Peach extract induces systemic and local immune responses in an experimental food allergy model.

Peach allergy is among the most frequent food allergies in the Mediterranean area, often eliciting severe anaphylactic reactions in patients. Due to the risk of severe symptoms, studies in humans are limited, leading to a lack of therapeutic options. This study aimed to develop a peach allergy mouse model as a tool to better understand the pathomechanism and to allow preclinical investigations on the development of optimized strategies for immunotherapy. CBA/J mice were sensitized intraperitoneally with peach extract or PBS, using alum as adjuvant. Afterwards, extract was administered intragastrically to involve the intestinal tract. Allergen provocation was performed via intraperitoneal injection of extract, measuring drop of body temperature as main read out of anaphylaxis. The model induced allergy-related symptoms in mice, including decrease of body temperature. Antibody levels in serum and intestinal homogenates revealed a Th2 response with increased levels of mMCPT-1, peach- and Pru p 3-specific IgE, IgG1 and IgG2a as well as increased levels of IL-4 and IL-13. FACS analysis of small intestine lamina propria revealed increased amounts of T cells, neutrophils and DCs in peach allergic mice. These data suggest the successful establishment of a peach allergy mouse model, inducing systemic as well as local gastrointestinal reactions.

Epicutaneous immunotherapy

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Molecular cloning of plane pollen allergen Pla a 3 and its utility as diagnostic marker for peach associated plane pollen allergy.

BACKGROUND: Non-specific lipid transfer proteins (nsLTP) are considered to provoke allergic symptoms to plane tree pollen, which are frequently associated with peach allergy. OBJECTIVE: The objective was to clone the cDNA of plane pollen nsLTP Pla a 3, to characterize IgE-binding and allergenic potency of recombinant Pla a 3 in comparison to its natural counterpart and peach nsLTP Pru p 3. METHODS: Natural Pla a 3 was purified from plane pollen and analysed by mass spectrometry (MS). Recombinant Pla a 3 was characterized by SDS-PAGE and CD spectroscopy. Specific IgE to extract, components of plane pollen and Pru p 3 was measured by ImmunoCAP in sera of patients allergic to either plane pollen (n = 10), peach (n = 15) or both (n = 15). Biological potency of the proteins was investigated by in vitro mediator release assays and IgE cross-reactivity by competitive ELISA. RESULTS: Two Pla a 3 isoforms were identified. Recombinant Pla a 3 showed high purity, structural integrity, IgE-binding capacity comparable to nPla a 3 and biological potency. Sensitization to plane pollen extract was confirmed in 24/25 plane pollen allergics. The frequency of sensitization to Pla a 3 was 53% among patients allergic to both plane pollen and peach and 10% among plane pollen allergics tolerating peach where most patients were sensitized to Pla a 1. Pla a 3 and Pru p 3 showed strong bi-directional IgE cross-reactivity in patients allergic to peach and plane pollen, but not in peach allergics tolerating plane pollen. Levels of IgE-binding were generally higher to Pru p 3 than to Pla a 3. CONCLUSION: Sensitization to Pla a 3 is relevant in a subgroup of plane pollen allergics with concomitant peach allergy. IgE testing with Pla a 3 may serve as a marker to identify plane pollen allergic patients at risk of LTP-mediated food reactions and thereby improve in vitro diagnostic procedures.

Epicutaneous immunotherapy with a hypoallergenic Bet v 1 suppresses allergic asthma in a murine model.

BACKGROUND: Due to reduced allergic potency, hypoallergenic variants have been suggested as safer and potentially more efficacious alternative to the corresponding wild-type allergens in allergen-specific immunotherapy. Here, we aimed at investigating the efficacy of recombinant Bet v 1B2, a hypoallergenic folding variant of Bet v 1, in epicutaneous immunotherapy to suppress asthmatic features using a murine model of birch pollen allergy. METHODS AND RESULTS: Before, or after sensitization with rBet v 1 plus ALUMW and intranasal challenges with birch pollen extract, BALB/c mice received epicutaneous immunization (EPI) with rBet v 1, or rBet v 1B2 on their depilated back. Prophylactic EPI with rBet v 1B2, but not with rBet v 1, suppressed serum levels of Bet v 1-specific IgE antibodies and reduced the number of eosinophils and the concentrations of Th2 cytokines in bronchoalveolar lavage. In an established allergic condition, serum levels of Bet v 1-specific IgE antibodies were similar between PBS-treated control mice and EPI-treated mice. However, therapeutic EPI with rBet v 1B2, but not with rBet v 1, significantly suppressed the development of airway inflammation and lung function impairment. CONCLUSION: This study is the first to show the effect of therapeutic EPI with a recombinant form of a hypoallergenic folding variant on the suppression of asthmatic features. Our results suggest that rBet v 1B2 along with its reduced IgE-binding capacity could be a preferred therapeutic allergen than wild-type rBet v 1 in epicutaneous immunotherapy of birch pollen-induced allergic asthma, in particular due to a lower risk of allergic side effect.

