Antigen-specific T-cell responses in humans after intranasal immunization with a meningococcal serogroup B outer membrane vesicle vaccine

We have studied the ability of the Norwegian group B meningococcal outer membrane vesicle (OMV) vaccine, when administered intranasally without adjuvant, to induce T-cell responses in humans. A group of 12 vaccinees was immunized with four doses of OMVs (250 micrograms of protein/dose) at weekly intervals, and a single booster dose was given 5 months later. In vitro T-cell proliferation in response to the OMV vaccine, purified PorA (class 1) protein, PorB (class 3) protein, and one unrelated control antigen (Mycobacterium bovis BCG) was measured by [3H]thymidine incorporation into peripheral blood mononuclear cells obtained from the vaccinees before and after the immunizations. The nasal OMV immunizations induced antigen-specific T-cell responses in the majority of the vaccinees when tested against OMVs (7 of 12) and the PorA antigen (11 of 12). None of the vaccinees showed a vaccine-induced T-cell response to the PorB antigen after the initial four doses. Although some individuals responded to all the vaccine antigens after the booster dose, this response was not significant when the vaccinees were analyzed as a group. We have also demonstrated that the PorA antigen-specific T-cell responses correlated with anti-OMV immunoglobulin A (IgA) levels in nasal secretions, with anti-OMV IgG levels in serum, and with serum bactericidal activity. In conclusion, we have shown that it is possible to induce antigen-specific T-cell responses in humans by intranasal administration of a meningococcal OMV vaccine without adjuvant.     

CD4(+) T-lymphocyte and immunoglobulin G2 responses in calves immunized with Anaplasma marginale outer membranes and protected against homologous challenge

Protective immunity against the ehrlichial pathogen Anaplasma marginale has been hypothesized to require induction of immunoglobulin G2 (IgG2) antibody against outer membrane protein epitopes and coordinated activation of macrophages for phagocytosis and killing. In the present study, cell-mediated immune responses, including induction of IgG isotype switching, were characterized in calves immunized with purified outer membranes of the Florida strain of A. marginale. Importantly, these calves were subsequently shown to be protected upon experimental challenge with the Florida strain, and calves which developed the highest IgG2 titers were completely protected against infection. Peripheral blood mononuclear cells (PBMC) obtained after immunization proliferated strongly in response to both whole A. marginale homogenates and purified outer membranes, and this responsiveness persisted until the time of challenge. Responding cells were shown to be CD4(+) T cells, and CD4(+) T-cell lines cultured for 2 to 4 weeks also proliferated specifically in response to A. marginale and produced high titers of gamma interferon. The helper T-cell response included recognition of conserved epitopes, as PBMC proliferation was stimulated by the homologous Florida strain, four genetically distinct A. marginale strains, and Anaplasma ovis. The outer membrane proteins stimulating the PBMC responses in protected calves included major surface proteins (MSPs) MSP-1, MSP-2, and MSP-3, which were previously shown to induce partial protection against infection. These studies demonstrate, for the first time, potent helper T-cell responses in cattle protectively immunized with outer membranes against A. marginale challenge and identify three MSPs that are recognized by immune T cells. These experiments provide the basis for subsequent identification of the helper T-cell epitopes on MSP-1, MSP-2, and MSP-3 that are needed to evoke anamnestic antibody and effector T-cell responses elicited by protein or nucleic acid immunization.     

Specificity of human bactericidal antibodies against PorA P1.7,16 induced with a hexavalent meningococcal outer membrane vesicle vaccine

