Objective To investigate the effect of hepatitis B virus (HBV) on the immune function of natural killer (NK) cells.Methods Healthy human peripheral blood-derived NK cells were cultured alone,or co-cultured with plasmacytoid dendritic cell (pDC) (NK∶ pDC=5∶1) for 48 h with or without HepG 2.2.15-derived HBV.Cell activation was assessed by flow cytometry.The specific enzyme linked immunosorbent assay (ELISA) and intracellular cytokine staining (ICS) were used to determine the cytokine production,the cytotoxic effect of NK cells on the carboxyfluorescein diacetate succinimidyl ester (CFSE)-labelled K562 target cells as well as the granzyme and perforin levels in NK cells.Paired results were analysed using Wilcoxon signed rank test.Results HBV did not affect interleukin (IL)-12/IL-18 and IL-18/interferon α (IFNα)-induced interferon γ (IFNγ) production by NK cells when NK cells were cultured alone (both P＞0.05).However,HBV significantly inhibited pDC-induced IFNγ production by NK cells (146.1 pg/mL),while CpG enhanced pDC-induced IFNγ production by NK cells significantly (1135.4 pg/mL,P=0.0005).HBV did not affect pDC-induced NK cell activation and cytotoxicity to K562 target cells as well as intracellular granzyme and perforin levels.ConclusionHBV does not activate but inhibits pDC-induced NK cell function,which may contribute to the persistence of HBV infection.

Objective To identify the histological features as well as factors influencing the course of HBeAg-negative chronic hepatitis B virus ( HBV)-infected patients with persistently normal alanine amino-transferase (ALT) levels (PNAL). Methods Ninety-eight HBeAg-negative chronic HBV-infected patients with PNAL who underwent percutaneous liver biopsy were recruited from October 2003 to March 2008. The ALT level, HBV markers, HBV DNA level and liver histological changes were detected. Comparison of means was done by t test and single factor analysis of variance. Nonparametric statistics was done by Marm-Whitey U test and Kruskal-Wallis test. Analysis of independent risk factor was done using Logistic model. The dianostic value of ALT level to significant liver histological changes was evaluated by receiver performance curve. Results Twenty-two point four percent and 17.3% of subjects had the histological activity index (HAI)≥4and fibrosis (F) score≥3 respectively. Subgroup analysis showed that subjects with ALT＞0.50 × upper limit of normal (ULN) had a significantly higher rate of HAI≥4 and F score≥3 than those with ALT≤0.50×ULN (HAI≥4:36.4% vs 11.1%, χ2 =8.881, P=0.003;F score≥3:27.3% vs 9.3%, χ2 =5.487, P= 0.019, respectively), and older subjects (more than 45 years old) had a higher proportion of HAI ≥4 than the younger (33.3% vs 13.4%, χ2 =4.923, P=0.027). Multivariate Logistic regression analysis revealed that a decade increase in age was the independent predictor of HAI≥4 (OR=2.410, P=0.023).Receive operating characteristic (ROC) curve showed that 87.0% and 90.7% of subjects with ALT＜0.50× ULN had histological changes of HAI＜4 and F score＜3 respectively. The proportions of HAI≥4 and F score≥3 in subjects with HBV DNA＜1×104 copy/mL were 14.9% and 12.8%, respectively. Conclusions Significant histological changes may be present in part of the subjects with persistently normal ALT and different HBV DNA levels, so that liver biopsy is very important, especially in those with age ＞45 years.Half time the ULN may serve as an appropriate cutoff value of normal ALT level for managing Chinese HBeAg-negative chronic HBV-int'ected patients.

Objective To investigate the expression and function of retinoic acid-inducible gene Ⅰ(RIG-Ⅰ) in monocyte-derived dendritic cells (MoDC) at different stages of hepatitis B virus(HBV)infection and to explore the role of RIG-Ⅰ in the disease progression after HBV infection. Methods Peripheral blood samples were collected from 28 hepatitis B virus-infected persons, including 21 cases of chronic hepatitis B (CHB) and 7 of acute hepatitis B (AHB). Eighteen healthy subjects were recruited as controls. Purified CD14~+ monocytes were isolated by CD14 microbeads. MoDCs were induced from CD14~+ monocytes with granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4 for 7 days, and then were infected with vesicular stomatitis virus (VSV) to stimulate RIG-Ⅰ expression. The mRNA expression levels of RIG-Ⅰ, interferon (IFN )-promoter stimulating factor-1 (IPS-1) and IFN-β at 16 hours and 24 hours after infection with VSV were measured by real-time quantitative polymerase chain reaction (PCR). Data with normal distribution were tested by analysis of variance. Continuous variables between groups were compared using Mann-Whitney U test. Comparison among multiple groups was done by Kruskal-Wallis test. Results The expression levels of RIG-Ⅰ in MoDCs from CHB patients were significantly lower than those in AHB patients and healthy controls at 16 hours (2.44±2.03, 19. 54±3. 15, 21. 48±8. 39, respectively; F=7.451,P=0.002) and 24 hours (2. 68±2. 93, 10. 31 ±3. 88, 14. 01 ±5. 04, respectively, F = 7. 908, P = 0. 001)following VSV stimulation. The IPS-1 levels in both CHB patients and AHB patients were higher than those in healthy controls at 16 hours (2. 05±l. 08, 1. 99±1. 56, 0. 60±0. 31, respectively) F=7.246,P =0.003) and 24 hours (2. 27±2. 16, 3.24 ± 1.21, 1. 08±0. 73, respectively; F= 13. 598, P = 0. 001).Furthermore, the IFN-β expression levels were significantly lower in CHB patients compared to AHB patients and healthy controls at 16 hours and 24 hours after VSV stimulation. Conclusions The expressions of RIG-Ⅰ and IPS-1 in MoDC are abnormal in HBV infected persons, which indicates that RIG-Ⅰ signaling pathway might be blocked by HBV. The impaired function of MoDC may play a role in HBV infection and chronicity.