Kinetics of G-CSF-induced granulocyte mobilization in healthy subjects: effects of route of administration and addition of dexamethasone

BACKGROUND: Granulocyte donors are frequently given G-CSF with or without dexamethasone approximately 18 hours before apheresis to increase cell yields. The purpose of this study was to assess the kinetics of G-CSF plus dexamethasone neutrophil mobilization to determine whether the neutrophils can be mobilized and collected the same day. STUDY DESIGN AND METHODS: Sixteen subjects were given four separate mobilization regimens: IV G-CSF (5 microg/kg), subcutaneous G-CSF (5 microg/kg), IV G-CSF (5 microg/kg) plus oral dexamethasone (8 mg), and subcutaneous G-CSF (5 microg/kg) plus oral dexamethasone (8 mg). Blood cell counts were measured before and after G-CSF administration. RESULTS: Following all four mobilization regimens, neutrophil counts fell 0.5 hour after the mobilizing agents were given, rose above baseline levels at Hour 2, and increased further with each time interval to Hour 8. In the absence of dexamethasone at Hours 2 through 8, there was no difference in neutrophil counts by subcutaneous or IV G-CSF administration routes. The addition of dexamethasone enhanced mobilization of neutrophils from Hours 3 through 24. Through Hour 8, there was no difference in the degree of mobilization among the subcutaneous G-CSF plus dexamethasone and the IV G-CSF plus dexamethasone regimens. However, at Hour 24, neutrophil counts were sustained at higher levels with subcutaneous G-CSF plus dexamethasone than with IV G-CSF plus dexamethasone. CONCLUSIONS: Granulocyte mobilization response to subcutaneous G-CSF plus dexamethasone is sustained at peak levels for 8 to 24 hours after coadministration of the two drugs. There was no advantage to giving G-CSF intravenously.