New light on an old syndrome: role of Api g 7 in mugwort pollen related celery allergy

BACKGROUND

Celery root is known to cause severe allergic reactions in patients sensitized to mugwort pollen.

OBJECTIVE

To study clinically well-characterized patients with celery allergy by IgE testing with a comprehensive panel of celery allergens to disentangle the molecular basis of the "celery-mugwort-syndrome".

METHODS

Patients with suspected food allergy to celery underwent a standardized interview. Main inclusion criteria were a positive food challenge with celery or an unambiguous case history of severe anaphylaxis. IgE to celery allergens (rApi g 1.01, rApi g 1.02, rApi g 2, rApi g 4, nApi g 5, rApi g 6, rApi g 7), and to mugwort allergens (rArt v 1, rArt v 3, rArt v 4) were determined by ImmunoCAP. IgE levels ≥ 0.35kUA/L were regarded positive.

RESULTS

Seventy-nine patients with allergy to celery were included. Thirty patients suffered from mild oral or rhino-conjunctival symptoms and 49 from systemic reactions. Sixty-eight % had IgE to celery extract, 80% to birch pollen and 77% to mugwort pollen. A combination of Api g 1.01, 1.02, 4, 5, and 7 increased diagnostic sensitivity for celery allergy to 92%. The LTPs Api g 2 and Api g 6 were not relevant in our celery allergic population. IgE to Api g 7, detected in 52% of patients, correlated closely (r=0.86) to Art v 1 from mugwort pollen. Eleven out of 12 patients with monosensitization to Api g 7 were IgE negative to celery extract. The odds ratio for developing a severe anaphylactic reaction rather than only mild oral symptoms was about 6 times greater (odds ratio 5.87; 95% CI 1.08-32.0, p=0.0410) for Api g 7 sensitized versus Api g 7 non-sensitized subjects.

CONCLUSION

There is an urgent need for routine diagnostic tests to assess sensitization to Api g 7 not only to increase test sensitivity, but also to identify celery allergic patients at risk of a severe allergic reaction to celery.

Predictors of Food Sensitization in Children and Adults Across Europe

BACKGROUND

The geographical variation and temporal increase in the prevalence of food sensitization (FS) suggest environmental influences.

OBJECTIVE

To investigate how environment, infant diet, and demographic characteristics, are associated with FS in children and adults, focusing on early-life exposures.

METHODS

Data on childhood and adult environmental exposures (including, among others, sibship size, day care, pets, farm environment, and smoking), infant diet (including breast-feeding and timing of introduction to infant formula and solids), and demographic characteristics were collected from 2196 school-age children and 2185 adults completing an extensive questionnaire and blood sampling in the cross-sectional pan-European EuroPrevall project. Multivariable logistic regression was applied to determine associations between the predictor variables and sensitization to foods commonly implicated in food allergy (specific IgE ≥0.35 kU_A/L). Secondary outcomes were inhalant sensitization and primary (non-cross-reactive) FS.

RESULTS

Dog ownership in early childhood was inversely associated with childhood FS (odds ratio, 0.65; 95% CI, 0.48-0.90), as was higher gestational age at delivery (odds ratio, 0.93 [95% CI, 0.87-0.99] per week increase in age). Lower age and male sex were associated with a higher prevalence of adult FS (odds ratio, 0.97 [95% CI, 0.96-0.98] per year increase in age, and 1.39 [95% CI, 1.12-1.71] for male sex). No statistically significant associations were found between other evaluated environmental determinants and childhood or adult FS, nor between infant diet and childhood FS, although early introduction of solids did show a trend toward prevention of FS.

CONCLUSIONS

Dog ownership seems to protect against childhood FS, but independent effects of other currently conceived environmental and infant dietary determinants on FS in childhood or adulthood could not be confirmed.

Prevalence of Food Sensitization and Food Allergy in Children Across Europe

BACKGROUND

For adults, prevalence estimates of food sensitization (FS) and food allergy (FA) have been obtained in a standardized manner across Europe. For children, such estimates are lacking.

OBJECTIVES

To determine the prevalence of self-reported FA, FS, probable FA (symptoms plus IgE sensitization), and challenge-confirmed FA in European school-age children.

METHODS

Data on self-reported FA were collected through a screening questionnaire sent to a random sample of the general population of 7- to 10-year-old children in 8 European centers in phase I of the EuroPrevall study. Data on FS and probable FA were obtained in phase II, comprising an extensive questionnaire on reactions to 24 commonly implicated foods, and serology testing. Food challenge was performed in phase III.

RESULTS

Prevalence (95% CI) of self-reported FA ranged from 6.5% (5.4-7.6) in Athens to 24.6% (22.8-26.5) in Lodz; prevalence of FS ranged from 11.0% (9.7-12.3) in Reykjavik to 28.7% (26.9-30.6) in Zurich; and prevalence of probable FA ranged from 1.9% (0.8-3.5) in Reykjavik to 5.6% (3.6-8.1) in Lodz. In all centers, most food-sensitized subjects had primary (non-cross-reactive) FS. However, FS due to birch pollen related cross-reactivity was also common in Central-Northern Europe. Probable FA to milk and egg occurred frequently throughout Europe; to fish and shrimp mainly in the Mediterranean and Reykjavik. Peach, kiwi, and peanut were prominent sources of plant FA in most countries, along with notably hazelnut, apple, carrot, and celery in Central-Northern Europe and lentils and walnut in the Mediterranean.

CONCLUSIONS

There are large geograhical differences in the prevalence of FS and FA in school-age children across Europe. Both primary and cross-reactive FS and FA occur frequently.

Analgetikaunverträglichkeit: Intoleranz oder Allergie?

