Abstract: Objective To investigate the expression of cytokines in monocyte-derived dendritic cells (MoDC) after Toll like receptor (TLR) 3 being triggered in acute-on-chronic liver failure (ACLF) patients. Methods Peripheral blood was collected from 60 ACLF patients, 40 chronic hepatitis B (CHB) patients, and 20 healthy individuals who are served as normal controls (NC). Purified monocytes were isolated by combination of Histopaque-1.077 and CD14 Microbeads. MoDCs were induced from CD14+ monocytes and stimulated such cells in vitro with poly (I︰C). TLR3, NF-κB and IRF3 were detected by real-time PCR. Supernatant fluids from the cultures were analyzed for levels of 6 different pro-infl ammatory cytokines, interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70, and TNF-α by fl owcytomix measurements. Results With the progress of the disease, the expression of NF-κB was signifi cantly higher in turn, while the level of IRF3 decreased, among three groups. The amounts of IL-10 produced were lower in ACLF than CHB (P = 0.021), but this difference did not achieve statistical signifi cance (P ＜ 0.05) compared to NC. The production of IL-12p70 in MoDC of ACLF was extremely decreased than other two groups (P ＜ 0.001). IL-8 levels were signifi cantly lower in ACLF than in CHB. While, significantly lower amounts were found of IL-8 on MoDCs in CHB than in NC (P ＜ 0.005). IL-1β levels were lower in ACLF than in NC (P = 0.001). Expression of IL-1β was also lower in CHB than in NC (P = 0.007). Conclusions The results suggest impaired TLR3 pathway signaling in MoDC from patients with ACLF, resulting in secretion of selective pro-infl ammatory cytokines integral to the infl ammatory response that may be critical in the pathogenesis of ACLF.