T cell hyperreactivity to IL-6 in chronic nonviremic HBV carriers despite normal IL-6 receptor or gp130 expression

We previously showed that T cells from chronic nonviremic HBsAg carriers activated with immobilized OKT3 MAb are hyperreactive to monocyte accessory signals, mainly to interleukin-6 (IL-6). We have further characterized this T cell hyperreactivity using phytohemagglutinin (PHA) as the primary activating signal. PHA-stimulated T cells from nonviremic patients had a significantly higher response to addition of monocytes, monocyte supernatants, and IL-6 alone or combined with IL-1 beta when compared to controls. We examined if these effects could be mediated by a differential expression of IL-6 receptor (p80) or gp130 on resting or PHA-stimulated T cells. We found that PHA, IL-6, IL-1 beta, or IL-2 induced only small changes of the dull p80 expression on T cells. In contrast, we found a significant increase of gp130 expression on PHA-activated T cells compared to unstimulated T cells, which was down-regulated by the presence of IL-6. However, no significant differences in p80 or gp130 expression were detected between patients and controls within all the culture conditions tested. Our results confirm that IL-6 is involved in the in vitro T cell hyperreactivity of nonviremic HBV carriers and indicate that this effect is not mediated by disturbances of IL-6 receptor expression.

[Immunoclinical, molecular and immunopathologic approach to chronic viral hepatitis. Therapeutic considerations]

Through a pilot study which includes a clinical, molecular and immunopathological approach to the chronic Hepatitis induced by HBV or by HCV, we determined that 66% of HBsAg carriers are in the "non viremic" phase. The positive HBeAg "viremic" carriers showed HBV-DNA quantitation which varies between > 50 pg to > 100 pg. Both types of carries are infected with the "wild" type HBV. Each subgroup of positive surface antigemia carriers demonstrated a differential immunopathological response. So far, 96% of the HCV carriers investigated, showed HCV-RNA associated to repeatedly positive anti-HCV antibodies. Those patients with increased ALT values uniformly expressed liver histopathological signs of inflammation caused by HCV; demonstrating also the presence of peripheral blood mononuclear cells infected with HCV. At the present, the genotypes investigation indicates a predominance of HCV genotype II (1b). Autoimmune phenomenons associated to HCV have been detected only in 3 patients. The therapeutic approach with interferon alpha applied to the HCV infection preliminary showed similar results to those reported worldwide. Currently, a comprehensive approach to the chronic HBV and chronic HCV infections requires the application of Immunochemistry, Molecular Biology and Cellular Immunology combined technologies.

Special aspects of hepatitis B virus and delta virus infection in Latin America

Viral hepatitis is a common condition in Latin America. Central and South American countries report several thousand new cases of viral hepatitis each year. This article reviews the hepatitis B virus and hepatitis delta virus infections as major public health problems in Latin America. Their causes, symptoms, and special problems related to these strains of hepatitis are discussed in detail.

CD3- and CD28-activating pathways in HCV infection

We investigated the proliferative response and IL-2 receptor (IL-2R) expression in peripheral blood mononuclear cells (PBMC) activated with anti-CD3 mAb alone or in combination with anti-CD28 mAb in a group of hepatitis C virus (HCV)-infected patients with detectable viremia demonstrated by "nested" PCR. PBMC from HCV patients and controls showed similar proliferative responses either to anti-CD3 mAb, 64.1, and/or to anti-CD28 mAb, 9.3. No differences were found in anti-CD3 or anti-CD3 plus anti-CD28-induced proliferative responses between patients who demonstrated circulating PBMC bearing HCV-RNA when compared to those with negative HCV-RNA PBMC. Moreover, flow cytometry studies confirmed that anti-CD3 alone or in combination with anti-CD28 were able to induce a significant increase of IL-2R expression in patients or controls PBMC. Both groups showed similar basal CD28 expression. These results indicate that both CD3- and CD28-activating pathways are preserved in HCV-infected patients with chronic active liver disease.

