Vaccines for birch pollen allergy based on genetically engineered hypoallergenic derivatives of the major birch pollen allergen, Bet v 1

BACKGROUND: We have recently engineered recombinant derivatives of the major birch pollen allergen Bet v 1 (rBet v 1 fragments and trimer) with strongly reduced allergenic activity. OBJECTIVE: The aim of this study was the in vivo characterization of potential allergy vaccines based on Al(OH)3-adsorbed genetically modified rBet v 1 derivatives in mice. METHODS: BALB/c mice were immunized either with courses of nine injections of increasing doses of Al(OH)3-adsorbed rBet v 1 wild-type, rBet v 1 fragments, rBet v 1 trimer or Al(OH)3 alone in weekly intervals or with three high-dose injections applied in intervals of 3 weeks. Humoral immune responses to rBet v 1 wild-type and homologous plant allergens were measured by ELISA and Western blotting, and the ability of mouse antibodies to inhibit the binding of allergic patients IgE to Bet v 1 was studied by ELISA competition experiments. RESULTS: In both schemes, hypoallergenic rBet v 1 derivatives induced low IgE but high IgG1 responses against rBet v 1 wild-type. The IgG1 antibodies induced by genetically modified rBet v 1 derivatives cross-reacted with natural Bet v 1 and its homologues from alder (Aln g 1) as well as hazel (Cor a 1) and strongly inhibited the binding of birch pollen allergic patients' IgE to Bet v 1 wild-type. CONCLUSION: Genetically modified hypoallergenic rBet v 1 derivatives induce blocking antibodies in vivo. Their safety and efficacy for the treatment of birch pollen and associated plant allergies can now be evaluated in clinical immunotherapy studies.     

Skin test evaluation of genetically engineered hypoallergenic derivatives of the major birch pollen allergen, Bet v 1: results obtained with a mix of two recombinant Bet v 1 fragments and recombinant Bet v 1 trimer in a Swedish population before the birch pollen season.

BACKGROUND: More than 95% of birch pollen-allergic subjects react with the major birch pollen allergen, Bet v 1, and almost 60% of them are sensitized exclusively to this allergen. OBJECTIVE: The aim of this study was to compare the in vivo biologic activity of genetically engineered hypoallergenic derivatives of Bet v 1 (an equimolar mixture of 2 recombinant [r] Bet v 1 fragments and of rBet v 1 trimer) with that of rBet v 1 wild-type by skin prick and intradermal testing. METHODS: Birch pollen-allergic patients who had not received immunotherapy (n = 23), a group of allergic patients without birch pollen allergy (n = 12), and nonatopic persons (n = 8) from northern Europe (Sweden) underwent skin prick and intradermal testing with different concentrations of the recombinant allergens and commercial birch pollen extract before the birch pollen season. Immediate and late-phase reactions were recorded and allergen-specific IgE and IgG subclass responses were determined by CAP radioallergosorbent test and ELISA, respectively. RESULTS: Atopic persons without birch pollen allergy and nonatopic individuals did not have skin reactions to rBet v 1 wild-type and genetically engineered hypoallergenic derivatives. By intradermal testing, 8 of 23 and 13 of 23 birch pollen-allergic patients did not react with the highest concentration (1 microg/mL) of the rBet v 1 fragment mix and rBet v 1 trimer, respectively, compared with 1 with rBet v 1 wild type. Likewise, the highest concentration (100 microg/mL) of fragment mix or trimer failed to elicit a positive skin prick test in 18 of 23 and 15 of 23 patients in comparison with 0/23 with the monomer. No late reactions were observed. CONCLUSION: The recombinant hypoallergenic birch pollen allergens can probably be used for patient-tailored immunotherapy with a reduced risk to induce anaphylactic reactions.     

