence of AZA or DAC at the indicated concentrations. Two days later, cells were harvested and used as targets for HSPC-NK cells with or without drug washout. The same numbers of viable AML cells were plated for each condition. The numbers of viable AML cells were determined by FCM after 1 to 3 days of coculture and were used for calculation of AML cell survival, NK-specific killing for each independent treatment, and overall effect of NK cells, as indicated. (B-D) Effect of HMAs pretreatment and HSPC-NK cells on THP-1 cells at day+1. Data were obtained after drug washout and are depicted as the mean ± standard error of the mean (SEM) of 3 independent experiments (1-way ANOVA; **P < .01). (E-F) Effect of HMA pretreatment and HSPC-NK cells on KG1a cells. Data were obtained without drug washout and are depicted as the mean ± SEM of 3 independent experiments. Data shown in panel E were obtained at day+1 and in panel F are depicted the relative numbers of viable AML cells quantified from day 0 to day+3. “No NK” is indicated by open bars; “+NK” is indicated by solid bars (B,E). A, AZA; D, DAC.