A set of isogenic strains was constructed from the meningococcal reference strain H44/76 (B:15:P1.7,16) which differed only in their outer membrane protein (OMP) compositions. First, three isogenic strains lacking the expression of either class 3 (PorB) or class 4 (RmpM) OMP or both were obtained. Second, three isogenic class 1 OMP loop-deficient strains of H44/76 lacking the predicted loop 1 or 4 or both of class 1 OMP (PorA) were obtained. Third, three isogenic class 1 OMP strains which differed by point mutations in the predicted loop 4 of subtype P1.16 were constructed. Strains were constructed through transformation with gene constructs made in Escherichia coli and their homologous recombination into the meningococcal chromosome. This study describes the contribution of one of the six class 1 OMPs, PorA P1.7,16, in the development of bactericidal antibodies after a single immunization of adult volunteers with 50 or 100 micrograms of protein within a hexavalent PorA outer membrane vesicle vaccine. PorA-, PorB-, and RpmM-deficient isogenic strains were used to define the human immune response against PorA. The loop-deficient isogenic strains were used to define the contribution of loops 1 and 4 of PorA in the development of bactericidal anti-PorA antibodies. The isogenic strains carrying a point mutation in loop 4 were used to study the cross-reactivity of the induced bactericidal antibodies against target strains showing microheterogeneity. The results indicate that a single immunization with the hexavalent PorA vaccine induced a dose-dependent bactericidal immune response, which is directed mainly against PorA. The epitope specificity of antibodies is directed mostly against loop 1, although loop 4 and as-yet-unidentified epitopes of PorA P1.7,16 are also involved.     

Aberrant T-cell function in vitro and impaired T-cell dependent antibody response in vivo in vitamin A-deficient rats

We have previously reported that vitamin A deficiency resulted in a reduced IgA antibody response to cholera toxin (CT) after per-oral immunization. In the present investigation we have studied the in vivo and in vitro immune response in vitamin A-deficient rats to two parenterally applied antigens, beta-lactoglobulin (beta-LG) and picrylsulphonic acid (TNP)-Ficoll. The serum IgG and IgM antibody responses to the T-cell dependent antigen beta-LG were significantly lower in the vitamin A-deficient rats than in the pair-fed control rats. No such differences were seen with the IgG and IgM responses to the T-cell independent antigen TNP-Ficoll. However, the biliary IgA and the serum IgE antibodies against both antigens were decreased in the vitamin A-deficient rats. In vitro lymphocyte stimulation with concanavalin A (Con A) or beta-LG gave higher T-cell proliferation rates in the vitamin A-deficient than in the control rats. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) levels in supernatants from Con A-stimulated mesenteric lymph node cells were also higher in the vitamin A-deficient rats, while IL-6 levels were decreased, which is consistent with an up-regulated Th1 activity. Proliferation studies on purified accessory cells and T cells from the deficient and the control rats, mixed in different combinations, showed that the T cells, but not the accessory cells, were disturbed in the vitamin A-deficient rats. Despite the increased T-cell activity in vitro the vitamin A-deficient rats had a lower delayed-type hypersensitivity (DTH) reaction than the pair-fed control rats. In conclusion, the increased IL-2 and IFN-gamma levels may reflect an up-regulation of Th1 cell function, while the decreased IgA, IgE and IL-6 levels indicate a suppression of Th2 cells. The disturbed T-lymphocyte function is manifested in vivo as a decreased DTH reaction and suppressed antibody production, the latter possibly due to a lack of B-cell switching and proliferation factors in vitamin A-deficient rats.     

Specific immune response in adult medical personnel immunized with acellular pertussis vaccine with special emphasis on T helper cell response

Recent epidemiologic data have indicated that adults are the most important reservoir that transmit pertussis to children. However, conventional whole cell pertussis vaccine is contraindicated in adults and children over 7 years of age because of the unacceptably high rate of adverse reactions. The aim of this study is to evaluate the specific cellular immune responses and adverse reactions to a less reactogenic acellular pertussis vaccine in adult volunteers. Eighty healthy medical personnel in Chang Gung Children's Hospital were enrolled. Volunteers in each group received: (1) Td + full strength acellular pertussis vaccine (PT, 1 microgram/0.5 ml; FHA, 4 micrograms/0.5 ml); (2) Td + half strength acellular pertussis vaccine; (3) Td alone. Lymphocyte phenotypic analysis, antigen-specific antibody titers, antigen-specific proliferative response and cytokine levels were evaluated before and 1 month after vaccination. Our data revealed: (1) the adverse reactions were minimal; (2) phenotypic analysis showed no non-specific activation of helper T or memory T cell after vaccination; (3) both PT and FHA-specific antibody titers increased significantly after vaccination, (4) PT antigens had a mitogenic effect on cord blood mononuclear cells and peripheral blood mononuclear cells of the adult volunteers; (5) FHA-specific T cell proliferative responses significantly increased after vaccination; (6) the cytokine production pattern showed predominant activation of Th 1 cells as reflected in increased production of gamma-IFN after vaccination. Acellular pertussis vaccine can effectively induce both humoral and cellular immune response in adults.     

