The specificity of the antibody response to internal antigens of Ascaris: heterogeneity in infected humans, and MHC (H-2) control of the repertoire in mice.

Children from an area of Africa endemic for the large roundworm of humans, Ascaris lumbricoides, were found to vary considerably in the specificity of their serum IgG response to the internal antigens of the parasite. This was particularly noticeable for responses to a 14-kD protein (ABA-1) of the parasite that has previously been shown to be the subject of a strong IgE antibody response in infected animals. The possibility that this heterogeneity in immune repertoire has a genetic basis was explored in inbred mice infected with Ascaris suum. This showed that no strain responded to all the potential antigens, that the recognition profiles of strains bearing independent haplotypes were unique, and only H-2-identical strains had responses of similar specificities. Major histocompatability complex (MHC) restriction was confirmed using H-2-congenic animals on BALB and B10 backgrounds, which responded according to their H-2 haplotype. It is likely, therefore, that it is the MHC which controls the repertoire to Ascaris antigens in infected people. If this is so, then there will be implications for immunopathology associated with ascariasis, and possibly also for resistance and susceptibility to infection.     

Antigen-specific modulation of murine IgE and IgG2a responses with glutaraldehyde-polymerized allergen is independent of MHC haplotype and Igh allotype.

C57BL/6 mice treated with high Mr, glutaraldehyde-polymerized ovalbumin of highly restricted heterogeneity (termed OVA-POL) exhibit IgE responses upon later exposure to unmodified OVA which, at peak, are 1-3% of those observed in untreated controls. Concomitantly, anti-OVA IgG2a responses are elevated 250-1000-fold via an interferon-gamma (IFN-gamma)-dependent mechanism (ref. 4). Here, the impact of OVA-POL treatment on antigen-specific primary and secondary IgE responses is examined in 14 strains of mice. The data indicate that the capacity of this modified allergen to induce pronounced inhibition of IgE responses (75-99%), paralleled by up to 1000-fold increases in IgG2a responses, is not genetically restricted. Moreover, these changes in antibody production were (i) antigen-specific, (ii) isotype-specific and (iii) operated independently of the responder status, MHC or Igh haplotype of the responder mice. In contrast, treatment with unmodified OVA under the same conditions was without effect on IgE production and led to minor increases in anti-OVA IgG2a production.     

Genetic control of immune responses in mice to synthetic peptides of a Streptococcus mutans surface protein antigen.

The immune responses to a cell surface protein antigen (PAc) of Streptococcus mutans and a peptide corresponding to residues 301 to 319 of the protein antigen [PAc(301-319)] in various strains of mice were studied, with attention being given to the haplotype of major histocompatibility complex (MHC) class II genes. Subcutaneous immunization of mice carrying the MHC class II I-Ad gene [BALB/c, B10.D2, B10.GD, and (B10.D2 x B10.G)F1 mice] with the peptide induced strong serum immunoglobulin G (IgG) responses to recombinant PAc (rPAc) and the peptide. Subcutaneous immunization of mice carrying the haplotype k or b of the H-2 I-A gene (C3H/HeN, C57BL/6, B10.BR, B10.A, or B10 mice) with the peptide induced intermediate serum IgG responses to rPAc and the peptide, and subcutaneous immunization of mice carrying the haplotype s or q of the H-2 I-A gene (DBA/1, B10.S, or B10.G mice) induced weak serum IgG responses to rPAc and the peptide compared with the responses of mice carrying the I-Ad gene. PAc(301-319) strongly induced PAc(301-319)-specific T-cell proliferation in B10.D2 mice but not in B10.G mice. The T-cell proliferation in B10.D2 mice was inhibited by treatment of antigen-presenting cells with anti-I-Ad monoclonal antibody but not with anti-I-Ab monoclonal antibody. These results indicate that the immune responses to the peptide in mice are genetically restricted or dominated by the MHC class II gene (I-Ad). To map antigenic epitopes in PAc(301-319) and PAc in mice bearing different H-2 haplotypes, 10 overlapping decapeptides covering PAc(301-319) and 153 decapeptides covering the entire mature PAc were synthesized. Of 10 decapeptides covering PAc(301-319), 6, 7, 1, and 1 decapeptides showed strong reactions with anti-PAc(301-319) sera from B10.D2 (H-2d), B10.GD (H-2g2), B10.BR (H-2k), and B10.A (H-2a) mice, respectively. None of these overlapping decapeptides reacted with anti-PAc(301-319) sera from B10.S (H-2s) and B10.G (H-2q) mice. Epitope-scanning analyses of the mature PAc molecule showed that antigenic epitopes scattered throughout the molecule and that antigenic epitope patterns differed in mice with different H-2 haplotypes. In addition, there was little overlap of immunogenic peptides among the mice with different haplotypes.     

