Mobilization Factors of Peripheral Blood Stem Cells in Healthy Donors

As a source of hematopoietic stem cells for transplantation, the use of peripheral blood stem cells (PBSCs) has become routine and comparable to that of the use of bone marrow. Recently, elderly patients with hematological malignancies also have been allowed to receive minitransplantations with nonmyeloablative conditioning regimens under sufficient PBSC infusion. As a result of these minitransplantations, elderly donors have been chosen increasingly from the siblings of elderly patients. We analyzed factors influencing the condition of CD34+ cells in the first days of collection in 49 healthy donors from July 1995 to January 2001. The median dose of recombinant human granulocyte colony-stimulating factor was 8 microg/kg/day (range 8 - 10) over 3 days. The target number of CD34+ cells used in this study was > or = 3 x 10(6) cells/kg of recipient body weight. The median apheresis volume was 12 L. Except for one 60 year old man, we obtained an adequate number of stem cells. In the regression analysis, a negative correlation was seen between donor age and the number of CD34+ cells/kg of recipient body weight per 12 L volume (Y = aX + b; a = -0.07507; b = 6.629996; r = -0.50985; p = 0.000252). Significantly higher apheresis results were obtained in donors younger than 45 years compared with donors 45 years old and older (p < 0.0227). There were no correlations among the number of CD34+ cells, donor body weight, and the number of leukocytes in peripheral blood on the first day of apheresis.