Reducing the solubility of the major birch pollen allergen Bet v 1 by particle-loading mitigates Th2 responses.

BACKGROUND: Solubility is a common feature of allergens. However, the causative relationship between this protein-intrinsic feature and sensitization capacity of allergens is not fully understood. This study aimed to proof the concept of solubility as a protein intrinsic feature of allergens. METHODS: The soluble birch pollen allergen Bet v 1 was covalently coupled to 1 µm silica particles. IgE-binding and -cross-linking capacity was assessed by inhibition ELISA and mediator release assay, respectively. Alterations in adjuvanticity by particle-loading were investigated by activation of dendritic cells, mast cells and the Toll-like receptor 4 pathway as well as by Th2 polarization in an IL-4 reporter mouse model. In BALB/c mice, particle-loaded and soluble Bet v 1 were compared in a model of allergic sensitization. Antigen uptake and presentation was analysed by restimulating human Bet v 1-specific T cell lines. RESULTS: Covalent coupling of Bet v 1 to silica particles resulted in an insoluble antigen with retained IgE-binding and -cross-linking capacity and no increase in adjuvanticity. In vivo, particle-loaded Bet v 1 induced significantly lower Bet v 1-specific (s)IgE, whereas sIgG1 and sIgG2a levels remained unaffected. The ratio of Th2 to Th1 cells was significantly lower in mice sensitized with particle-loaded Bet v 1. Particle-loading of Bet v 1 resulted in a 24-fold higher T cell activation capacity in Bet v 1-specific T cell lines, indicating more efficient uptake and presentation than of soluble Bet v 1. CONCLUSIONS: Our results show that solubility is a decisive factor contributing to the sensitization capacity of allergens. The reduction in sensitization capacity of insoluble, particle-loaded antigens results from enhanced antigen uptake and presentation compared to soluble allergens.

IL-10-modulated dendritic cells from birch pollen- and hazelnut-allergic patients facilitate Treg-mediated allergen-specific and cross-reactive tolerance.

BACKGROUND: Approximately 70% of individuals allergic to birch pollen (Bet v 1.01 [Bet]) develop a secondary food allergy (e.g., hazelnut: Cor a 1.04 [Cor]), due to allergen cross-reactivity. However, standard immunotherapy for type I allergies often does not improve the food allergy sufficiently. We analyzed the allergen-specific and cross-reactive suppressive capacity of primary human regulatory T cells (Treg) induced by autologous IL-10-modulated dendritic cells (IL-10 DC) in vitro and in vivo. METHODS: CD4+ T cells of patients with birch pollen and associated hazelnut allergies were differentiated into Bet-specific or non-specific induced Treg (iTreg). After Bet- or Cor-specific restimulation the phenotype, proliferation, and suppressive capacity of iTreg subsets were analyzed. iTreg function was further investigated in humanized mouse models of airway and intestinal allergy, generated by engraftment of peripheral blood mononuclear cells from allergic donors into immunodeficient animals. RESULTS: After IL-10 DC priming and allergen-specific restimulation (Bet or Cor), non-specific control iTreg remained anergic, whereas Bet-specific iTreg proliferated extensively and exhibited a regulatory phenotype (enhanced expression of CTLA-4, PD-1, TNFR2, IL-10). Accordingly, activated Bet-specific iTreg displayed a high capacity to suppress Bet- and Cor-induced responder Th2 cell responses in vitro, indicating induction of both allergen-specific (birch) and cross-reactive tolerance (hazelnut). In vivo, the beneficial effect of Bet-specific iTreg was verified in humanized mouse models of allergic airway and intestinal inflammation, resulting in reduced allergen-induced clinical symptoms, and immune responses. CONCLUSION: Human IL-10 DC-induced iTreg facilitate allergen-specific and cross-reactive tolerance. Therefore, they are potential candidates for regulatory cell therapy in allergic and autoimmune diseases.

Profiles of apple allergen components and its diagnostic value in Northern China.

