Objective To compare the effects of fentanyl,sufentanil and remifentanil on the immune function of dendritic cells in human umbilical cord blood.Methods Human umbilical cord blood mononuclear cells were obtained by density gradient centrifugation and seeded in 24-well plates with a density of 1 × 106/ml (2ml/hole).The cells were randomly divided into 7 groups (n =15 each):control group (group C),fentanyl 1.0 ng/ml group (group F1),fentanyl 5.0 ng/ml group (group F5),sufentanil 0.1 ng/ml group (group S1),sufentanil 0.5 ng/ml group (group S5),remifentanil 1.0 ng/ml group (group R1),and remifentanil 5.0 ng/ml group (group R5).The cells were incubated for 10 days in serum-free culture medium containing 50 ng/ml recombinant human granulocyte colony stimulating factor,10 ng/ml recombinant human interleukin-4 or the corresponding concentration of fentanyl,sufentanil or remifentanil,and then 50 ng/ml recombinant human tumor necrosis factor alpha was added to the culture medium and the cells were incubated for another 4 days in the seven groups.Three holes in each group were chosen and the cell morphology was examined with inverted microscope.Six holes in each group were chosen for determination of the concentration of IL-12 in the supernatant and expression of CD80/CD86.Six holes in each group were chosen for measurement of the cell viability.Results Compared with group C,the concentration of IL-12 and cell viability were significantly decreased and the expression of CD80/CD86 was down-regulated in groups F5,S1,S5,R1 and R5 (P ＜ 0.05).The concentration of IL-12,cell viability and expression of CD80/CD86 were significantly lower in groups S1 and R1 than in group F1 (P ＜ 0.05).Compared with group F5,the concentration of IL-12 was significantly decreased in group S5,and the concentration of IL-12 and cell viability were significantly decreased and the expression of CD80/CD86 was down-regulated in group R5 (P ＜ 0.05).The concentration of IL-12 and cell viability were significantly lower in group R1 than in group S1 (P ＜ 0.05).The concentration of IL-12,cell viability and expression of CD80/CD86 were significantly lower in group R5 than in group S5 (P ＜ 0.05).Conclusion Remifentanil has stronger inhibitory effect on the immunological function of dendritic cells in human umbilical cord blood than sufentanil,and the inhibitory effect of sufentanil is stronger than that of fentanyl.