Objective:To study the effect of IL-6 in SLE serum on the differentiation and maturation of dendritic cells(DCs)derived from cord blood CD34+ hematopoietic precursor cells(HPCs). Methods:CD34+HPCs were isolated and purified from cord blood by magnetic cell sorting system(MACS), and cultured with GM-CSF+IL-4+TNF-α. Normal serum or SLE serum with high level of IL-6 was added into culture medium respectively. The phenotypes of DCs(HLA-DR,CD80,CD86,CD83 and CD1a) were analyzed by FCM. Their abilities of stimulating allogenic T lymphocytes proliferation were examined by CCK-8, and ELISA was used to assess the IL-12, IL-10 and IFN-γ concentration in the culture supernatant. Results:The serum level of IL-6 was significantly higher in SLE patients than in controls. When cultured in SLE serum with high level of IL-6, CD34+HPCs could be induced to differentiate into DCs which produced little IL-10, little IFN-γ and lower IL-12, but expressed higher levels of HLA-DR, CD80 and CD86, and showed increased abilities of stimulating allogenic T lymphocytes proliferation compared with those cultured in normal serum. Conclusion: The high level of IL-6 in SLE serum has abnormal impacts on the differentiation and maturation of DCs and alters their characteristics, which may be involved in the initiation and maintenance of SLE.