Zusammenfassung. Nichtsteroidale Analgetika (NSAID) können sowohl nicht immunologisch vermittelte Intoleranzreaktionen als auch allergische Reaktionen auslösen. Die Intoleranzreaktionen sind häufiger. Klinisch lassen sich Intoleranzreaktionen nicht von allergischen Reaktionen vom Soforttyp unterscheiden. Sie äussern sich hauptsächlich mit kutanen und respiratorischen Symptomen. Da der Wirkmechanismus der nicht-selektiven NSAID, nämlich die Hemmung der Cylclooxygease (COX), v. a. der COX-1, auch die Ursache für die Intoleranzreaktion auf NSAID ist, ist bei vielen Patienten eine Unverträglichkeit auf verschiedene strukturell nicht verwandte COX-1-Hemmer zu befürchten (breite NSAID-Intoleranz). Bei der Allergie auf ein NSAID ist jedoch nur eine Kreuzreaktion zu strukturverwandten NSAID zu erwarten. Wichtig für den Patienten ist es, im Rahmen der allergologischen Abklärung für ihn gut verträgliche Ausweichanalgetika zu identifizieren.

Food Allergy in Adults: Substantial Variation in Prevalence and Causative Foods Across Europe

BACKGROUND

According to the community-based EuroPrevall surveys, prevalence of self-reported food allergy (FA) in adults across Europe ranges from 2% to 37% for any food and 1% to 19% for 24 selected foods.

OBJECTIVE

To determine the prevalence of probable FA (symptoms plus specific IgE-sensitization) and challenge-confirmed FA in European adults, along with symptoms and causative foods.

METHODS

In phase I of the EuroPrevall project, a screening questionnaire was sent to a random sample of the general adult population in 8 European centers. Phase II consisted of an extensive questionnaire on reactions to 24 preselected commonly implicated foods, and measurement of specific IgE levels. Multiple imputation was performed to estimate missing symptom and serology information for nonresponders. In the final phase, subjects with probable FA were invited for double-blind placebo-controlled food challenge.

RESULTS

Prevalence of probable FA in adults in Athens, Reykjavik, Utrecht, Lodz, Madrid, and Zurich was respectively 0.3%, 1.4%, 2.1%, 2.8%, 3.3%, and 5.6%. Oral allergy symptoms were reported most frequently (81.6%), followed by skin symptoms (38.2%) and rhinoconjunctivitis (29.5%). Hazelnut, peach, and apple were the most common causative foods in Lodz, Utrecht, and Zurich. Peach was also among the top 3 causative foods in Athens and Madrid. Shrimp and fish allergies were relatively common in Madrid and Reykjavik. Of the 55 food challenges performed, 72.8% were classified as positive.

CONCLUSIONS

FA shows substantial geographical variation in prevalence and causative foods across Europe. Although probable FA is less common than self-reported FA, prevalence still reaches almost 6% in parts of Europe.

Allergen Recognition Patterns in Walnut Allergy Are Age Dependent and Correlate with the Severity of Allergic Reactions

BACKGROUND

Walnut is an important elicitor of food allergy in children and adults with a high rate of severe reactions. Multicenter studies using a common clinical protocol and a comprehensive allergen are lacking.

OBJECTIVE

To investigate potential correlations between molecular sensitization patterns and clinical characteristics of walnut-allergic patients.

METHODS

A total of 91 walnut-allergic subjects and 24 tolerant controls from Switzerland, Germany, and Spain were included. Walnut allergy was established by food challenge in all but anaphylactic subjects. Specific IgE (sIgE) to walnut extract, rJug r 1 (2S albumin), rJug r 3 (nonspecific lipid transfer protein 1), nJug r 4 (11S globulin), rJug r 5 (PR-10 protein), 2 vicilin fractions, profiling, and cross-reactive carbohydrate determinant was determined by ImmunoCAP. A threshold of 0.10 kU_A/L was used for positivity.

RESULTS

Sensitivity of sIgE to walnut extract was 87% and increased to 96% for the sum of all walnut components. sIgE to walnut extract and all walnut components, except rJug r 5, was significantly higher in patients younger than 14 years at inclusion. Stratification by age at onset of walnut allergy led to similar results. All patients younger than 14 years had severe reactions, whereas 38% of patients 14 years or older were mild reactors. Severe reactors (n = 70) had higher sIgE levels than did mild reactors (n = 21) to walnut extract (P < .0001), rJug r 1 (P < .0001), nJug r 4 (P = .0003), and both vicilin fractions (P < .0001), but not to Jug r 3 and Jug r 5.

CONCLUSIONS

Sensitization to walnut storage proteins is acquired in childhood and correlates with severe reactions. sIgE levels to storage proteins Jug r 1 and Jug r 4 and vicilin fractions, but not to nonspecific lipid transfer protein and PR-10 proteins, correlate with systemic reactions to walnut.

European Surveillance System on Contact Allergies (ESSCA): Contact allergies in relation to body sites in patients with allergic contact dermatitis

Background

Analyses of the European Surveillance System on Contact Allergies (ESSCA) database have focused primarily on the prevalence of contact allergies to the European baseline series, both overall and in subgroups of patients. However, affected body sites have hitherto not been addressed.

Objective

To determine the prevalence of contact allergies for distinct body sites in patients with allergic contact dermatitis (ACD).

Methods

Analysis of data collected by the ESSCA (www.essca‐dc.org) in consecutively patch tested patients, from 2009 to 2014, in eight European countries was performed. Cases were selected on the basis of the presence of minimally one positive patch test reaction to the baseline series, and a final diagnosis of ACD attributed to only one body site.

Results

Six thousand two hundred and fifty‐five cases were analysed. The head and hand were the most common single sites that ACD was attributed to. Differences between countries were seen for several body sites. Nickel, fragrance mix I, cobalt and methylchloroisothiazolinone/methylisothiazolinone were the most frequent allergens reported for various body sites.

Conclusions

Distinct allergen patterns per body site were observed. However, contact allergies were probably not always relevant for the dermatitis that patients presented with. The possibility of linking positive patch test reactions to relevance, along with affected body sites, should be a useful addition to patch test documentation systems.

Erratum to: Risk and safety requirements for diagnostic and therapeutic procedures in allergology: World Allergy Organization Statement

[This corrects the article DOI: 10.1186/s40413-016-0122-3.].

Standardization of double blind placebo controlled food challenge with soy within a multicentre trial

Background

Multicentre trials investigating food allergies by double blind placebo controlled food challenges (DBPCFC) need standardized procedures, challenge meals and evaluation criteria. We aimed at developing a standardized approach for identifying patients with birch related soy allergy by means of DBPCFC to soy, including determination of threshold levels, in a multicentre setting.

