To investigate the protective effect of epigallocatechin gallate(EGCG)on the immune func- tion of dendritic cells(DCs)after ultraviolet B irradiation(UVB)and its underlying mechanisms,the monocytes were isolated from peripheral blood and cultivated into DCs with cytokines,such as GM-CSF and IL-4.DCs were harvested after cultivation for 7 d and subjected to irradiation with different dosages of UVB.Then,200μg/ml of EGCG were added in certain groups immediately after irradiation.DCs simply treated with UVB or treated with both UVB and EGCG were co-cultured with lymphocytes,and MTF assay was used to detect the ability of DCs to stimulate proliferation of lymphocytes.Surface markers CDS0,CD86,HLA-DR and CD40 were detected by flow cytometry,and the levels of IL-10 and IL-12 secreted from DCs 24 h after cultivation were measured by ELISA.It was demonstrated that UVB irradiation could inhibit the ability of DCs to stimulate the proliferation of lymphocytes and surface expressions of CDS0,CD86,HLA-DR and CD4 on DCs in a dose-dependent manner.The inhibition rate of DCs was improved to some extent after treatment with 200μg/ml of EGCG.When the concentra- tion of EGCG exceeded 100μg/ml,the enhancing effect of EGCG on the expression of the co-stimulat- ing molecules on DCs could be demonstrated in a dose-dependent manner.UVB showed no significant influence on the secretion of IL-10 and IL-12 from DCs,while EGCG could down-regulate the secretion level of IL-12 and up-regulate that of IL-10.It is concluded that EGCG can antagonize the inhibitory effect on DCs induced by UVB irradiation.This function has some relationship with its protecting effect of the expression of the co-stimulating molecule on the surface of DCs and the secretion level of IL-10 and IL-12.
展开▼