Serological and skin-test diagnosis of birch pollen allergy with recombinant Bet v I, the major birch pollen allergen

Background Type I allergy represents a severe health problem in industrialized countries where up to 20% of the population suffer froin allergic rhinitis, conjunctivitis and allergic asthma bronchiale and in severe cases from anaphylaxis. leading to death.
Objective The aim of this study was to evaluate recombinant Bet v I, the major birch pollen allergen for in vivo and in vitro diagnosis of birch pollen allergy.
Methods A group of 51 birch pollen allergic patients and eight non-allergic control individuals were tested for birch pollen allergy by skin-prick and intradennal testing, comparing commercial birch pollen extracts with recombinant Bet v I. Quantitative and qualitative serological testing was done with natural and recombinant allergens by radioallergosorbent test (RAST), enzyme-linked immunosorbent assay (ELISA) and immunoblotting.
Results Recombinant Bet v I allowed accurate in vivo and in vitro diagnosis of tree pollen allergy in 49/51 patients tested. No false positive results were obtained in any in vitro assay system (ELISA. Westernblot) or by skin testing (skin-prick, intradermal test) with recombinant Bet v I.
Conclusion Our results document that recombinant Bet v I produced in bacterial expression systems allows accurate in vitro and in vivo diagnosis of birch pollen allergy in > 95% of birch pollen allergic patients.     

Modulation of allergic immune responses by mucosal application of recombinant lactic acid bacteria producing the major birch pollen allergen Bet v 1

BACKGROUND: Probiotic lactic acid bacteria (LAB) are able to modulate the host immune system and clinical trials have demonstrated that specific strains have the capacity to reduce allergic symptoms. Therefore, we aimed to evaluate the potential of recombinant LAB producing the major birch pollen allergen Bet v 1 for mucosal vaccination against birch pollen allergy. METHODS: Recombinant Bet v 1-producing Lactobacillus plantarum and Lactococcus lactis strains were constructed. Their immunogenicity was compared with purified Bet v 1 by subcutaneous immunization of mice. Intranasal application of the live recombinant strains was performed to test their immunomodulatory potency in a mouse model of birch pollen allergy. RESULTS: Bet v 1 produced by the LAB was recognized by monoclonal anti-Bet v 1 and IgE antibodies from birch pollen-allergic patients. Systemic immunization with the recombinant strains induced significantly lower IgG1/IgG2a ratios compared with purified Bet v 1. Intranasal pretreatment led to reduced allergen-specific IgE vs enhanced IgG2a levels and reduced interleukin (IL)-5 production of splenocytes in vitro, indicating a shift towards non-allergic T-helper-1 (Th1) responses. Airway inflammation, i.e. eosinophils and IL-5 in lung lavages, was reduced using either Bet v 1-producing or control strains. Allergen-specific secretory IgA responses were enhanced in lungs and intestines after pretreatment with only the Bet v 1-producing strains. CONCLUSIONS: Mucosal vaccination with live recombinant LAB, leading to a shift towards non-allergic immune responses along with enhanced allergen-specific mucosal IgA levels offers a promising approach to prevent systemic and local allergic immune responses.     

IgE mimotopes of birch pollen allergen Bet v 1 induce blocking IgG in mice

BACKGROUND: The induction of nonanaphylactogenic 'blocking' IgG antibodies capable of inhibiting the IgE/allergen interaction represents a favorable therapeutic concept for type I allergy. However, IgG antibodies to allergens may block or enhance specific IgE binding, depending on the recognized epitope. Taking the major birch pollen allergen Bet v 1 as a model, we developed a strategy for the precise induction of IgG antibodies of a desired epitope specificity. METHODS: Random phage display peptide libraries were applied to define peptide structures mimicking natural epitopes (mimotopes) of Bet v 1. Selections were performed with BIP 1, a murine monoclonal antibody known to enhance the IgE binding to Bet v 1, and with anti-Bet v 1 IgE purified from patients' sera. The characterized Bet v 1 mimotopes were used to localize the corresponding epitope at the surface of Bet v 1 by a computer-aided mathematical approach based on the three-dimensional structure and the chemical character of the amino acids. The Bet v 1 mimotopes were further used to immunize BALB/c mice. The specificity of the induced antibodies was tested by immunoblotting and inhibition assays. RESULTS: With the three-dimensional epitope search it became possible to localize a discontinuous IgE epitope on the surface of Bet v 1 in a substantial distance from the IgG epitope of the monoclonal antibody BIP 1. Moreover, we could demonstrate that phage displaying mimotopes are immunogenic vectors for the precise induction of epitope-specific IgG. Immunization with BIP 1 mimotopes induced IgG enhancing the IgE binding to Bet v 1, whereas immunization with IgE mimotopes resulted in IgG capable of blocking human IgE binding in vitro. CONCLUSION: Allergen mimotopes can be used for the induction of anti allergen IgG of desired specificity. We propose that mimotope immunotherapy based on IgE mimotopes generated by biopannings may represent a future concept for therapy of type I allergy.     

