Allergenic crossreactivities. Pollens and vegetable foods.
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Allergens↗
Biomedical subjects
C Ebner
Publications and source records attributed to C Ebner.
Recombinant Bet v 1, the major birch pollen allergen, induces hypersensitivity reactions equal to those induced by natural Bet v 1 in the airways of patients allergic to tree pollen.
BACKGROUND: Atopic allergens produced by recombinant DNA methods are promising tools for diagnosis and therapy of Type I allergy. To evaluate the immunologic properties of these molecules, it is necessary to compare them with natural allergens in vitro and in vivo. OBJECTIVE: The study was carried out to determine whether the potency of recombinant Bet v 1 (rBet v 1) is comparable to that of natural Bet v 1 (nBet v 1) in inducing allergic reactions in the nose and bronchi. METHODS: Thirteen patients allergic to birch pollen with bronchial asthma and/or rhinitis were investigated. Skin prick tests and nasal and bronchial challenges were performed with rBet v 1 and nBet v 1. RESULTS: In patients allergic to birch pollen, both allergens induced comparable skin reactions. In subjects with rhinitis rBet v 1 was equally potent in inducing nasal reactions (mean PD(+60)NR +/- SD, 10.48 +/- 17.42 microg vs 7.98 +/- 8.9 microg, p > 0.05). In patients with asthma, rBet v 1 was equally potent in inducing bronchial reactions (PD20 FEV1, 0.81 +/- 1.74 microg vs 0.62 +/- 1.44 microg, p > 0.05) as nBet v 1. CONCLUSION: No significant differences were observed between natural and recombinant allergen. We conclude that allergens produced by recombinant techniques can induce typical allergic reactions in important target organs of Type I allergy: the nose and bronchi.
Adult↗
Cell surface characterization of T lymphocytes and allergen-specific T cell clones: correlation of CD26 expression with T(H1) subsets.
To evaluate the possibility of using surface molecules as markers for human T helper cell subsets, we studied the expression of surface molecules on T cell clones (TCCs) specific for the major birch pollen allergen, Bet v 1. No difference in the expression of the respective receptors for interferon-gamma (IFN-gamma), IL-4, IL-6, or IL-10 could be detected on T(H) subsets, nor did CD25 expression (IL-2R alpha-chain) differ significantly. However, high expression of CD26 antigen (dipeptidyl peptidase IV) correlated with a T(H1)/T(H0)-like phenotype, whereas T(H2)-like clones displayed a lower expression of CD26 antigen. Comparing cytokine production and CD26 expression simultaneously, we found a correlation between the IL-4/IFN-gamma ratio and the density of CD26 per cell. We could show that the amount of IL-4 secretion, and not of IFN-gamma secretion, was responsible for this correlation. To evaluate whether CD26 antigen expression is regulated by stimuli inducing a T(H1)- or T(H2)-like phenotype, peripheral blood mononuclear cells (PBMC) were cultured in the presence of IL-4, IFN-gamma, and IL-12, respectively. Incubation with IL-4 led to T cells with a T(H2)-like cytokine pattern and a significantly lower expression of CD26; IFN-gamma and IL-12 led to a T(H1) shift associated with an increased expression of CD26 on CD4+ T cells. By means of intracellular cytokine detection we analyzed expression of CD26 on CD4+ PBMC stimulated to produce IFN-gamma or IL-4 on a single cell level. All activated, cytokine-producing CD4+ T cells expressed CD26, but the increase in CD26 expression was higher in cells producing IFN-gamma. These data suggest that regulation of CD26 cell surface expression correlates with the production of T(H1)-like cytokines.
Allergens↗
Major cat and dog allergens share IgE epitopes.
