Treatment of normal donors with rhG-CSF 16 micrograms/kg for mobilization of peripheral blood stem cells and their apheretic collection for allogeneic transplantation

BACKGROUND: Utilization of peripheral blood stem cells (PBSC) in allogeneic transplantation requires a method for their mobilization and collection that is not inconvenient for the donor. METHODS: We administered rhG-CSF (filgrastim) 16 micrograms/kg subcutaneously for 4 days in five normal subjects (age 18-31, M = 3, F = 2), previously selected as HLA-identical donors of siblings with leukemia. All the donors gave written informed consent. On days 4 and 5 (in one donor on day 6 too), 10:l leukapheretic collection was performed with a CS-3000 (Baxter) or an AS-104 (Fresenius) cell separator through the antecubital vein. RESULTS: The WBC count reached a median peak of 57.0 x 10(9)/L on day 5. The peripheral blood CFU-GM peaked to a median level of 8908/mL on day 5 with a median increase over baseline values of 39.1 times. The CD34+ cells peaked to (median) 147.0 x 10(6)/L on day 4 with a median increase of 65.3 times. A lesser enrichment was recorded for BFU-E (median increase 12.7 times) and CFU-GEMM (median increase 15.2 times). Even CD3+ and CD56+CD3- cells increased (median 1.7 and 1.5 times, respectively). A median of 771 x 10(8) MNC (range 672-1378), 116.4 x 10(6) CFU-GM (range 47.7-145.1) and 754 x 10(6) CD34+ cells (range 477-2599) were apheretically collected. Concerning side effects, mild to moderate back pain and general minor discomfort were reported by all donors. The platelet level regularly but transiently decreased after completion of the apheretic procedures with a median nadir of 69 x 10(9)/L (range 43-126) on (median) day 7, but in no case did thrombocytopenia cause bleeding. The thrombocytopenia was more pronounced with the CS-3000 than the AS-104 apparatus. CONCLUSIONS: rhG-CSF 16 micrograms/kg x 4 days is an efficient schedule for PBSC mobilization in healthy donors, but lower doses and even a single apheresis procedure might prove similarly adequate.