Susceptibility of NKG2D-L⁻ and NKG2D-L⁺ leukemic blasts to “single-KIR” NK-cell lines. (A) Myeloblastic CD45-dim (R1) and monoblastic CD45-intermediate (R2) cells from a patient with AML M5 were purified by FACS-sorting to obtain the NKG2D-L⁻ and NKG2D-L⁺ blasts (purity > 98%). The same purification procedure was applied to blasts from a patient with CMML (not shown). (B) Specific lysis of purified AML M5 and CMML patient-derived myeloblastic cells (◇) and monoblastic cells (●) by mismatched “single-KIR” NK-cell lines. Blocking α-NKG2D mAbs were preincubated with NK effectors before the cytotoxicity assay at the indicated E/T ratios (●). (* P < .05, significant difference between cytolysis of myeloblastic and monoblastic cells.)