Background: Limited is known on the profiles of apple allergy in China. Objective: To explore the clinical significance of apple allergen components in northern China. Methods: This study recruited 40 participants and categorized into apple tolerance (n = 19) and allergy (n = 21) group. The latter was categorized into oral allergy symptoms (OAS, n = 14) and generalized symptoms (GS, n = 7). All participants underwent ImmunoCAP screening to assess sIgE levels of birch, apple, and their components. Results: The sensitization rates were 90% for Bet v 1, 85% for Mal d 1, 35% for Bet v 2, and 20% for Mal d 3. The overall positive rate for apple allergens was 97.5%, with half demonstrating mono-sensitization to Mal d 1. Birch, Bet v 1 and Mal d 1 sIgE levels had consistent areas under the curve (AUC 0.747, p = 0.037; AUC 0.799, p = 0.012; AUC 0.902, p < 0.001 respectively) in diagnosing apple allergy. The optimal cut-off values were determined to be 22.85 kUA/L (63.6% sensitivity, 85.7% specificity), 6.84 kUA/L (81.8% sensitivity, 71.4% specificity) and 1.61 kUA/L (93.8% sensitivity, 75.0% specificity), respectively. No allergens or components demonstrated diagnostic value in distinguishing between OAS and GS. Mal d 3 sensitization was correlated with mugwort allergy and higher risk of peach, nuts or legumes generalized allergy. Conclusion: Mal d 1 was major allergen and the best for diagnosing apple allergy. Mal d 3 does not necessarily indicate severe allergic reaction to apples in northern China but may indicate mugwort sensitization and an increased risk of peach, nuts or legumes allergy.

Outcomes of apple oral immunotherapy in pollen food allergy syndrome.

Oral immunotherapy with apple induces tolerance for an entire apple (128 g) in patients with pollen food allergy syndrome who previously tolerated a median amount of 4 g of apple.

Trimeric Bet v 1-specific nanobodies cause strong suppression of IgE binding.

Background: Around 20% of the population in Northern and Central Europe is affected by birch pollen allergy, with the major birch pollen allergen Bet v 1 as the main elicitor of allergic reactions. Together with its cross-reactive allergens from related trees and foods, Bet v 1 causes an impaired quality of life. Hence, new treatment strategies were elaborated, demonstrating the effectiveness of blocking IgG antibodies on Bet v 1-induced IgE-mediated reactions. A recent study provided evidence for the first time that Bet v 1-specific nanobodies reduce patients´ IgE binding to Bet v 1. In order to increase the potential to outcompete IgE recognition of Bet v 1 and to foster cross-reactivity and cross-protection, we developed Bet v 1-specific nanobody trimers and evaluated their capacity to suppress polyclonal IgE binding to corresponding allergens and allergen-induced basophil degranulation. Methods: Nanobody trimers were engineered by adding isoleucine zippers, thus enabling trimeric formation. Trimers were analyzed for their cross-reactivity, binding kinetics to Bet v 1, and related allergens, and patients' IgE inhibition potential. Finally, their efficacy to prevent basophil degranulation was investigated. Results: Trimers showed enhanced recognition of cross-reactive allergens and increased efficiency to reduce IgE-allergen binding compared to nanobody monomers. Furthermore, trimers displayed slow dissociation rates from allergens and suppressed allergen-induced mediator release. Conclusion: We generated high-affine nanobody trimers that target Bet v 1 and related allergens. Trimers blocked IgE-allergen interaction by competing with IgE for allergen binding. They inhibited IgE-mediated release of biological mediators, demonstrating a promising potential to prevent allergic reactions caused by Bet v 1 and relatives.

[Study on allergen components of birch pollen in Beijing area].