MPLA shows attenuated pro-inflammatory properties and diminished capacity to activate mast cells in comparison with LPS.

BACKGROUND: Monophosphoryl lipid A (MPLA), a nontoxic TLR4 ligand derived from lipopolysaccharide (LPS), is used clinically as an adjuvant in cancer, hepatitis, and malaria vaccines and in allergen-specific immunotherapy. Nevertheless, its cell-activating effects have not been analyzed in a comprehensive direct comparison including a wide range of different immune cells. Therefore, the objective of this study was the side-by-side comparison of the immune-modulating properties of MPLA and LPS on different immune cells. METHODS: Immune-activating properties of MPLA and LPS were compared in human monocytes and mast cells (MCs), a mouse endotoxin shock model (ESM), and mouse bone marrow (BM)-derived myeloid dendritic cells (mDCs), T cells (TCs), B cells, and MCs. RESULTS: In a mouse in vivo ESM and a human ex vivo monocyte activation test (MAT), MPLA induced the same cytokine secretion pattern as LPS (ESM: IL-6, IL-12, TNF-α; MAT: IL-1ß, IL-6, TNF-α), albeit at lower levels. Mouse mDCs and ex vivo isolated B cells stimulated with MPLA required a higher threshold to induce TRIF-dependent cytokine secretion (IL-1ß, IL-6, IL-10, and TNF-α) than did LPS-stimulated cells. In mDC:DO11.10 CD4 TC cocultures, stimulation with MPLA, but not with LPS, resulted in enhanced OVA-specific IL-4 and IL-5 secretion from DO11.10 CD4 TCs. Unexpectedly, in both human and mouse MCs, MPLA, unlike LPS, did not elicit secretion of pro-inflammatory cytokines. CONCLUSIONS: Compared to LPS, MPLA induced a qualitatively similar, but less potent pro-inflammatory immune response, but was unable to activate human or mouse MCs.

What makes an allergen?

Allergic diseases are an immune disorder reacting to certain type of allergen(s). Remarkably only a small number of proteins of the plant and animal proteome act as allergens. Therefore, allergens have been clustered according to their common structural, biochemical and functional features. Evidence has accumulated that some allergens possess intrinsic adjuvant properties to stimulate the innate immunity. The adjuvant properties appear to contribute to the allergenicity of the respective proteins, namely the ability to cause allergic sensitization in susceptible subjects or allergic reactions in sensitized individuals. Here, we discuss how allergens interact with the innate immune cells, in particular dendritic cells and epithelial cells, via binding to pattern recognition receptors, exhibiting proteolytic activities and/or inducting type 2 innate lymphoid cells (ILC2), thereby contributing to the sensitization and development of allergic diseases.

Epicutaneous immune modulation with Bet v 1 plus R848 suppresses allergic asthma in a murine model.