Anti-CD3-activated T cells from chronic nonviremic HBV carriers are hyperreactive to monocytic accessory signals

We analyzed T cell responses through the CD3 activation pathway in a group of chronic HBV carriers. PBMC stimulated with the mAb OKT3 showed higher proliferative response in HBV-DNA(-) carriers compared to HBV-DNA(+) carriers and to controls. In contrast, no differences in proliferative responses were observed between HBV-DNA(-) carriers and controls in cell cultures stimulated with immobilized 64.1 mAb (SPB-64.1) which induces proliferation in the absence of monocytes. We further examined T cell responses in the presence of monocytes and their soluble factors to immobilized OKT3 mAb (SPB-OKT3). Purified T cells did not proliferate to SPB-OKT3. When autologous monocytes were added, higher proliferative response, IL-2 production, and IL-2 receptor expression were observed in HBV-DNA(-) carriers than in controls. An enhanced cell proliferation was also obtained when monocyte supernatants were added to T cells cultured with SPB-OKT3. Moreover, when IL-6 alone or combined with IL-1 was added to SPB-OKT3-stimulated T cell cultures, a significantly higher increase in T cell proliferation was detected in HBV-DNA(-) carriers. Our results thus show a T cell hyperreactivity to accessory signals from monocytes (mainly IL-6) in HBV-DNA(-) carriers, that is probably related to an ongoing viral clearance.

Assessment of former and newly developed HBV assays in a Third World setting

Newly available HBV serological assays have not been established routinely in most underdeveloped countries. Utilizing enzyme-immune assays to determine the presence of pre-S1 antigen and anti-pre-S2, and using two conventional hybridization techniques and the PCR assay to detect HBV-DNA, we studied 30 HBsAg chronic carriers and as a reference group 10 subjects whose only HBV routine marker was anti-HBc. Seventy-nine percent of the HBeAg positive carriers showed detectable HBV-DNA by a non-radioactive slot-blotting technique. The PCR assay was more sensitive than the slot-blotting technique, detecting HBV-DNA in anti-HBe positive patients with moderate or normal ALT activity. Pre-S1 antigen was mostly related to the presence of HBsAg and anti-pre-S2 was associated with active viremic state, increased ALT activity (ranges 51 to 640 IU/L), and with self-limited HBV infection. The presence of HBV-DNA in the group with anti-HBc only was detectable solely by the PCR assay. For an underdeveloped country the addition of a PCR assay or pre-S/anti-pre-S protein tests to the current assessment procedures of HBV chronic infection should be used only in selective cases. HBeAg/anti-HBe serological evaluation and HBV-DNA detection by a non-isotopic conventional hybridization technique still remain as useful tools to screen initially for the presence of viremia in chronic HBsAg carriers. The presence of HBV-DNA in individuals with anti-HBc only suggests that anti-HBc screening should be maintained and expanded to all the blood banks of less industrialized countries where the rate of HBV infection in apparently healthy people tends to be high.

Risk factors for dialysis-associated hepatitis C in Venezuela

Utilizing the first and second generation of enzyme immunoassays which detect antibodies to the C virus we investigated the frequency of anti-HCV antibodies in 315 patients undergoing hemodialysis. Other subpopulations at risk were used as reference groups. One hundred and twenty-three samples (39%) from the hemodialysis group repeatedly showed anti-HCV positive antibodies while only 19% and 1% were positive in the reference groups. The rate of anti-HCV reactive patients correlated with time on hemodialysis (less than 1 year, 17%; 1 to 5 years 43%; greater than 5 years, 64%; r = 0.94, P less than 0.001) and with the number of blood transfusions (1 to 10, 40%; greater than 10, 76%; r = 0.97; P less than 0.001). Length of time on hemodialysis was shown to be the major risk factor in thirty-three anti-HCV positive patients who had no previous record of blood transfusions. Co-infection with HBV was demonstrated in 41% out of 123 anti-HCV reactive patients, and increased alanine aminotransferase (ALT) activity was documented in this co-infected group. Our results further extend the observations on the predisposing factors to HCV spread in hemodialysis units, and suggest that in these renal patients co-infection with C and B viruses is a major cause of rising ALT activity.

[Cost-benefits of vaccination against hepatitis B in hospital personnel in Venezuela]

A cost-benefit study for hepatitis B vaccination in Venezuelan hospital workers was performed through a decision tree analysis model, which includes the probabilities for the different outcomes of the hepatitis B virus infection (HBV). The current average cost of HBV infection to the Venezuelan Government was estimated at US$ 1,759 per patient. Implementation of selective vaccination or a mass vaccination campaign for the hospital workers would reduce the total cost of HBV infection to 51% or 28%, respectively, saving $17 to $26 million. This type of economic analysis may influence the distribution of the resources to be allocated for the control of HBV infection in Venezuela.