Objective:To explore the allergen components of birch pollen in the Beijing area and interpret its clinical significance. Methods:A total of 58 patients with birch pollen allergy were included in the cross-sectional study and divided into allergic rhinitis（AR） and allergic asthma（AA） groups according to clinical manifestations. Concentration of birch pollen allergen sIgE, as well as Bet v 1, Bet v 2, Bet v 4 and Bet v 6 sIgE were detected by ImmunoCAP immunolinked immunoassay. Differences of sIgE concentration of birch pollen allergen component in AR and AA were analyzed. Results:There were 44（75.9%） cases of AR and 14（24.1%） cases of AA were enrolled. All the 18 patients with spring pollen allergy were AR patients without AA. There were 40 cases with both spring and autumn pollen allergy, of which 26 cases（65%） were AR and 14 cases（35%） were AA. The sIgE of birch pollen allergen was level 2 or above in all subjects. 94.8% were positive for any four allergen components. 77.6% were mono-sensitized to any allergen component while 17.2% were dual-sensitized. The positive rate of Bet v 1 and/or Bet v 2 was 93.1%. The positive rates of four protein components were: Bet v 1（82.8%）, Bet v 2（29.3%）, Bet v 6（1.7%）, Bet v 4（0%）. sIgE of birch pollen was positively correlated with sIgE level of Betv 1（r=0.898, P<0.001）. The sIgE concentration of Bet v2 in AA group was significantly higher than that in AR group（[4.34±14.35] kUA/L vs [1.56±3.26] kUA/L, P<0.05）. There was no significant difference in other components. Conclusion:Bet v 1 is the main allergen component of birch pollen in the Beijing area, and Bet v 1 plus Bet v 2 can diagnose more than 90% of birch pollen allergy.

Allergenicity and structural properties of new Cor a 1 isoallergens from hazel identified in different plant tissues.

The hazel allergen Cor a 1 is a PR-10 protein, closely related to the major birch pollen allergen Bet v 1. Hazel allergies are caused by cross-reactive IgE antibodies originally directed against Bet v 1. Despite the importance of PR-10 proteins in allergy development, their function and localization in the plant remain largely elusive. Therefore, the presence of Cor a 1 mRNA and proteins was investigated in different tissues, i.e., the female flower, immature and mature nuts, catkins, and pollen. Four yet unknown Cor a 1 isoallergens, i.e., Cor a 1.0501-1.0801, and one new Cor a 1.03 variant were discovered and characterized. Depending on the isoallergen, the occurrence and level of mRNA expression varied in different tissues, suggesting different functions. Interestingly, Cor a 1.04 previously thought to be only present in nuts, was also detected in catkins and pollen. The corresponding Cor a 1 genes were expressed in Escherichia coli. The purified proteins were analysed by CD and NMR spectroscopy. Immunoblots and ELISAs to determine their allergenic potential showed that the new proteins reacted positively with sera from patients allergic to birch, hazel and elder pollen and were recognized as novel isoallergens/variants by the WHO/IUIS Allergen Nomenclature Sub-Committee.

rBet v 1a-BanLecwt induce upregulation of IL-10 and IFN-γ gene expression in Caco-2/THP-1 co-culture and secretion of IL-10 and IFN-γ/IL-4 levels in PBMCs of birch pollen allergic donors.

Novel allergen immunotherapy (AIT) approaches necessitate the use of more effective and safe therapeutics, which can be accomplished by employing novel adjuvants for improved innate immune cell activation, as well as hypoallergenic allergen forms. In this study, we investigate the immunomodulatory effects of a chimera rBet v 1a-BanLecwt (rBv1a-BLwt; Cwt) composed of the major birch pollen allergen Bet v 1a and banana lectin (BanLecwt; BLwt) and two novel chimeras, rBv1l-BLH84T (rBet v 1l-BanLecH84T; C1) and rBLH84T-Bv1l (rBanLecH84T-Bet v 1l; C2), both composed of BLH84T and hypoallergenic birch pollen allergen Bv1l in the co-culture model Caco-2/THP-1, and PBMCs from donors with birch pollen allergy. The chimeric molecules rBv1l-BLH84T (C1) and rBLH84T-Bv1l (C2) were created in silico and then produced in E. coli using recombinant DNA technology. Real-time PCR analysis of gene expression following compound treatment in the co-culture model revealed that all three chimeras have the potential to induce the anti-inflammatory cytokine IL-10 gene expression in Caco-2 cells and IFN-γ gene expression in THP-1 cells. Sandwich ELISA revealed that Cwt increased IL-10 secretion and IFN-/IL-4 levels in PBMCs from birch pollen allergic donors, whereas C1 and C2 were less effective. The findings suggest that Cwt should be analyzed further due to its potential benefit in AIT.