BACKGROUND: Patients allergic to cats and dogs frequently display IgE reactivity against allergens from different animals, suggesting a cross-sensitization to common allergenic determinants. Although albumins have been recognized as relevant cross-reactive allergens, little is known regarding cross-reactive epitopes of the major cat and dog allergens. OBJECTIVE: In this study, sera from patients allergic to cats and/or dogs were used to investigate the presence of common IgE epitopes among the major cat and dog allergens. METHODS: The IgE reactivity profile of 109 patients who were allergic to allergens from several species of animals was determined with nitrocellulose-blotted cat and dog allergens. Sera from patients who were strongly allergic to the major cat and dog allergens were tested for the presence of cross-reactive IgE antibodies by one-dimensional and two-dimensional immunoblot inhibition experiments and by quantitative measurements obtained with the CAP-FEIA system (Pharmacia). RESULTS: Sixty-eight of 109 patients with animal allergy showed IgE reactivity to cat allergens and dog allergens. Sera from patients with both cat and dog allergy detected allergens of similar molecular weight in nitrocellulose-blotted cat and dog hair/dander extracts. Common, as well as species-restricted, IgE epitopes of the major cat and dog allergens could be demonstrated by IgE inhibition studies. CONCLUSION: Shared IgE epitopes of the major cat and dog allergens may provide an explanation for the clinical observation that allergies to cats and dogs are frequently associated.
Albumins↗
Modulation of the allergic immune response in BALB/c mice by subcutaneous injection of high doses of the dominant T cell epitope from the major birch pollen allergen Bet v 1.
Several in vitro and in vivo studies indicate that application of high doses of dominant T cell epitopes can induce a state of antigen-specific non-responsiveness (anergy). In the present study, we developed a murine model of an allergic immune response to Bet v 1, the major birch pollen allergen. Mice were sensitized by injection of rBet v 1 and the allergic state was proven by the presence of allergen-specific IgE and positive immediate-type skin tests to Bet v 1. In epitope mapping experiments, an immunodominant T cell epitope of Bet v 1 in BALB/c mice was identified by the use of overlapping peptides. This peptide (BV 139) was subsequently employed for treatment. Two tolerization protocols were used: in one approach, the peptide was administered to naive mice before immunization (group BV139-S), in the second, already sensitized mice were treated (S-BV139). The results demonstrated that administering high doses of the dominant T cell epitope of Bet v 1 profoundly diminished T cell proliferation to the peptide in the BV139-S group, and to the peptide as well as to the whole protein in the S-BV139 group. Skin test reactivity to Bet v 1 was reduced in the BV139-S group. However, no differences in terms of specific antibody production between treated and untreated mice could be observed. This study provides evidence that administration of dominant T cell epitopes can down-regulate the allergen-specific T cell response. Proceeding on the assumption that the T lymphocyte response to allergens is crucial for the induction and maintenance of the allergic disease, a modulation of the immune response to allergens by treatment with T cell epitope peptides could represent a promising concept for immunotherapy in the future.
Adjuvants, Immunologic↗
Bet v 1, the major birch pollen allergen, conjugated to crystalline bacterial cell surface proteins, expands allergen-specific T cells of the Th1/Th0 phenotype in vitro by induction of IL-12.
Modulation of allergic immune responses by using adequate adjuvants is a promising concept for future immunotherapy of type I hypersensitivity. In the present study, recombinant Bet v 1 (rBet v 1, the major birch pollen allergen) was conjugated to cross-linked crystalline surface layer proteins (SL) derived from Gram-positive eubacteria. T cell lines (TCL) and clones (TCC) were established from peripheral blood of birch pollen-allergic patients. TCL and TCC were induced either using rBet v 1 alone or rBet v 1/SL conjugates (rBet v 1/SL) as initial antigen stimulus. Cytokine production after re-stimulation with rBet v 1 was investigated. TCL initiated with rBet v 1/SL showed significantly increased IFN-gamma production as compared to rBet v 1 -selected TCL. TCC were established from TCL of five patients. As expected, the majority of CD4+ TCC induced by rBet v 1 (55%) displayed a Th2-like pattern of cytokine production. However, only 21% of Bet v 1-specific TCC isolated from TCL established with the Bet v 1/SL revealed this phenotype. The majority of SL-specific TCC (80%) belonged to the Th1 phenotype. In cultures of peripheral blood mononuclear cells, both, SL and Bet v 1/SL (but not rBet v 1) stimulated the production of high levels of IL-12, a pivotal mediator of Th1 responses. Moreover, stimulation of rBet v 1-induced TCC with rBet v 1/SL led to an increased IFN-gamma production. This effect could be reversed by neutralizing anti-IL-12 mAb. Together these results indicate an adjuvant effect of SL mediated by IL-12. Our results indicate that bacterial components, such as SL, displaying adjuvant effects may be suitable for immunotherapeutical vaccines for type I allergy.
