In vitro response to HBsAg of peripheral blood lymphocytes from recipients of hepatitis B vaccine

Undetectable plasma HIV RNA load predicts success after hepatitis B vaccination in HIV-infected persons

Human immunodeficiency virus (HIV)-infected patients respond poorly to hepatitis B vaccination. Records of 194 HIV-infected patients were reviewed for factors associated with successful hepatitis B vaccination. Thirty-four patients (17.5%) developed a protective antibody response. In a logistic regression model, only a plasma HIV RNA level of <400 copies/mL at the time of vaccination was associated with a protective antibody response (P=.003).

Enumeration of hepatitis B surface antigen-specific B lymphocytes in responder and non-responder normal individuals vaccinated with recombinant hepatitis B surface antigen

Determination of the frequency of specific B lymphocytes has important implications for investigation of the immune response to different antigens and pathogens. Unresponsiveness to some viruses and antigens, such as hepatitis B virus (HBV) and its surface antigen (HBsAg), has been attributed to lack or insufficient production of the specific B-cell repertoire. In this study, peripheral blood B lymphocytes of 45 adult normal individuals vaccinated with recombinant hepatitis B vaccine were transformed with Epstein-Barr virus (EBV) and cultured at different dilutions on human fetal fibroblasts as a feeder layer. The vaccinees were classified into good, poor and non-responder groups. Following 2 to 3 weeks of incubation, culture supernatants were collected from wells containing transformed and proliferating B lymphocytes. The supernatants were subsequently screened for the presence of total immunoglobulin and antibody to HBsAg (anti-HBs) by enzyme-linked immunosorbent assay (ELISA). Accordingly, positive and negative wells were enumerated in each plate and the frequency of B lymphocytes producing anti-HBs antibody was estimated based on the Poisson statistical analysis. The total number of CD19+ B lymphocytes were counted in the peripheral blood of all subjects by flow cytometry. Our results demonstrated a similar precursor frequency of specific B lymphocytes in all subject groups before vaccine administration (< 2 x 10(-5)). Following vaccination, however, a significant increase in the number of specific B lymphocytes was observed in good-responder (1.5 x 10(-4)) and to a lesser extent poor-responder (3.5 x 10(-5)) individuals, but not in non-responders. These findings suggest a defect in either the primary B-cell repertoire or helper T-cell function in non-responder individuals.

Characterization of the T cell recognition of hepatitis B surface antigen (HBsAg) by good and poor responders to hepatitis B vaccines

To study the regulation of the human cellular immune response to HBsAg we produced a series of HBsAg-specific T cell lines from good and poor responders to the hepatitis B vaccine. All T cell lines expressed CD4 on their membrane and could therefore be considered of the helper/inducer phenotype. The different HBsAg-specific T cell lines were restricted by HLA-DRB5*0101, DRB1*1201, -DRB1*0701, -DRB1*0301, -DPB1*0201, -DPB1*0402, and -DPB1*0901. In good responders to the hepatitis B vaccine different HLA molecules could act as restricting element. In poor responders the diversity of HLA class II restriction determinants was more limited. This leads us to conclude that the immune response to HBsAg is multispecific and polyclonal in good responders and paucispecific and oligoclonal in poor responders to the hepatitis B vaccine. By using a panel of synthetic peptides representing selected sequences of the HBsAg, the fine specificities of each of these T cell lines could be determined. Strikingly, the majority of the identified T cell epitopes was located in and around the first hydrophobic transmembranous region of the HBsAg. This was observed in T cell lines from good and poor vaccine responders, without distinction. The remarkable T cell immunogenicity of this region may reside in its richness in binding motifs for a variety of HLA class II determinants.

A prospective study of in vitro anti-HBs producing B cells (spot-ELISA) following primary and supplementary vaccination with a recombinant hepatitis B vaccine in insulin dependent diabetic patients and matched controls

A prospective study of the immune response after hepatitis B vaccination was carried out in 32 insulin dependent diabetes mellitus (IDDM) patients and their age and sex matched healthy controls. A sensitive, immunoenzymatic technique was used, able to detect in vitro specific antibody production by mitogen stimulated individual B cells. In-vivo serologic response after vaccination with a standard scheme (0, 1 and 6 months) of 20 micrograms recombinant hepatitis B (HB) vaccine was significantly impaired in the IDDM patients both with respect to the number of nonresponders (25 versus 3%, P less than 0.05) and antibody titers reached (1,377 vs. 9,060 IU/L, P less than 0.05). The total number of in vitro IgM- and IgG-class immunoglobulin producing B cells as detected by the spot-ELISA, was found to be comparable in both groups. Specific IgG anti-HBs (and to a lesser extent IgM anti-HBs) showed impairment in the diabetic population as a whole. The number of IgG anti-HBs producing B cells was markedly depressed one month following vaccination, which is probably a reflection of homing of B cells outside the circulation. Responding subjects were identified early during their vaccination by the detection of in vitro anti-HBs production using the spot-ELISA. Non-responding healthy subjects and IDDM patients as a group showed a low number of IgG anti-HBs spots, suggesting a reduced specific memory B cell frequency. In 13 of 15 hypo- and nonresponders with positive IgG anti-HBs spots supplementary vaccination(s) resulted in improved anti-HBs levels.

