Aim To study the mouse bone marrow-derived immature CD11b⁺Gr-1⁺ myeloid progenitor cells in mice stimulated by acute inflammatory LPS,and induced to differentiate into macrophage-like cells phagocytized oxidized low density lipoprotein(ox-LDL)to form into foam cells.Methods Mice were injected with lipopoly saccharide(LPS)(5 μg/g weight,IP),24 hours later flow cytometry was used to analyze bone marrow,spleen,and peripheral blood CD11b⁺Gr-1⁺ myeloid precursor cells,CD11b+ Gr-1-mononuclear cells,and CD11b-Gr-1+ granulocyte changed in proportion.Experimental in vitro formation of foam cells,mononuclear cells obtained from mice bone marrow were cultured in DMEM + fetal bovine serum(FBS)medium,co-cultured with granulocyte-macrophage colony-stimulating factor(GM-CSF)for 48 hours to differentiate into monocyte /macrophage-like cells,then co-cultured with ox-LDL(100 mg /L)for 48 hours to form lipid burdened foam cells.Oil red O staining identified foam cells.Results(1)LPS intraperitoneal injection can promote the CD11b + Gr-1+ myeloid precursor cells from bone marrow to mobilizate significantly and to release into the peripheral tissue;the amount of CD11b⁺Gr-1⁺ myeloid precursor cells and CD11b+ Gr-1-mononuclear cells in spleen and circulating pool increased significantly.(2)CD11b⁺Gr-1⁺ myeloid precursor cells which were isola-ted from bone marrow were co-cultured with GM-CSF differentiated into monocyte /macrophage-like cells,and then were incubated with ox-LDL to form lipid burdened cells(foam cells).Oil red O staining showed the cytoplasm of foam cells with red-dyed,large lipid droplets,nuclear were squeezed by the lipid droplets to the corner.Conclusion Acute inflammatory stimulus LPS can mobilize the mouse bone marrow CD11b⁺Gr-1⁺ myeloid precursor cells to release to the circulation and peripheral tissue.CD11b⁺Gr-1⁺ myeloid precursor cells can be induced to differentiate and phagocytize ox-LDL to form into foam cells.