Methods

Microbiologically stable soy challenge meals were composed of protein isolate with consistent Gly m 4 levels. Patients sensitized to main birch allergen Bet v 1 and concomitant sensitization to its soy homologue Gly m 4 underwent DBPCFC. Outcome was defined according to presence and/or absence of ten objective signs and intensity of eight subjective symptoms as measured by visual analogue scale (VAS).

Results

138 adult subjects (63.8% female, mean age 38 years) underwent DBPCFC. Challenge meals and defined evaluation criteria showed good applicability in all centres involved. 45.7% presented with objective signs and 65.2% with subjective symptoms at soy challenge. Placebo challenge meals elicited non-cardiovascular objective signs in 11.6%. In 82 (59.4%) subjects DBPCFC was judged as positive. 70.7% of DPBCFC+ showed objective signs and 85.4% subjective symptoms at soy challenge. Subjective symptoms to soy challenge meal in DBPCFC+ subjects started at significantly lower dose levels than objective signs (p < 0.001). Median cumulative eliciting doses for first objective signs in DBPCFC+ subjects were 4.7 g [0.7–24.7] and 0.7 g [0.2–4.7] total soy protein for first subjective symptoms (p = 0.01).

Conclusions

We present the hitherto largest group of adults with Bet v 1 and Gly m 4 sensitization being investigated by DBPCFC. In this type of food allergy evaluation of DBPCFC outcome should not only include monitoring of objective signs but also scoring of subjective symptoms. Our data may contribute to standardize DBPCFC in pollen-related food allergy in multicentre settings.

Trial registration

EudraCT: 2009-011737-27.

Risk and safety requirements for diagnostic and therapeutic procedures in allergology: World Allergy Organization Statement

One of the major concerns in the practice of allergy is related to the safety of procedures for the diagnosis and treatment of allergic disease. Management (diagnosis and treatment) of hypersensitivity disorders involves often intentional exposure to potentially allergenic substances (during skin testing), deliberate induction in the office of allergic symptoms to offending compounds (provocation tests) or intentional application of potentially dangerous substances (allergy vaccine) to sensitized patients. These situations may be associated with a significant risk of unwanted, excessive or even dangerous reactions, which in many instances cannot be completely avoided. However, adverse reactions can be minimized or even avoided if a physician is fully aware of potential risk and is prepared to appropriately handle the situation. Information on the risk of diagnostic and therapeutic procedures in allergic diseases has been accumulated in the medical literature for decades; however, except for allergen specific immunotherapy, it has never been presented in a systematic fashion. Up to now no single document addressed the risk of the most commonly used medical procedures in the allergy office nor attempted to present general requirements necessary to assure the safety of these procedures. Following review of available literature a group of allergy experts within the World Allergy Organization (WAO), representing various continents and areas of allergy expertise, presents this report on risk associated with diagnostic and therapeutic procedures in allergology and proposes a consensus on safety requirements for performing procedures in allergy offices. Optimal safety measures including appropriate location, type and required time of supervision, availability of safety equipment, access to specialized emergency services, etc. for various procedures have been recommended. This document should be useful for allergists with already established practices and experience as well as to other specialists taking care of patients with allergies.

The conformational IgE epitope profile of soya bean allergen Gly m 4

BACKGROUND

Birch pollen-related soya allergy is mediated by Gly m 4. Conformational IgE epitopes of Gly m 4 are unknown.

OBJECTIVE

To identify the IgE epitope profile of Gly m 4 in subjects with birch pollen-related soya allergy utilizing an epitope library presented by Gly m 4-type model proteins.

METHODS

Sera from patients with (n = 26) and without (n = 19) allergy to soya as determined by oral provocation tests were studied. Specific IgE (Bet v 1/Gly m 4) was determined by ImmunoCAP. A library of 59 non-allergenic Gly m 4-type model proteins harbouring individual and multiple putative epitopes for IgE was tested in IgE binding assays. Primary, secondary and tertiary protein structures were assessed by mass spectrometry, circular dichroism and nuclear magnetic resonance spectroscopy.

RESULTS

All subjects were sensitized to Gly m 4 and Bet v 1. Allergen-specific serum IgE levels ranged from 0.94 to > 100 kU_A /L. The avidities of serum IgE were 5.06 ng (allergic) and 1.8 ng (tolerant) as determined by EC₅₀ for IgE binding to Gly m 4. 96% (46/48) of the protein variants bound IgE. Model proteins had Gly m 4-type conformation and individual IgE binding clustered in six major surface areas. Gly m 4-specific IgE binding could be inhibited to up to 80% by model proteins harbouring individual IgE binding sites in an epitope-wise equimolar fashion. Receiver operating curve analysis revealed an area under fitted curve of up to 0.88 for model proteins and 0.66 for Gly m 4.

CONCLUSION AND CLINICAL RELEVANCE

Serum levels and avidity of Gly m 4-specific IgE do not correlate with clinical reactivity to soya. Six IgE-binding areas, represented by 23 amino acids, account for more than 80% of total IgE binding capacity of Gly m 4. Model proteins may be used for epitope-resolved diagnosis to differentiate birch-soya allergy from clinical tolerance.

[Not Available]

Zusammenfassung. Jeder vierte Erwachsene in der Schweiz ist gegen mindestens ein Lebensmittel sensibilisiert. Da nur 25–50 % der Sensibilisierten eine Nahrungsmittelallergie entwickeln, ist das ungezielte Einsetzen von Hauttests oder auf IgE-Antikörper-Nachweis basierten In-vitro-Tests im Sinne eines Nahrungsmittelallergie-Screenings unsinnig. Diese Testverfahren sollen erst bei Vorliegen einer suggestiven Anamnese einer Nahrungsmittelallergie veranlasst werden. Häufig kann die definitive Klärung der Relevanz einer Sensibilisierung gegen Lebensmittel erst durch die orale Provokationstestung erbracht werden. Die sogenannte Komponenten-spezifische Diagnostik, bei der nach IgE-Antikörpern gegen Einzelallergene gesucht wird, hilft bei gewissen Nahrungsmitteln, eine Risikobewertung der Sensibilisierung vorzunehmen. Die Verwendung von wissenschaftlich nicht validierten Testmethoden zur Diagnose einer Nahrungsmittelunverträglichkeit oder Allergie ist strikt abzulehnen, denn sie führt häufig zu nicht-indizierten und damit unsinnigen Diäten.