Mutations that change the immunological subtype of hepatitis B virus surface antigen and distinguish between antigenic and immunogenic determination

The molecular basis of the d or y immunological subtype of hepatitis B virus (HBV) surface antigen (HBsAg) has been investigated by mutation of specific amino acid residues. When combined with substitution of serine 113 by threonine, replacement of arginine 122 by lysine or of tyrosine 134 by phenylalanine, or both of these changes, altered the antigenic subtype of HBsAg from y+d- to y+d+. These same mutations had a more dramatic effect on the subtype of antibodies induced by the antigens, a combination of all three mutations completely changing the subtype from y to d. Our study thus identifies residues in HBsAg that not only affect the subtype but discriminate between changes in antigenic and immunogenic behaviour. It also shows how the y and d subtypes may be manifest by the same molecule.

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.

Modulation of the immunological response to hepatitis B virus by antibodies

Antibodies to HBsAg of IgG class enhanced the helper activity of a human T cell clone to promote the in vitro synthesis of immunoglobulins by autologous B lymphocytes. Using two different assay systems, the effect of antigen-specific antibodies on the helper function of a HBsAg-reactive T cell clone was studied. The monoclonal antibody to HBsAg A5C3 (IgG) increased significantly the T cell-dependent production of immunoglobulins by Staphyloccocus aureus-stimulated autologous B lymphocytes. Furthermore, the results obtained with a different type of assay showed that A5C3 also increased the synthesis of antibody to HBsAg by the autologous B cells in the presence of HBsAg and the helper T cell clone. On the other hand, when the monoclonal antibody to HBsAg of IgM class, H5D3 or the F(ab')2 fragment of A5C3 were tested, no significant enhancement of the helper activity of the T cell clone was observed. Experiments performed in mice showed that the in vivo antibody to HBsAg response to low concentrations of HBsAg was significantly enhanced by mixing this antigen with monoclonal antibody to HBsAg of IgG class. No effect was observed when a monoclonal antibody to HBsAg of IgM class was used to prepare the immune-complexed immunogen. The results presented here suggest that antibodies play a critical role in their own production through regulating the activity of helper T cells. This phenomenon might contribute to the increased antibody synthesis of in vivo secondary immune responses and could be of use in designing more efficient vaccine programs in man.

Human T cell clones reactive with hepatitis B virus (HBV) surface antigen from a HBV vaccine recipient

Five T-cell clones reactive with HBsAg were obtained from peripheral blood lymphocytes of a HBV vaccine recipient by means of in vitro stimulation of lymphocytes for 5 days by HBsAg and subsequent re-culture of lymphocytes with HBsAg, feeder cells and T cell growth factor (TCGF) for 6 days, followed by the limiting dilution method. Clones, and subclones derived from one original clone showed a specific proliferative response to HBsAg in the presence of autologous feeder cells but not to unrelated antigens, such as influenza virus antigens, herpes simplex antigens, toxoplasma antigens, and PPD. All clones were found to have a surface marker of helper/inducer phenotype, Leu 1+, Leu 2a-, and Leu 3a+, detected by an indirect immunofluorescence method. These clones, however, did not show a substantial helper effect for in vitro anti-HBs production by autologous B cells. This suggests that the mechanism of the helper effect by specific T-cell clones is implicated, and functions of such clones other than specific helper effect on antibody-producing B cells must be considered.

In vitro synthesis of antibody to hepatitis B virus antigen by circulating lymphocytes from chronic HBsAg carriers and patients with acute hepatitis B

It is not clear what determines the outcome of hepatitis B surface antigen (HBsAg) infection, although evidence suggests that the absence of antibody to HBsAg (anti-HBs) is responsible for the development of the carrier state. The synthesis of immunoglobulin G (IgG), anti-HBs and antibody to hepatitis B core antigen (anti-HBc) was measured in pokeweed mitogen-stimulated cultures of peripheral blood mononuclear cells from 12 chronic HBsAg carriers, 5 patients with acute hepatitis B (AHB) during recovery phase and 11 subjects with anti-HBs in serum (controls). All 3 groups showed similar amounts of IgG synthesis. Anti-HBc was detectable in lymphocyte cultures of 10 of 12 chronic HBsAg carriers and 2 of 5 AHB patients, but in none of the controls. Anti-HBs was found in cultures from 6 of 11 controls, and not in carriers or AHB patients. Both in vitro anti-HBc and anti-HBs levels correlated significantly with serum titers of anti-HBc and anti-HBs respectively. B cells from controls cocultured with irradiated (helper) T cells from carriers and AHB patients produced anti-HBs normally. In contrast, B cells from 11 of 12 carriers and 3 of 5 AHB patients cocultured with irradiated control T cells did not synthesize detectable amounts of anti-HBs although they synthesized normal amounts of IgG and anti-HBc. T cells from 8 of 12 carriers and all AHB patients suppressed anti-HBs synthesis by mixtures of control B cells and control irradiated T cells, but these T cells did not affect IgG synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of the human immune response to HBsAg: effects of antibodies and antigen conformation in the stimulation of helper T cells by HBsAg

The role of accessory cells (antigen-presenting cells) in binding HBsAg in the response of human T cells to this antigen was studied. Antibodies to HBsAg of IgG class increased significantly the amount of HBsAg that was captured and internalized by accessory cells in vitro. On the other hand, antibodies to HBsAg of IgM class or the F(ab')2 and Fab fragments of antibodies to HBsAg of IgG class did not modify the amount of HBsAg associated to these cells. HBsAg that was subjected to various denaturing treatments (acid, organic solvents, urea and heat) was compared for its capacity to react with antibody to HBsAg and stimulate the response of helper T lymphocytes. Results presented here indicate that HBsAg denatured by treatment with formic acid was captured by accessory cells and presented to the T cells much more efficiently than the native HBsAg. These results suggest that the response of helper T lymphocytes to some antigens such as HBsAg can be affected greatly by the presence of antibodies or the antigens' conformation.