CD33 and acute myeloid leukemia: Similar to the experiments in which no healthy donor T-cells were added, there was no significant correlation between drug-induced cytotoxicity and CD33 expression levels on AML blasts at lower E:T cell ratios (with E:T = 1:3, P = 0.86 and P = 0.50 at 250 and 500 pg/mL, respectively; with E:T = 1:1, P = 0.43 and P = 0.16 at 250 and 500 pg/mL, respectively; Fig 3A and 3B).