Food allergy in adolescence and adulthood

In young children, food allergy is usually acquired via the gastrointestinal tract and directed toward egg and milk. Adolescent and adult patients, however, mainly acquire food allergy via primary sensitization to inhalant allergens on the basis of cross-reactivity between proteins in inhalant sources and in food. This type of food allergy is frequently mediated by sensitization to broadly represented allergens, or so-called panallergens. Food allergic reactions in adult patients - similar to those in children - range in severity from very mild and local symptoms, as in contact urticaria of the oral mucosa, to systemic symptoms involving distal organs, to a fatal outcome. Plant foods, such as fruits, nuts, and vegetables, are the most prevalent allergenic foods in this age group.

A Novel Multipeptide Microarray for the Specific and Sensitive Mapping of Linear IgE-Binding Epitopes of Food Allergens

BACKGROUND

The identification of B-cell epitopes of food allergens can possibly lead to novel diagnostic tools and therapeutic reagents for food allergy. We sought to develop a flexible, low-tech, cost-effective and reproducible multipeptide microarray for the research environment to enable large-scale screening of IgE epitopes of food allergens.

METHODS

Overlapping peptides (15-mer, 4 amino acid offset) covering the primary sequence of either peanut allergen Ara h 1 or all 3 subunits of the soybean allergen Gly m 5 were simultaneously synthesized in-house on a porous cellulose matrix. Identical peptide microarrays created with up to 384 duplicate peptide-cellulose microspots each were investigated for specificity and sensitivity in IgE immunodetection and in direct experimental comparison to the formerly established SPOT™ membrane technique.

RESULTS

The in-house microarray identified with 98% reproducibility the same IgE-binding peptides as the SPOT™ membrane technique. Additional IgE-binding peptides were identified using the microarray. While the sensitivity was increased between 2- and 20-fold, the amount of human serum required was reduced by at least two thirds over the SPOT™ membrane technique using the microarray. After subtraction of the potential background, we did not observe non-specific binding to the presented peptides on microarray.

CONCLUSIONS

The novel peptide microarray allows simple and cost-effective screening for potential epitopes of large allergenic legume seed storage proteins, and it could be adapted for other food allergens as well, to study allergenic epitopes at the individual subject level in large paediatric and adult study groups of food allergic subjects.

Food allergy in the Netherlands: differences in clinical severity, causative foods, sensitization and DBPCFC between community and outpatients

BACKGROUND

It is unknown whether food allergy (FA) in an unselected population is comparable to those from an outpatient clinic population.

OBJECTIVE

To discover if FA in a random sample from the Dutch community is comparable to that of outpatients.

METHODS

This study was part of the Europrevall-project. A random sample of 6600 adults received a questionnaire. Those with symptoms to one of 24 defined priority foods were tested for sIgE. Participants with a positive case history and elevated sIgE were evaluated by double-blind placebo-controlled food challenge (DBPCFC). Outpatients with a suspicion of FA were evaluated by questionnaire, sIgE and DBPCFC.

RESULTS

In the community, severe symptoms were reported less often than in outpatients (39.3% vs. 54.3%). Participants in the community were less commonly sensitized to any of the foods. When selecting only those with a probable FA (i.e. symptoms of priority food and elevation of sIgE to the respective food), no major differences were observed with respect to severity, causative foods, sensitization and DBPCFC between the groups.

CONCLUSION

In the Netherlands, there are large differences in self-reported FA between community and outpatients. However, Dutch community and outpatients with a probable FA do not differ with respect to severity, causative foods, sensitization and DBPCFC-outcome.

[Food allergy:definitions, prevalence, diagnosis and therapy]

Food allergy is phenotypically an extremely heterogeneous group of diseases affecting multiple organs, sometimes in an isolated way, sometimes simultaneously, with the severity of reactions ranging from mild and local to full-blown anaphylaxis. Mechanistically, it is defined as a Th2-driven immune disorder in which food-specific IgE antibodies are at the basis of immediate-type adverse reactions. The sites of sensitization and symptoms do not necessarily overlap. Food allergy, which is the theme of this paper, is often confused with other adverse reactions to food of both animmune (e.g., celiac disease) and non-immune (e.g., lactose intolerance) nature. To reliably diagnose food allergy, a careful history (immediate-type reactions) needs to be complemented with demonstration of specific IgE (immune mechanism) and confirmed by an oral challenge. Co-factors such as exercise, medication, and alcohol may help trigger food allergy and further complicate accurate diagnosis. Where food extract-based diagnostic tests are poorly correlated to symptom severity, new generation molecular diagnostics that measure IgE against individual food allergens provide clinicians and patients with more reliable symptom severity risk profiles. Molecular diagnostics also support establishing whether food sensitization originates directly from exposure to food or indirectly (cross-reactivity) from pollen sensitization. Epidemiological surveys have indicated that allergy to peach primarily originates from peach consumption in Europe, whereas in China it is the result of primary sensitization to mugwort pollen, in both cases mediated by an allergen molecule from the same family. Epidemiological surveys give insight into the etiology of food allergy, the size of the problem (prevalence), and the risk factors involved, which together support evidence-based strategies for prevention. Over the past decade, food allergy has increased in the affluent world. Economic growth and urbanization in upcoming economies are likewise expected to lead to increased prevalence of food allergies, sometimes to different foods due to dietary habits. Molecular allergology and biotechnology now offer the possibility to combat the increasing burden of food allergy by developing safe immunotherapies for food allergy, using hypoallergenic mutant recombinant molecules. The first clinical trials to evaluate such approaches are underway. Last but not least, the identification and clinical risk characterization of a more and more complete list of food allergens additionally provides the allergenicity risk assessment of genetically modified foods a firmer basis.