Characterization of T-cell responses to the house dust mite allergen Der p II in mice. Evidence for major and cryptic epitopes.

Major histocompatibility complex (MHC) congenic strains can be defined as high and low responders to the major house dust mite allergen Der p II on the basis of the ability to sensitize T cells for in vitro lymphokine release. Mice of the H-2b haplotype were high responders, H-2k were intermediate and H-2d low responders. Like responses to other proteins, only a limited number of epitopes could be located by the response of T cells from mice immunized with allergen to a series of overlapping peptides. The epitopes for H-2b mice were 11-35, 78-104 and 105-129, 36-50 and 78-104 for H-2k mice and 36-60 for H-2d. Immunization with the peptides however revealed that spleen-adherent cells were required for lymph node cells to recall responses to the whole protein and in addition that mice could be sensitized by cryptic epitopes defined by peptides 22-50 and 1-20 for H-2b mice. Peptides containing these cryptic epitopes did not normally induce responses in mice primed with the allergen, but when they were used for immunizing they could prime mice for responses to the peptide and the whole allergen. The results both help to define a model for studying the presentation of allergens and have significant implications for peptide-based immunotherapy.     

N-terminal amino acid sequence identity between a major allergen of Ascaris lumbricoides and Ascaris suum, and MHC-restricted IgE responses to it.

A protein allergen of the parasitic nematode Ascaris has been purified to homogeneity by immunoaffinity chromatography. It is the most abundant protein species in the parasite's body fluid and has been named ABA-1. The allergen's molecular weight (MW) has been previously estimated at 14,000, but this sizing is currently under re-evaluation. The immunological activity of the protein was intact after purification, as attested by immunoprecipitation and passive cutaneous anaphylaxis. The IgE response to ABA-1 was under major histocompatibility complex (MHC) restriction in the rat, in which only RT1u strains were found to respond following infection with the parasite. The tissue-invasive and intestinal stages of both Ascaris lumbricoides (of humans) and Ascaris suum (of pigs) have an antigen of similar MW to ABA-1 in their secretions or among their somatic antigens. These are antigenically indistinguishable; they were found to have similar amino acid compositions, and their N-terminal amino acid sequences were identical to 41 residues. Finally, the apparent MW, amino acid composition and isoelectric point of ABA-1 all argue for close similarity to the previously described Allergen A of the parasite.     

Bicistronic expression plasmid encoding allergen and anti-IgE single chain variable fragment antibody as a novel DNA vaccine for allergy therapy and prevention

Several approaches have been applied in order to alleviate the difficulties allergic patients are suffering from. Among them DNA vaccination and anti-IgE antibody have shown promising results. Herewith, a combination of both strategies is proposed to minimize IgE production while inducing high levels of blocking IgG and strong Th1 immune responses. A bicistronic expression plasmid including an internal ribosomal entry site (IRES) can express both, allergen and a single chain variable fragment (scFv) antibody against human IgE within antigen presenting cells (APCs) including B cells. Presentation of allergen derived peptides via MHC I and MHC II stimulates specific Th1 responses resulting in high levels of IFN-gamma and IgG. Anti-IgE scFv antibody binds to newly synthesized IgE molecules within B cell cytoplasm and also to free serum IgE, thereby inhibiting attachment of IgE to its receptors on basophils and mast cells. Also, IgE-anti-IgE complex functions as blocking antibody and neutralizes allergens entering the body. Additionally, anti-IgE scFv antibody binds to membrane bound IgE (mIgE) on B cells and interferes with IgE expression. Using assays, such as enzyme linked immunosorbent assay (ELISA), IgG and IgE production in response to this expression system can be evaluated. Also, rat basophil leukemia cell assay (using RBL-2H3 cells) can show the amount of functional IgE in sera as basophil mediator release is regarded as an indicator of the allergic hypersensitive reactions. The proposed approach may result in high levels of blocking IgG and low levels of IgE secretion from B cells. Additionally, it can inhibit activity of IgE in degranulation of basophils and mast cells.     