Oligomerization and tyrosine nitration enhance the allergenic potential of the birch and grass pollen allergens Bet v 1 and Phl p 5.

Protein modifications such as oligomerization and tyrosine nitration alter the immune response to allergens and may contribute to the increasing prevalence of allergic diseases. In this mini-review, we summarize and discuss relevant findings for the major birch and grass pollen allergens Bet v 1 and Phl p 5 modified with tetranitromethane (laboratory studies), peroxynitrite (physiological processes), and ozone and nitrogen dioxide (environmental conditions). We focus on tyrosine nitration and the formation of protein dimers and higher oligomers via dityrosine cross-linking and the immunological effects studied.

Profiles of Birch Allergen Component Sensitization and Its Association with Pollen Food Allergy Syndrome in Northern China.

Purpose: To investigate the major allergen components associated with birch pollen allergy in northern China and elucidate clinical relevance to pollen food allergy syndrome (PFAS). Methods: Fifty-eight patients were recruited for a cross-sectional study and categorized into two groups: PFAS group and non-PFAS group, as well as apple allergy group and non-apple allergy group. The sIgE levels of birch pollen and its components, namely Bet v 1, Bet v 2, Bet v 4, and Bet v 6, were analyzed. Results: Among 58 participants, 44 individuals (75.9%) reported PFAS. 32 out of 44 (72.7%) participants reported apple allergy. Bet v 1 exhibited the highest sensitization rate at 82.8%, followed by Bet v 2 (29.3%) and Bet v 6 (1.7%). The combined sensitization rate for Bet v 1 and/or Bet v 2 was 93.1%. A total of 77.6% of the subjects demonstrated sensitization to single component, while 19.0% exhibited sensitization to two components. The sIgE levels of birch pollen and Bet v 1 were significantly elevated in PFAS group compared to non-PFAS group (p=0.001, p<0.001, respectively), as well as in apple-allergic and non-apple-allergic group (p<0.001, p<0.001, respectively). The optimal cut-off values for birch pollen and Bet v 1 sIgE were determined to be 7.09 kUA/L (with a sensitivity of 84.1% and specificity of 78.6%) and 5.11 kUA/L (with a sensitivity of 75.0% and specificity of 85.7%) when diagnosing PFAS. In terms of apple allergy, the optimal cut-off value were 9.40 kUA/L (with a sensitivity of 81.3% and specificity of 76.9%) and 6.53 kUA/L (with a sensitivity of 84.4% and specificity of 84.6%), respectively. Conclusion: The predominant sensitization pattern is mono-sensitization to Bet v 1, but when considering immunotherapy, Bet v 2 should also be taken into account. Bet v 1 serves as a valuable biomarker for diagnosing PFAS and apple allergy.

[TWO CASES OF ALLERGY WITH MUNG BEAN SPROUTS].

Patient 1 was a female patient in her teens who presented with swelling of the lips and oral discomfort after consuming mung bean sprouts. She had a history of this reaction since the age of 6 years and showed positive on a prick-to-prick test for mung bean sprouts. Patient 2 was a male patient in his twenties who also showed positive for mung bean sprouts as well as soybean sprout. Both patients were positive for IgE specific to birch, Gly m4, and Bet v1.Mung beans belong to the PR-10 family because they contain the allergenic component, Vig r1. A cross reaction to mung bean may occur in a patient with birch allergy as in the present cases. Mung bean sprouts are a cheap and common dietary item in Japan where, however, only a few cases of mung bean sprouts allergy have been reported. Mung bean sprouts allergy should be diagnosed with appropriate testing; if the patient has allergic reactions for this food item, an allergologist should provide detailed dietary guidance for avoiding pollen-food allergy syndrome.

Natural human Bet v 1-specific IgG antibodies recognize non-conformational epitopes whereas IgE reacts with conformational epitopes.