BACKGROUND: Combining allergen(s) with an adjuvant is a strategy to improve the efficacy and safety of allergen-specific immunotherapy. Here, we aimed at investigating the adjuvant effects of polyadenylic-polyuridylic acid (poly(A:U)), a TLR3 agonist, and R848 (resiquimod), a TLR7 agonist, in epicutaneous immunotherapy with Bet v 1, the major birch pollen allergen, to intervene in birch pollen allergy. METHODS AND RESULTS: BALB/c mice received epicutaneous immunization (EPI) with recombinant Bet v 1 (rBet v 1) alone, or plus poly(A:U), or R848 on their depilated back using patches. Among the groups, EPI with rBet v 1 and R848 induced detectable levels of IFN-γ-producing CD4(+) T cells in lymph nodes and Bet v 1-specific IgG2a antibodies in the sera of mice. Before or after EPI, mice were sensitized with rBet v 1 plus aluminium hydroxide adjuvant and intranasally challenged with birch pollen extract. Prophylactic EPI with rBet v 1 plus R848 inhibited the production of biologically active Bet v 1-specific IgE antibodies in sensitization. Prophylactic and therapeutic EPI with rBet v 1 plus R848 suppressed lung inflammation upon challenges. Remarkably, only rBet v 1 plus R848 reduced the development of enhanced pause (PenH), a substituted parameter for airway hyper-reactivity, in challenged mice. In contrast to R848, poly(A:U) did not present adjuvant effect on the suppression of asthmatic features. CONCLUSION: Epicutaneous immunization with rBet v 1 plus R848 induced predominant Bet v 1-specific Th1 responses and efficiently suppressed asthmatic features elicited by birch pollen. R848 could be a promising adjuvant in epicutaneous immunotherapy for birch pollen-induced allergic asthma.

Immunoglobulin E reactivity and allergenic potency of Morus papyrifera (paper mulberry) pollen.

BACKGROUND: Paper mulberry (Morus papyrifera) pollen is considered to be one of the most clinically relevant aeroallergens in Pakistan. To date, the allergenicity of the pollen has not been investigated. OBJECTIVE: To characterize the sensitization profile of mulberry-allergic patients and the proteins of paper mulberry pollen contributing to pollinosis in the Pakistani population. METHODS: Proteins were extracted from mulberry pollen using different protocols. Immunoglobulin (Ig) E binding proteins to mulberry pollen was determined by ImmunoCAP testing and immunoblotting using sera from 29 mulberry pollen-allergic patients with positive skin prick test results to mulberry pollen antigens. The histamine release assay was performed in vitro to determine the allergenic potency of pollen extracts and a partially purified mulberry pollen allergen. The protein was identified using N-terminal sequencing and matrix-assisted laser desorption/ionization-time of flight spectrometry (MALDI-TOF/TOF). RESULTS: IgE sensitization to mulberry pollen was confirmed by positive ImmunoCAP results to pollen from Morus alba (white mulberry) in 23 out of 29 mulberry pollen-allergic patients. A 10-kDa protein from the paper mulberry pollen extract was considered a major allergen, along with additional IgE-reactive proteins. Sera from 79% of the patients reacted to the 10-kDa allergen, which showed substantial capacity to trigger histamine release in 3 out of 4 patients. N-terminal sequencing and MALDI-TOF/TOF yielded an amino acid sequence with no homology to known proteins. CONCLUSIONS: Mulberry-allergic patients are sensitized to multiple mulberry pollen allergens. We identified a novel 10-kDa protein that was a major allergen and should be further investigated for diagnostic and therapeutic purposes.

Vaccination with recombinant modified vaccinia virus Ankara prevents the onset of intestinal allergy in mice.

BACKGROUND: Modified vaccinia virus Ankara (MVA)-encoding antigens are considered as safe vaccine candidates for various infectious diseases in humans. Here, we investigated the immune-modulating properties of MVA-encoding ovalbumin (MVA-OVA) on the allergen-specific immune response. METHODS: The immune-modulating properties of MVA-OVA were investigated using GM-CSF-differentiated BMDCs from C57BL/6 mice. OVA expression upon MVA-OVA infection of BMDCs was monitored. Activation and maturation markers on viable MVA-OVA-infected mDCs were analyzed by flow cytometry. Secretion of INF-γ, IL-2, and IL-10 was determined in a co-culture of BMDCs infected with wtMVA or MVA-OVA and OVA-specific OT-I CD8(+) and OT-II CD4(+ ) T cells. BALB/c mice were vaccinated with wtMVA, MVA-OVA, or PBS, sensitized to OVA/alum and challenged with a diet containing chicken egg white. OVA-specific IgE, IgG1, and IgG2a and cytokine secretion from mesenteric lymph node (MLN) cells were analyzed. Body weight, body temperature, food uptake, intestinal inflammation, and health condition of mice were monitored. RESULTS: Infection with wtMVA and MVA-OVA induced comparable activation of mDCs. MVA-OVA-infected BMDCs expressed OVA and induced enhanced IFN-γ and IL-2 secretion from OVA-specific CD8(+ ) T cells in comparison with OVA, wtMVA, or OVA plus wtMVA. Prophylactic vaccination with MVA-OVA significantly repressed OVA-specific IgE, whereas OVA-specific IgG2a was induced. MVA-OVA vaccination suppressed TH 2 cytokine production in MLN cells and prevented the onset of allergic symptoms and inflammation in a mouse model of OVA-induced intestinal allergy. CONCLUSION: Modified vaccinia virus Ankara-ovalbumin (MVA-OVA) vaccination induces a strong OVA-specific TH 1- immune response, likely mediated by the induction of IFN-γ and IgG2a. Finally, MVA-based vaccines need to be evaluated for their therapeutic potential in established allergy models.