Value of allergy tests for the diagnosis of food allergy

Eosinophilic esophagitis (EoE) is a chronic T helper 2-type inflammatory disorder. Concurrent allergic diseases have been observed in EoE cases at a high prevalence. The observation that EoE responds to dietary treatment suggests that EoE is an antigen-driven process. However, the pathogenesis by which allergens mediate the eosinophilic disease in the esophagus needs further clarification. In immediate-type food allergy, diagnosis is based on a careful case history followed by a search for food-specific IgE either by skin testing [skin prick test (SPT)] or in vitro (e.g. ImmunoCAP). In children with atopic dermatitis and a food allergy to milk, eggs, peanuts, fish or wheat, the SPT and in vitro determination of specific IgE show excellent sensitivity and negative predictive values, whereas the positive predictive values are low. In pollen-related secondary food allergy, sensitivity and negative predictive values of IgE testing is much lower. Consequently, oral food provocation is the gold standard for the diagnosis of food allergy. Similarly, in EoE patients, SPT, atopy patch test and in vitro determination of IgE to foods do not reliably predict food allergy, and the average positive predictive values of these allergy tests are below 50%. In conclusion, the value of allergy tests to identify triggering foods are limited, and triggering foods have to be identified by an elimination diet and consequent reintroduction of single foods under biopsy control. However, due to the high prevalence of concurrent allergic diseases among EoE patients, an allergy work-up is urgently indicated in each patient with EoE.

Additional indications for the low allergenic properties of the apple cultivars Santana and Elise

Patients with Oral Allergy Syndrome (OAS) to fresh apple may tolerate low allergenic apple cultivars. We aimed to investigate if the low allergenic properties of Elise and Santana, as previously identified in a Dutch population, could be generalised within North West Europe within the birch pollen region with regard to both the prevalence and degree of sensitization. Prick-to-prick tests (PTP) were performed in eighty-five adult patients with OAS to fresh apple in Great Britain, Switzerland and Northern Italy, before the birch pollen season, using the putatively low allergenic apple cultivars Elise, Santana, Granny Smith, Modi and Mcintosh, as well as the putatively high allergenic apple cultivars Golden Delicious and Kanzi. No significant differences in percentages of negative responses of PTPs were found between the three countries. Negative responses did not differ from negative responses to the different apple cultivars we previously found in 2006/2007 in the Netherlands. The size of the PTPs of all apple cultivars tested were correlated to the size of the skin prick tests with birch pollen. These results add to the indications for the low allergenic properties of the low allergenic apple cultivars Santana and Elise, as the number of negative responses were reproducible in three countries within the birch pollen region and were similar to previous results in the Netherlands. These results justify oral challenge studies with Elise and Santana within the birch pollen region, to establish the low allergenic properties for the benefit for apple allergic consumers for definite conclusions.

Challenges in testing genetically modified crops for potential increases in endogenous allergen expression for safety

Premarket, genetically modified (GM) plants are assessed for potential risks of food allergy. The major risk would be transfer of a gene encoding an allergen or protein nearly identical to an allergen into a different food source, which can be assessed by specific serum testing. The potential that a newly expressed protein might become an allergen is evaluated based on resistance to digestion in pepsin and abundance in food fractions. If the modified plant is a common allergenic source (e.g. soybean), regulatory guidelines suggest testing for increases in the expression of endogenous allergens. Some regulators request evaluating endogenous allergens for rarely allergenic plants (e.g. maize and rice). Since allergic individuals must avoid foods containing their allergen (e.g. peanut, soybean, maize, or rice), the relevance of the tests is unclear. Furthermore, no acceptance criteria are established and little is known about the natural variation in allergen concentrations in these crops. Our results demonstrate a 15-fold difference in the major maize allergen, lipid transfer protein between nine varieties, and complex variation in IgE binding to various soybean varieties. We question the value of evaluating endogenous allergens in GM plants unless the intent of the modification was production of a hypoallergenic crop.

Allergic reactions to food proteins

Four to eight percent of the population are estimated to be food-allergic. Most food allergies in adolescents and adults are acquired on the basis of cross-reaction to pollen allergens. Theses allergens are ubiquitous in the plant kingdom. Therefore pollen-allergic patients might acquire a multitude of different plant food allergies, and even react to novel foods to which they have never previously been exposed. A curative therapy for food allergy does not yet exist. Food-allergic patients have to rely on strict avoidance diets, The widespread use of industrially processed foods poses a general problem for food-allergic patients. Although the most frequent allergens must be declared openly in the list of ingredients, involuntary contamination with allergy-provoking compounds can occur. The precautionary labelling "may contain" is sometimes applied even if the chance of contamination is very low; on the other hand, foods not declared to contain possible traces of allergenic components may actually contain relevant amounts of allergenic proteins. Switzerland is the only country in Europe with legal regulations on contamination by allergenic food; however, the allowance of 1 g/kg is too high to protect a relevant proportion of food-allergic individuals.

Development of a standardized low-dose double-blind placebo-controlled challenge vehicle for the EuroPrevall project

BACKGROUND

  Double-blind placebo-controlled food challenge (DBPCFC) is the gold standard for diagnosing food allergy. Standardized materials and protocols are essential for comparing DBPCFC results for multicentre studies such as EuroPrevall. This required the development and piloting of a standardized vehicle and low-dose protocol for confirming food allergy and determination of minimum eliciting doses (MEDs).

METHODS

  A low-dose DBPCFC protocol was developed, with eight titrated protein doses from 3 μg to 1 g. This was delivered using a simple, microbiologically stable food base incorporating allergenic food ingredients manufactured at three sites and centrally distributed to clinical centres. Allergen blinding was assessed by a professional sensory testing panel using a triangle test. Homogeneity and allergen content were confirmed by ELISA and clinical efficacy was assessed in a pilot study, using celeriac and hazelnut as exemplars.

RESULTS

  Celeriac and hazelnut ingredients were sufficiently blinded in the dessert. The dessert meals were successfully piloted with hazelnut in allergy clinics in Spain, the Netherlands and Italy and with celeriac and hazelnut in Zurich. The challenges elicited a range of subjective and objective reactions ranging in severity from mild itching of the oral mucosa to bronchospasm.

CONCLUSIONS

  A standardized challenge vehicle proven to sufficiently blind processed, powdered hazelnut and celeriac ingredients and that can be reproducibly manufactured has been developed. This pilot study shows that the vehicle is promising for the confirmation of food allergy and determination of MEDs in adults and children with body weight >28.8 kg (approximately 7-11 years old).

