Flow cytometric detection of LSCs in a patient treated for AML. BM from a patient treated for AML was tested for MRD. Cells with the typical immunophenotype of LSCs had been demonstrated at this patient's presentation: CD34⁺CD123⁺CD117⁺HLA-DR⁻CD38⁻. After therapy, sequential gating for the presence of this phenotype was performed and detected 0.02% of these cells. In the scattergram, gate P1 was drawn around agranular cells (low side scatter, SSC) of small size (low forward scatter, FSC). In the blast gate, a second gate (P2) was drawn around cells with CD117 expression (blue dots), whereas the population of red cells in the first gate was CD117⁻. In the blast cell characterization contour plot, blast cells within the CD117⁺ cell population were demonstrated by expression of CD123, but negativity for HLA-DR. The small cell cluster with high HLA-DR expression represents some normal stem cells.