Identification of immature 5-LO⁺/CD34^dim cells in highly purified freshly prepared HPCs.

Fresh HPCs were isolated to high purity, and fluorescence immunohistochemistry was performed as described in “Materials and methods” using (A) anti–5-LO antiserum, 1550 (red, Cy3), (B) CD34 (green, Cy2), (C) merge of A and B, and (D) DNA stain Hoechst 33258 on an identical field. The arrow in panel C indicates patches of CD34 antigen in a single 5-LO⁺/CD34^dim immature leukocyte close to 3 other 5-LO⁻/CD34⁺ HPCs. Bars indicate 10 μm.