The impact of the age of HLA-identical siblings on mobilization and collection of PBSCs for allogeneic hematopoietic cell transplantation.

With the increasing age of patients undergoing allogeneic hematopoietic cell transplantation (HCT), the age of matched related sibling donors (MRDs) is expected to increase. Donor safety and the impact of donors' age on mobilization, collection of peripheral hematopoietic progenitor cells (HPCs), subsequent engraftment and the incidence of GVHD were retrospectively analyzed. A total of 167 patients received HCT from an MRD. Median donors' age was 48 years (67 (40%) donors were ≥50 years including 34 donors ≥60 years). Side effects under mobilization and apheresis were age independent. Grafts from donors <50 years contained more CD34+ cells (median 9 × 10(6)/kg recipient's body weight (RBW)) compared with older donors (median 5.9 × 10(6)/kg RBW) (P<0.0005), whereas harvests from donors ≥60 years contained more natural killer (NK) cells (P=0.003). Engraftment occurred at a median of 12 days after HCT irrespective of donors' age. Increasing age of MRD did not preclude successful mobilization, collection of HPC and engraftment. In the context of more NK cells in grafts from elderly donors, the impact of donors' age on outcome after HCT warrants further studies. Although short-term toxicities of apheresis were not increased with increasing age, long-term donor safety remains an important issue.