Objective       To explore the change of SOCS3 expression and underlying molecular mechanism during the disturbance of differentiation and maturation of mouse bone marrow derived dendritic cells (BMDCs) induced by IL-6.      Methods        To obtain immature BMDCs

mouse bone marrow cells were isolated and cultured in complete culture medium containing GM-CSF and IL-4 following the removement of the nonadherent cells. The maturation of BMDCs was induced by LPS. The expression of SOCS3 molecules on LPS-treated BMDCs with or without IL-6 treatment was analyzed by real-time RT-PCR and Western blotting. The methylation level of CpG island of SOCS3 gene’s promoter in BMDCs was evaluated after LPS treatment in the presence or absence of IL-6 by methylation specific PCR (MS-PCR).      Results      The expression of SOCS3 at mRNA and protein levels in BMDCs were upregulated obviously after LPS stimulation

compared to cells treated by culture media only

and that at mRNA and protein levels in BMDCs treated by LPS plus IL-6 were much lower (P0.05)

compared with the cells incubated with LPS alone. LPS plus IL-6 treatment resulted in much higher methylation level in the potential CpG island predicted in SOCS3 gene’s promoter region.      Conclusion       IL-6 exerts a negative effect on the differentiation and maturation of BMDCs induced by LPS

through inducing CpG island methylation in SOCS3 promoter and thus suppressing its expression.