:Objective Toinvestigatethe role of NF-κB played in the process ofthe cord blood monocytes differentiating into dendritic cells(DCs)induced by astragaluspolysaccharide(APS)and to explore the signal transduction pathway involved in thisprocess.Methods Umbilica]cord blood was collected in aseptic conditions.The cord bloodmonocytes were obtained by density gradient centrifugation and were divided into threegroups afterwards.In the control group.cells were cultivated in the RPMI 1640 completemedium.In the APS group.cells were cultivated in the RPMI 1640 complete medium containing100 mg/L APS.In the PDTC group:cells were treated with 10 μmol/L disulfidecarbamate(PDTC).NF-κB inhibitor in 30 min followed by cultivalion in theRPMI 1640 complete medium containing 100 mg/L APS.,The morphological changes were observedduring the process of cultivation by the optical microscope and transmission electronmicroscopy.Cells were collected 12 d later and the cellular immunophenotyping was assayedby FCM.,The activation and migration of NF-κB fluorescence in the cellswas examined by the immunoflouresce microscopy.Results (1)Cells in the control group grownup without cluster forformation and were found fusiform and macrophage-like in 12 d.Cellsin the APS group grown up in clnstem,and morphological changes were found from thecircular shape to a typical dendritic cells-like shape.Cells in the inhibitor group grownup slowly and without cluster formation,and cell morphdogy had no significantchange.(2)The expression of DCs-specific antigen CD80,CD83 and CD86 in the APS group washigher than that in the control group and inhibitom group(P 0.05).(3)NF-κB fluorescence in the nucleiwas examined by the immunoflourescence microscopy and was much higher in the APS groupthan that in khe other groups,especially in 72 h with the activation rate of NF-κB(75.20±7.37)%,while(13.20±3.46)% of PDTC group and(8.20 ±1.92)%,respectively(P<0.01).ConclusionAstragalus polysaccharide can induce the differentiation of umbilical cord blood cellsinto DCs,and NF-κB is the key component of the signal transduction pathway involved in thisprocess. Key words: Cord blood; Dendritic cells(DCs); Astragaluspolysaccharides(APS)/pharmacology; Signal transduction pathway