Examples of flow cytometric differentiation patterns for granulocytes and monocytes and lineage infidelity marker expression on myeloid progenitor cells. (A) The relationship between CD11b (x-axis) and CD13 (y-axis) during granulocyte maturation in 1 normal control (left graph) and 3 MDS samples; UPNs correspond to Table 3. Granulocytes were selected by CD45 expression and intermediate to high SSC. A white arrow in the panel of the control sample on the left indicates the development of granulocytes from immature to mature forms. Graphs of patients with MDS demonstrate abnormal maturation or aberrant antigen expression compared with the control sample. (B) The relationship between CD16 (x-axis) and CD13 (y-axis) for granulocytes. Development from immature to mature granulocytes is illustrated by a sickle-shaped white arrow in the graph of the control sample. Graphs of patients with MDS show aberrant antigen expression and maturation compared with the normal control. (C) The relationship between HLA-DR (x-axis) and CD11b (y-axis) during monocyte maturation. Monocytic cells were selected by SSC, CD45, and CD14 expression. A white arrow in the control sample depicts normal maturation of immature blasts toward maturing monocytes. The monocytic subpopulation in the MDS samples either lack expression of HLA-DR or show overexpression of this antigen or overexpression of CD11b. (D) Expression of CD7 (x-axis) on myeloid progenitors, defined by CD45^dimSSC^low/int and CD34 expression, is depicted. Percentages of myeloid blasts and percentages of CD7⁺ blasts are indicated in the graphs.