CD34+ primary AML blasts become sensitized to DNT-mediated cytotoxicity after daunorubicin pre-treatment. a & b Primary AML blasts from patients were grouped according to whether the patients had undergone complete remission (chemotherapy-susceptible, n = 8) or were relapse/resistant (chemotherapy-resistant, n = 5). Primary AML blasts were cultured for 24 h in complete media and either a 0.25 μg/mL AraC, or b 0.4 μg/mL DNR, followed by a 2 h incubation with DNTs at an E:T ratio of 2:1. % Specific killing by DNTs after chemotherapy pre-treatment is shown in comparison to the vehicle control as pre-treatment. c & d Averages from Figs. 4a and b were plotted in pairs (each pair represents an individual patient) to compare the overall effect of c) AraC or d) DNR on the susceptibility of primary AML samples to DNTs. e Normal PBMCs (n = 2), obtained from healthy donors (HDs), along with KG1a were pre-treated with AraC, DNR, or the vehicle control, followed by a co-culture with DNTs at varying E:T ratios. All of the cytotoxicity assays were performed using DNTs that were allogeneic to the patient or HD samples. *, p < 0.05; **, p < 0.01; ***, p < 0.001.