Inhalation exposure of mice to trimellitic anhydride induces both IgG and IgE anti-hapten antibody

The development of antibody responses resulting from inhalation exposure to chemical allergens has been studied in mice. Inhalation exposure of BALB/c mice to atmospheres containing approximately 5 mg/m3 of the respiratory allergen trimellitic anhydride (TMA) resulted in the appearance of both serum IgG and IgE anti-hapten antibody. IgE anti-TMA was first detectable 2-3 weeks following the initiation of exposure and was still present at 6 weeks. Under the same conditions of exposure, 2,4-dinitrochlorobenzene (DNCB), a contact allergen which apparently lacks the capacity for respiratory sensitization, failed to elicit detectable amounts of anti-dinitrophenol (DNP) antibody. Exposure to increased concentrations of atmospheric DNCB (15 mg/m3) did, however, result in an IgG anti-DNP response but not in IgE antibody. These data demonstrate firstly, that atmospheres containing low molecular weight respiratory allergens can initiate specific IgE responses in mice, and secondly, that inhaled chemicals may differ in their ability to induce IgE antibody.     

Genetic Control of Resistance to Mercury-Induced Immune/Autoimmune Activation

Previous studies have shown that genetic factors control the susceptibility to mercury-induced immunoglobulin (Ig)G1 antibody formation, IgE synthesis, renal IgG deposits and antinucleolar autoantibodies (ANolA) production in the susceptible mice. In this study, we examined the genetic control of resistance to these characteristics after HgCl2 injection in F1 hybrid crosses between the highly mercury resistant DBA/2 and mercury susceptible NZB (H-2d), SJL (H-2 s), A.CA (H-2f) and DBA/1 (H-2q) mice and also in backcross hybrids between (DBA/2 x SJL)F1 and SJL mice. We observed that mercury-induced immune/autoimmune manifestations were profoundly downregulated in most (if not all) of the F1 hybrids, indicating that the resistance to mercury was a dominant trait. Analysis of mercury-induced immune/autoimmune responses in the (DBA/2 x SJL) x SJL backcross hybrids suggested that only one gene or a cluster of genes determined the resistance to the ANolA production, whereas the resistance to other characteristics was controlled by two and/or three gene loci. By H-2 genotyping the backcross mice, it was found that H-2d haplotype per se could confer resistance to ANolA production. However, we did not find any significant association between the H-2d haplotype and the resistance to increase of IgG1 and IgE synthesis and the development of renal IgG1 deposits. Thus, while in DBA/2 mice, gene(s) in the H-2 loci strictly contribute to the inheritance of resistance to ANolA production; non-H-2 genes mainly govern the inheritance of unresponsiveness regarding other characteristics.     

Measurement of murine IgE antibody responses to dust mite allergens by in vitro assay.

In an analysis of murine immune responses to the dust mite allergen Der p 1, treatment with purified allergen induced a significant increase in the level of circulating IgE immunoglobulin (from less than 100 ng/ml in normal mice to 1,350 ng/ml in mice receiving the allergen). Even so, specific IgE antibodies binding to purified Der p 1 were not detected in a conventional ELISA, and the major response appeared to be the induction of high titre IgG antibodies. Specific circulating murine IgE antibodies were however detected using the following assay format: murine IgE was captured to anti-murine IgE antibody coated wells; Der p 1 was added and bound by immobilized anti-Der p 1 IgE antibodies; the captured Der p 1 was then detected by the addition of monoclonal IgG antibodies against Der p 1 and these antibodies were measured by the addition of anti-murine IgG antibody-enzyme conjugate with which colour development is produced after substrate addition. This assay establishes a procedure to measure circulating anti-Der p 1 IgE antibodies which are present together with competing high titre IgG anti-Der p 1 antibodies.     