Immunoglobulin E Reactivity and Allergenic Potency of Morus papyrifera (Paper Mulberry) Pollen

Antecedentes: El polen de la morera del papel se considera uno de los aeroalérgenos más relevantes en Pakistán, cuyas propiedades alergénicas no han sido estudiadas hasta el momento actual. Objetivo: El objetivo de este estudio fue caracterizar el perfil de sensibilización de los pacientes alérgicos a las proteínas de este polen que contribuye a la polinosis en Pakistán. Métodos: La extracción de las proteínas de este polen fue realizada mediante diferentes protocolos. La unión de la IgE a proteínas del polen de la morera del papel, perteneciente a la familia de las moráceas fue determinada mediante InmunoCAP e Inmunoblotting utilizando suero de 29 pacientes alérgicos a este polen con prueba cutánea positiva. Se realizó test de liberación de histamina in vitro para determinar la potencia alergénica de los extractos de polen y de un alérgeno parcialmente purificado. Se secuenciaron la N-terminal y MALDI-TOF/TOF para identificar la proteína. Resultados: En cuanto a los resultados obtenidos se confirmó la sensibilización a dicho polen mediante ImmunoCAP frente a polen de Morus alba en 23 de los 29 pacientes alérgicos al polen de morera del papel. Una proteína de 10 kDa del extracto de dicho polen se consideró como el alérgeno mayor sobre el resto de las proteínas reactivas a la IgE. El suero del 79% de los pacientes reaccionó con este alérgeno de 10 kDa, el cual mostró capacidad para liberar histamina in vitro en 3 de 4 pacientes. La secuenciación N-terminal y MALDI-TOF/TOF arrojó una secuencia de aminoácidos con ausencia de homología con otras proteínas conocidas. Conclusiones: En conclusión, los pacientes alérgicos al polen de morera del papel están sensibilizados a múltiples alérgenos de este polen. Se identifica una nueva proteína de 10 kDa como alérgeno mayoritario que deberá ser investigado con fines diagnósticos y terapéuticos (AU)

Background: Paper mulberry (Morus papyrifera) pollen is considered to be one of the most clinically relevant aeroallergens in Pakistan. To date, the allergenicity of the pollen has not been investigated. Objective: To characterize the sensitization profile of mulberry-allergic patients and the proteins of paper mulberry pollen contributing to pollinosis in the Pakistani population. Methods: Proteins were extracted from mulberry pollen using different protocols. Immunoglobulin (Ig) E binding proteins to mulberry pollen was determined by ImmunoCAP testing and immunoblotting using sera from 29 mulberry pollen–allergic patients with positive skin prick test results to mulberry pollen antigens. The histamine release assay was performed in vitro to determine the allergenic potency of pollen extracts and a partially purified mulberry pollen allergen. The protein was identified using N-terminal sequencing and matrix-assisted laser desorption/ionization–time of flight spectrometry (MALDI-TOF/TOF). Results: IgE sensitization to mulberry pollen was confirmed by positive ImmunoCAP results to pollen from Morus alba (white mulberry) in 23 out of 29 mulberry pollen–allergic patients. A 10-kDa protein from the paper mulberry pollen extract was considered a major allergen, along with additional IgE-reactive proteins. Sera from 79% of the patients reacted to the 10-kDa allergen, which showed substantial capacity to trigger histamine release in 3 out of 4 patients. N-terminal sequencing and MALDI-TOF/TOF yielded an amino acid sequence with no homology to known proteins. Conclusions: Mulberry-allergic patients are sensitized to multiple mulberry pollen allergens. We identified a novel 10-kDa protein that was a major allergen and should be further investigated for diagnostic and therapeutic purposes (AU)

Identification of a Dau c PRPlike protein (Dau c 1.03) as a new allergenic isoform in carrots (cultivar Rodelika).

