The Effect of Rhg-CSF on MDSC In Bone Marrow and Peripheral Blood Cells

As granulocyte colony-stimulating factor, recombinant human granulocyte colony stimulating factor (rhG-CSF) is widely used in neutropenic patients. In addition to stimulating the growth of granulocyte, rhG-CSF can promote hematopoietic stem cells from bone marrow (BM) to peripheral blood (PB) and has the effect of immune regulation. Myeloid-derived suppressor cells (MDSC) are a group of heterogeneous cells, derived from bone marrow progenitor cells and immature myeloid cells. Recently, MDSC is researched in the field of solid tumor, but not in the field of hematopoietic stem cell transplantation. Here, we investigate rhG-CSF's effect on MDSC in healthy donors’ BM, PB and the relationship between MDSC and graft-verse-host disease (GVHD).

We obtained the BM and PB samples before mobilization and the BM APB and peripheral blood stem cell collection (PBSC) on the 5th day after the rhG-CSF mobilization from 12 healthy donors, respectively. Then we used the flow cytometry to check the absolute number of MDSC. Finally, we analyzed the relationship between the number of MDSC and the incidence of GVHD.

In normal physiological conditions, the MDSC could be detected in healthy donor's PB and BM. In PB, the proportion of MDSC in the mononuclear cells was 1.35 ± 0.35%. In BM, the proportion was 2.44 ± 1.11%. The proportion in BM is higher than that in PB, the difference was statistically significant (P=0.047). On the 5th day after the rhG-CSF mobilization, the MDSC ratio of mononuclear cell in PB were 4.01 ± 1.82%. In BM, the ratio was 4.38 ± 2.19%. The difference between the ratio of MDSC in BM and PB was no significant (P=0.076). The number of mobilized peripheral blood MDSC was significantly higher than that before mobilization (P=0.015), while the difference between the numbers of bone marrow MDSC cells before and after mobilization was not significant (P=0.083). The numbers of MDSC in collection and the incidence of GVHD had a significant negative correlation (P=0.048).

MDSC could be detected in the healthy donors’ PB and BM, the numbers of MDSC in BM were higher than that in PB. The rhG-CSF could mobilize more MDSC from BM to the peripheral blood, and the increased s of MDSC in PB after rhG-CSF mobilization might be related to the low incidence of GVHD in hematopoietic stem cell transplantation.

Supported by National Natural Science Foundation of China (30971300), Science and Technology Planning Project of Guangdong Province of China (2009A030200007) and China Postdoctoral Science Foundation (200902332, 20080440776).

No relevant conflicts of interest to declare.