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C Balsano

Publications and source records attributed to C Balsano.

44 records · Page 3Linked to original sources
PubMed1991

Significance of anti-HBx antibodies in hepatitis B virus infection.

Serological responses to hepatitis B virus-X determinants have been noted in human sera, but conflicting findings concerning the correlation of anti-HBx antibodies with different stages of hepatitis B virus infection or pathological sequelae have been reported. Using an adenovirus-based eukaryotic vector, the 17 kD X protein was efficiently expressed in 293 cells. Cellular extracts containing the eukaryotic X protein have been used to screen for anti-HBx antibodies by immunoblot analysis in a large panel of sera from patients affected by hepatitis B virus chronic hepatitis, hepatocellular carcinoma and acute viral hepatitis. Sera from 32 of 171 (19%) chronic hepatitis B virus patients were positive for anti-HBx antibodies. Only one of thirty-two (3%) HBsAg-negative, anti-HBs/anti-HBc-positive chronic hepatitis serum was anti-HBx positive. Very few sera from primary hepatocellular carcinoma patients showed positivity for anti-HBx (8 of 149 or 5%). Anti-HBx were also detected in 8 of 48 (17%) acute viral hepatitis patients. In the four cases that were followed up weekly, anti-HBx antibodies appeared 3 to 4 wk after the onset of the clinical signs. To compare the X protein expressed in eukaryotic and prokaryotic cells as a substrate for anti-HBx antibody detection, 171 sera were screened with HBx fusion proteins expressed in Escherichia coli. The prokaryotic cell extract test seems to be more sensitive. During the chronic phase of hepatitis B virus infection, the presence of anti-HBx antibodies detected with the eukaryotic cell extract correlates with the presence of well-established markers of ongoing viral replication: serum hepatitis B virus-DNA (p less than 0.001) and intrahepatic HBcAg expression (p less than 0.001).

Biomarkers↗
PubMed1990

Hepatitis B virus (HBV) X gene expression in human cells and anti-HBx antibodies detection in chronic HBV infection.

All mammalian hepatitis B virus genomes contain an open reading frame X (X-ORF) of unknown function which could encode a protein of 17 kDa. Using a plasmid containing the entire X-ORF preceded by the adenovirus type 2 major late promoter and its tripartite leader sequence efficient expression of the HBV X-gene was achieved. The X protein of 17 kDa was characterized by immunoblotting and immunoprecipitated with an antiserum prepared against a X fusion protein produced in E. coli. By cell fractionation and indirect immunofluorescence the X-protein was found at least in part associated with nuclei. Human cell extracts containing the X protein have been used to screen human sera for anti-HBx antibodies. Such antibodies were detected in sera from patients with active chronic hepatitis with ongoing viral replication. The efficient expression of the HBV X protein obtained will facilitate its functional analysis.

Cell Fractionation↗
PubMed1990

Liver-derived T cell clones in autoimmune chronic active hepatitis: accessory cell function of hepatocytes expressing class II major histocompatibility complex molecules.

Thirty T cell clones were generated from T cell blasts, infiltrating the liver of autoimmune chronic active hepatitis (CAH) patients, stimulated with autologous hepatocytes expressing class II major histocompatibility complex (MHC) molecules and interleukin 2 (IL2). Sixteen clones were CD4+ and 14 were CD8+; all were CD25+ and WT31+, revealing that all cell lines expressed the alpha/beta chains of T cell receptor. Five CD4+ and 4 CD8+ T clones proliferated in response to hepatocytes expressing both class I and class II antigens. The hepatocyte recognition was MHC restricted because only class II MHC-matched hepatocytes were able to stimulate the CD4+ T clones, while only class I-matched hepatocytes stimulated CD8+ T clones, and because MoAbs to monomorphic determinants of class II antigens or to class I antigens appeared to block the response of the CD4+ and CD8+ T clones, respectively. These findings, together with the observation that autologous irradiated peripheral blood mononuclear cells (iPBMC) were unable to stimulate the clones, indicate that the response of these clones was directed to a liver membrane antigen in association with class II or class I MHC molecules on the surface of the hepatocytes. All the CD8+ T clones and 5 CD4+ T clones expressed high cytotoxic activity in a lectin-dependent cell-mediated cytotoxicity assay; 10 CD8+ and 3 CD4+ T clones also showed natural killer (NK)-like function. The cytolytic machinery was also present in those clones (both CD8 and CD4) recognizing the HLA-matched hepatocytes. All liver-derived T clones were able to produce high amounts of interferon (IFN)-gamma, as well as being capable of secreting IL2, following PHA stimulation.