Differential kinetics and distribution of antibodies in serum and nasal and vaginal secretions after nasal and oral vaccination of humans

Although nasal vaccination has emerged as an interesting alternative to systemic or oral vaccination, knowledge is scarce about the immune responses after such immunization in humans. In the present study, we have compared the kinetics and organ distribution of the antibody responses after nasal and oral vaccination. We immunized female volunteers nasally or orally with cholera toxin B subunit (CTB) and determined the specific antibody levels in serum and nasal and vaginal secretions, as well as the number of circulating antibody-secreting cells, before immunization and 1, 2, 3, 6, and 26 weeks thereafter. Nasal vaccination induced 9-fold CTB-specific immunoglobulin A (IgA) and 56-fold specific IgG antibody increases in nasal secretions, whereas no significant IgA increase was seen after oral vaccination. Both oral and nasal vaccination resulted in 5- to 6-fold CTB-specific IgA and 20- to 30-fold specific IgG increases in vaginal secretions. Strong serum responses to CTB were also induced by both routes of vaccination. A notable difference between nasal and oral vaccination was that the nasal route elicited a specific antibody response with a later onset but of much longer duration than did the oral route. We conclude from this study that the nasal route is superior to the oral route for administering at least nonliving vaccines against infections in the upper respiratory tract, whereas either oral or nasal vaccination might be used for eliciting antibody responses in the female genital tract.     

Induction of immune responses to HIV-1 by canarypox virus (ALVAC) HIV-1 and gp120 SF-2 recombinant vaccines in uninfected volunteers. NIAID AIDS Vaccine Evaluation Group

OBJECTIVE: To determine the ability of live attenuated canarypox virus expressing HIV antigens to induce CD8+ cytotoxic T-cell responses and to prime for neutralizing antibody responses to boosting with purified recombinant gp120 subunit vaccine. DESIGN: A prospective, double-blind, randomized, immunogenicity and safety study was conducted in healthy adults at low risk for acquiring HIV infection and who were seronegative for HIV. METHODS: CD8+ cytotoxic T-cells directed against Env or Gag expressing target cells were measured after live recombinant canarypox-HIV-1 vaccine priming (vaccine given at days 0, 7, 14 and 21). Neutralizing antibodies were measured after subunit boosting (vaccine given at days 28 and 84). RESULTS: CD8+ CTL were induced in 64% of volunteers by the live recombinant canarypox-HIV-1 vaccine. All volunteers who received two doses of subunit vaccine after live recombinant canarypox priming developed neutralizing antibodies directed against laboratory strains of HIV-1 and seven out of eight volunteers tested developed neutralizing antibodies to the primary isolate, BZ167, but to none of eight other primary isolates. Unprimed controls had low or absent neutralizing antibodies after two doses of subunit vaccine. CONCLUSIONS: The live canarypox vector was safe, stimulated cytotoxic T-cells and primed for a vigorous neutralizing antibody response upon boosting with subunit gp120 vaccine. This vaccine combination should be evaluated further for inducing protection against HIV infection.     

Intranasal immunization confers protection against murine Pneumocystis carinii lung infection

To evaluate the feasibility of mucosal immunization against Pneumocystis carinii (Pc) experimental infection, female BALB/c mice were intranasally immunized three times with soluble Pc antigens plus cholera toxin fraction B (Pc-CTB); control groups received either Pc antigen, CTB, or phosphate-buffered saline (PBS) alone. Two weeks after the last immunization, five animals from each group were sacrificed, and cellular and humoral immune responses were evaluated. The remaining five mice were CD4 depleted using a monoclonal antibody against mouse CD4 and inoculated with viable Pc. Significantly higher specific lymphoproliferative responses from tracheobronchial lymph node cells, immunoglobulin M (IgM) and IgG antibody levels in serum, and bronchoalveolar lavage (BAL)-derived IgA antibody concentrations were observed in the Pc-CTB group of mice relative to control groups (P < 0.01). Five weeks after challenge, no Pc organisms were observed in the lung smears of the Pc-CTB group, while the animals receiving antigen, adjuvant, or PBS had progressively higher numbers of Pc microorganisms. By Western blot analysis, a strongly reactive 55- to 60-kDa antigen was recognized by BAL IgA and by serum IgG. In summary, mucosal immunization elicited specific cellular and humoral immune responses and protected against Pc lung infection after immunosuppression.     

