Biological functions of melanoma-associated antigens

To date, dozens of melanoma-associated antigens (MAGEs) have been identified and classified into 2 subgroups, I andⅡ. Subgroup I consists of antigens which expression is generally restricted to tumor or germ cells, also named as cancer/testis (CT) antigen. Proteins and peptides derived from some of these antigens have been utilized in promising dinical trials of immunotherapies for gastrointestinal carcinoma,esophageal carcinoma, pulmonary carcinoma and so on. Various MAGE family members play important physiological and pathological roles during embryogenesis, germ cell genesis,apoptosis, etc. However, little is known regarding the role of MAGE family members in cell activities. It is reasonable to speculate that the genes for subgroup IMAGEs, which play important roles during embryogenesis, could be later deactivated by a genetic mechanism such as methylation.In the case of tumor formation, these genes are reactivated and the resultant proteins may be recognized and attacked by the immune system. Thus, the subgroup IMAGEs may play important roles in the immune surveillance of certain tumor types. Here, we review the classifications of MAGE family genes and what is known of their biological functions.

In vitro resistance to interferon of hepatitis B virus with precore mutation

AIM: Chronic hepatitis B virus (HBV) infection is predominantly treated with interferon alpha (IFN-α), which results in an efficient reduction of the viral load only in 20-40% of treated patients. Mutations at HBV precore prevail in different clinical status of HBV infection. The roles of precore mutation in the progression of chronic hepatitis and interferon sensitivity are still unknown. The aim of this study was to explore if there was any relationship between HBV precore mutation and sensitivity to interferon in vitro. METHODS: HBV replication-competent recombinant constructs with different patterns of precore mutations were developed. Then the recombinants were transiently transfected into hepatoma cell line (Huh7) by calcium phosphate transfection method. With or without IFN, viral products in culture medium were collected and quantified 3 d after transfection. RESULTS: We obtained 4 recombinant constructs by orientation-cloning 1.2-fold-overlength HBV genome into pUC18 vector via the EcoRI and Hind lll and PCR mediated site-directed mutagenesis method. All the recombinants contained mutations within precore region. Huh7 cells transfected with recombinants secreted HBsAg and HBV particles into the cell culture medium, indicating that all the recombinants were replication-competent. By comparing the amount of HBV DNA in the medium, we found that HBV DNA in medium reflecting HBV replication efficiency was different in different recombinants. Recombinants containing precore mutation had fewer HBV DNAs in culture medium than wild type. This result: showed that recombinants containing precore mutation had lower replication efficiency than wild type. HBV DNA was decreased in pUC18-HBV1.2-WT recombinants after IFN was added while others with precore mutations were not, indicating that HBV harboring precore mutation was less sensitive to IFN in cell culture system. CONCLUSION: These data indicate that HBV harboring precore mutation may be resistant to IFN in vitro.

Dendritic cells from chronic hepatitis B patients can induce HBV antigen-specific T cell responses

AIM: To determine whether dendritic cells (DCs) from chronic hepatitis B patients could induce HBV antigenspecific T cell responses or not. METHODS: DCs were generated from peripheral blood mononuclear cells of patients with chronic hepatitis B (CHB) infection and healthy donors. We compared the phenotypes of these DCs and their ability to secrete cytokines and to participate in mixed lymphocyte reactions. In addition, autologous lymphocytes were cultured with DCs loaded with HBV core region peptide HBcAg8-27, an epitope recognized by cytotoxic T lymphocytes(CTL), and bearing human leucocyte antigen (HLA)-A2 for 10 d. Cytokine secretion and lytic activity against peptide-pulsed target cells were assessed. RESULTS: DCs with typical morphology were generated successfully by culturing peripheral blood mononuclear cells (PBMCs) from CriB patients with AIM-V containing GM-CSF and IL-4. Compared with DCs from normal donors, the level of CD80 expressed in DCs from CHB patients was lower, and DCs from patients had lower capacity of stimulate T cell proliferation. When PBMCs isolated from patients with chronic or acute hepatitis B infection and from normal donors were cocultured with HBcAg18-27 peptide, the antigen-specific memory response of PBMCs from acute hepatitis B patients was stronger than that of PBMCs from chronic hepatitis B patients or normal donors. PBMCs cocultured with DCs treated with HBcAg18-27 CTL epitope peptide induced an antigen-specific T cell reaction, in which the level of secreted cytokines and lyric activity were higher than those produced by memory T cells. CONCLUSION: DCs from patients with CHB can induce HBV antigen-specific T cell reactions, including secretion of cytokines essential for HBV clearance and for killing cells infected with HBV.

