Potentiation of GM-CSF or GCSF Induced Mobilization of Circulating Progenitor Cells by Pretreatment with IL-3 and Harvest by Apheresis

Recombinant human colony-stimulating factors (CSFs) are increasingly used for mobilizing progenitor cells in the peripheral blood (PB). 7 patients were treated with GM-CSF or GCSF at a dose of 5μg/kg/d for 5 days and after a treatment free interval received another cycle of the same cytokine after pretreatment with IL-3. Pretreatment with 5μg/kg/d of IL-3 for 7 days did not mobilize by itself but significantly potentiated GM-CSF or GCSF induced mobilization of PB progenitor cells in all 5 patients tested. As compared to the mobilization capacity of GM-CSF or GCSF alone, 7 day IL-3 pretreatment potentiated maximum values of CFU-GM by 3.7-6.3 fold in patients receiving GM-CSF (n=2) and by 1.8-3.3 fold in patients receiving GCSF leading to a 10-23 fold increase in numbers of circulating CFU-GM by the combination IL-3/GM-CSF, and a 26-101 fold increase by IL-3/GCSF, respectively. Stem cell apheresis in patients treated with IL-3 + GCSF or GM-CSF yielded enough PB-stem cells to ensure complete engraftment after ablative chemotherapy.