IL-3Rα expression on FA leukemic cells and normal CD34⁺ cells. (A) Low-density bone marrow cells from an FA-A AML patient were enriched for CD34⁺ cells by selection on an immunoaffinity column (Miltenyi Biotec), expanded in stem-cell medium for 3 days, and subjected to flow cytometric analysis. The gates indicate the total CD34⁺ population and the CD34⁺CD38⁻ population. The histograms indicate the IL-3Rα labeling for the 2 gated populations. (B) The same analysis as in panel A but for the CD34-enriched bone marrow cells from a normal donor. (C) IL-3Rα expression on 4 additional FA-AML samples. Four primary FA-AML specimens were labeled with antibodies for CD34, CD38, and IL-3Rα and analyzed by flow cytometry. (D) The same analysis as in panel C but for the CD34⁺ bone marrow cells from 4 FA patients with BMF. The histograms show IL-3Rα labeling for the CD34⁺CD38⁻ or CD34⁺ gated populations from each sample. The red sections indicate IL-3Rα staining and the green sections indicate parallel labeling with an isotype control antibody. For each sample, 50 000 events were analyzed.