Challenge to Predict Mobilized Peripheral Blood Stem Cells on the Fourth Day of Granulocyte Colony-Stimulating Factor Treatment in Healthy Donors: Predictive Value of Basal CD34+ Cell and Platelet Counts

A longitudinal, prospective, observational, single-center cohort study on healthy donors was designed to identify predictors of CD34⁺ cell mobilization on day 4 after granulocyte colony-stimulating factor (G-CSF) administration. As potential predictors of mobilization, age, sex, body weight, height, blood volume, WBC count, peripheral blood (PB) mononuclear cell count, platelet (Plt) count, and hematocrit and hemoglobin levels were considered. Two different evaluations of CD34⁺ cell counts were determined for each donor: baseline (before G-CSF administration) and in PB on day 4 after G-CSF administration. One hundred twenty-two consecutive healthy donors with a median age of 47.5 years were enrolled. The median value of CD34⁺ on day 4 was 43 cells/µL (interquartile range, 23 to 68), and 81.1% of donors had ≥20 cells/µL. Basal WBC count, Plt count, and CD34⁺ were significantly higher for the subjects with CD34⁺ levels over median values on day 4. A multivariate quartile regression analysis, adjusted by sex, age, basal CD34⁺, and basal Plt count, showed a progressively stronger relationship between baseline CD34⁺ and Plt levels and the CD34⁺ levels on day 4. The basal CD34⁺ cut-off level to predict the levels of CD34⁺ on day 4 was either ≤2 cells/μL or ≥3 cells/μL and that of basal Plt count was ≤229 × 10⁹/L or ≥230 × 10⁹/L, respectively, to determine whether mobilization therapy should or should not be attempted. PB stem cell mobilization with G-CSF was highly effective on day 4, and herein we describe a model for predicting the probability of performing PB stem cell collection after a short course of G-CSF.