Adjuvants, Immunologic↗
Immunological changes during specific immunotherapy of grass pollen allergy: reduced lymphoproliferative responses to allergen and shift from TH2 to TH1 in T-cell clones specific for Phl p 1, a major grass pollen allergen.
BACKGROUND AND OBJECTIVE: The mechanisms operative in specific immunotherapy (SIT) of Type I allergy are not completely understood. In the present study we evaluated immunological changes during SIT in pollinosis. METHOD: Eight patients suffering from pollinosis (monosensitized to grass pollen) were treated with conventional SIT. All subjects had IgE specific for Phl p 1, a major allergen of timothy grass. In vitro changes in the immunological reactivity to grass pollen extract and to recombinant Phl p 1 were evaluated. Subjects were examined at three occasions: before, after 3 months and after 1 year of SIT. RESULTS: Serological analysis revealed a marked increase of grass pollen- and Phl p 1-specific IgG, titres of specific IgE did not change significantly. Lymphoproliferative responses to grass pollen extract and rPhl p 1 were reduced already after 3 months of treatment. Accordingly, the cloning efficiency for Phl p 1-specific T-cell clones (TCC) dropped markedly in all patients. The majority of allergen-specific TCC raised before SIT revealed a TH2-like pattern of cytokine production, TCC established after SIT revealed TH1 characteristics. This shift was due to a decrease in IL-4 rather than an increase in IFN-production by T cells. Investigations of the epitopes recognized by T cells before and after SIT did not reveal the outgrowth of new ('protecting') specificities. We could not observe induction of allergen-specific CD8+ lymphocytes (supressor cells). CONCLUSION: Our data indicate that -- on the level of TH lymphocytes -- SIT induces tolerance to the allergen and a modulation of the cytokine pattern produced in response to allergen stimulation.
Adult↗
Food allergy to pumpkinseed--characterization of allergens.
In recent years, pumpkinseed has become increasingly popular as a foodstuff. Here we report the occurrence of allergic reactions (itching and swelling of oral mucosa, and asthma) to this member of the Cucurbitaceae family. We investigated three patients suffering from symptoms after ingestion of roasted pumpkinseed. All the patients fished for sport and used pressed pumpkinseed flour as bait. Sera were tested by the immunoblot technique for IgE reactivity with proteins of pumpkinseed extract. The immunoblot revealed pumpkinseed allergens of 13, 14, 36, 48, 77, and 87 kDa. Inhibition experiments with recombinant birch profilin were performed: IgE binding to the 14-kDa allergen was completely blocked by preincubation of the sera with recombinant birch profilin. In conclusion, type I allergy to pumpkinseed is rare, and the patients' histories suggest inhalation of pumpkinseed flour during fishing to be the relevant route of sensitization, leading to food allergy to pumpkinseed.
Adult↗
Heterogeneity in the polyclonal T cell response to birch pollen allergens.