IgE-isotype-specific suppressor cells in the mouse: characterization using tetraparental chimera mice of high (DBA/2) and low (SJL) IgE responder embryos

Tetraparental chimera mice were developed by aggregation of IgE high responder (DBA/2) and IgE low responder (SJL) embryos. Anti-dinitrophenyl (DNP) IgE antibody response in such mice (SJL----DBA/2) upon challenge with DNP-keyhole-limpet hemocyanin (KLH) in alum was clearly suppressed, while anti-DNP IgG antibody response was not. High-titer anti-DNP IgE and IgG antibody response developed in F1 hybrid mice of SJL and DBA/2 (SDF1) mice. The experimental results suggest that high IgE antibody production is the dominant trait, and the IgE-specific suppressor gene in SJL mice is autosomal recessive. IgE-specific suppressor T cells in SJL mice actively suppressed IgE antibody formation by DBA/2 immuno-competent cells across the histocompatibility barrier. Hapten-specific B cells and carrier-specific T cells were prepared in SJL----DBA/2 and SDF1 mice by immunization with DNP-KLH or ovalbumin (OA) in alum and transferred to irradiated SDF1 mice followed by challenge with DNP-OA. Hapten-specific B cells and carrier-specific helper T cells clearly developed in SDF1 mice. Recipient mice transferred with DNP-KLH-primed SDF1 spleen cells and OA-primed SDF1 spleen cells showed high-titer anti-DNP IgE and IgG antibody responses. OA-primed SJL----DBA/2 spleen cells cotransferred with DNP-KLH-primed SDF1 spleen cells and OA-primed SDF1 spleen cells completely abolished secondary anti-DNP IgE antibody response. The data suggest that carrier-specific helper T cells for IgE and IgG antibody responses are distinct. The regulatory role of IgE-isotype-specific suppressor cells were considered to be the interference of cooperative cellular interaction between IgE B cells and carrier-specific, IgE-specific helper T cells.     

Maternal allergen immunization during pregnancy in a mouse model reduces adult allergy-related antibody responses in the offspring

BACKGROUND: The immune status and allergen exposure of the mother may influence the immune response in the offspring after birth. This relationship may be important both for allergen avoidance strategies and, alternatively, for allergy prophylaxis by allergen exposure of the mother. OBJECTIVE: The aim of the present study was to investigate the effect of allergen immunization of the mother during pregnancy and postpartum, in relation to the allergy-related immune response (IgE) and the non-allergy-related (IgG2a) response in the offspring. METHODS: Pregnant NIH/OlaHsd females were immunized three times during pregnancy and one time postpartum with ovalbumin and the adjuvant Al(OH)3, and the offspring's ovalbumin-specific IgE, IgG1 and IgG2a responses were measured after challenge with the same allergen as young adults. Ovalbumin-specific IgE, IgG1 and IgG2a responses were also analysed in offspring of NIH/OlaHsd females immunized once at different times during pregnancy: about 3 days into pregnancy, mid-pregnancy (10 days into pregnancy) and about 4 days before giving birth (17 days into pregnancy). RESULTS: Allergen immunization of mother during pregnancy and postpartum significantly reduced the IgE response in the progenies, whereas the IgG2a response to the same allergen was increased. Allergen immunization of the mother 3 days into pregnancy resulted in a significantly lower IgE response in offspring compared with the response in offspring of non-immunized mothers and in offspring of mothers immunized 17 days into pregnancy. CONCLUSIONS: Maternal allergen immunization might favour selection for an allergen-specific Th1-dependent antibody response in the offspring. Our results indicate that IgE suppression is stronger after maternal allergen exposure during early pregnancy than after exposure in late pregnancy.     