The Pictorial Representation of Illness and Self Measure (PRISM) instrument reveals a high burden of suffering in patients with chronic urticaria

BACKGROUND

Chronic urticaria severely affects quality of life. To date, no gold standard has been established to measure the burden of suffering, which often correlates poorly with the skin symptoms observed in patients with chronic urticaria.

OBJECTIVE

To investigate the effect of psychological factors on the course of urticaria.

METHODS

Health-related quality of life was assessed in 95 patients with chronic urticaria using the following instruments: Pictorial Representation of Illness and Self Measure (PRISM), Dermatology Life Quality Index (DLQI), and Skindex-29. Correlations were calculated. Cognitive flexibility and its correlation with the course of urticaria were assessed. Two case reports are presented to further elucidate features of PRISM.

RESULTS

PRISM revealed a high burden of suffering that was consistent with considerably impaired quality of life as measured by DLQI and Skindex-29 in the same patients. However, no significant correlation was observed between PRISM and the 2 quality of life questionnaires. From the baseline visit to the follow-up visit, quality of life scores improved significantly (DLQI, P = .001; Skindex-29, P = .001), whereas the PRISM score remained unchanged (P = .085). Disease course was favorable more often in cognitively flexible patients (n=54) (91%) than cognitively inflexible patients (P = .007).

CONCLUSIONS

PRISM revealed a high burden of suffering in chronic urticaria and provided helpful additional information for the management of these patients. In our cohort, cognitive flexibility was a positive predictive marker for the course of chronic urticaria.

[Urticaria - the most frequent dermatological disease]

Urticaria is a very frequent disease. The life time risk to experience at least one episode of urticaria is around 15 - 25 %. This article summarizes the most important definitions, classifications and diagnostic procedures in urticaria, as well as the evidence based management of urticaria. The recommendations given in this article are in accordance with two recent position papers by the European Academy of Allergology and Clinical Immunology (EAACI), the Global Allergy and Asthma European Network (GA2LEN), the European Dermatology Forum (EDF), and the World Allergy Organization (WAO).

[Atopic dermatitis - current insights into path physiology and management]

Atopic eczema (AE) is a multifaktoriell skin disease caused by a variety of factors such as genetic conditions, alterated skin structure, immunologic deviations, psychological and environmental factors, among others. There are two main subtypes of AE, i.e. the IgE-associated ("extrinsic atopic eczema") and the non-IgE-associated type ("intrinsic atopic eczema") with different prognosis concerning the development of respiratory diseases ("atopy march"). The role of allergens varies: while in early childhood food allergens may play a role, mites and microbial antigens may become more relevant in adolescence and adulthood. Recently, it was demonstrated that Filaggrin is a major gene for atopic eczema. The altered skin structure and a deficiency in antimicrobial peptides favour colonization with Staphylococcus aureus; their enterotoxins with superantigenic activity stimulate activation of T cells and macrophages. Also sensitization to the yeast Malassezia spp. occurs almost exclusively in AE patients. So far, AE skin lesions are orchestrated by the local tissue expression of proinflammatory cytokines and chemokines with activation of T lymphocytes, dendritic cells, macrophages, keratinocytes, mast cells, and eosinophils which lead to the skin inflammatory responses. From the therapeutic point of view, a step wise approach using emollients as a basic treatment is recommended. Modern topical corticosteroids of moderate to medium potency applied once per day and only on several days per week offer an efficient anti-inflammatory treatment with moderate side effects. Topic immunomodulatory drugs (tacrolimus and pimecrolimus) have in addition substantially improved the treatment of AE. Proactive treatment approaches also in disease-free intervals may reduce exacerbations and total drug use. Phototherapy and wet dressings are both efficient and safe additional tools in more severe forms. For generalized severe forms systemic drugs such as Cyclosporin A are very helpful. Various Biologicals and antipruriginous substances are under clinical investigation and may add to an improved therapy in the future.

Vaccine hypersensitivity--update and overview

Concerns about possible reactions to vaccines or vaccinations are frequently raised. However, the rate of reported vaccine-induced adverse events is low and ranges between 4.8-83.0 per 100,000 doses of the most frequently used vaccines. The number of true allergic reactions to routine vaccines is not known; estimations range from 1 per 500,000 to 1 per 1,000,000 doses for most vaccines. When allergens such as gelatine or egg proteins are components of the formulation, the rate for serious allergic reactions may be higher. Nevertheless, anaphylactic, potentially life-threatening reactions to vaccines are still a rare event (approximately 1 per 1,500,000 doses). The variety of reported vaccine-related adverse events is broad. Most frequently, reactions to vaccines are limited to the injection site and result from a non specific activation of the inflammatory system by, for example, aluminium salts or the active microbial components. If allergy is suspected, an accurate examination followed by algorithms is the key for correct diagnosis, treatment and the decision regarding revaccination in patients with immediate-type reactions to vaccines.

Component-resolved diagnosis of kiwifruit allergy with purified natural and recombinant kiwifruit allergens

BACKGROUND

Kiwifruit is one of the most common causes of food allergic reactions. Component-resolved diagnostics may enable significantly improved detection of sensitization to kiwifruit.

OBJECTIVE

To evaluate the use of individual allergens for component-resolved in vitro diagnosis of kiwifruit allergy.

METHODS

Thirty patients with a positive double-blind placebo-controlled food challenge to kiwifruit, 10 atopic subjects with negative open provocation to kiwifruit, and 5 nonatopic subjects were enrolled in the study. Specific IgE to 7 individual allergens (nAct d 1-5 and rAct d 8-9) and allergen extracts was measured by ImmunoCAP.

RESULTS

The diagnostic sensitivities of the commercial extract and of the sum of single allergens were 17% and 77%, respectively, whereas diagnostic specificities were 100% and 30%. A combination of the kiwi allergens Act d 1, Act d 2, Act d 4, and Act d 5 gave a diagnostic sensitivity of 40%, whereas diagnostic specificity remained high (90%). Exclusion of the Bet v 1 homolog recombinant (r) Act d 8 and profilin rAct d 9 from this allergen panel reduced sensitivity to 50% but increased specificity to 40%. Kiwifruit-monosensitized patients reacted more frequently (P < .001) with Act d 1 than polysensitized patients, whereas the latter group reacted more frequently with rAct d 8 (P = .004).