Antibody Formation↗
PubMed1990

Hepatitis B virus X protein transactivates the long terminal repeats of human immunodeficiency virus types 1 and 2.

The X gene product of the hepatitis B virus (HBV) has been expressed transiently in HepG2 cells, and the 17-kilodalton protein has been detected by Western (immuno-) blot analysis. Cotransfection of the X gene with the long terminal repeat of human immunodeficiency virus type 1 or 2 results in a stimulation of long terminal repeat-directed expression that is higher than the X-induced stimulation of the HBV enhancer linked to either autologous promoter or to the heterologous simian virus 40 promoter. A frameshift mutation abolished this transactivation. In vitro nuclear transcription assays revealed that HBV X acts at the transcriptional level. The carboxy terminus of the HBV X protein does not seem to be necessary for its transactivating activity, as demonstrated by using HBV X protein deletion mutants.

Blotting, Western↗
PubMed1989

Recognition of hepatitis B virus envelope proteins by liver-infiltrating T lymphocytes in chronic HBV infection.

The Ag specificity and cytotoxic function of human T cell clones, generated from lymphocytes infiltrating the liver of a chronic hepatitis B patient, were studied. Both class I- and class II-restricted T clones specifically proliferated to hepatitis B virus envelope proteins, but not to hepatitis B core Ag. The fine specificity of T cells was studied by using rAg having different composition in relation to HBV-envelope proteins or synthetic peptides of preS regions. The antigenic determinant recognized by T cell clones mapped to the preS2 region based on the response to r(preS1+preS2+S) and to r(preS2+S) and the failure to respond to S or preS1 alone. More precise epitope mapping was based on synthetic preS2 peptides 120-150 or 120-134, which stimulated both class I- and class II-restricted T clones, whereas preS2 153-171 or preS1 1-110 peptides did not; thus, the preS2 120-134 appears to contain both the residues binding to class I molecules and the residues binding to class II molecules. Moreover, strong and specific cytotoxic responses of these clones were observed only when HLA-matched EBV-lines, used as target cells, were previously sensitized with r(preS1+preS2+S) or preS2 peptides, which were shown to stimulate the clones. Thus, a preS2 epitope can represent a target Ag for liver-infiltrating T cells, which could kill the hepatocytes expressing the Ag plus the appropriate MHC molecule.

Adult↗
PubMedDate not supplied

Expression of class I and class II major histocompatibility complex antigens on human hepatocytes.

We analyzed whether normal human hepatocytes, which normally do not display Class II major histocompatibility complex antigens, can be induced to express them in vitro, and whether this induction has an in vivo counterpart in chronic liver diseases. While both alpha- and gamma-interferon induced expression of Class I antigens, only gamma-interferon induced expression of Class II antigens on hepatocytes in vitro. Recombinant interleukin 2 had no effect on major histocompatibility complex antigen expression. Both Class I and Class II antigens could be detected by indirect immunofluorescence on hepatocytes from patients with various forms of chronic liver disease, regardless of etiology. These findings suggest that gamma-interferon produced by T lymphocytes that infiltrate the liver during the course of chronic hepatitis induces Class II major histocompatibility complex antigen expression and may endow the hepatocytes with the capacity to perform accessory (antigen-presenting) cell functions.

Antibodies, Monoclonal↗
PubMedDate not supplied

The molecular basis of myocardial hypertrophy.

Myocardial hypertrophy is an adaptive response of the heart to several pathological situations aimed at maintaining adequate cardiac contractile function. This process is characterized by complex qualitative and quantitative changes of both cardiomyocytes and nonmyocyte cardiac cells. The initial stimulus inducing these cellular responses is parietal stretch subsequent to either a pressure or volume overload. Many substances locally produced and acting in a paracrine-autocrine fashion are involved in the response to stretch by cardiac cells. The stretch, and, similarly, various growth factors (i.e. angiotensin II. endothelins, transforming growth factor beta, fibroblast growth factors), are able to modulate the expression of several protooncogenes in the cells of the myocardium, and these events are linked to the development of cardiac hypertrophy. Major goals of future research will include the detection of the molecular mechanisms enabling the cardiomyocyte, a terminally differentiated muscle cell, to respond to a mitogenic stimulus with hypertrophic rather than hyperplastic growth, as well as the identification of drugs able to block the evolution of hypertrophy to heart failure.

Adult↗