Homeostatic γδ T Cell Contents Are Preserved by Granulocyte Colony-Stimulating Factor Priming and Correlate with the Early Recovery of γδ T Cell Subsets after Haploidentical Hematopoietic Stem Cell Transplantation

Emerging evidence from graft manipulations and immunotherapeutic treatments has highlighted a favorable effect of gamma delta T cells in the setting of allogeneic hematopoietic stem cell transplantation (alloHSCT). However, gamma delta T cell subsets and their distinct features in the allograft have not been characterized. Additionally, whether homeostatic gamma delta T cell fractions are influenced by treatment with granulocyte colony-stimulating factor (G-CSF) remains elusive. We initially compared the phenotypes of gamma delta T cell subsets, including CD27(+), CD27(-), V delta 1(+), V delta 2(+), V delta 1(+)CD27(+), V delta 1(+)CD27(-), V delta 2(+)CD27(+), and V delta 2(+)CD27(-) cells, in the peripheral blood of 20 healthy donors before and after G-CSF mobilization. The effects of G-CSF on the cytokine production capacities of gamma delta T cell subsets were also detected. Moreover, the correlation between donor homeostatic gamma delta T cell content and the early recoveries of gamma delta T cell subgroups after haploidentical HSCT was investigated in 40 pairs of donors and recipients. We found that both the proportions and IFN-gamma secretion capacities of peripheral gamma delta T cell subsets were preserved in G-CSF-primed grafts. Homeostatic V delta 1 and V delta 2 proportions of donors significantly correlated with the early recoveries of V delta 1 and V delta 2 cells after haploidentical HSCT. Interestingly, a higher day 30 V delta 1 concentration was associated with a lower incidence of cytomegalovirus reactivation in recipients. These results not only clarify the preservation of gamma delta T cell phenotypes and functional features by G-CSF mobilization but also suggest the importance of homeostatic gamma delta T cell content for immune recovery after alloHSCT. (C) 2017 American Society for Blood and Marrow Transplantation.