Preferential mobilization CD34^dimCD45RA⁺CD123⁺⁺cells by plerixafor. (A) Eight healthy donors were mobilized sequentially with plerixafor (0.24 mg/kg SC), then 10 days later with G-CSF (10 μg/kg per day × 5 days). Plerixafor mobilized a population of CD34^dim cells that were present, on average, in nearly fivefold higher numbers compared with the G-CSF–mobilized CD34⁺ cells (P = .02). (B) Coexpression of CD45RA and CD123 on CD34⁺ cells identifies the CD34^dim subset preferentially mobilized by plerixafor. CD45RA and CD123 expression on purified CD34⁺ cells was evaluated by flow cytometry before and after treatment with plerixafor. (C) Relative contributions of CD34 subsets after plerixafor. Healthy donors were treated with a single injection of plerixafor (n = 5). CD34⁺ cells in the peripheral blood of donors before and after plerixafor were purified by CD34 immunomagnetic selection; expression of CD45RA and CD123 was evaluated by flow cytometry. The relative contribution of each CD34⁺ subset is shown as a function of time. (D-F) Healthy donors were treated with a single injection of plerixafor (n = 31) or given 10 μg/kg per day G-CSF (n = 17) for 5 days. CD34⁺ cells from the plerixafor- or G-CSF–mobilized leukapheresis products, normal healthy bone marrow (n = 5), or cord blood (n = 9) were purified by CD34 immunomagnetic selection; the expression of CD45RA and CD123 was evaluated by flow cytometry. (D) Representative flow cytometry profiles. (E) Relative contribution of each CD34⁺ subset. (F) Absolute number of different CD34⁺ cells subsets in leukapheresis products. Statistical comparisons were performed using an unpaired 2-tailed Student t test. *P < .05, **P < .01, ***P < .001. Data are mean ± standard deviation.