Nasal challenges with recombinant derivatives of the major birch pollen allergen Bet v 1 induce fewer symptoms and lower mediator release than rBet v 1 wild-type in patients with allergic rhinitis

BACKGROUND: Genetic engineering of the major birch pollen allergen (Bet v 1) has led to the generation of recombinant Bet v 1 derivatives with markedly reduced IgE-binding capacity, but with retained T cell activating ability. OBJECTIVE: To compare the mucosal reactivity to rBet v 1 derivatives with rBet v 1 wild-type as basis for new therapeutic strategies for birch pollen allergy based on mucosal tolerance induction. METHODS: Outside the pollen season, 10 patients with birch pollen allergic rhinitis and mild asthma underwent four nasal challenge-sessions in a randomized, double-blind, and cross-over design, employing increasing doses of rBet v 1 fragment mix, rBet v 1 trimer, rBet v 1 wild-type and diluent (albumin). Nasal lavage fluids (NAL) were collected before the challenge-series as well as 10 min, 4 and 24 h thereafter. Nasal lavage fluid levels of tryptase as well as EPO and ECP were measured as indices of mast cell and eosinophil activity, respectively. RESULTS: All 10 patients tolerated the highest accumulated dose, 8.124 microg, when challenged with rBet v 1 trimer, eight with rBet v 1 fragments compared to one when challenged with rBet v 1 wild-type. No late phase reactions were observed. The change in tryptase levels (pre-challenge vs. 10 min) was significantly lower after challenges with rBet v 1 trimer and rBet v 1 fragments than with rBet v 1 wild-type. The change in EPO/ECP concentration pre-challenge versus 4 h post-challenge was lower for rBet v 1 trimer and the change was significantly lower when pre-challenge versus 24 h post-challenge to rBet v 1 fragments and rBet v 1 wild-type was examined. CONCLUSION: The derivatives induced significantly fewer symptoms and lower mast cell and eosinophil activation than rBet v 1 wild-type upon application to the nasal mucosa. They could in the future be candidates for immunotherapy based on mucosal tolerance induction.     

Mucosal tolerance as therapy of type I allergy: intranasal application of recombinant Bet v 1, the major birch pollen allergen, leads to the suppression of allergic immune responses and airway inflammation in sensitized mice

BACKGROUND: Several studies have demonstrated that mucosal administration of soluble antigens can prevent the onset or reduce the severity of certain autoimmune diseases or allergies. Few studies exist showing the efficacy of mucosal tolerance for therapy of such diseases. OBJECTIVE: The aim of the present study was to modulate an allergic immune response by intranasal antigen administration in an already sensitized organism. METHODS: A murine model of allergic asthma to birch pollen (BP) and its major allergen Bet v 1 was utilized. Sensitized mice were intranasally treated with recombinant (r)Bet v 1 in different concentrations and at different intervals. On the day the mice were killed, blood and bronchoalveolar lavage fluids were taken and immediate type I skin tests were performed. T cell proliferation and cytokine production (interleukin (IL)-5, interferon (IFN)-gamma) were measured in spleen and lung cell cultures. RESULTS: Mucosal treatment with rBet v 1 (3 x 50 microg in 4 day intervals) led to a reduction of type I skin reactions, suppressed immunoglobulin (Ig)G1/IgE antibody levels and markedly decreased IL-5 and IFN-gamma production in vitro in spleen and lung cell cultures. Moreover, lung inflammation (i.e. eosinophilia and IL-5 levels in bronchoalveolar lavage fluids) was significantly suppressed by the treatment. CONCLUSION: Our results demonstrate that intranasal treatment with rBet v 1 reduced systemic allergic immune responses as well as airway inflammation in BP-sensitized mice. We therefore suggest that mucosal tolerance induction with recombinant allergens could be a promising concept for the therapy of allergic diseases.     