Association of interleukin-12 p40 gene 3'-untranslated region polymorphism and outcome of HCV infection

AIM: To investigate the effect of interleukin-12 p40 gene (IL12E 3'-untranslated region polymorphism on the outcome of HCV infection.METHODS: A total of 133 patients who had been infected with HCV for 12-25 (18.2±3.8) years, were enrolled in this study. Liver biochemical tests were performed with an automated analyzer and HCV RNA was detected by fluorogenic quantitative polymerase chain reaction. B-mode ultrasound was used for liver examination. Polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) was used for the detection of IL12B (1188A/C) polymorphism.RESULTS: Self-limited infection was associated with AC genotype (OR = 3.48; P = 0.001) and persistent infection was associated with AA genotype (OR = 0.34; P = 0.014)at site 1188 of IL12B. In patients with persistent HCV infection, no significant differences were found regarding the age, gender, duration of infection and biochemical characteristics (P>0.05). According to B-mode ultrasound imaging and clinical diagnosis, patients with persistent infection were divided into groups based on the severity of infection. No significant differences were found in the frequency of IL-12 genotype (1188A/C) between different groups (P>0.05).CONCLUSION: The polymorphism of II12B (1188A/C)appears to have some influence on the outcome of HCV infection.

Prospective study in 142 cases of hepatitis C virus infection

AIM: There is limited information on the natural history ofHCV infection in China. We investigated the outcome ofHCV infection after nine-year follow-up and the risk factorsin blood donors in China in order to provide the foundationfor prevention and therapy.METHODS: A total of 172 cases of HCV infection with anti-HCV positive and ALT abnormality were enrolled in thearchives when was screened blood in Hebei Province in1993. In them 142 blood donors were followed up till July2002. No antiviral treatment was applied to them duringthe period of infection. In the present study, anti-HCV, HCV-RNA and aminotransferase were detected and genotypingwas conducted by the method of restriction fragment lengthpolymorphism(RFLP). B-type ultrasound detection wasperformed in all the patients. Age, sex, alcohol consumptionand clinical symptoms were questioned.RESULTS: After nine years' follow-up, 10.56% (15/142)of the cases were negative for anti-HCV and 16.42% (12/134)of them were negative for HCV-RNA. The genotypes lb,2a and lb/2a were 91.07%, 6.25% and 2.68% respectively.Twelve cases (8.45%) were negative for both HCV RNAand anti-HCV. The rate of chronicity in this group was83.58% (112/134), and the rate of viral spontaneousresolution was 16.42% (22/134). The mean level of ALT,AST, y-GT in HCV RNA positive cases was significantlyhigher than that in HCV RNA negative cases (P<0.001).The abnormal rate of ALT and/or AST in male donors wassignificantly higher than that in female donors (P = 0.005).The rate of progression to liver cirrhosis from chronic hepatitisC was significantly higher in the cases of super-infectionwith HBV than that in the cases of single HCV infection.Overdose alcohol consumption promoted the progressionto chronicity.CONCLUSION: This area (Hebei Province) has a higherrate of chronicity in HCV infection, and measures shouldbe taken to prevent its progression to serious liver diseases,especially for patients super-infected with HCV and HBV.

Frequency ofT-cell FoxP3＋ Treg and CD4＋/CD8＋ PD-1 expression is related to HBeAg seroconversion in hepatitis B patients on pegylated interferon

Background Host immune responses against hepatitis B virus （HBV） induced by antiviral therapy play a crucial role in viral clearance. To further investigate the immune mechanisms underlying the differences between respondents and non-respondents, we analyzed myeloid dendritic cells （mDCs）, plasmacytoid dendritic cells （pDCs）, FoxP3＋ regulatory T cells （FoxP3＋ Treg） and programmed death 1 （PD-1） expression in CD4＋/CD8＋ T cells in chronic hepatitis B patients undergoing pegylated interferon （PeglFN）α-2b treatment. Methods Patients received PeglFNα-2b for 24 or 48 weeks, with follow-up at 24 weeks. The frequencies of mDCs, pDCs, FoxP3＋ Treg, and PD-1 expression by CD4＋/CD8＋ T cells were evaluated by flow cytometry at baseline, weeks 4 and 12, end of treatment, and follow-up （12/24 weeks）. Results In HBeAg seroconverters （respondents）, the mDC relative frequency decreased at week 4 and then rebounded at week 12. The pDC relative frequency decreased consistently. In non-HBeAg seroconverters （non-respondents）, both mDC and pDC frequencies decreased slightly. The FoxP3＋ Treg relative frequency decreased during treatment and remained low during follow-up in respondents, while in non-respondents it decreased slightly during therapy but rebounded after discontinuation. In patients with HBeAg 〈17.55 PEI-U/ml at week 12 and 〈8.52 PEI-U/ml at week 24, the FoxP3＋ Treg frequency decreased during treatment and at follow-up. In respondents, CD4~PD-1 and CD8＋PD-1 levels decreased at week 4 and remained low at week 12. In non-respondents, PD-1 expression decreased at week 4 but rebounded at week 12. Conclusions The results indicate that the dynamic changes in DCs, FoxP3＋ Treg frequency, and PD-1 expression by CD4＋ and CD8＋ T cells exhibit different trends in HBeAg and non-HBeAg seroconversion patients. During PeglFNa-2b treatment of chronic hepatitis B patients, these changes may be of predictive value for HBeAg seroconversion. HBsAg and HBeAg levels are related to FoxP3＋ Treg frequency.