BACKGROUND: The nature of epitopes on Bet v 1 recognized by natural IgG antibodies of birch pollen allergic patients and birch pollen-exposed but non-sensitized subjects has not been studied in detail. OBJECTIVE: To investigate IgE and IgG recognition of Bet v 1 and to study the effects of natural Bet v 1-specific IgG antibodies on IgE recognition of Bet v 1 and Bet v 1-induced basophil activation. METHODS: Sera from birch pollen allergic patients (BPA, n = 76), allergic patients without birch pollen allergy (NBPA, n = 40) and non-allergic individuals (NA, n = 48) were tested for IgE, IgG as well as IgG1 and IgG4 reactivity to folded recombinant Bet v 1, two unfolded recombinant Bet v 1 fragments comprising the N-terminal (F1) and C-terminal half of Bet v 1 (F2) and unfolded peptides spanning the corresponding sequences of Bet v 1 and the apple allergen Mal d 1 by ELISA or micro-array analysis. The ability of Bet v 1-specific serum antibodies from non-allergic subjects to inhibit allergic patients IgE or IgG binding to rBet v 1 or to unfolded Bet v 1-derivatives was assessed by competition ELISAs. Furthermore, the ability of serum antibodies from allergic and non-allergic subjects to modulate Bet v 1-induced basophil activation was investigated using rat basophilic leukaemia cells expressing the human FcεRI which had been loaded with IgE from BPA patients. RESULTS: IgE antibodies from BPA patients react almost exclusively with conformational epitopes whereas IgG, IgG1 and IgG4 antibodies from BPA, NBPA and NA subjects recognize mainly unfolded and sequential epitopes. IgG competition studies show that IgG specific for unfolded/sequential Bet v 1 epitopes is not inhibited by folded Bet v 1 and hence the latter seem to represent cryptic epitopes. IgG reactivity to Bet v 1 peptides did not correlate with IgG reactivity to the corresponding Mal d 1 peptides and therefore does not seem to be a result of primary sensitization to PR10 allergen-containing food. Natural Bet v 1-specific IgG antibodies inhibited IgE binding to Bet v 1 only poorly and could even enhance Bet v 1-specific basophil activation. CONCLUSION: IgE and IgG antibodies from BPA patients and birch pollen-exposed non-sensitized subjects recognize different epitopes. These findings explain why natural allergen-specific IgG do not protect against allergic symptoms and suggest that allergen-specific IgE and IgG have different clonal origin.

Impact of meteorological parameters and air pollutants on airborne concentration of Betula pollen and Bet v 1 allergen.

The intensity of birch pollen season is expressed by seasonal pollen integral (SPIn, the sum of the mean daily pollen concentration during the birch pollination period) and the amount of Bet v 1 allergen released per birch pollen grain expressed by pollen allergen potency (PAP). Betula pollen and Bet v 1 allergen were simultaneously measured in the air of Bratislava from 2019 to 2022 by using two Burkard traps (Hirst-type and cyclone) in order to evaluate the causes of the seasonal variation in the SPIn and PAP levels. The highest SPIn (19,975 pollen/m3) was observed in 2022 and the lowest one (1484 pollen/m3) in 2021. The average daily PAP level (4.0 pg Bet v 1/pollen) was highest in 2019 and lowest (2.5 pg Bet v 1/pollen) in 2020. We found that seasonal variation in SPIn was associated mainly with the changes in environmental conditions during the pre-season period, whereas the year-to-year variation in PAP levels was attributed to environmental conditions during both pre- and in-season periods. Our results indicate that rainy weather in June 2020 and cold overcast weather in January‒February 2021 resulted in low SPIn in 2021. On the other hand, dry weather in June 2021 and warm weather in January‒February 2022 resulted in high SPIn in 2022. The low average daily PAP level in 2020 was associated with (1) low levels of gaseous air pollutants in March, when the ripening of pollen takes place; (2) an earlier start of the birch main pollen season (MPS); and (3) dry weather during the MPS. On the other hand, high PAP level in 2019 was associated with higher levels of air pollutants in March and during the MPS.

The History and Science of the Major Birch Pollen Allergen Bet v 1.