Immune responses after immunization with plasmid DNA encoding Bet v 1, the major allergen of birch pollen

Background: Immunization with plasmid DNA encoding various antigens is a promising method in vaccine research. Recent studies also indicate that DNA-based immunization might represent a potential approach in allergen-specific immunotherapy. Objective: In this study we have characterized the immune responses induced by recombinant Bet v 1a and plasmid DNA encoding for Bet v 1a, the major allergen of birch pollen in a mouse system. Methods: Balb/c mice were injected intraperitoneally with recombinant Bet v 1a and intradermally with plasmid DNA encoding for the gene of Bet v 1a (pCMV-Bet). In addition, the effect of immunostimulatory DNA sequences was investigated by appending CpG motifs to the gene of Bet v 1a, coinjecting CpG-oligodeoxynucleotides together with the pCMV-Bet construct, or both. IgE and IgG antibody responses, as well as IgG subclasses, were measured by ELISA in sera after each immunization. IFN-γ and IL-4 levels were also measured by ELISA in sera and supernatants of allergen-stimulated spleen cells. Results: The primary humoral response to a single treatment with pCMV-Bet was very weak, but the reaction could be boosted to higher levels by 2 additional injections. On the other hand, proliferation assays of spleen cells and measurements of cytokine levels already indicated a cellular response after the first injection of plasmid DNA. After 2 immunizations with pCMV-Bet, the ratio of IgG1 to IgG2a pointed to a T_H1 subclass profile. IgE was not detectable in any group at any time during the immune reaction. Accordingly, IL-4 levels were markedly reduced in the serum, as well as in the supernatants, of stimulated spleen cells. Animals immunized with pCMV-Bet containing appended CpG motifs at the 3’ end of the Bet v 1a gene and/or with the CpG-ODN GCTAGACGTTAGCGT plus pCMV-Bet displayed reduced humoral responses against Bet v 1a when compared with animals injected with pCMV-Bet alone. The levels of IFN-γ measured after allergen stimulation of isolated spleen cells were significantly higher in animals immunized with pCMV-Bet plus CpG motifs than with pCMV-Bet alone. Immunization with recombinant Bet v 1a protein elicited a strong T_H2 -type response, including IgE production, a high titer of IgG1, and IL-4 production in both serum and supernatants of proliferation cultures. Conclusion: In contrast to immunization with protein, DNA immunization induces a strong T_H1 -type response against a relevant inhalant allergen. Our data support the concept of developing a novel type of allergen immunotherapy based on plasmid DNA immunization. (J Allergy Clin Immunol 1999;103:107-13.)     

Bet v 1, the major birch pollen allergen, initiates sensitization to Api g 1, the major allergen in celery: evidence at the T cell level

Due to IgE cross-reactivity, birch pollen-allergic individuals frequently develop type I hypersensitivity reactions to celery tuber. We evaluated the T cell response to the major allergen in celeriac, Api g 1, and the cellular cross-reactivity with its homologous major allergen in birch pollen, Bet v 1. Api g 1-specific T cell lines (TCL) and clones (TCC) were established from peripheral blood mononuclear cells of allergic patients. Epitope mapping of Api g 1 with overlapping Api g 1-derived peptides revealed one dominant T cell-activating region, Api g 1(109-126). TCL and TCC generated with Api g 1 cross-reacted with the birch pollen allergen and, although initially stimulated with the food allergen, cellular responses to Bet v 1 were stronger than to Api g 1. Epitope mapping with Bet v 1-derived peptides revealed that T cells specific for several distinct epitopes distributed over the complete Bet v 1 molecule could be activated by Api g 1. Bet v 1(109-126) was identified as the most important T cell epitope for cross-reactivity with Api g 1. This epitope shares 72% amino acid sequence similarity with the major T cell-activating region of the food allergen, Api g 1(109-126). Our data provide evidence that humoral as well as cellular reactivity to the major celery allergen is predominantly based on cross-reactivity with the major birch pollen allergen. The activation of Bet v 1-specific Th2 cells by Api g 1, in particular outside the pollen season, may have consequences for birch pollen-allergic individuals.     

