Objective:Bone marrow-derived dendritic cells ( DCs) were extracted and gave tanshinone ⅡA to intervene ,and we observed the change of DCs function ,which investigate the effects of tanshinone ⅡA in immune system.Methods:Extract bone mar-row-derived DCs,and cells were cultured in complete medium with 10 ng/ml GM-CSF and IL-4.On day 5,magnetic cell sorting was used to purify DCs,and the purify must be up to 90%.Then,a certain concentration of tanshinone ⅡA or LPS was gave to the cell cul-ture,and cells and supernatant were collected for following experiments .We used flow cytometry to detect phenotype , and enzyme-linked immunosorbent assay(ELISA) was used to detect cytokine production of TNF-αand IL-12.Also,allogeneic mixed lymphocyte reaction was used to detect the ability of DCs to induce T cell proliferation and polarization .Results:When the concentration of tanshi-none ⅡA was 500 ng/ml,the inhibition of secretion of TNF-αwas maximal.So we chose that concentration .Compared with the control group,DCs in experimental group had reduced expression of CD 80,CD86 and MHCⅡ(P<0.05).Compared with the control group ,DCs in experimental group displayed the reduced level of IL-12 and TNF-α(P<0.05).Compared with the control group,DCs in experimen-tal group had reduced ability to induce T cell proliferation (P<0.05).Compared with the control group ,DCs in experimental group in-duced T cell to secret increased level of IL-4,and reduced level of IFN-γ(P<0.05).Conclusion:TanshinoneⅡA can inhibit the den-dritic cells maturation induced by LPS ,which takes part in immune system and autoimmune diseases .