Allergic and anaphylactic response to sesame seeds in mice: identification of Ses i 3 and basic subunit of 11s globulins as allergens

BACKGROUND: Allergy to sesame seeds is an emerging food allergy of a serious nature due to a high risk of systemic anaphylaxis. Although a mouse model to study sesame anaphylaxis is desirable, currently it is not available. Here, using a transdermal exposure model system, we tested the hypothesis that sesame seed elicits IL-4-associated IgE antibody response with consequent clinical sensitization in mice. METHODS: Groups of BALB/c mice were exposed to sesame seed extract or saline or a control food (vanilla bean extract) by transdermal applications. Systemic IgE, IgG1 and IgG2a antibody responses were examined using preoptimized ELISA. Type 2 and type 1 cytokine responses were evaluated by ex vivo antigen-mediated activation of spleen cells. Clinical response to oral sesame challenge was studied. Western blot and N-terminal amino acid sequence analyses were performed to identify the sesame allergens. RESULTS: Transdermal exposure to sesame elicited robust IgE and IgG1 but very little IgG2a antibody responses. IgE response to transdermal exposure in two high-IgE responder mice strains with disparate MHC confirmed the intrinsic allergenicity of sesame seed. Transdermal sensitization was associated with activation of IL-4 but not IFN-gamma. Furthermore, oral exposure to sesame resulted in clinical signs of systemic anaphylaxis. Western blot and sequence analysis identified four allergens including Ses i 3 and the basic subunit of 11s globulins. CONCLUSION: These data argue that transdermal exposure to sesame seed can result in IL-4 activation, IgE response and clinical sensitization for systemic anaphylaxis.     

On the diversity and heterogeneity of H-2(d)-restricted determinants and T cell epitopes from the major bee venom allergen.

One of the main limitations of using synthetic peptides for immunotherapy in allergic patients is the difficulty to delineate the immunodominant T cell epitopes which are necessarily dependent on HLA molecules. We have thus addressed the question of the role of MHC II molecules in immunodominant epitopes selection in the particular case of the major bee venom allergen (API m1). To exhaustively and easily explore it, we used BALB/c mice whose H-2 haplotype is associated with high IgE and IgG responses to API m1. By means of extensive sets of synthetic peptides, we investigated the specificity of polyclonal T cells and monoclonal hybridomas from mice immunized with API m1 and delineated four immunodominant regions, restricted to either the I-E(d) or the I-A(d) molecule. All the peptides were also tested for their capacity to bind to immunopurified MHC II molecules. Eight determinants of high affinity were identified. They clustered into three distinct regions and were largely overlapping. They included all the immunodominant epitopes, but half of them were not capable of stimulating T cells. Strikingly, interacting surfaces with either the TCR or MHC II molecule greatly differed from one determinant to another. In one case, we observed that flanking regions exerted a particular action on T cell stimulation which prevented the fine epitope localization. Our results underline the diversity and complexity of MHC II-restricted determinants and T cell epitopes from the major bee venom allergen, even in a single haplotype. These data also participate in the development of alternative approaches to conventional immunotherapy.     

The ABA-1 allergen of the nematode Ascaris suum: epitope stability, mass spectrometry, and N-terminal sequence comparison with its homologue in Toxocara canis.

ABA-1 is a major allergen of nematode parasites of the genus Ascaris which includes the large roundworms of humans and pigs, A. lumbricoides and A. suum, respectively. The allergen was purified from A. suum by immunoaffinity chromatography for immunochemical examination. The IgE antibody repertoire is under MHC control in infected rodents and the IgE-binding epitopes were robust to treatment with heat or periodate, and electroblotting on nitrocellulose. This implies that the IgE epitopes comprise primary peptide sequence or an unusually stable secondary or tertiary structure. The molecular mass of ABA-1 is controversial, but mass spectrometry analysis indicated that there were five components of similar size, with the major species being 14,643.2 +/- 1.4 D. Finally, N-terminal sequence analysis of ABA-1 and TBA-1 (the homologue in the canine nematode infective to humans, Toxocara canis) revealed a high degree of similarity, and we have previous evidence that ABA-1 homologues are widespread amongst ascaridid parasites of humans. ABA-1 and its homologues might, therefore, be important to the immunopathology of many infections with nematode parasites, upon which the genetic constitution of the hosts will also have a bearing.     