The term allergy was coined in 1906 by the Austrian scientist and pediatrician Clemens Freiherr von Pirquet. In 1976, Dietrich Kraft became the head of the Allergy and Immunology Research Group at the Department of General and Experimental Pathology of the University of Vienna. In 1983, Kraft proposed to replace natural extracts used in allergy diagnostic tests and vaccines with recombinant allergen molecules and persuaded Michael Breitenbach to contribute his expertise in molecular cloning as one of the mentors of this project. Thus, the foundation for the Vienna School of Molecular Allergology was laid. With the recruitment of Heimo Breiteneder as a young molecular biology researcher, the work began in earnest, resulting in the publication of the cloning of the first plant allergen Bet v 1 in 1989. Bet v 1 has become the subject of a very large number of basic scientific as well as clinical studies. Bet v 1 is also the founding member of the large Bet v 1-like superfamily of proteins with members-based on the ancient conserved Bet v 1 fold-being present in all three domains of life, i.e., archaea, bacteria and eukaryotes. This suggests that the Bet v 1 fold most likely already existed in the last universal common ancestor. The biological function of this protein was probably related to lipid binding. However, during evolution, a functional diversity within the Bet v 1-like superfamily was established. The superfamily comprises 25 families, one of which is the Bet v 1 family, which in turn is composed of 11 subfamilies. One of these, the PR-10-like subfamily of proteins, contains almost all of the Bet v 1 homologous allergens from pollen and plant foods. Structural and functional comparisons of Bet v 1 and its non-allergenic homologs of the superfamily will pave the way for a deeper understanding of the allergic sensitization process.

Chemical modification by peroxynitrite enhances TLR4 activation of the grass pollen allergen Phl p 5.

The chemical modification of aeroallergens by reactive oxygen and nitrogen species (ROS/RNS) may contribute to the growing prevalence of respiratory allergies in industrialized countries. Post-translational modifications can alter the immunological properties of proteins, but the underlying mechanisms and effects are not well understood. In this study, we investigate the Toll-like receptor 4 (TLR4) activation of the major birch and grass pollen allergens Bet v 1 and Phl p 5, and how the physiological oxidant peroxynitrite (ONOO-) changes the TLR4 activation through protein nitration and the formation of protein dimers and higher oligomers. Of the two allergens, Bet v 1 exhibited no TLR4 activation, but we found TLR4 activation of Phl p 5, which increased after modification with ONOO- and may play a role in the sensitization against this grass pollen allergen. We attribute the TLR4 activation mainly to the two-domain structure of Phl p 5 which may promote TLR4 dimerization and activation. The enhanced TLR4 signaling of the modified allergen indicates that the ONOO--induced modifications affect relevant protein-receptor interactions. This may lead to increased sensitization to the grass pollen allergen and thus contribute to the increasing prevalence of allergies in the Anthropocene, the present era of globally pervasive anthropogenic influence on the environment.

The role of IgG1 and IgG4 as dominant IgE-blocking antibodies shifts during allergen immunotherapy.

BACKGROUND: The induction of allergen-specific IgE-blocking antibodies is a hallmark of allergen immunotherapy (AIT). The inhibitory bioactivity has largely been attributed to IgG4; however, our recent studies indicated the dominance of IgG1 early in AIT. OBJECTIVES: Here, the IgE-blocking activity and avidity of allergen-specific IgG1 and IgG4 antibodies were monitored throughout 3 years of treatment. METHODS: Serum samples from 24 patients were collected before and regularly during AIT with birch pollen. Bet v 1-specific IgG1 and IgG4 levels were determined by ELISA and ImmunoCAP, respectively. Unmodified and IgG1- or IgG4-depleted samples were compared for their inhibition of Bet v 1-induced basophil activation. The stability of Bet v 1-antibody complexes was compared by ELISA and by surface plasmon resonance. RESULTS: Bet v 1-specific IgG1 and IgG4 levels peaked at 12 and 24 months of AIT, respectively. Serological IgE-blocking peaked at 6 months and remained high thereafter. In the first year of therapy, depletion of IgG1 clearly diminished the inhibition of basophil activation while the absence of IgG4 hardly reduced IgE-blocking. Then, IgG4 became the main inhibitory isotype in most individuals. Both isotypes displayed high avidity to Bet v 1 ab initio of AIT, which did not increase during treatment. Bet v 1-IgG1 complexes were enduringly more stable than Bet v 1-IgG4 complexes were. CONCLUSIONS: In spite of the constant avidity of AIT-induced allergen-specific IgG1 and IgG4 antibodies, their dominance in IgE-blocking shifted in the course of treatment. The blocking activity of allergen-specific IgG1 should not be underestimated, particularly early in AIT.

