Cell-mediated immunity to hepatitis B surface antigen in blood donors with persistent antigenaemia

Cellular immune response to hepatitis B virus antigens. An overview

It has been suggested that the cellular immune response to HBV antigens is responsible for hepatocellular injury in acute and chronic hepatitis B. However, definitive immunological studies have so far been hampered by the lack of appropriate model systems to study HBV antigen-specific T cells. The availability of highly purified and recombinant HBV antigens and of experimental techniques to maintain in continuous growth antigen-specific T cells derived not only from the peripheral blood but also from the liver should allow a better understanding of the fine immunopathogenetical mechanisms involved in viral clearance and liver damage. Whether some important biological characteristics of HBV antigens described in the mouse system, such as the high immunogenicity of the pre-S antigens and the capacity of the nucleocapsid of HBV to be a T cell-dependent and -independent antigen, are relevant to the immunopathogenesis of liver damage during natural HBV infection in man remains to be evaluated.

Selective sensitization of peripheral blood T lymphocytes to hepatitis B core antigen in patients with chronic active hepatitis type B

The proliferative response of peripheral blood T cells to hepatitis B surface antigen (HBsAg), pre-S antigen and hepatitis B core antigen (HBcAg) has been studied in 20 patients with hepatitis B virus induced chronic active hepatitis (CAH) and in 12 control subjects. Eleven of the 20 CAH patients showed a significant T lymphocyte proliferative response to HBcAg, whereas no proliferation was detectable in response to envelope antigens (HBs and pre-S) in any patient. T cell subset fractionation revealed that HBcAg specific proliferation was limited to the CD4+ (helper/inducer) population. CD8+ (suppressor/cytotoxic) T cells were unresponsive to HBcAg and did not suppress the proliferative response of autologous CD4+ cells. The HBcAg specific T cell proliferative response did not correlate with serum anti-core antibody titres or with biochemical evidence of liver disease. The present results show the selective presence of HBcAg-sensitized T cells in the peripheral blood of patients with HBsAg positive CAH and suggest that the peripheral lymphoid compartment may not reflect immunopathogenetically important cellular events operative at the site of tissue injury.

A specific immune response to purified HA antigen (HAAg) demonstrated by leukocyte migration inhibition in patients recovering from viral hepatitis A

The mechanism responsible for liver cell necrosis in patients with hepatitis A is not known. Since the type of hepatic lesions and the clinical presentation of acute hepatitis B are similar and are probably related to the cell-mediated immune response to a viral antigen located in the liver cell, it is possible that a similar mechanism is involved in hepatitis A. In the present paper, immune reactivity to hepatitis A antigen (HAAg) was measured in 13 patients at the time of recovery from hepatitis A, by using the leukocyte migration inhibition test (LMIT) under agarose with purified HAAg as antigen. Eleven normal subjects without history of hepatitis and 4 patients convalescent from hepatitis B were used as controls. Inhibition of leukocyte migration by HAAg was found in 11 of the 13 patients, with an average migration index (MI) of 77.0% (SEM 3.5). No such inhibition was found in any of the controls: MI = 100.8% (SEM 1.0), P less than 0.0001. These findings show that, like for HBsAg in hepatitis B, an immune response specific for HAAg can be demonstrated by the LMIT after HAV infection. This response could perhaps be related to the liver injury associated to hepatitis A.

Congenital X-linked hypogammaglobulinemia and asymptomatic hepatitis B antigen carrier state

Hepatitis occurring in patients with congenital X-linked or common variable hypogammaglobulinemia has been reported to follow a usual pattern of rapid progression from acute hepatitis to either chronic active hepatitis or death. This article describes a 21-year-old black man with congenital X-linked hypogammaglobulinemia who has been known to be a hepatitis B-associated antigen carrier during a 9-year follow up period. Liver enzyme studies are normal. His immunologic studies demonstrate no impairment of cellular immunity. His brother, who has the same disease and lives in the same household, has remained negative for hepatitis B-associated antigen. This patient demonstrates that not all hypogammaglobulinemia patients invariably have a severe clinical course with hepatitis.