CONCLUSION

Use of single kiwifruit allergen ImmunoCAP increases the quantitative test performance and diagnostic sensitivity compared with the commercial extract. Bet v 1 homolog and profilin are important allergens in pollen-related kiwifruit allergy, whereas actinidin is important in monoallergy to kiwifruit, in which symptoms are often more severe.

Relevance of IgE binding to short peptides for the allergenic activity of food allergens

BACKGROUND

Analysis of IgE antibody binding to epitopes provides information for food allergy diagnosis and management and construction of hypoallergenic candidate vaccines, but the contribution of sequential epitopes to functionally relevant IgE binding is not fully understood.

OBJECTIVES

We sought to study the impact of IgE-binding peptides described as major sequence epitopes in the literature on IgE-binding capacity of 2 selected food allergens.

METHODS

IgE-binding peptides of the food allergens Ara h 2 (peanut) and Pen a 1 (shrimp) were identified. Synthetic soluble peptides representing the identified sequences were assessed for their capacity to inhibit IgE binding to the parent allergens by means of ELISA and in mediator release assay. The IgE-binding capacity of unfolded recombinant (r) Ara h 2 was analyzed. A hybrid tropomyosin carrying the IgE-binding regions of Pen a 1 grafted into the structural context of the nonallergenic mouse tropomyosin was applied in ELISA inhibition experiments and ImmunoCAP analysis.

RESULTS

Although IgE-binding peptides representing sections of the allergen sequences were detected, no relevant capacity to inhibit the IgE binding to the parent allergen in ELISA or basophil activation test was observed. Unfolded rAra h 2 showed reduced IgE-binding capacity compared with folded rAra h 2 and failed to elicit mediator release. Hybrid tropomyosin bound less IgE than rPen a 1 in ImmunoCAP analysis and revealed marginal inhibitory capacity.

CONCLUSION

Peptides identified as major sequence epitopes on Pen a 1 and Ara h 2 show little contribution to the IgE binding of the allergens studied.

Clinical presentation and diagnosis of meat allergy in Switzerland and Southern Germany

STUDY/PRINCIPLES

The aim of this study was to investigate the clinical characteristics of meat allergy, to validate the routine diagnostic tools and to compare our results with data from the literature.

METHODS

We recruited within the framework of the EU-project REDALL adult patients and children with a positive case history of meat allergy. Definitive inclusion criteria were either a history of an anaphylactic reaction to meat or a positive titrated double-blind placebo-controlled food challenge with the incriminated meat. Sensitisation to meat was assessed in all patients by skinprick-testing with meat extracts and in vitro determination of specific IgE to pork, beef and chicken (CAP-FEIA).

RESULTS

Between 3/2003 to 6/2005 we identified thirteen patients with a positive case history of a meat allergy to either chicken (n = 6), beef (n = 5) or pork (n = 2), respectively. Meat allergy associated symptoms as reported by the patients ranged from contact urticaria of the oral mucosa (oral allergy syndrome, OAS) to anaphylactic reactions. Skin testing with the responsible meat was positive in nine patients, and in vitro determination of specific IgE in four patients. Under DBPCFC one patient responded with nausea and dysphagia after 10.2 g of chicken and two patients either with urticaria or nausea, diarrhoea, emesis and abdominal pain at 0.102 g and 34 g of beef, respectively.

CONCLUSION

Meat allergy seems to be an uncommon food allergy in Central Europe. Meat induced symptoms range from OAS to severe anaphylactic reactions. The routine-diagnostic tools, i.e., skin testing and in vitro determination of specific IgE had a low sensitivity among our patients.

Component-resolved in vitro diagnosis of hazelnut allergy in Europe

BACKGROUND

Food allergy to hazelnut occurs both with and without concomitant pollen allergy.

OBJECTIVE

We sought to evaluate a panel of hazelnut allergens for diagnosis of hazelnut allergy in Spain, Switzerland, and Denmark.

METHODS

Fifty-two patients with a positive double-blind, placebo-controlled food challenge result with hazelnuts; 5 patients with a history of anaphylaxis; 62 patients with pollen allergy but hazelnut tolerance; and 63 nonatopic control subjects were included. Serum IgE levels to hazelnut extract, recombinant hazelnut allergens (rCor a 1.04, rCor a 2, rCor a 8, rCor a 11), and native allergens (nCor a 9, nCor a Bd8K, nCor a Bd11K) were analyzed by means of ImmunoCAP.

RESULTS

Among patients with hazelnut allergy, 91% (Switzerland/Spain, 100%; Denmark, 75%) had IgE to hazelnut extract, 75% to rCor a 1.04, 42% to rCor a 2, 28% to rCor a 8, and 2% to rCor a 11. The highest rate of sensitization to Cor a 1.04 was found in the northern regions (Switzerland/Denmark, 100%; Spain, 18%), whereas IgE to the lipid transfer protein rCor a 8 prevailed in Spain (Spain, 71%; Switzerland, 15%; Denmark, 5%). IgE to profilin rCor a 2 was equally distributed (40% to 45%). Among control subjects with pollen allergy, 61% had IgE to hazelnut extract, 69% to rCor a 1.04, 34% to rCor a 2, 10% to rCor a 8, and 6% to rCor a 11.

CONCLUSION

Component-resolved in vitro analyses revealed substantial differences in IgE profiles of hazelnut allergic and hazelnut tolerant patients across Europe.

Characterization of Bet v 1-related allergens from kiwifruit relevant for patients with combined kiwifruit and birch pollen allergy

Allergy to kiwifruit appears to have become more common in Europe and elsewhere during the past several years. Seven allergens have been identified from kiwifruit so far, with actinidin, kiwellin and the thaumatin-like protein as the most relevant ones. In contrast to other fruits, no Bet v 1 homologues were characterized from kiwifruit so far. We cloned, purified, and characterized recombinant Bet v 1-homologous allergens from green (Actinidia deliciosa, Act d 8) and gold (Actinidia chinensis, Act c 8) kiwifruit, and confirmed the presence of its natural counterpart by inhibition assays. Well-characterized recombinant Act d 8 and Act c 8 were recognized by birch pollen/kiwifruit (confirmed by double-blind placebo-controlled food challenge) allergic patients in IgE immunoblots and ELISA experiments. The present data point out that Bet v 1 homologues are allergens in kiwifruit and of relevance for patients sensitized to tree pollen and kiwifruit, and might have been neglected so far due to low abundance in the conventional extracts used for diagnosis.