Influence of plant lipids on immune responses in mice to the major Brazil nut allergen Ber e 1

BACKGROUND: Lipids, particularly bacterial lipopolysaccharide, can impact on immune responses to proteins, with low doses enhancing type 2 responses. OBJECTIVE: We have examined the influence of natural plant lipid extracts on antibody responses provoked in mice by recombinant Ber e 1, the major allergen in Brazil nuts. METHODS: BALB/c strain mice were immunized (by intraperitoneal injection) with natural or recombinant Ber e l produced in Pichia pastoris and admixed with various lipid fractions isolated from Brazil nuts. Serum samples were analysed for specific IgE antibody by homologous passive cutaneous anaphylaxis assay and for IgG by enzyme-linked immunosorbant assay. RESULTS: Exposure to recombinant (lipid-free) Ber e 1 alone failed to induce detectable IgG or IgE antibody. Co-administration of the total lipid fraction (with reduced triglyceride levels), sterol-rich, or polar lipid fractions, resulted in marked adjuvant effects on IgG and IgE. However, the beta-sitosterol and glycolipid-rich fractions were associated with only low-level IgG antibody, and had little impact on IgE antibody production. Natural Ber e 1 containing endogenous lipids also provoked IgG and IgE antibody responses. Identical IgE and IgG antibody responses were detected regardless of whether natural or recombinant Ber e 1 was used as substrates for analyses. CONCLUSION: Endogenous Brazil nut lipids are required for the induction of optimal antibody responses to Ber e 1 in the BALB/c strain mouse. Appropriate antibody binding sites are present on both natural and recombinant forms of Ber e 1, suggesting that the impact of lipid is at the induction phase, rather than antibody recognition, and is possibly required for efficient antigen presentation.     

No role of interleukin-4 in CD23/IgE-mediated enhancement of the murine antibody response in vivo

Antigen-specific IgE up-regulates the specific IgM, IgG1, IgG2a and IgE response in vivo when given to mice together with antigen. The enhancement is mediated by the low-affinity receptor for IgE, Fc?RII or CD23, as demonstrated both in CD23-deficient mice and by blocking CD23 with anti-CD23 monoclonal antibodies. A possible mechanism behind the regulatory effects of CD23 is that the IgE/CD23/antigen complex is endocytosed by B cells, leading to increased antigen processing and presentation on major histocompatibility complex (MHC) class II molecules toT helper cells. In the present study we have found that the expression of CD23 is reduced fivefold on splenic B cells in mice genetically deficient for IL-4. When IL-4-deficient mice and normal littermates were immunized with 2,4,6-trinitrophenyl (TNP)-specific IgE followed by bovine serum albumin (BSA)-TNP or with BSA-TNP alone, the BSA-specific IgG1 and IgG2a responses were equally well augmented by IgE in all mice. In addition, a low but significant IgE response was seen even in the IL-4-deficient mice. Thus, enhancement of the antibody response through IgE and CD23 occur in the absence of IL-4 and is not dependent on CD23 up-regulation.     

Divergent immune responses to respiratory and contact chemical allergens: antibody elicited by phthalic anhydride and oxazolone

In previous studies we observed that exposure of mice to the contact allergen 2,4-dinitrochlorobenzene (DNCB) and the respiratory allergen trimellitic anhydride (TMA) resulted in qualitatively different immune responses characteristic of selective Th1- and Th2-type T helper cell activation respectively. The purpose of the present investigation was to determine whether the effects recorded with DNCB and TMA are characteristic of immune responses to contact and respiratory chemical allergens in general. Experiments have been performed with phthalic anhydride, a known human respiratory sensitizer, and with oxazolone, a potent contact allergen. Under conditions of exposure where both chemicals elicited an IgG anti-hapten antibody response, only phthalic anhydride caused an increase in the serum concentration of IgE. Furthermore, like TMA, phthalic anhydride preferentially induced IgG2b rather than IgG2a antibody. In contrast, oxazolone, like DNCB, induced a markedly stronger IgG2a than IgG2b antibody response. These data provide confirmatory evidence that chemical respiratory allergens and chemical contact allergens elicit qualitatively different immune responses which reflect their clinical effects in man.     