BACKGROUND: Immunodominant epitopes of Bet v 1a had been identified before, using recombinant (r) Bet v 1a-reactive T cell clones generated from peripheral blood mononuclear cells of patients allergic to birch pollen. This study aimed at evaluating the T cell-stimulating capacity of immunodominant Bet v 1a-derived peptides in a polyclonal system corresponding more closely to the situation in patients. METHODS: Short-term T cell lines (TCL) were established in presence of a protein extract of birch pollen (BP extract). TCL proliferation induced by the BP extract, by natural Bet v 1, rBet v 1a, rBet v 2 or 5 selected immunodominant Bet v 1a-derived peptides was determined. RESULTS: Consistent with the knowledge that Bet v 1 is the major IgE-binding allergen of birch pollen, we found comparable T cell reactivity to natural Bet v 1 and the BP extract within the majority of the TCL. Accordingly, the response to rBet v 2 was low compared with the reactivity to the BP extract. The response of the TCL to rBet v 1a proved to be highly heterogeneous. Furthermore, the TCL response to the 5 immunodominant Bet v 1a-derived peptides showed considerable diversity. The proliferative responses of most TCL (with one exception) following stimulation by these peptides were low, in relation to the expansion induced by the BP extract. CONCLUSION: These findings argue against the use of selected peptides derived from Bet v 1a in specific immunotherapy of patients with birch allergy.
Allergens↗
Prenatal contact with inhalant allergens.
Pollen contact in early infancy may enhance the risk for subsequent pollen allergy. In this study likelihood of a prenatal antigen contact, as a result of inhalation of pollen allergens by the mother, was investigated. Due to the seasonal occurrence of allergens studied, the date of priming can be estimated, and this can supply data about the maturation of the fetal immune system. Proliferative responses of umbilical cord blood mononuclear cells (UCB MNCs) to the recombinant major allergens of birch (rBet v 1) and timothy grass (rPhl p 1) were analyzed throughout the whole year. A positive proliferative response was regarded as the criterion for a prenatal contact of the immune system with the allergen. Prenatal priming with both allergens was observed. Timothy grass pollen displayed considerably higher antigenicity than did birch pollen. The susceptibility of the fetal immune system to be primed by these allergens varies during the gestation period. The majority of positive responses to rPhl p 1 and rBet v 1 were found in UCB samples in which antigen contact (the respective pollen season) took place in the first 6 mo of pregnancy. Our results offer indirect evidence that, shortly after migration of T cell precursors to the epithelial thymus, T cells are mature enough for priming with antigens. No relationship was found between the susceptibility of the fetal immune system to be primed by these allergens and the clinical history of the family concerning type I allergy.
Allergens↗
Characterization of allergens from deer: cross-reactivity with allergens from cow dander.
BACKGROUND: Animal hair/dander proteins frequently cause Type I hypersensitivities. Species-specific and broadly cross-reacting allergens have been characterized in the past. METHODS: Sera from eight individuals suffering from symptoms due to exposure to deer and deer-derived products were investigated by immunoblotting. Extracts from deer, dog, cat, horse, rabbit and cow, respectively, were tested for IgE-binding. To reveal cross-reactivities patients' sera were preadsorbed with these extracts prior to testing with deer extract. RESULTS: Deer allergens with the molecular mass of 22 and 25 kD (major allergens), as well as 60 kD were identified. The 22 and 25 kD allergens are cross-reactive with the corresponding cow allergens. CONCLUSION: Deer allergy is a rare sensitization mainly affecting persons exposed to deer, who displayed an atopic disposition. From our results it can be assumed that this hypersensitivity is partly associated with allergy to cow dander.
Adult↗
Mechanisms of Fc epsilon RI-IgE-facilitated allergen presentation by dendritic cells.
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Allergens↗
Characterization of allergens in Apiaceae spices: anise, fennel, coriander and cumin.