Non-anaphylactic surface-exposed peptides of the major birch pollen allergen, Bet v 1, for preventive vaccination

BACKGROUND: Almost 100 million allergic patients are sensitized to the major birch pollen allergen, Bet v 1, a 17 kDa protein containing most of the IgE epitopes present in pollens of trees belonging to the Fagales order and plant-derived food. OBJECTIVE: Our aim was to develop an approach for the rational design of B cell epitope-derived, non-allergenic peptide allergy vaccines. METHODS: According to the three-dimensional (3-D) structure of birch pollen allergen, Bet v 1, six peptides comprising 25-32 preferably solvent-exposed amino acids were synthesized. RESULTS: Because of lack of secondary structure, the peptides showed no allergenic activity in allergic patients. In a mouse model of birch pollen allergy, peptide vaccination induced Bet v 1-specific IgG and prevented IgE-mediated allergic sensitization to Bet v 1. The protective role of peptide-induced blocking antibodies is demonstrated by inhibition of allergic patients IgE binding to the allergen and by blocking of allergen-induced basophil degranulation. CONCLUSION: Our results indicate the mechanistic importance of blocking antibodies for allergy vaccination and present a B cell epitope-based approach for the rational design of safe peptide allergy vaccines whenever the structure of the disease-eliciting allergen is known.     

Intranasal immunization with a dominant T-cell epitope peptide of a major allergen of olive pollen prevents mice from sensitization to the whole allergen

Mucosal tolerance induction with vaccines based on peptides representing T-cell epitopes of allergens is a promising way for treating allergic diseases. Ole e 1 is the main allergen of olive pollen, which is an important cause of allergy in Mediterranean countries. The aim of this study was to evaluate the ability of the peptide T109-K130 containing a dominant T-cell epitope of Ole e 1, to modulate the allergen-specific immune response in a prophylactic mouse model. Mice were intranasally treated with the peptide 1 week prior to sensitization with Ole e 1. Blood, lungs and spleens were collected and analysed for immune response. Intranasal pretreatment of mice with the peptide led to suppress serum specific IgE, IgG1 and IgG2a antibody levels, and markedly reduced proliferative T-cell response and Th2-cytokine production, but increased IFN-gamma secretion in spleen cell cultures. Increased mRNA IL-10 levels were observed in lungs from pretreated mice. Pathologic alterations of the lung associated with airway inflammation (peribronchial/perivascular infiltrates, eosinophilia and mucus production) were significantly suppressed after pretreatment. Similar results were obtained when mice were sensitized 10 weeks after treatment. Our results demonstrate that intranasal administration of a single T-cell peptide protects mice against subsequent sensitization to the allergen, possibly via IFN-gamma and IL-10. This study emphasizes the usefulness of nasal peptide T-based vaccines against allergy.     

Characterization of the protective and therapeutic efficiency of a DNA vaccine encoding the major birch pollen allergen Bet v 1a