Cell-mediated immunity to hepatitis B surface antigen in man

An aqueous preparation of hepatitis B virus (HBV) vaccine was used as an intradermal skin test antigen to assess delayed hypersensitivity to hepatitis B surface antigen (HBsAg). Thirty-five persons were tested including 10 individuals seronegative for all HBV markers, 10 positive for HBsAg (chronic carriers) and 15 positive for antibody to HBsAg (anti-HBs), five of whom had received the HBV vaccine. All patients were also studied for lymphocyte blastogenic responses to phytohaemagglutinin, concanavalin A, pokeweed mitogen and purified HBsAg. Only one individual had a positive delayed skin test reaction to HBsAg. This person had received the HBV vaccine and had high titres of anti-HBs in serum. However, neither this individual nor any other subject exhibited a positive lymphocyte blastogenic response to HBsAg in vitro. Thus, delayed hypersensitivity skin test reactivity to HBsAg was not detected after natural infection with HBV and was rarely present in hyperimmunized individuals. In vitro assays of immune responsiveness failed to demonstrate cellular immunity to HBsAg even in hyperimmunized persons. These studies provide no evidence that cell-mediated immunity to HBsAg plays a role in the immunopathogenesis of acute or chronic type B hepatitis.

Effects of interferon and adenine arabinoside treatment of hepatitis B virus infection on cellular immune responses

Fifteen patients with chronic hepatitis B were treated with adenine arabinoside (Ara-A) or human leukocyte interferon (HLI). Cellular immune response to hepatitis B virus surface antigen and antigens prepared from herpes simplex virus, varicella zoster virus, and cytomegalovirus was measured by a lymphocyte blast transformation assay and an assay for interferon production. Measurements were made before, during, and after antiviral treatment. Unlike patients convalescing from acute hepatitis B, only 2 of 15 patients with chronic hepatitis B had significant blast transformation to hepatitis B surface antigen. One such response occurred during the pretreatment period of HLI therapy, and the other was in a patient undergoing low-dose (<10(5) U/kg per day) HLI therapy. Mononuclear cell cultures were tested for interferon production in the presence of hepatitis B surface antigen. Cells from only 1 of 15 patients produced detectable levels of interferon. In contrast, all of these patients had normal cellular immune responses to herpesvirus antigens. Transformation responses to herpes antigens decreased three- to fivefold after patients were treated with >10(5) U of HLI per kg per day. Antiviral therapy with <10(5) U of HLI per kg per day or Ara-A did not produce a detectable depression of transformation response. Ara-A produced marked lymphocytopenia and a marked lymphocyte fragility after 5 or more days of therapy. In vitro Ara-A was toxic to lymphocytes at concentrations as low as 0.5 mug/ml. These changes in lymphocyte parameters may affect the outcome of antiviral therapy.

Immunological aspects of cryoprecipitates from the sera of chronic HBsAg carriers

The sera of chronic hepatitis B surface antigen (HBsAg) carriers and seropositive controls were examined for the presence of immune complexes by cryoprecipitation. Cryoprecipitates (CP) were tested for HBsAg, antibody to HBsAg (anti-HBs), major classes of immunoglobulins, components of the complement system, rheumatoid factor and the ability to activate the alternative pathway of the complement system. For this analysis the methods employed included: radioimmunoassay, reverse passive haemagglutination, immunofluorescence, sucrose density gradient ultracentrifugation, agar-gel diffusion, immunoelectrophoresis, counterimmunoelectrophoresis, latex agglutination, and a haemolytic method for the detection of the activation of the alternative pathway of the complement system. HBsAg was frequently observed in the CP from chronic HBsAg carriers. No anti-HBs activity was detected in the serum of chronic HBsAg carriers. However, the CP from a number of chronic HBsAg carriers contained immunoglobulins and components of the complement system in the absence of rheumatoid factor, anti-HBs activity and were able to activate the alternative pathway of the complement system. On immunoelectrophoresis, a component of the CP reacting with anti-IgG, ANTI-IgA and anti-HBs antisera and demonstrating an altered (faster) electrophoretic mobility was observed. The nature of the CP strongly suggests the presence of circulating immune complexes in asymptomatic chronic HBaAg carriers. These immune complexes may be important in the eventual expression and outcome of clinical disease in apparently healthy carriers of HBsAg.