BACKGROUND: Symptoms elicited by IgE-mediated food allergy range from mild local to severe systemic reactions. Allergens in spices are particularly dangerous due to their hidden presence in many dishes. OBJECTIVES AND METHODS: According to clinical observations, mugwort and birch pollen allergy, and hypersensitivity to spices are frequently associated, but the crossreacting compounds were not defined so far. We tested sera of 15 patients who experienced adverse reactions to spiced food and characterized their IgE-binding patterns on anise, fennel, coriander and cumin extracts through immunoblot and inhibition experiments. RESULTS: The use of anti-Bet v 1 (MoAb) and anti-profilin (rabbit) antibodies revealed the presence of crossreacting allergens in the tested spice extracts. Inhibition experiments showed that IgE-binding to allergens in Apiaceae spices could be blocked by preincubation of sera with rBet v 1 or rBet v 2 (birch profilin). Moreover, we detected crossreacting allergenic molecules in the molecular weight range of 60 kDa. IgE-binding to spice allergens occurred only with sera of 10/15 (66%) patients with allergy to pollen (birch, mugwort) and/or celeriac. In five out of 15 (33%) patients with a history of adverse reaction to spices, but without pollen and celeriac allergy, no IgE-binding to any spice protein could be demonstrated. It is possible that these clinical reactions could be elicited by other types of hypersensitivity (Type II, III, IV), however, as spices contain highly reactive substances, the symptoms may most likely be classified as food-intolerant. CONCLUSIONS: Bet v 1- and profilin-related allergens may, besides higher molecular weight allergenic molecules, be responsible for Type I allergy to anise, fennel, coriander or cumin, members of the Apiaceae.
Adult↗
Peripheral blood dendritic cells express Fc epsilon RI as a complex composed of Fc epsilon RI alpha- and Fc epsilon RI gamma-chains and can use this receptor for IgE-mediated allergen presentation.
Originally limited to basophils and mast cells, the spectrum of high affinity IgE receptor (Fc epsilon RI-bearing cells has expanded recently to include Langerhans cells, dermal dendritic cells (DC), monocytes, and eosinophils. As a result of studies on the distribution, structure, and function of Fc epsilon RI on APCs, we discovered a minor nonbasophil, nonmonocyte PBMC population that can bind IgE via Fc epsilon RI. This receptor occurs on the surface of these cells as a multimeric structure containing Fc epsilon RI alpha- and Fc epsilon RI gamma-chains but, unlike its counterpart on basophils, lacking Fc epsilon RI beta. Further experiments revealed that these Fc epsilon RI alpha gamma-expressing cells closely resemble peripheral blood DC by immunophenotype (HLA-DRhigh, HLA-DQhhigh; CD4+, CD11a+, CD32+, CD33+, B7/2 (CD86)+; CD11blow, CD14low, CD40low, CD54low, CD64low) and cell morphology. These features allowed us to isolate Fc epsilon RI-expressing DC from the peripheral blood and to investigate their immunostimulatory properties. We found Fc epsilon RI-positive DC to be efficient stimulators of both primary (allogeneic MLR) and Fc epsilon RI/IgE-dependent, secondary T cell responses at low cell numbers. Thus, Fc epsilon RI-expressing DC may not only amplify established type I allergic immune reactions but, unlike Fc epsilon RI-positive semiprofessional APCs, may be able to prime naive T cells to common and/or cryptic epitopes of IgE-reactive Ags.
Allergens↗
Oxide-cluster nucleation, growth, and saturation on Si(001)-(2 x 1) surfaces: Atomic-scale measurements and models.
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Journal Article↗
Simulations of low-temperature annealing of crystal surfaces.
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Journal Article↗
Dissection of immunoglobulin E and T lymphocyte reactivity of isoforms of the major birch pollen allergen Bet v 1: potential use of hypoallergenic isoforms for immunotherapy.