BACKGROUND: Up to 25% of food allergic subjects in central Europe suffer from carrot allergy. Until now, two isoforms of the major carrot (Daucus carota) allergen Dau c 1 have been described: Dau c 1.01, comprising five variants (Dau c 1.0101-Dau c 1.0105) and Dau c 1.02. OBJECTIVE: To investigate potential allergenic properties of a Dau c PRPlike protein, a novel isoform of the PR-10 protein family in carrot. METHODS: Dau c PRPlike cDNA from carrot roots (cv Rodelika) was cloned after RT-PCR and 5'RACE. Dau c PRPlike protein was expressed in E. coli, purified under native conditions by Ni-NTA chromatography and analysed by CD spectroscopy. Immuno-reactivity of the rDau c PRPlike protein was compared with rDau c 1.0104 and rDau c 1.0201 in terms of IgE binding (immunoblotting, ImmunoCAP), IgE cross-reactivity (ELISA inhibition) and in vitro mediator release with sera from carrot allergic patients. mRNA expression of Dau c PRPlike protein in wild-type and transgenic carrot roots was analysed by qRT-PCR. RESULTS: The Dau c PRPlike protein was identified as a new allergenic isoform, Dau c 1.03, in carrot roots. 68% of carrot allergic patients were sensitized to rDau c 1.03. The IgE-reactivity of rDau c 1.03 strongly correlated with reactivity to rDau c 1.0104, but not to rDau c 1.0201. The extent of IgE cross-reactivity and allergenic potency of Dau c 1 isoforms varied between the individual sera tested. Dau c 1.03 mRNA transcripts were up-regulated in Dau c 1.01 and Dau c 1.02 gene-silenced carrot roots. CONCLUSION AND CLINICAL RELEVANCE: Dau c 1 isoforms display distinct IgE epitope heterogeneity. Dau c 1.03 appears to contribute to the allergenicity of carrots and the manifestation of carrot allergy. The epitope diversity of different Dau c 1 isoforms should be considered for component-resolved diagnosis and gene silencing of carrot allergens.

Performance of different in vitro techniques in the molecular diagnosis of peanut allergy.

INTRODUCTION: Peanut allergy is an increasingly serious disorder with a heterogeneous pattern of sensitization across different countries. In vitro diagnostic techniques may help in establishing these patterns. OBJECTIVES: To analyze the usefulness of determining specific immunoglobulin E (sIgE) with the ImmunoCAP fluorescence enzyme immunoassay (FEIA), the ImmunoCAP ISAC CRD103 microarray (ISAC), and the basophil activation test (BAT) in the molecular diagnosis of peanut allergy. METHODS: In 26 peanut-allergic patients, sIgE antibodies against allergic components were measured with FEIA, ISAC, and BAT. RESULTS: The major peanut component in our population wasAra h 9.The detection of sIgE toAra h 9 using FEIA and BAT with this allergen yielded a sensitivity of 92% and 88% and a specificity of 95% and 100%, respectively. Overall diagnosis of peanut allergy by ISAC showed a sensitivity of 11% but a specificity of 95% since Ara h 9 was not present in the microarray version used. There was diagnostic agreement between the 3 techniques for the peanut allergens studied. CONCLUSIONS: The determination of sIgE to Ara h 9 using FEIA and BAT offers high sensitivity and specificity in the diagnosis of peanut allergy in the Spanish population. The CRD103 version of ISAC is not of value in our region as it does not include the most common allergen, Ara h 9.

Pru p 3, the nonspecific lipid transfer protein from peach, dominates the immune response to its homolog in hazelnut.

