Influence of recombinant human granulocyte colony stimulating factor (rhG-CSF) on CD34+ hematopoietic stem cells and regulatory T cells in healthy donors

Abstract

Objective To investigate the influence of recombinant human granulocyte colony stimulating factor (rhG-CSF) on CD34+ hematopoietic stem cells and regulatory T cells in healthy donors. Method Seventy-five healthy donors were retrospectively analyzed in this study, including 65 related donors and 10 unrelated donors. All the donors were mobilized with rhG-CSF (5-7.5 μg·kg-1·d-1). Blood routine and the percentage of CD34+ stem cells in peripheral blood were monitored during mobilization. Bone marrow stem cells on day 4, and peripheral blood stem cells on day 5 and/or 6 were collected for related donors. Peripheral blood stem cells were collected on day 5 for unrelated donors. Flow cytometry was used to detect CD34+ cells, total T lymphocytes (CD3+ ), and regulatory T cells (CD4+ CD25+ CD127-). Result After rhG-CSF mobilization, the percentage of CD34+ stem cells was 0.13%±0.07% in bone marrow harvests, and 0.36%±0.21% in peripheral blood products (u=7.167, P<0.001). When converted to absolute number, the CD34+ cells were (53.25±33.59)/μl in bone marrow harvests, which was significantly lower than that (874.33±540.15)/μl in peripheral blood products (u=6.714, P<0.001). The percentage of regulatory T cells was 0.81% (0.40%, 6.09%) in bone marrow harvests, and 1.03% (0.41%, 5.70%) in peripheral blood products, without significant difference (u=0.131, P=0.894). The absolute number of regulatory T cells was obviously lower in bone marrow harvests (129.12±100.90)/μl than in peripheral blood products (3357.34±2831.72)/μl (u=6.389, P<0.001). Although the absolute number of T cells was higher in peripheral blood products (51 221.92±17 128.01)/μl than in bone marrow harvests (2 101.82±1 288.93)/μl (u=6.784, P<0.001), no significant difference was detected for regulatory T cells/total T cells ratio (0.069±0.048 versus 0.067±0.048/μl; t=0.211, P=0.833). Conclusion High frequency and absolute number of CD34+ stem cells in peripheral blood harvests may be partially associated with rapid hematopoietic reconstitution after transplantation. Similar regulatory T cells/total T cells ratio may contribute to the similar occurrence of acute graft versus host disease. Key words: Granulocyte colony stimulating factor; Hematopoietic stem cells; Mobilization; T-Lymphocytes, regulatory; Bone marrow; Peripheral blood