BACKGROUND: An estimated 100 million individuals suffer from birch pollen allergy. More than 95% of birch pollen-allergic subjects react with the major birch pollen allergen Bet v 1a, and almost 60% of them are sensitized exclusively to this allergen. OBJECTIVE: DNA immunization using the Bet v 1a gene was evaluated with respect to its prophylactic and therapeutic efficacy. METHODS: A DNA vaccine containing the entire Bet v 1a cDNA under the control of a CMV-promoter was constructed. In order to estimate the protective efficiency, animals received three injections of this vaccine prior to sensitization with recombinant Bet v 1a. Vice versa, in a therapeutic approach, sensitization was followed by treatment with the DNA vaccine. RESULTS: The Bet v 1a DNA vaccine induced strong Bet v 1-specific antibody responses with a Th1-biased response type. Animals which received the DNA vaccine were protected against a following allergic sensitization with Bet v 1a. The protective effect was characterized by suppression of Bet v 1-specific immunoglobulin (Ig)E production, lack of basophil activation and enhanced interferon (IFN)-gamma expression. In a therapeutic situation, treatment of sensitized animals with DNA vaccines decreased IgE production, IgE-mediated basophil release and drastically reduced anaphylactic activity as measured by passive cutaneous anaphylaxis assays. Concerning the cellular immune response, DNA immunization induced a sustaining and dominant shift from a Th2 type response towards a balanced Th1/Th2 type response as indicated by increased IFN-gamma but unchanged IL-5 levels in lymphoproliferation assays. CONCLUSION: The results demonstrate the allergen-specific protective and therapeutic efficacy of a DNA vaccine encoding the clinically highly relevant allergen Bet v 1a indicating the suitability of this concept for the treatment of allergic diseases.     

Oligodeoxynucleotides containing CpG motifs modulate the allergic TH2 response of BALB/c mice to Bet v 1, the major birch pollen allergen.

BACKGROUND: The use of adequate adjuvants to modulate the allergic T(H2)-type immune response is a promising concept for future immunotherapy of type I allergy. Bacterial DNA or oligodeoxynucleotides containing CpG motifs (CpG-ODNs) have been demonstrated to foster T(H1)-type immune responses. OBJECTIVE: We investigated the adjuvanticity of CpG-ODNs and their capability to modulate the allergic T(H2) response in a mouse model. METHODS: BALB/c mice were treated with CpG-ODNs and Bet v 1, the major birch pollen allergen, in different experimental setups. Allergen-specific antibody responses, T(H) cytokines, and eosinophilic infiltration of the airways were investigated. RESULTS: Intraperitoneal administration of Bet v 1 together with aluminium hydroxide led to a typical T(H2) response. In contrast, coadminstration of CpG-ODNs with Bet v 1 in aluminium hydroxide resulted in markedly increased T(H1) activities (high IgG2a levels) and subsequently to reduced airway inflammation. The T(H1)-like immune response indicated by these humoral findings was also reflected by decreased IL-5 and increased IFN-gamma levels in cell cultures. CpG-ODNs as sole adjuvants with Bet v 1 did not lead to measureable Ig responses after subcutaneous or intraperitoneal immunizations; after intranasal application, 3 of 10 mice reacted. Nevertheless, a prophylactic effect was obtained with all routes tested; that is, mice treated subsequently with an established aerosol sensitization protocol displayed altered immune responses characterized by drastically elevated levels of Bet v 1-specific IgG2a, indicating a T(H1)/T(H0)-like immunity. Application of CpG-ODNs after aerosol sensitization also induced IgG2a. CONCLUSION: By inducing T(H1)/T(H0)-biased immune responses to allergens, the use of CpG-ODNs as adjuvants may have important impacts for new forms of specific immunotherapy in type I hypersensitivity.     

Isolation and characterization of the 18-kDa major apple allergen and comparison with the major birch pollen allergen (Bet v I)

