Altered hematopoiesis in patients with MDS-PA. (A) Identification of various immature and mature cell types in the tumor microenvironment of a representative patient, using multidimensional flow cytometry and principal component analysis (PCA): CD34⁺CD117⁺ myeloid/erythroid and CD34⁺CD117^– lymphoid precursors within CD34⁺ HPCs, mesenchymal stem cells, basophils, eosinophils, mast cells, monocytes, 4 neutrophil subsets (promyelocyte, myelocyte, metamyelocyte, and band/mature neutrophils), 2 nucleated red blood cell subsets (proerythroblasts and erythroblasts), and lymphocytes. (B) Percentage of CD34⁺CD117⁺ myeloid/erythroid precursors within CD34⁺ HPCs in patients with (n = 33) or without (n = 243) MDS-PA at diagnosis. (C) Immunophenotypic characterization of neutrophil maturation dissected into the promyelocytic, myelocytic, metamyelocytic, and band/mature neutrophil stages based on differential expression of CD11b and CD13. (D) Percentage of myelocytes within the neutrophil compartment in patients with (n = 22) or without (n = 62) MDS-PA after HDT/ASCT. (E) Percentage of metamyelocytes within the neutrophil compartment in patients with (N = 19) or without (N = 40) MDS-PA at diagnosis. *P ≤ .05.