Cellular immunity in current active pulmonary tuberculosis

A group of 10 patients with recently diagnosed pulmonary TB were studied and compared to 10 bacillus Calmette-Guérin (BCG) immunized healthy individuals. Cellular immune mechanisms were explored in vitro utilizing fresh and precultured peripheral blood mononuclear cells exposed to PHA, PPD, and recall antigens (SK/SD and CA). Proliferative assays were also carried out in the presence of either each patient's serum (autologous serum) or cocultured with CD3(+)-depleted adherent cells. Serum measurements of soluble interleukin-2 (IL-2) receptor and synthesis of IL-2 generated by mononuclear cells stimulated with PPD and SK/SD were also performed. Patient sera were able to inhibit autologous as well as allogeneic cell responses, and a significant adherent cell suppressive effect was observed. As a whole the group of patients showed decreased blast transformation to PPD, preserved proliferative responses to other recall antigens, and a low PPD-induced generation of IL-2. Furthermore, as possible evidence of preactivated T cells, these patients demonstrated high soluble IL-2 receptor serum levels. Early compromise of specific cell-mediated immunity, including IL-2 abnormalities, may be of significance in newly diagnosed pulmonary TB.

[Hepatitis C in Venezuela. Preliminary report]

Five hundred serum samples from volunteers blood donors were investigated in order to determine the presence of anti-HCV antibodies by an enzyme-linked immunoassay recently developed worldwide. Prevalence of true-positive samples was 1.2% (6/500), 2 fold higher than the reported prevalence in most of the industrialized countries. From these 6 sera, one (16.6%) showed simultaneous reactivity for HBV anticore antibody. Three sera (25%) from 12 patients with diagnosis of Non-A Non-B hepatitis were reactive for anti-HCV antibodies while in a group of 32 sera with negative HAV and HBV screening, 4 (12.5%) showed anti-HCV antibodies. Two samples out of 16 sera persistently positive for anticore demonstrated the presence of anti-HCV antibodies. The anti-HCV antibodies were undetectable in two cases of autoimmune chronic hepatitis. Our results indicate that in Venezuela, HCV represents a significant problem of public health coexisting in certain cases with HBV infection.

[Evaluation of a molecular hybridization trial for the detection of circulating DNA of hepatitis B virus. Immunoclinical correlation]

Immunoclinical correlation of the HBV circulating DNA was performed. The DNA was detected by means of a hybridization technique set-up in fluid phase using a complementary DNA probe labelled with 125I (Abbott-Genostics). The correlation was carried-out in 12 serum including 8 from known HBV carriers with or without liver disease. Only the positive HBeAg serum shown circulating viral DNA in ranges between 60 to 2800 pcg/ml. The assay shows to be easy to perform, however the expensive cost plus the use of a short-life isotope makes difficult in routine use, which still is under research. The immunopathogenic significance of the findings is discussed.

[Molecular biology techniques for detection of delta hepatitis virus. I: Obtaining the specific diagnostic probe]

A specific probe to detect DHV genomes was developed using as a source the p alpha-1 recombinant plasmid. The probe was labelled by using the non-isotopic method which allows its longer storage. The sensitivity of this DHV probe varies between 1 to 5 pcg.

[Absence of delta agent infection in high risk male subjects infected with B virus and human immunodeficiency virus]

Positive contacts to DV were investigated among 50 males, 48 homosexuals and 2 heterosexuals intravenously drug-addicts. None shown presence of anti-VD antibodies, while 98% and 50% from the total group demonstrated confirmed reactivity to HIV and HBV respectively. Further, 19 subjects who notified 5 or more sexual partners per year, shown one or more positive HBV markers, finding only observed in 6 subjects from 31 who notified less than 5 partners per year (p less than 0.001). The absence of DV positive contacts suggest that epidemiologically the DV seems to be loss of non-influenced by the sexual condition of the exposed population.

Characterization of cell-mediated immunity in long-term survivors of gastric or colorectal cancer

Cell-mediated immunity was assessed in 12 patients who were long-term survivors of gastric and colorectal adenocarcinomas. A slight decrease in the T-lymphocyte count was accompanied by preserved proliferative reactivity to mitogens (phytohemagglutinin) or alloantigens in 75 percent of the patients. The influence of autologous patient serum on in vitro lymphoproliferative test results was not significant. Selected sera from both study groups showed values of immune complexes that were within the normal range. The colorectal cancer group had antibody-dependent cellular cytotoxicity within the ranges already established for the normal control subjects. Cellular immune mechanisms seem to have been well preserved in long-term survivors of gastric or colorectal carcinoma.