The major allergen from birch pollen, Bet v I, and the cross-reacting 18-kDa major allergen from Golden Delicious and Granny Smith apples were isolated by micropreparative SDS-PAGE followed by electroelution. In the case of apples, highly active, low-temperature extracts were used. The purity of the allergens was checked by analytic SDS-PAGE and immunoblotting with allergic patients’ sera, as well as by N-terminal amino acid microsequencing, and the allergens were found to be very pure. The strong immunologic activity of the isolates was determined by the enzyme allergosorbent test (EAST) and EAST inhibition assays; this activity was, in the case of Bet v I, similar to that of a preparation obtained by monoclonal antibody affinity chromatography. The allergenic potency of Bet v I and of the cross-reactive apple allergen was determined by EAST inhibition and dose-related histamine release. With both assay systems, the allergenic reactivity of Bet v I was considerably higher than that of the major apple allergen. Fürthermore, skin prick tests with the purified allergens and with whole allergenic extracts were performed on a group of 33 patients suffering from birch-pollen and apple hypersensitivity, and on a control group of 10 patients. The frequency of positive prick test results in the allergic patient group ranged from 73% for the major allergen from Golden Delicious apples to 97% with Bet v I and whole birch pollen extract, respectively. In contrast to our low-temperature extracts, commercial prick test solutions of four different manufacturers were found to be unreliable for the diagnosis of apple allergy. The skin test results again indicated the strong immunologic activity of the allergen isolates and the predominance of the major allergens in context with birch-pollen and apple hypersensitivity. Taken together, the results support the view that the 18-kDa major allergen represents most of the allergenicity of the the apple fruit, and that all allergenic epitopes of the apple proteins are present on Bet v I.     

Bet v 1142-156 is the dominant T-cell epitope of the major birch pollen allergen and important for cross-reactivity with Bet v 1-related food allergens

BACKGROUND: Individuals with birch pollen allergy frequently experience hypersensitivity reactions to certain foods, primarily because of IgE antibodies specific for the major birch pollen allergen Bet v 1 that cross-react with homologous food allergens. OBJECTIVE: We sought to characterize the major T-cell epitopes of Bet v 1 and to investigate their involvement in the cellular cross-reactivity with homologous food allergens. METHODS: T-cell epitope mapping of Bet v 1 was performed by testing Bet v 1-specific T-cell lines derived from 57 individuals with birch pollen allergy, with overlapping peptides representing the entire allergen. T-cell lines and T-cell clones were stimulated with Bet v 1-related major allergens from apple (Mal d 1), cherry (Pru av 1), hazelnut (Cor a 1), celery (Api g 1), carrot (Dau c 1), and soybean (Gly m 4) and with peptides deduced from the C-terminal amino acid sequences of these molecules. Results Bet v 1 142-156 , positioned in the highly conserved C-terminal region of Bet v 1, was identified as the major T-cell epitope recognized by 61% of individuals. Most T lymphocytes specific for Bet v 1 142-156 were activated by one or more homologous food proteins or the respective peptides, as indicated by proliferation and cytokine production. CONCLUSION: The major T-cell epitope of Bet v 1, Bet v 1 142-156 , plays an important role in the cellular cross-reactivity between this respiratory allergen and related food allergens. Thus T lymphocytes specific for Bet v 1 142-156 might be activated by various Bet v 1-related food allergens in vivo, even out of the pollen season.     

Recombinant birch allergens (Bet v 1 and Bet v 2) and the oral allergy syndrome in patients allergic to birch pollen.

BACKGROUND: IgE cross-reactivity between pollen and food allergens represents the molecular basis for oral allergy syndrome (OAS). OBJECTIVE: To evaluate specific IgE for Bet v 1 and Bet v 2 in the serum of patients sensitized to birch pollen and to identify whether IgE antibodies to Bet v 1 and Bet v 2 were predictors of OAS. METHODS: Thirty-three patients with skin prick test results and radioallergosorbent assay test results positive to birch pollen, 12 (36%) of whom had OAS symptoms, were enrolled in the study. Serum levels of specific IgE were determined by the fluoroenzyme immunoassay technique. RESULTS: The t test revealed significantly higher serum IgE levels against Bet v 1, Bet v 2, and birch pollen in the 12 symptomatic patients with respect to those without OAS (32.4 vs 12.4 kU/L, 7.6 vs 1.3 kU/L, and 42.3 vs 17.3 kU/L, respectively). Attempts to establish a threshold value of serum IgE antibirch pollen and the appearance of OAS revealed that a level of 20 kU/L or more yields an efficiency of the test equal to 70%. CONCLUSIONS: In our study, quantitative birch specific IgE level proved useful in predicting clinical allergy symptoms with birch exposure.