67LR expression increases in circulating CD34⁺ and CD34⁺/CD38^– cells during G-CSF administration. (A) Western blot analysis with an anti-67LR polyclonal antibody of PBMNCs collected from 2 representative donors before (day 0) or at different time points (days 3 and 5) of G-CSF administration, of highly purified circulating CD34⁺ cells collected from the same donors at day 5 of G-CSF administration, and of highly purified BM CD34⁺ cells collected from 2 different donors. Treatment by G-CSF increases 67LR production, especially in CD34⁺ cells. (B) 67LR expression in CD34⁺/CD38^– progenitor cells during G-CSF–induced stem-cell mobilization from a representative case. Immunophenotyping of 67LR-expressing cells was performed on enriched CD34⁺/CD38^– cells (see “Materials and methods”) collected at day 0 (top panel) and day 5 (bottom panel) of G-CSF administration on a mononuclear gate by triple staining with a PerCP-conjugated anti-CD34, a PE-conjugated anti-CD38, and an anti-67LR polyclonal antibody detected by a FITC-conjugated antirabbit antibody. CD34⁺/CD38^– cells expressing 67LR were evaluated within the gate of CD34⁺CD38^– cells (circled). Treatment by G-CSF increases 67LR production even in CD34⁺/CD38^– cells.