Granulocyte–macrophage colony-stimulating factor increases the proportion of circulating dendritic cells after autologous but not after allogeneic hematopoietic stem cell transplantation

Background aimsGranulocyte–macrophage (GM) colony-stimulating factor (CSF) has been used as an adjuvant in cancer immunotherapy. We tested the hypothesis that GM-CSF (Leukine®; sargramostim) improves immune reconstitution after hematopoietic stem cell transplantation (HSCT) based on our prior in vitro work that demonstrated the pro-inflammatory effects of GM-CSF on dendritic cells (DC).MethodsGM-CSF was administered to donors, along with standard granulocyte (G) CSF, during stem cell mobilization, and to recipients from the day prior to transplant until engraftment. Eighteen patients consented to the GM-CSF+ protocol and were compared with 17 matched controls undergoing HSCT during the same time period (GM-CSF−).ResultsNumbers of white blood cells (WBC) and CD34+ stem cells in the graft were comparable to controls. Surprisingly, contrary to our hypothesis, the allogeneic donor graft had significantly decreased numbers of CD3+ T cells and their subsets (CD4+, CD4+ CD45RA+, CD4+ CD45RO+, CD8+ and CD8+ CD45RO+), DC (both myeloid and plasmacytoid) and natural killer (NK) cells (CD16+ CD56+). In the GM-CSF arm, following allogeneic transplantation, the levels of DC, T cells and NK cells did not increase with treatment. Conversely, autologous transplant patients receiving GM-CSF had a higher proportion of DC at the time of engraftment.ConclusionsThese findings demonstrate that administration of GM-CSF improves DC reconstitution after autologous rather than allogeneic HSCT.