Predictors for the Efficacy of Peripheral Blood Progenitor Cell (PBPC) Collection–Results from 4050 Harvests Performed in a Single Centre

Background: Peripheral blood progenitor cells (PBPCs) are routinely applied worldwide for allogeneic related and unrelated stem cell transplantation. Factors influencing the mobilisation of PBPC’s in healthy donors are poorly understood. The database of the Apheresis Centre at the University of Dresden was evaluated to identify predictors of PBPC mobilisation.

Methods: 4050 PBPC collections (3928 first donations, 122 second donations) of healthy unrelated donors between 1/1996 and 1/2008 were carried out according to a standardized protocol and prospectively documented in a database. Peripheral blood CD 34 counts were performed before each leukapheresis. CD 34 yield of every PBPC product was calculated in absolute numbers and per kg body weight of the recipient. All parameters are presented as median and range. Mann-Whitney test was performed for discrete variables. Correlation analysis by Pearson was applied for continuous variables. Multivariate regression analysis was carried out to detect factors independently predicting mobilization efficacy.

Results: The range of peripheral CD 34+ haematopoietic stem cells obtained on day 5 was 8.7–285/μl (median 67.5/μl) in male and 6–282/μl, (median 51/μl) in female donors. The median CD 34 yield from the first leukapheresis was 5.88 ×10⁸. Inadequate CD34-yields (< 2 × 10⁶/kg) were obtained only in 18 donors (0.45%). Peripheral CD 34 count at day 5 is significantly correlated with (positive linear regression): BMI, baseline platelet count, male sex, G-CSF application (split dose), baseline leukocyte count. Peripheral CD 34 count at day 5 correlates negatively with: female sex, single dose G-CSF application, regular alcohol consumption and regular smoking status. Linear regression analyses revealed no significant influence of donor age. Multivariate correlation analysis included sex, BMI, baseline platelets, G-CSF-application, baseline leukocytes, age and smoking. This model explained 21.2 % of the variabilityA strong correlation exists between peripheral CD 34-counts at day 5 and apheresis yield (70% of the variability explained).

Conclusions: A dose of 7.5 μg/kg/d lenograstim proved to be safe and effective in a large cohort of unrelated donors for mobilizing sufficient haematopoietic progenitor cells for allogeneic transplantation. Our analysis of 4050 donations revealed significant, but very weak correlations of the peripheral CD 34-counts with donor characteristics and life style parameters. No single parameter derived from donor baseline investigation reliably predicts CD 34 yield. Further evaluation of healthy donors including comprehensive genomic linkage analysis is necessary to elucidate the variable efficiency of PBPC mobilization