BACKGROUND: Nonspecific lipid transfer proteins (nsLTPs) are important food allergens. Often, patients allergic to the nsLTP in peach suffer from allergy to hazelnuts. We aimed to analyse the T-cell response to Cor a 8, the nsLTP in hazelnut and its immunological cross-reactivity with the nsLTP in peach, Pru p 3. METHODS: Cor a 8-reactive T-cell lines (TCL) established from patients allergic to hazelnut and peach were stimulated with 12-mer peptides representing the complete amino acid sequence of Cor a 8 to identify its T-cell-activating regions and with Pru p 3 to investigate cellular cross-reactivity. T-cell clones specific for different major T-cell-activating regions of Pru p 3 were stimulated with Cor a 8. Both nsLTPs were subjected to endolysosomal degradation assays. Immunoglobulin E (IgE) cross-reactivity between Cor a 8 and Pru p 3 was assessed in inhibition enzyme-linked immunosorbent assay. RESULTS: No major T-cell-activating region was found among 26 T-cell-reactive peptides identified in Cor a 8. Although generated with Cor a 8, 62% of the TCL responded more strongly to Pru p 3. This cross-reactivity was mediated by T cells specific for the immunodominant region Pru p 3(61-75) . Peptide clusters encompassing this region were generated during lysosomal degradation of both nsLTPs. Cor a 8 was more rapidly degraded by lysosomal proteases than Pru p 3. Pre-incubation of sera with Pru p 3 completely abolished IgE binding to Cor a 8, which was not the case vice versa. CONCLUSIONS: T-cell reactivity to Cor a 8 is predominantly based on cross-reactivity with Pru p 3, indicating that the latter initiates sensitisation to its homolog in hazelnut. The limited allergenic potential of Cor a 8 seems to be associated with rapid lysosomal degradation during allergen processing and the lack of major T-cell-activating regions.

The non-specific lipid transfer protein, Ara h 9, is an important allergen in peanut.

BACKGROUND: Plant food allergy in the Mediterranean area is mainly caused by non-specific lipid transfer proteins (nsLTP). The aim of this study was to characterize peanut nsLTP in comparison with peach nsLTP, Pru p 3, and assess its importance in peanut allergy. METHODS: Peanut-allergic patients from Spain (n=32) were included on the basis of a positive case history and either a positive skin prick test or specific IgE to peanut. For comparison, sera of 41 peanut-allergic subjects from outside the Mediterranean area were used. Natural Ara h 9 and two isoforms of recombinant Ara h 9, expressed in Pichia pastoris, were purified using a two-step chromatographic procedure. Allergen characterization was carried out by N-terminal sequencing, circular dichroism (CD) spectroscopy, immunoblotting, IgE inhibition tests and basophil histamine release assays. RESULTS: Compared with natural peanut nsLTP, the recombinant proteins could be purified in high amounts from yeast supernatant (> or =45 mg/L). The identity of the proteins was verified by N-terminal amino acid sequencing and with rabbit nsLTP-specific antibodies. CD spectroscopy revealed similar secondary structures for all preparations and Pru p 3. The Ara h 9 isoforms showed 62-68% amino acid sequence identity with Pru p 3. IgE antibody reactivity to rAra h 9 was present in 29/32 Spanish and 6/41 non-Mediterranean subjects. Recombinant Ara h 9 showed strong cross-reactivity to nPru p 3 and similar IgE-binding capacity as nAra h 9. The two Ara h 9 isoforms displayed similar IgE reactivity. In peanut-allergic patients with concomitant peach allergy, Ara h 9 showed a weaker allergenic potency than Pru p 3 in histamine release assays. CONCLUSIONS: Ara h 9 is a major allergen in peanut-allergic patients from the Mediterranean area. Ara h 9 is capable of inducing histamine release from basophils, but to a lesser extent than Pru p 3.

The principle of homologous groups in regulatory affairs of allergen products--a proposal.

Among other legal regulations, the Note for Guidance on Allergen Products CPMP/BWP/243/96 released by the European Medicines Agency provides regulatory instructions regarding the quality of allergen extracts for diagnostic or therapeutic purposes. The current revision of this guideline intends to transform the so-called 'principle of taxonomic families' to the 'principle of homologous groups'. According to this concept, the data of one allergen extract demonstrating stability, efficacy and safety can, to a limited extent, be extrapolated to other allergen extracts belonging to the same homologous groups. The present work proposes the formation of homologous groups for pollen species and animal-derived materials on the basis of similar biochemical composition and homology/cross-reactivity of allergens or allergen sources. Some tree pollen species could be assigned to three different homologous groups, some weed pollen species to one homologous group and numerous grass pollen species to one homologous group on condition that data rely on single defined representative species. A homologous group for mites is limited to the Dermatophagoides species and the grouping of vertebrate-derived materials such as dander could be possible under restrictions. The criteria for the formation of the proposed homologous groups are illustrated in detail to provide an opportunity for extending existing homologous groups by further species in case of new insights in allergens and cross-reactivity of allergen sources. In this way, the concept of homologous groups could serve as a dynamic tool in the regulation of allergen products.

