OBJECTIVE Ginsenoside metabolite compound K(CK)is a degradation product of ginsenoside in the intestine by bacteria.The anti-inflammatory and immunomodulatory activities of CK have been reported.This study investigated whether CK exerted its immunoregulatory effect through modulation of dendritic cells(DCs)function.METHODS In vivo,severity of collegen-induced arthritis(CIA),T cells and DCs subsets,phenotype of DC were assayed by flow cytometry,CCL19 and CCL21 level in lymph nodes assayed by ELISA.In vitro,bone marrow-derived DCs from normal mice were matured with lipopolysaccharide and treated with CK for 48 h.In vivo,bone marrow-derived DCs were generated from CIA mice before and 2 weeks into CK treatment.DCs were analyzed for migration,phenotype and T-cell stimulatory capacity.RESULTS CK alleviated the severity of CIA,decreased pD Cs and mo-DCs,increased na?ve T cells in CIA mice lymph nodes,and suppressed CCL21 expression in lymph nodes.CK suppressed DCs migration induced by CCL21 and T cells-stimulatory capability of DC,down-regulated LPS-induced expression of CD80,CD86,MHCII and CCR7 on DCs.CONCLUSION This study elucidated the novel immunomodulatory property of CK via impairing function of DCs in priming T cells activation.These results provide an interesting novel insight into the potential mechanism by which CK contribute to the restoration of immunoregulation in autoimmune conditions. OBJECTIVE Ginsenoside metabolite compound K (CK) is a degradation product of ginsenoside in the intestine by bacteria. The anti-inflammatory and immunomodulatory activities of CK have been reported. This study examined whether CK exerted its immunoregulatory effect through modulation of dendritic cells (DCs) function.METHODS In vivo, severity of collegen-induced arthritis (CIA), T cells and DC subse subsets, phenotype of DC were assayed by flow cytometry, CCL19 and CCL21 level in lymph nodes assayed by ELISA. In vitro, bone marrow-derived DCs from normal mice were matured with lipopolysaccharide and treated with CK for 48 h. In vivo, bone marrow-derived DCs were generated from CIA mice before and 2 weeks into CK treatment. DCCs were analyzed for migration, phenotype and T-cell stimulatory capacity. RESULTS CK alleviated the severity of CIA, decreased pD Cs and mo-DCs, increased na? Ve T cells in CIA mice lymph nodes, and suppressed CCL21 expression in lymph nodes. CK suppressed DCs migration induced by CCL21a nd T cells-stimulatory capability of DC, down-regulated LPS-induced expression of CD80, CD86, MHCII and CCR7 on DCs.CONCLUSION This study elucidates the novel immunomodulatory property of CK via impairing function of DCs in priming T cells activation.These results provide an interesting novel insight into the potential mechanism by which CK contribute to the restoration of immunoregulation in autoimmune conditions.