These results might account for the low rate of fetal transmission and the associated risk of placental damage and preterm labor. Disclosures: The following people have nothing to disclose: Silvia Giugliano, Lucy Golden-Mason, Anita Kramer, Michael Gale, Virginia D. Winn, Hugo R. Rosen BACKGROUD&AIMS: The polymorphisms in IL-28B (IFN-λ3) gene are strongly associated with HCV clearance. However, the precise role of IFN-λ in HCV

elimination is largely unknown. It is generally accepted that the augmentation of intrahepatic ISGs, induced by endogenous IFNs, is prerequisite for anti-HCV response. Hepatocytes are reported to produce IFN-λs but not IFN-α/β, and drive intrahepatic ISGs; BAY 80-6946 molecular weight however, an involvement of other IFN-producers, such as dendritic cells (DCs) is yet to be determined. We reported that human BDCA3+DCs are main producer of IFN-λs in response to HCV (Hepatology 201 3). Thus, we aimed to clarify the roles of intrahepatic MLN0128 manufacturer BDCA3+DCs and IFN-λs in the induction of ISGs in adjacent HCV-infected hepatocytes by using an in vitro culture system. METHODS: We compared the frequency of DCs in the periphery and in the liver from paired donors. Immuno-histo-chemical analysis was done for identification of intrahepatic BDCA3+DCs. For the functional analysis, we freshly sorted DCs from 400ml of peripheral

blood or from intra-hepatic lymphocytes collected from surgically-resected non-cancerous MCE liver tissue. We co-cultured DCs with JFH-1-infected Huh 7.5.1 cells and quantified IFN-γs and IFN-λ by ELISA. Known 13 ISGs and HCVRNA levels in Huh7.5.1 were examined by qRT-PCR. RESULTS: The frequency of BDCA3+DCs in PBMC was extremely low (0.05%) but significantly higher in liver-infiltrated lymphocytes (0.3%). BDCA3+DCs, as defined as BDCA3+CLEC9A+ cells, were mainly localized in sinusoid lesions of the liver. BDCA3+DCs, from PBMC and liver, released large

amount of IFN-λ and pDCs released IFN-α in the presence of JFH-1-Huh7.5.1. The supernatants collected from HCV-stimulated BDCA3+DCs or pDCs suppressed HCV replication in a concentration-dependent manner, indicating that DCs are able to release bioactive IFNs. Most of 1 3 ISGs were significantly induced, and the up-regulated ISG profiles did not differ between BDCA3+DCs and pDCs. The induction of antiviral ISGs with BDCA3+DCs, such as ISG 15 and IFIT1, was positively correlated with the quantity of IFN-λ3 (ISG 15, r2=0.8, P<0.0001, IFIT1, r2=0.7, P<0.0001, respectively). In contrast, no correlation was found between the induction of RNF125orCXCL10and IFN-λ3 levels. ISG15 and IFIT1 were significantly more induced with BDCA3+DCs from IL-28B major than the mionor. CONCLUSIONS:Human BDCA3+DCs, being accumulated in the liver, produce IFN-λ in the presence of HCV-infected hepatocytes.