Introduction of General Chapters on standard methods for allergen quantification in the European Pharmacopoeia.

The Biological Standardization Project BSP090 has been successfully concluded in 2021. As a result, two standard methods for quantification of the major allergens Bet v 1 and Phl p 5 will be implemented in the European Pharmacopoeia (Ph. Eur.). The General Chapter describing the protocol of the respective Bet v 1-specific ELISA has already been adopted by the Ph. Eur. Commission and will become an official part of the Ph. Eur. in the beginning of 2023. As this will be the first allergen-specific standard method in the EU, this paper intends to summarize the preceding process and outline the measures necessary to comply with the new regulatory requirement.

Peptide epitopes as biomarkers of soya sensitization in rBet v 1 immunotherapy of birch-related soya allergy.

BACKGROUND: There are no diagnostic and/or prognostic markers of the treatment outcome in patients receiving allergen immunotherapy (AIT). Although numerous allergen epitopes are known, their value in this context has not been investigated. This paper deals with re-evaluation of sera from patients who underwent AIT against rBet v 1 for treatment of their soya allergy (BASALIT trial). OBJECTIVE: To evaluate the diagnostic and/or prognostic potential of allergen epitopes recognition by antibodies from patients with birch-related soya allergy before and after rBet v 1-immunotherapy. METHODS: PR-10 epitope-binding profiles from 34 patients were identified in silico using a statistical peptide phage display at start and at end of AIT. IgE- and IgG-binding to these peptide epitopes was measured in peptide microarrays. Clinical relevance of epitopes was evaluated by comparing these measurements to a number of treatment outcome measures recorded during double-blind placebo-controlled food challenge at start and end of AIT. RESULTS: We showed that IgG- and IgE-recognition of peptide epitopes after AIT were surrogate markers of 5 out of 12 analysed treatment outcome measures using this patient cohort. Seven epitopes were identified from multiple PR-10 allergen sequences. Twenty-six peptide epitopes were used for IgG and IgE measurements. IgE-binding to one of the epitopes was associated with stronger intensity of oral tingling/itching after ingesting soya at start of AIT. IgG recognizing two other epitopes at start of AIT could predict decreased Cor a 1-specific IgE concentration (p = .043) and decreased lip swelling intensity (p = .016) after AIT. Tolerance to increasing amounts of soy at food challenge correlated with IgG-binding to another epitope at start of AIT (p = .046). CONCLUSION: IgG- and IgE-binding to peptide epitopes in PR-10 is a potential indicator of the outcome and clinical course of AIT of soya-sensitized patients with rBet v 1.

Birch Pollen Allergens.

Birch belongs to the order Fagales and the family Betulaceae. Birch pollen is one of the most important airborne inhaled allergens in the north temperate zone, leading to allergic rhinitis, asthma and pollen-related food allergy. The sensitization rate to birch pollen is about 8-16% in the general population and 7-57% in patients seen at various allergy centers. Seven birch pollen allergens have been recognized by the International Allergen Nomenclature Sub-committee, with Bet v 1 as the sole major allergen. Component-resolved diagnostics can help to discriminate broad cross-reactivity and false-positive diagnoses of pollen allergy caused by specific IgE to pan-allergens such as Bet v 2, 4 or Bet v 7 from true birch allergy represented by the major allergen Bet v 1-specific IgE. Patients with allergic symptoms to birch pollen showed significantly higher serum anti-Bet v 1 IgE concentrations than asymptomatic individuals with birch sensitization. A higher level of IgE to Bet v 1 also predicted oral allergy syndrome after the ingestion of Rosaceae fruits, nuts, or Apiaceae vegetables, which have cross-reactive homologous allergens with birch allergens. Bet v 1 is one of the first allergens developed using recombinant technology. Many forms of genetically modified Bet v 1 hypo-allergens have been developed and have shown benefit in animal models or even clinical trials of allergen immunotherapy.