Flow cytometric analysis of nonadherent cells in mixed CD34⁺ hematopoietic and stromal cell cultures. Suspensions of nonadherent cells from 3-week-old mixed stromal cell/hematopoietic cell culture initiated by CD34⁺ bone marrow cells were analyzed by flow cytometry. Cell suspensions containing 1 × 10⁵ nonadherent cells were stained with fluorescently labeled CD13, CD19, CD33, CD38, and IgG isotope monoclonal antibodies as described in Materials and Methods. (A) FACS plots of nonadherent cells stained with antibodies Isotype control IgG1 monoclonal antibodies conjugated with PE and FITC. Nonspecifically stained cells are shown as large black dots and comprised 0.4% of the events in the data file. (B) FACS plots of nonadherent cells stained with antibodies CD13/33 PE and CD19 FITC. CD13/CD33⁺ myelomonocytic cells were present at frequency of 80% and CD19 B cells were present at a frequency of 1.4% and are shown as a large green block of dots. The position of the CD19⁺ cells in plot of forward scatter versus side scatter is shown by the arrow in the right hand panel. (C) FACS plots of nonadherent cells stained with antibodies CD38 PE CD34 FITC. CD38⁺, CD34⁻ were 88.06%: 5% of the cells were CD34⁺ and are shown as large black dots in the left panels. The position of the CD34⁺ cells in the plot of forward scatter versus side scatter is shown by the arrow in the right hand panel.