Mobilization of Hematopoietic Progenitors from Normal Donors Using the Combination of Granulocyte-Macrophage Colony-Stimulating Factor and Granulocyte Colony-Stimulating Factor Results in Fewer Plasmacytoid Dendritic Cells in the Graft and Enhanced Donor T Cell Engraftment with Th1 Polarization: Results from a Randomized Clinical Trial

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) both mobilize CD34⁺ stem cells into the blood when administered before apheresis but have distinct effects on dendritic cell (DC) differentiation. We previously demonstrated that the combination of GM+G-CSF results in fewer plasmacytoid DCs (pDCs) when used to mobilize peripheral blood stem cells for autologous transplantation. To test the hypothesis that the content of pDCs in an allograft can be modulated with the cytokines used for mobilization, we randomized the human leukocyte antigen-matched sibling donors of 50 patients with hematological malignancies to a mobilization regimen of either GM+G-CSF (n = 25) or G-CSF alone (n = 25). Primary and secondary endpoints included the cellular constituents of the mobilized grafts, the kinetics of posttransplantation immune reconstitution, and clinical outcomes of the transplantation recipients. Grafts from donors receiving GM+G-CSF contained equivalent numbers of CD34⁺ cells with fewer pDCs and T cells, with a higher fraction of Th1-polarized donor T cells than G-CSF mobilized grafts. Immune recovery was enhanced among recipients of GM+G-CSF. Survival was not significantly different between transplantation recipients in the two arms. The use of GM+G-CSF modulates immune function and recovery after allogeneic transplantation and should be explored in larger studies powered to evaluate clinical outcomes.