Kinetics of hepatitis B surface antigen-specific immune responses in acute and chronic hepatitis B or after HBs vaccination: stimulation of the in vitro antibody response by interferon gamma

Because cellular and humoral immune responses against the hepatitis B virus (HBV) surface antigen (HBs) might be crucial to overcome HBV infection, HBs-specific B- and T-cell responses of HBV patients and HBs vaccine recipients were analyzed quantitatively and functionally. In patients with acute hepatitis B (AHB), transient high anti-HBs-secreting B-cell frequencies were observed early after clinical onset, whereas 1 patient who probably developed chronic infection and chronic HBV carriers had absent or weak B- and T-cell responses. In HBs vaccine recipients, maximal HBs-specific B- and T-cell responses were detected after the first injection that decreased gradually before anti-HBs antibodies appeared in serum. Years after vaccination, anti-HBs-secreting B cells were enriched in the bone marrow. After in vitro stimulation with HBsAg, peripheral blood mononuclear cells (PBMC) of only 1 of 5 acute and 1 of 6 chronic HBV patients, but of all 6 vaccine recipients, secreted varying amounts of interferon gamma (IFN-gamma), but no interleukin-4 (IL-4) or IL-5. Furthermore, the addition of IFN-gamma, but not of IL-2, -4, -12, or IFN-alpha, resulted in strong increases of anti-HBs-secreting B cells in vaccine recipients and chronic carriers. In conclusion, circulating anti-HBs-secreting B cells were significantly higher in early acute hepatitis B or early after HBs vaccination than in chronic hepatitis B and decreased in the follow-up as a result of compartmentalization to lymphoid tissues. Release of IFN-gamma by antigen-stimulated T cells might be critical for anti-HBs formation.     

Live attenuated simian immunodeficiency virus (SIV)mac in macaques can induce protection against mucosal infection with SIVsm

OBJECTIVE: To investigate whether vaccination of macaques with attenuated simian immunodeficiency virus (SIV)macC8 could induce long-term protective immunity against rectal exposure to SIVsm and intravenous exposure to the more divergent HIV-2. DESIGN AND METHODS: Eight months after vaccination with live attenuated SIVmacC8, four cynomolgus monkeys were challenged with SIVsm intrarectally and another four vaccinated monkeys were challenged with HIV-2 intravenously. Sixteen months after SIVmacC8 vaccination, another two monkeys were challenged with SIVsm across the rectal mucosa. Two vaccinees shown to be protected against SIVsm were rechallenged 8 months after the first challenge. Ten naive animals were used as controls. Serum antigenaemia, virus isolation, antibody responses, cell-mediated immunity and CD4+ and CD8+ T-cell subpopulations were monitored. PCR-based assays were used to distinguish between virus populations. RESULTS: At the time of challenge, eight out of 10 vaccinees were PCR-positive for SIVmacC8 DNA but no virus could be isolated from peripheral blood mononuclear cells. After SIVsm challenge, three out of six vaccinees were repeatedly SIVsm PCR-negative. In one of the three infected monkeys, the challenge virus was initially suppressed but the monkey ultimately developed AIDS after increased replication of the pathogenic virus. Rechallenged monkeys remained protected. All HIV-2-challenged vaccinees became superinfected. All controls became infected with either SIVsm or HIV-2. At the time of challenge the vaccinees had neutralizing antibodies to SIVmac but no demonstrable cross-neutralizing antibodies to SIVsm or HIV-2. Titres of antigen-binding or neutralizing antibodies did not correlate with protection. Cytotoxic T-cell responses to SIV Gag/Pol and virus-specific T-cell proliferative responses were low. CONCLUSION: The live attenuated SIVmacC8 vaccine was able to induce long-term protection against heterologous intrarectal SIVsm challenge in a proportion of macaques but not against the more divergent HIV-2, which was given intravenously.     

