BACKGROUND: Recombinant human G–CSF is widely used to mobilize PBPCs in healthy donors for allogeneic transplantation. There have been concerns about donor safety because of splenic ruptures during G–CSF application. To address this problem, changes in splenic size in 91 healthy donors during G–CSF mobilization of allogeneic PBPCs were investigated.

STUDY DESIGN AND METHODS: For mobilization, G–CSF in a dosage of 7.5 μg per kg per day was administered for 5 days and PBPC collection started Day 5. Splenic size was determined by ultrasound before G–CSF application was started and on the day of the first apheresis.

RESULTS: The mean increase in splenic length was 11 mm (range, 0‐28 mm; p<0.0001), whereas a mean increase of 5 mm in width (range, 0‐14 mm; p<0.0001) was measured. No major side effects could be observed. There was no significant correlation between the increase in splenic size and the hematologic values, or the age and body‐mass index. In a multivariant analysis, no independent risk factor for the development of a spleen enlargement over 19 mm in length and 9 mm in thickness was found in 20 percent of investigated donors.

CONCLUSION: In this prospective trial, a significant spleen enlargement was observed in healthy donors during G–CSF mobilization of allogeneic PBPCs. Further investigations are needed to define the degree of spleen enlargement with higher G–CSF dosages to improve donor safety.