We dissected the T cell activation potency and the immunoglobulin (Ig) E-binding properties (allergenicity) of nine isoforms of Bet v 1 (Bet v 1a-Bet v 1l), the major birch pollen allergen. Immunoblot experiments showed that Bet v 1 isoforms differ in their ability to bind IgE from birch pollen-allergic patients. All patients tested displayed similar IgE-binding patterns toward each particular isoform. Based on these experiments, we grouped Bet v 1 isoforms in three classes: molecules with high IgE-binding activity (isoforms a, e, and j), intermediate IgE-binding (isoforms b, c, and f), and low/no IgE-binding activity (isoforms d, g, and 1). Bet v 1a, a recombinant isoform selected from a cDNA expression library using IgE immunoscreening exhibited the highest IgE-binding activity. Isoforms a, b, d, e, and 1 were chosen as representatives from the three classes for experimentation. The potency of each isoallergen to activate T lymphocytes from birch pollen-allergic patients was assayed using peripheral blood mononuclear cells, allergen-specific T cell lines, and peptide-mapped allergen-specific T cell clones. Among the patients, some displayed a broad range of T cell-recognition patterns for Bet v 1 isoforms whereas others seemed to be restricted to particular isoforms. In spite of this variability, the highest scores for T cell proliferative responses were observed with isoform d (low IgE binder), followed by b, 1, e, and a. In vivo (skin prick) tests showed that the potency of isoforms d and 1 to induce typical urticarial type 1 reactions in Bet v 1-allergic individuals was significantly lower than for isoforms a, b, and e. Taken together, our results indicate that hypoallergenic Bet v 1 isoforms are potent activators of allergen-specific T lymphocytes, and Bet v 1 isoforms with high in vitro IgE-binding activity and in vivo allergenicity can display low T cell antigenicity. Based on these findings, we propose a novel approach for immunotherapy of type I allergies: a treatment with high doses of hypoallergenic isoforms or recombinant variants of atopic allergens. We proceed on the assumption that this measure would modulate the quality of the T helper cell response to allergens in vivo. The therapy form would additionally implicate a reduced risk of anaphylactic side effects.
Allergens↗
Biological and immunological importance of Bet v 1 isoforms.
In 2D-PAGE analysis of Bet v 1, the major birch pollen allergen, up to 12 isoforms can be demonstrated that differ in their isoelectric points from about pH 4.9 to pH 5.9. The molecular weights of these isoforms seem to be rather similar, but minor variations can also be seen. Preliminary experiments with birch leaves seem to indicate that in aging leaves some isoforms can be found that do not occur in pollen. In birch cells cultured in vitro, Bet v 1 isoforms can be induced by bacterial infection that do not occur in pollen (Swoboda et al. (1995), Pant, Cell and Environment 18, 865-874). In a recent paper (Swoboda et al (1995)., J. Biol. Chem. 270, 2607-2613) we show that in natural Bet v 1 from pollen the isoforms are due to different protein sequences. The derived protein sequences of 10 different isoforms (corresponding to 13 different cDNAs) were determined and confirmed by plasma desorption mass spectrometry of purified natural Bet v 1 after trypsin and endoproteinase Glu-C digestion. These experiments also showed that pollen Bet v 1 isoforms were reactive to patients' sera to different degrees and that common post-synthetic modifications (besides N-terminal methionine cleavage) did not occur on Bet v 1. Recombinant isoforms were produced in E. coli, purified and tested with selected patients allergic to birch pollen (Ferreira et al., J. Exp. Med., in the press). The pattern of IgE binding to Bet v 1 isoforms widely differs. Also, T-cell clones from individual patients in some cases are specific to peptides occurring only in certain isoforms. It was of particular interest that three of the naturally occurring pollen Bet v 1 isoforms do not or hardly bind IgE of untreated patients allergic to Bet v 1. However, a comparison of IgE reactivity in patients before and after conventional immunotherapy with natural pollen extract clearly showed that this form of immunotherapy induced IgE to the isoforms that had been unreactive in untreated patients. One of these, Bet v 1d, showed a particularly strong potency towards T-cell stimulation. The isoform(s) that do not bind IgE in untreated patients but still show T-cell reactivity could be potentially utilized for a new form of immunotherapy that avoids the risk of anaphylaxis.
Allergens↗