IL-3 expands a CD45⁺ cell subset derived from hemopoietic progenitors. (A) The numbers of colonies obtained by culturing the indicated sorted cells for 4 days, with or without IL-3. Data are the mean of 10 fields (± SD; *P < .05, left panel, CD45⁺ vs CD14⁻, CD14⁺ and CD45⁻; right panel, CD34⁺ and CD133⁻ vs CD34⁻ and CD133⁺). Magnification, 10×. (B) Representative photomicrographs of colonies obtained from IL-3-cultured CD45⁺-sorted cells. Magnification, 10× (panel i) and 40× (panel ii). (C) FACS analysis was performed on IL-3–expanded CD45⁺-sorted cells. Black lines, preimmune IgG (negative control); gray lines, CD31, CD34, CD33, c-Kit, CD13, CD146, CD14, CD11b, CD83, CD16b, and CD3 markers. (D) Cell extracts from CD45⁺ cells, cultured with or without IL-3, were subjected to SDS-PAGE. The filter was IB with anti-KDR, anti-Tie2, anti–cyclin D1, and anti–β-actin antibodies. (E) Genotype of CD45⁺ cells isolated from patients harboring or not V617F JAK2 mutation. G/G represents WT and G/T represents heterozygous V617F JAK2 mutations, respectively. Three different experiments were performed with comparable results.