Objective    To investigate the effect of Lentivirus-mediated RNA interference (RNAi) of dendritic cells-specific ICAM-3 grabbing nonintegrin (DC-SIGN) gene on the maturity and function of human DC cells.     Methods    The peripheral blood mononuclear cells were obtained from healthy individuals

and then cultured in medium with GM-CSF and IL-4. Four days later

the cells were divided into RNAi group

negative control group and blank group. The culture medium was discharged 12 h after corresponding treatment. The infection efficiency and fluorescence intensity was calculated and observed with fluorescence microscopy in 60 h later. On the 6th day after culture

LPS was added to stimulate DCs to mature

and then on the next day

the cells were collected for the detection of DC-SIGN mRNA by RT-PCR and protein by Western blot analysis. The level of DC-SIGN on the surface of DCs was detected by flow cytometry. The levels of IL-12 and IL-10 in the supernatant were measured by enzymelinked immunosorbent assay (ELISA). Proliferation induction of DCs to CD4+T lymphocytes was measured by mixed lymphocyte reaction (MLR).     Results    The efficiency of infection of DCs was 85% when multiplicity of infection (MOI) was 20. The expression of DCSIGN mRNA was much lower in RNAi group (0.252 5±0.139 6) than in the other 2 groups (0.572 2±0.190 9 and 0.548 7±0.119 3) (F=8.142

P0.04). Western blot analysis showed that the protein level of DC-SIGN were 0.323 7±0.057 0 in RNAi group

which was significantly lower than the other 2 groups (0.590±0.014

0.578±0.023

F=51.376

P0.05). The expression of DC-SIGN on the surface of DCs was lower in RNAi group [(43.10±10.12)%] than in the other 2 groups [(73.05±8.11)%

(74.49±5.56)%

F=14.19

P0.05]. Expressions of HLA-DR and CD86 on DCs were not statistically significant among the 3 groups (P0.05).  IL-10 and IL-12 levels in the supernatant were not statistically significant among the 3 groups (P0.05). MLR showed the potency of proliferation induction of DCs to T lymphocytes was not statistically significant among the 3 groups (P0.05).     Conclusion    Lentivirus-mediated RNAi of DC-SIGN gene suppresses the gene expression on the surface of DCs effectively

but had no effect on the maturity and functions of DCs.