[Recombinant HMGB1 induces the differentiation of mouse myeloid cells into myeloid-derived suppressor cells in vitro].

Objective To investigate the effects of recombinant high mobility group box l (rHMGB1) on the differentiation of myeloid-derived suppressor cells (MDSCs) in vitro. Methods The cells were harvested from the bone marrow of BALB/c mice and cultured with rHMGB1, granulocyte-macrophage colony-stimulating factor (GM-CSF) combined with IL-6 (GM-CSF-IL-6), GM-CSF combined with IL-6 and rHMGB1 (GM-CSF-IL-6-rHMGB1), separately in vitro. The percentages of CD11b(+)Gr1(+)MDSCs, CD11c(+) cells and F4/80(+) macrophages were measured by flow cycometry (FCM) after treatment for 48 hours. Monocytic MDSCs (M-MDSCs) and granulocytic MDSCs (G-MDSCs) were isolated from the femurs of healthy BALB/c mice, and then stimulated with rHMGB1. The proportions of CD11b(+)Gr1(+)MDSCs, CD11c(+) cells and F4/80(+) macrophages were detected by FCM. Results FCM showed that the proportions of CD11b(+)Gr1(+)MDSCs in rHMGB1 group, GM-CSF-IL-6 group, GM-CSF-IL-6-HMGB1 group increased, while CD11c(+) cells and F4/80(+) macrophages decreased as compared with control group after 48 hours. Following rHMGB1 treatment, the percentages of M-MDSCs and G-MDSCs were raised and the proportions of CD11c(+) cells and F4/80(+) macrophages were reduced in rHMGB1-treated group, but there were no significant differences between M-MDSCs and G-MDSCs groups. Conclusion The rHMGB1 can induce MDSC differentiation; rHMGB1 combined with GM-CSF and IL-6 can more effectively promote MDSC differentiation in vitro.