Vaccine-induced, pseudorabies virus-specific, extrathymic CD4+CD8+ memory T-helper cells in swine

Pseudorabies virus (PRV; suid herpesvirus 1) infection causes heavy economic losses in the pig industry. Therefore, vaccination with live attenuated viruses is practiced in many countries. This vaccination was demonstrated to induce extrathymic virus-specific memory CD4+CD8+ T lymphocytes. Due to their major histocompatibility complex (MHC) class II-restricted proliferation, it is generally believed that these T lymphocytes function as memory T-helper cells. To directly prove this hypothesis, 15-amino-acid, overlapping peptides of the viral glycoprotein gC were used for screening in proliferation assays with peripheral blood mononuclear cells of vaccinated d/d haplotype inbred pigs. In these experiments, two naturally processed T-cell epitopes (T1 and T2) which are MHC class II restricted were identified. It was shown that extrathymic CD4+CD8+ T cells are the T-lymphocyte subpopulation that responds to epitope T2. In addition, we were able to show that cytokine secretion can be induced in these T cells through recall with inactivated PRV and demonstrated that activated PRV-primed CD4+CD8+ T cells are able to induce PRV-specific immunoglobulin synthesis by PRV-primed, resting B cells. Taken together, these results demonstrate that the glycoprotein gC takes part in the priming of humoral anti-PRV memory responses. The experiments identified the first T-cell epitopes so far known to induce the generation of virus-specific CD4+CD8+ memory T lymphocytes and showed that CD4+CD8+ T cells are memory T-helper cells. Therefore, this study describes the generation of virus-specific CD4+CD8+ T cells, which is observed during vaccination, as a part of the potent humoral anti-PRV memory response induced by the vaccine.     

IL-12 is a potent neonatal vaccine adjuvant

Neonatal animals show generally poor responsiveness to foreign antigens and are known to display polarized expression of Th2-like cytokines and antibody responses. We now report that newborn mice display a reduction in peripheral expression of the Th1-inducing cytokine, IL-12. Attempts to overcome this decrease by immunization and treatment with IL-12 within 24 h of birth resulted in elevated levels of IFN-gamma and IL-10 mRNA in the spleens of mice compared to animals exposed to antigen only. Moreover, such animals showed dramatic enhancement of IgG2a and IgG2b antibody levels upon adult challenge compared to mice primed with antigen alone. These effects appeared to be due to induction of neonatal B cell memory. IgG1 antibody levels, a measure of Th2 activity, were unaffected or even somewhat enhanced by neonatal IL-12 treatment. Taken together, these results provide evidence that IL-12 administration induces a Th1-like cytokine response in newborns and causes priming for heightened memory antibody responses in vivo. Our findings suggest the use of IL-12 as a vaccine adjuvant in neonates for inducing protection against common childhood pathogens.     

Serologic responses of young colostrum fed dairy calves to antigens of Pasteurella haemolytica A1

The potential and limitations of early calfhood vaccination to induce active immunity to Pasteurella haemolytica A1 in conventional colostrum fed calves were investigated. Holstein dairy calves (n = 29) were vaccinated at 2 and 4 weeks of age, or at 6 and 8 weeks of age with a commercial culture supernatant vaccine (Presponse, Langford Inc., Guelph, Ont., Canada), or remained unvaccinated as controls. Serum antibody titres were measured using an indirect bacterial agglutination assay, a leukotoxin neutralization assay, and enzyme immunoassays for antibodies of the IgM, IgG1, and IgG2 isotypes binding purified capsular polysaccharide of P. haemolytica A1. Seroconversion (fourfold or greater increase in serum antibody titre) rates were compared using Fisher's exact test. The effects of passive antibody titres and age on response to vaccination were assessed by linear modelling. Vaccination at 2 and 4 weeks of age was associated with 40%, and 0% of calves seroconverting on the basis of agglutinating antibody titres, and leukotoxin neutralizing titres respectively, and 50%, 0%, and 0% seroconverting on the basis of IgM, IgG1 and IgG2 antibodies to capsular polysaccharide, respectively. Agglutinating antibody responses were not related to prevaccination antibody titres, or to age at vaccination. Higher responses (p = 0.08) to leukotoxin were observed in older calves (after taking differences in prevaccination titres into account). Statistical analyses of responses to capsular polysaccharide among calves with comparable prevaccination IgG1 antibody titres revealed significantly higher IgM, IgG1 and IgG2 responses in older calves. Rising titres of IgM antibodies in nonvaccinated calves after 5 weeks of age suggest natural exposure to P. haemolytica A1 or antigens which result in serologic cross-reactions as a means of priming immune responses.     

