Abstract: Objective To explore the expression and the function of Toll-like receptors 4 in dendritic cells from periph2 eral blood of chronic hepatitis patients.Methods Monocytes from hepatitis B patients and health controls were incubated with GM-CSF and IL-4 and IFN-αto induce dendritic cells(DC).The response of allogeneic lymphocytes was detected by M TT assay.The concentration of cytokines in the supernatant was tested by EL ISA assay.The expression of TL R 4 mRNA was analyzed by R T-PCR.Results The proliferation of isotype xenoma lymphocyte induced by DC stimulation in health control group was obviously stronger than that of in chronic hepatitis-B patients group(P<0.01).The excretion level of IL-12 also increased(20.74±0.19 pg/ml vs 13.21±0.21pg/ml,P<0.01)compared with chronic hepatitis-B pa2 tients group.However the expression of TL R4 mRNA increased(P<0.01)in the patients group compared with health control group(0.79±0.11 pg/ml vs 1.26±0.07pg/ml,P<0.01).Conclusion The function of dendritic cells from peripheral blood of chronic hepatitis patients is defective and the defect may be related to the inhibition of IL-12 secretion caused by the overexpression of TL R4 mRNA.