Identification of a plane pollen lipid transfer protein (Pla a 3) and its immunological relation to the peach lipid-transfer protein, Pru p 3.

BACKGROUND: An association between plane tree pollen allergy and plant food allergy has been described, but the cross-reacting allergens have not yet been identified. The aim of this study was the identification of homologous non-specific lipid-transfer proteins (nsLTPs) in plane pollen, and to investigate its immunological relationship with the peach LTP, Pru p 3. METHODS: Three different patient groups were recruited in Spain: 22 plane pollen-allergic patients without food allergy (A), 36 plane pollen-allergic patients with peach allergy (B) and 10 peach-allergic patients without plane pollen allergy (C). Proteins from plane pollen extract were fractionated by ion-exchange and reversed-phase chromatography. Further methods applied were N-terminal amino acid sequence analysis, immunoblotting, enzyme allergosorbent test, CAP and basophil histamine release assays. RESULTS: A 10 kDa IgE-reactive protein was purified from plane pollen and identified as nsLTP. Pla a 3 was characterized as a minor allergen (27.3%) in plane pollen-allergic patients without food allergy (A) and as a major allergen in plane pollen-allergic patients with peach allergy (B) showing a prevalence of IgE-reactivity of 63.8%. Group B contained patients sensitized to Pru p 3 without IgE-reactivity to plane-LTP (16.6%). By contrast, Pla a 3 IgE-reactive patients without sensitization to Pru p 3 could be found (16.6%). The sera of patients sensitized to both LTPs (50%), Pla a 3 and Pru p 3, showed different biological activity in histamine release assay: depending on individual patient's sera tested, Pla a 3 showed a similar, a stronger or a weaker allergenic potency in comparison with Pru p 3. CONCLUSIONS: Plane LTP is a major allergen in plane pollen-allergic patients with peach allergy recruited in the Mediterranean area. The results of histamine release tests and different IgE-binding profiles pointed towards the existence of species-specific IgE epitopes. Likewise, no general conclusion on the sensitizer could be made.

A critical assessment of allergen component-based in vitro diagnosis in cherry allergy across Europe.

BACKGROUND: Food allergy to cherry occurs throughout Europe, typically with restricted oral reactions in the central and northern parts but with frequent systemic reactions in the Mediterranean region. Previous studies have demonstrated insufficient sensitivity of commercially available cherry extract reagents in the diagnosis of cherry allergy. OBJECTIVE: To assess the diagnostic performance of specific IgE tests based on recombinant cherry allergens in comparison with an extract-based assay and to skin prick test (SPT). A secondary objective was to analyse the frequency of systemic reactions in cherry-allergic subjects across Europe, including the largest population of LTP-sensitized subjects from central Europe studied to date. METHODS: A total of 186 subjects from central Europe and Spain were studied. Serum IgE was analysed with ImmunoCAP tests carrying rPru av 1, 3 and 4, combined and separately, and cherry extract. RESULTS: Among the central European cherry allergics, the mix of rPru av 1, 3 and 4 had a sensitivity of 95%, compared with 65% for cherry extract, and the IgE binding capacity of the recombinant mix was considerably higher. The sensitivity of the two tests was more comparable in the Spanish population, 95% and 86%, respectively. The recombinant allergen ImmunoCAP equalled SPT in terms of sensitivity and specificity. Consistent with previous reports, major geographic differences in sensitization pattern and prevalence of systemic reactions were found. A significantly higher rate of systemic reactions was found in Spanish patients sensitized to Pru av 3 whereas German patients sensitized to LTP only had oral allergy syndrome. CONCLUSIONS: The recombinant cherry allergen ImmunoCAP is a highly sensitive diagnostic tool, clearly superior to any diagnostic method based on cherry extract. Three cherry allergens are sufficient for detecting sensitization in 95% of cherry-allergic subjects. Systemic reactions are common in LTP-sensitized individuals but seem to require at least one additional causative factor.