The effect of T cell depletion with Campath-1M on immune reconstitution after chemotherapy and allogeneic bone marrow transplant as treatment for leukaemia

Thirty asthmatic children were examined allergic reaction against egg white, gelatin and vaccine solution before and after vaccination using skin prick test. We also measured the levels of specific IgE and IgG antibody against gelatin. The changes in clinical symptoms before and after vaccination were investigated in 25 asthmatic children by evaluating symptom and treatment score. The results were as follows; 1. In one subject who had delayed type of skin reaction to gelatin, the adverse reaction was also recognized at the skin site around 24 hrs after vaccination. In this subject, the levels of serum specific IgE and IgG to gelatin became positive after 5 months. 2. Specific IgE antibodies to gelatin were not detected in all subjects before and after vaccination. 3. The mean values of asthma symptom score before and after vaccination were 3.3 +/- 4.2 and 1.5 +/- 3.3 respectively. Those of treatment score before and after vaccination were 75.6 +/- 35.2 and 76.0 +/- 35.0 respectively. These results suggest that skin testing with gelatin and vaccine solution is useful as a screening method for predicting adverse reactions in asthmatic children and that influenza vaccination can be performed safely in skin test negative children.     

Antiviral immune responses in CTLA4 transgenic mice

The role of B7 binding CD28 in the regulation of T- and B-cell responses against viral antigens was assessed in transgenic mice expressing soluble CTLA4-Hgamma1 (CTLA4-Ig tg mice) that blocks B7-CD28 interactions. The results indicate that transgenic soluble CTLA4 does not significantly alter cytotoxic T-cell responses against replicating lymphocytic choriomeningitis virus (LCMV) or vaccinia virus but drastically impairs the induction of cytotoxic T-cell responses against abortively replicating vesicular stomatitis virus (VSV). While the T-independent neutralizing immunoglobulin M (IgM) responses were within normal ranges, the switch to IgG was reduced 4- to 16-fold after immunization with abortively replicating VSV and more than 30-fold after immunization with an inert VSV glycoprotein antigen in transgenic mice. IgG antibody responses to LCMV, as detected by enzyme-linked immunosorbent assay and by neutralizing action, were reduced about 3- to 20-fold and more than 50-fold, respectively. These results suggest that responses in CTLA4-Ig tg mice are mounted according to their independence of T help. While immune responses to nonreplicating or poorly replicating antigens are in general most dependent on T help and B7-CD28 interactions, they are most impaired in CTLA4-Ig tg mice. The results of the present experiments also indicate that highly replicating viruses, because of greater quantities of available antigens and by inducing as-yet-undefined factors and/or cell surface changes, are capable of compensating for the decrease in T help caused by the blocking effects of soluble CTLA4.     

gamma/delta T cell-deficient mice have impaired mucosal immunoglobulin A responses

Mucosal tissues of mice are enriched in T cells that express the gamma/delta T cell receptor. Since the function of these cells remains unclear, we have compared mucosal immune responses in gamma/delta T cell receptor-deficient (TCRdelta-/-) mice versus control mice of the same genetic background. The frequency of intestinal immunoglobulin (Ig) A plasma cells as well as IgA levels in serum, bile, saliva, and fecal samples were markedly reduced in TCRdelta-/- mice. The TCRdelta-/- mice produced much lower levels of IgA antibodies when immunized orally with a vaccine of tetanus toxoid plus cholera toxin as adjuvant. Conversely, the antigen-specific IgM and IgG antibody responses were comparable to orally immunized control mice. Direct assessment of the cells forming antibodies against the tetanus toxoid and cholera toxin antigens indicated that significantly lower numbers of IgA antibody-producing cells were present in the intestinal lamina propria and Peyer's patches of TCRdelta-/- mice compared with the orally immunized control mice. The selective reduction of IgA responses to ingested antigens in the absence of gamma/delta T cells suggests a specialized role for gamma/delta cells in mucosal immunity.     

