ABSTRACT
Objective To label granulocytes in a state of differentiation in mouse bone marrow (BM) with EdU (5-ethynyl-2′-deoxyuridine) for further understanding the changes in granulocyte produc-tion at different stages of differentiation during inflammation. Methods C57BL/6 mice were intraperitoneal-ly (i.p.) injected with EdU and heat-inactivated Escherichia coli(HI E.coli). BM cells were harvested at different time points after HI E.coli injection and then stained with fluorescent-conjugated antibodies(Abs). Myeloblasts,promyelocytes,myelocytes, metamyelocytes and band and segmented neutrophils were identi-fied by fluorescence-activated cell sorting(FACS). The percentage of EdU-positive cells in each population was recorded. Results The percentage of EdU-positive myeloblasts in mice increased by 10.0% at 24 h af-ter intraperitoneal injection with HI E.coli,but decreased by 75.0% and 23.0% at 48 h and 72 h,respec-tively. The percentage of EdU-positive promyelocytes declined by 23.0%,54.5%,64.3% and 77.8% at 24 h,48 h,72 h and 96 h,respectively. The percentage of EdU-positive myelocytes increased by 60.0% and 10.0% at 24 h and 48 h,but decreased by 80.0% and 90.0% at 72 h and 96 h. The percentage of EdU-positive metamyelocytes increased by 50.0% at 24 h,but decreased by 33.3%,61.5% and 66.7% at 48 h,72 h and 96 h. The percentage of EdU-positive band and segmented cells increased by 14.0% at 24 h,but decreased by 50.0%, 77.8% and 88.0% at 48 h, 72 h and 96 h. Conclusion Emergency granulopoiesis occurred 24 h after the establishment of HI E.coli-induced model of acute peritonitis, which meant that the proliferation of myeloid precursor cells,especially that of myelocytes and metamyelocytes,was accelerated and resulted in increasing number of mature neutrophils immigrating to sites of inflammation.