Identification of hematopoietic progenitor cell donor characteristics predicting successful mobilization: results of an Italian multicenter study.

Background: Peripheral blood (PB) hematopoietic progenitor cells (HPC) collected by apheresis are the first-choice source for allogeneic stem cell transplantation. The target HPC dose is usually considered to be 4 × 10(6) CD34+ cells/kg of the recipient, but higher doses are required in reduced-intensity conditioning and haploidentical transplants. Thus, prolonged stimulation and repeated collections or failure to reach HPC target may occur, increasing risks for donors and recipients. We carried out a retrospective multicenter study on healthy donors, to identify donor variables which may correlate with HPC mobilization.

Study Design And Methods: HPC allogeneic donations from sibling and unrelated donors performed in two centers from 1995 to 2012 were analyzed. We defined a mobilization cutoff of 50 × 10(6) CD34+ cells/L and tested somatic variables, blood counts, and granulocyte-colony-stimulating factor (G-CSF) dose and molecular form.

Results: A total of 360 donors were analyzed (male, 201; female, 159; sibling, 348; unrelated, 12; median [range] age, 44.8 [13-80] years). Median peak CD34+ in PB was 54.4 × 10(6) /L (range, 5 × 10(6) -299 × 10(6) ). By multivariate analysis, we identified the following variables to correlate with good mobilization: 1) male sex (p<0.0005); 2) younger age (p=0.007); 3) higher baseline (premobilization) white blood cell (WBC) count (p<0.0005); 4) higher G-CSF dosage (p<0.0005); and 5) use of lenograstim rather than filgrastim (p<0.002).

Conclusion: In healthy donors it is possible to predict successful HPC mobilization by donor sex, age, WBC count, and G-CSF form and dose. Furthermore, based on these data, it may be possible, at least in parental setting, to modulate G-CSF dosage on the basis of donor characteristics.