The immunotargeting approach to adjuvant-independent subunit vaccine design

Recently there has been considerable interest in exploring adjuvant-independent approaches to the enhancement of immunogenicity. One strategy which has emerged in response to this need is the immunotargeting approach to subunit vaccine design. Immunotargeting involves the conjugation of non-self antigens to monoclonal antibodies specific for cell surface determinants (e.g. class II MHC) on antigen presenting cells in vivo. Saline injections of these immunoconjugates have been shown to promote significant IgG responses to the delivered antigens in a number of different animal model studies. Oral and nasal immunizations in mice with anti-class II MHC immunoconjugates induce both secretory IgA and systemic IgG responses. Recombinant anticlass II MHC antibodies with defined B-cell and T-cell epitopes incorporated into their primary sequence have recently been used to induce epitope specific antibody responses in macaques. Thus the potential now exists for the rational design of adjuvant-independent human vaccine candidates based on a recombinant immunotargeting anti-body framework.     

How possible is the prevention of polycystic ovary syndrome development in adolescent patients with early onset of hyperandrogenism

OBJECTIVE: To investigate the variation in immune competence of two Australian pig breeds. DESIGN: A panel of immune tests were used to assess breed and sire differences in weaner piglets of Large White and Duroc breeds. PROCEDURE: All piglets were immunised against porcine leptospirosis. Blood samples were taken for studies on lymphocyte phenotypes, mitogenic responses of blood cells and serological analysis. RESULTS: Significantly larger blood leucocyte numbers were found in Large White piglets compared with Duroc piglets after vaccinations. No significant difference in concanavalin A induced blood cell proliferation was found between these two breeds before or after vaccinations. Some significant breed variation in blood lymphocyte phenotypes was found. While the age-related changes of lymphocyte phenotypes were similar for the two breeds, the Large White breed had significantly larger numbers of CD2+ and CD4+ cells than the Duroc breed after the two vaccinations. There were also significant sire effects on CD8+ cells within the Large White breed after the first vaccination. No significant breed difference was detectable in serum IgG concentrations but sire differences within each breed before the primary vaccination were found. The serum antibody response to vaccination against leptospirosis was generally small, and showed no variations due to either breed or sire. No gender effects were found during the entire study. CONCLUSION: The study demonstrated significant differences in some important immune components of the pig breeds studied. This may in turn indicate the variation in their immune competence or disease resistance. However, further investigation into the heritability and correlation with specific immune responses is required.     

CD40 cross-linking inhibits specific antibody production by human B cells

Ligation of CD40 on B cells is a co-stimulatory signal for proliferation, antibody secretion, heavy chain switching and rescue from apoptosis after somatic mutation in the germinal centre. The importance of these manifold responses to CD40 activation for humoral immunity is exemplified by the inability of boys with X-linked hyper IgM syndrome to make IgG, IgE or IgA due to a mutation in in the gene coding for CD40 ligand (CD40L). In the present study, we have investigated the effect of CD40 ligation on specific antibody production by human B cells to influenza virus. The antibody response was T cell dependent and specific for the strain of influenza virus used as antigen. Addition of either CD40 mAb or recombinant trimeric CD40L profoundly inhibited specific antibody production. Antibody production by unseparated tonsillar mononuclear cells and by T-depleted B cells stimulated with antigen in the presence of T cell replacing factor were equally inhibited with CD40 antibody showing that the effect was due to ligation of CD40 on B cells rather than blocking of T cell help. The specific antibody detected in these experiments was mostly IgG with little or no IgM and was obtained from surface IgM B cells consistent with activation of a secondary (memory) response. Co-stimulation of tonsillar B cells with CD40 antibody and anti-IgG induced proliferation of IgG+ B cells. These results suggest that CD40 ligation can inhibit specific antibody responses and stimulate proliferation in the same IgG+ (memory) B cell subpopulation. Addition of CD40 antibody during the first 24-48 h of the response was required for inhibition, suggesting that the effect was on early B cell activation and/or proliferation required for antibody production. There was no correlation, however, between the ability of CD40 mAb to stimulate proliferation and inhibit antibody production. We suggest that early activation of CD40 in the specific antibody response inhibits the formation of plasma cells and promotes instead the generation of memory cells.