Granulocyte Colony-Stimulating Factor Induces High Expression of HLA-G In CD3+CD4+ T Lymphocytes and CD3+CD8+ T Lymphocytes

Human leukocyte antigen –G (HLA–G) is a nonclassic HLA class I molecule and has the immunosuppressive activity. We investigate the effects of Granulocyte colony-stimulating factor (G-CSF) on the expression and secretion level of HLA-G in peripheral blood and bone marrow cells, and attempt to explain the mechanism of the low incidence of graft-versus-host disease (GVHD) in G-CSF-primed bone marrow (G-BM) or peripheral blood stem cells (G-PBSC) transplantation.

Bone marrow and peripheral blood cells of 10 donors were collected pre-mobilization and at day 5 after G-CSF mobilization. Flow cytometry was used to detect the expression of membrane-bound HLA-G (mHLA-G) of CD3+CD4+ T lymphocytes, CD3+CD8+ T lymphocytes, CD19+ B lymphocytes, CD56+ NK cell, CD14+ monocytes and CD33+ granulocytes. The levels of soluble HLA-G (sHLA-G) and cytokine were determined by enzyme-linked immunosorbent assay (ELISA). Bone marrow cells and peripheral blood cells of pre-mobilization were incubated for 24h, which are divided into 5 groups: (a) blank group, (b) with G-CSF, (c) with G-CSF and blocking antibody of IL-10, (d) with G-CSF and blocking antibody of IFN-γ, (e) with G-CSF, blocking antibody of IL-10 and blocking antibody of IFN-γ.

The levels of mHLA-G of CD3+CD4+ lymphocytes, CD3+CD8+ lymphocytes and the levels of sHLA-G at day 5 after G-CSF mobilization groups were significantly higher than the pre-mobilization groups both in bone marrow and peripheral blood cells, especially in CD3+CD8+ lymphocytes. The levels of mHLA-G of CD19+ B lymphocytes, CD56+ NK cells, CD14+ monocytes and CD33+ granulocytes had no significant difference in the two groups. The levels of IL-10 or IFN-γ in plasma of bone marrow or peripheral blood at day 5 after G-CSF mobilization groups were much higher than the pre-mobilization groups. The levels of mHLA-G of CD3+CD4+ lymphocytes, CD3+CD8+ lymphocytes and the levels of sHLA-G in bone marrow cells or peripheral blood cells incubating with G-CSF for 24h were significantly higher than the groups without incubating with G-CSF. And the blocking antibody of IL-10 or the blocking antibody of IFN-γ could not reduce the expression levels of mHLA-G and sHLA-G in vitro.

G-CSF can act on cells directly to increase the expression levels of HLA-G in CD3+CD4+ T lymphocytes and CD3+CD8+ T lymphocytes. It might be assciated with the low incidence of GVHD in G-BM transplantation or G-PBSC 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.