Hepatitis B surface antigen-specific cell-mediated immune responses in human chronic hepatitis B surface antigen carriers

The presence of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs), hepatitis B e antigen (HBeAg) and antibody (anti-HBe), the nature of T-cell function, and specific cell-mediated immunity to HBsAg were determined and evaluated serially in groups of subjects with chronic HBsAg carrier states and in seronegative controls. The techniques of in vitro lymphocyte transformation, spontaneous rosette formation, radioimmunoassay, reverse passive hemagglutination, passive hemagglutination, rheophoresis, and liver function tests were employed for these studies. For the lymphocyte transformation assay, multiple concentrations of phytohemagglutinin and purified HBsAg were used as stimulants. Cell-mediated immunity to HBsAg was detectable in 50% of the chronic HBsAg carriers (responders) at one or more concentrations of HBsAg. The remaining carriers (nonresponders) and controls failed to manifest HBsAg-specific lymphocyte transformation activity. The profile of the responders was characterized by elevated serum glutamic pyruvic transaminase levels, the presence of anti-HBe, high HBsAg titers, and the conspicuous absence of HBeAg in the serum. The nonresponders were characterized by normal serum glutamic pyruvic transaminase levels, the presence of HBeAg and anti-HBe, and lower HBsAg titers. These observations demonstrate the presence of specific cell-mediated immunity to HBsAg in chronic HBsAg carriers who manifest biochemical evidence of liver disease.

Immune mechanisms and the action of interferon in chronic hepatitis B virus infection

Cytotoxic T lymphocytes can eliminate cells infected with hepatitis B virus. A defect of T lymphocyte-mediated cytolysis seems to exist in chronic hepatitis B infection. T cell-mediated lysis is dependent on HLA antigens of the infected host and this may explain the increased or decreased frequency of particular HLA antigens in chronic carriers of hepatitis B virus. This virus may decrease the concentration of HLA antigens expressed on liver cells. Interferon increases the HLA antigen expression on T lymphocytes and hepatocytes, thereby enhancing T lymphocyte-mediate lysis of infected liver cells and elimination of the hepatitis B virus.

Immune response to HBsAg and the spectrum of liver lesions in HBsAg-positive patients with chronic renal disease

Evidence of chronic hepatitis was found on histological examination in nine out of 15 patients positive for hepatitis-B surface antigen (HBsAg) who had either chronic renal failure or a functioning renal transplant. Cirrhosis had already developed in three of the patients, who deteriorated rapidly and died. Liver biopsies from the remaining 12 patients showed the features of chronic aggressive hepatitis in two, chronic persistent hepatitis in four, and minor histological lesions in six. The persistence of HBsAg in patients with renal failure or in those receiving immunosuppressive drugs after a transplant must indicate some impairment of the normal immune response to hepatitis-B viral antigens. Nevertheless, cellular or humoral immunity to HBsAg was detected in all eight patients with chronic hepatitis tested compared with only one out of five with minimal liver lesions, which suggests that the severity of the liver damage may be directly related to the degree of immunocompetence.

Detection of HBSAG in fixed liver tissue - use of a modified immunofluorescent technique and comparison with histochemical methods

A modified immunofluorescent technique was used for the detection of HBSAg in formalin-fixed liver tissue, thereby allowing retrospective examination of paraffin sections and avoiding the need to split the sample at the time of biopsy. Comparison with two other methods, involving either orcein staining or standard haematoxylin and eosin (H and E) preparation for ground glass hepatocytes, showed slightly fewer positive hepatocytes in individual biopsies with the latter stain, but the specificity of both methods was high. In a series of 146 seropositive and 74 seronegative patients with a variety of liver disorders, hepatocytes positive for HBSAg were found in only one of 55 patients with acute hepatitis type B, whereas large numbers of positive cells were seen in all 22 healthy carriers of the surface antigen. In the 69 patients with chronic persistent or chronic aggressive hepatitis, the frequency of positive biopsies was 86% and 85% respectively. The positive cells in these cases were, in comparison with healthy carriers of HBSAg, much fewer in number and were scattered in random fashion throughout the lobule rather than occurring in discrete clumps or sheets. This variation in the intrahepatic expression of HBSAg may reflect differences in the immune response to hepatitis B viral antigens.