Low Responsiveness to Immunization with Immunoglobulin E/Antigen and Immunoglobulin G/Antigen Complexes in H-2Ab Mice

Immunoglobulin (Ig)E and IgG antibodies specific for 2,4, 6-trinitrophenyl (TNP) are able to enhance the carrier-specific antibody response to TNP-conjugated soluble proteins such as bovine serum albumin (BSA). We have recently reported that mice carrying the MHC class II Ab molecule are low responders to immunization with IgE/antigen complexes and now show that H-2Ab mice are also low responders to IgG/antigen complexes. In addition, we found that spleen cells from naive low- and high-responder mice captured IgE/antigen complexes exclusively on B cells, and that the binding was completely inhibited by monoclonal antibodies (MoAbs) against the low-affinity receptor for IgE (FcepsilonRII or CD23). The IgG/antigen complexes were targeted both to B cells and macrophages. The binding of IgG/antigen to B cells primarily seemed to be dependent on the low-affinity receptor for IgG (FcgammaRII or CD32), although some influence of complement receptor 2 (CR2 or CD21) was seen. Capture of IgG/antigen complexes on macrophages was partially blocked by MoAbs against FcgammaRII/III. There was no difference in expression of FcepsilonRII, FcgammaRII/III, CR1, CR2, and CR3 between low- and high-responder strains, thus excluding low levels of these FcRs and CRs as a reason for low responsiveness in H-2Ab mice.     

Suppression of allergic airway inflammation and IgE responses by a class I restricted allergen peptide vaccine

CD8 T cells are known to deviate CD4 T-cell responses from Th2 toward Th1. Reduction of Th2 cytokines and increased interferon-γ ameliorates allergic airway disease. We have developed a novel approach to the suppression of allergic airway inflammation, by designing a MHC class I-restricted allergen peptide vaccine, which induces potent and long-lived CD8 T-cell responses. Vaccination of C57BL/6 mice before allergen sensitization completely prevented allergen-specific immunoglobulin E (IgE) antibody responses. Vaccination after sensitization failed to suppress IgE, but inhibited accumulation of eosinophils and neutrophils in airways after subsequent allergen challenge. Vaccination suppressed Th2 airway infiltration and enhanced the lung Th1 response without inducing excessive CD8 cellular infiltration or interleukin-17, and the combination of class I peptide with adjuvant was more effective than adjuvant alone. Airway hyperreactivity was prevented by vaccination in an allergen-specific fashion. Class I peptide vaccines might therefore represent a robust and long-lasting immunotherapeutic strategy in allergic disease.     

Hazelnut Allergy: evidence that hazelnut can directly elicit specific IgE antibody response via activating type 2 cytokines in mice

BACKGROUND: Hazelnut is one of the major tree nuts that causes potentially fatal food allergy, with underlying mechanisms that are unclear at present. One suggestion is that hazelnut allergy results from immune crossreactivity of IgE antibodies produced against certain aeroallergens. We tested the hypothesis that hazelnut is intrinsically capable of eliciting an allergic response using a mouse model. METHODS: Groups of mice were injected intraperitoneally with hazelnut/filbert protein extract with or without alum as an adjuvant, and hazelnut-specific antibody (IgE, IgG1) responses were examined using optimized enzyme-linked immunosorbent assay. Hazelnut-specific type 2 and type 1 cytokine responses were evaluated by ex vivo antigen-mediated activation of spleen cells. RESULTS: Hazelnut elicited robust IgE and IgG1 antibody responses. Timecourse and dose-response analyses further provided evidence for memory type 2-dependent antibody responses to hazelnuts. Hazelnut-specific IgE response in two strains of mice with different MHC haplotypes and IgE response to hazelnut without the use of alum adjuvant asserted that hazelnut is intrinsically an allergenic food. The type 2 cytokine analyses revealed that hazelnut sensitization results from activation of IL-4 and IL-5, thus providing a mechanistic basis for hazelnut-specific IgE response. CONCLUSION: Our data argue that hazelnut - a widely consumed food - is intrinsically an allergenic food capable of directly eliciting hazelnut-binding specific IgE antibodies viaactivation of type 2 cytokines in mice.