Skin testing with food allergens. Guideline of the German Society of Allergology and Clinical Immunology (DGAKI), the Physicians' Association of German Allergologists (ADA) and the Society of Pediatric Allergology (GPA) together with the Swiss Society of Allergology

Skin testing has a central role in the diagnosis of food allergy. Prick testing is well- established as a routine diagnostic tool. Nonetheless, unstable allergens and the lack of standardized extracts create difficulties in the identification of sensitization to foods in patients with suspected food allergy. Therefore prick-to-prick tests with native (raw, fresh) foods are still recommended. The indications and contraindications are the same as those of routine skin testing in clinical allergology. We recommend a careful and restricted application of skin tests in patients with a history of severe anaphylaxis to foods.

Soybean (Glycine max) allergy in Europe: Gly m 5 (beta-conglycinin) and Gly m 6 (glycinin) are potential diagnostic markers for severe allergic reactions to soy

BACKGROUND

Soybean is considered an important allergenic food, but published data on soybean allergens are controversial.

OBJECTIVE

We sought to identify relevant soybean allergens and correlate the IgE-binding pattern to clinical characteristics in European patients with confirmed soy allergy.

METHODS

IgE-reactive proteins were identified from a soybean cDNA expression library, purified from natural soybean source, or expressed in Escherichia coli. The IgE reactivity in 30 sera from subjects with a positive double-blind, placebo-controlled soybean challenge (n = 25) or a convincing history of anaphylaxis to soy (n = 5) was analyzed by ELISA or CAP-FEIA.

RESULTS

All subunits of Gly m 5 (beta-conglycinin) and Gly m 6 (glycinin) were IgE-reactive: 53% (16/30) of the study subjects had specific IgE to at least 1 major storage protein, 43% (13/30) to Gly m 5 , and 36% (11/30) to Gly m 6. Gly m 5 was IgE-reactive in 5 of 5 and Gly m 6 in 3 of 5 children. IgE-binding to Gly m 5 or Gly m 6 was found in 86% (6/7) subjects with anaphylaxis to soy and in 55% (6/11) of subjects with moderate but only 33% (4/12) of subjects with mild soy-related symptoms. The odds ratio (P < .05) for severe versus mild allergic reactions in subjects with specific IgE to Gly m 5 or Gly m6 was 12/1.

CONCLUSION

Sensitization to the soybean allergens Gly m 5 or Gly m 6 is potentially indicative for severe allergic reactions to soy.

Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report

Serological tests for immunoglobulin G4 (IgG4) against foods are persistently promoted for the diagnosis of food-induced hypersensitivity. Since many patients believe that their symptoms are related to food ingestion without diagnostic confirmation of a causal relationship, tests for food-specific IgG4 represent a growing market. Testing for blood IgG4 against different foods is performed with large-scale screening for hundreds of food items by enzyme-linked immunosorbent assay-type and radioallergosorbent-type assays in young children, adolescents and adults. However, many serum samples show positive IgG4 results without corresponding clinical symptoms. These findings, combined with the lack of convincing evidence for histamine-releasing properties of IgG4 in humans, and lack of any controlled studies on the diagnostic value of IgG4 testing in food allergy, do not provide any basis for the hypothesis that food-specific IgG4 should be attributed with an effector role in food hypersensitivity. In contrast to the disputed beliefs, IgG4 against foods indicates that the organism has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which induces hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells. In conclusion, food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposition to food components. Therefore, testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food-related complaints.

Soy allergy in perspective

PURPOSE OF REVIEW

The purpose of this paper is to review and discuss studies on soy allergy.

RECENT FINDINGS

In Central Europe soy is a clinically relevant birch pollen-related allergenic food. Crossreaction is mediated by a Bet v 1 homologous protein, Gly m 4. Additionally, birch pollen allergic patients might acquire through Bet v 1 sensitization allergies to mungbean or peanut, in which Vig r 1 and Ara h 8 are the main cross-reactive allergens. Threshold doses in soy allergic individuals range from 10 mg to 50 g of soy and are more than one order of magnitude higher than in peanut allergy. No evidence was found for increased allergenicity of genetically modified soybeans.

SUMMARY

In Europe, both primary and pollen-related food allergy exist. The diagnosis of legume allergy in birch pollen-sensitized patients should not be excluded on a negative IgE testing to legume extracts. Bet v 1 related allergens are often underrepresented in extracts. Gly m 4 from soy and Ara h 8 from peanut are nowadays commercially available and are recommended in birch pollen allergic patients with suspicion of soy or peanut allergy, but negative extract-based diagnostic tests to screen for IgE specific to these recombinant allergens.

Potential, pitfalls, and prospects of food allergy diagnostics with recombinant allergens or synthetic sequential epitopes

This article aims to critically review developments in food allergy diagnostics with regard to the verification of specific IgE antibodies and the identification of the responsible allergens. Results of IgE-binding tests with food extracts are hampered by cross-reactive proteins, low-quality test agents, or both. Specificity can be increased by defining adequate cutoff values, whereas sensitivity can be improved by using high-quality test agents. IgE-binding tests with purified allergens enabled reliable quantification of allergen-specific IgE titers, with higher levels found in individuals with food allergy compared with individuals without food allergy. However, the overlap in individual test reactivity between allergic and nonallergic subjects complicates interpretation. Recombinant allergens and synthetic sequential epitopes enabled detection of sensitization profiles, with IgE specific to several allergens and substructures now being suggested as markers of severity, persistence, or both. However, high-power quantitative studies with larger numbers of patients are required to confirm these markers. IgE-binding tests merely indicate sensitization, whereas the final proof of clinical relevance still relies on family/case history, physical examinations, and provocation tests. Novel technologies promise superior diagnostics. Microarray technology permits simultaneous measurement of multiple IgE reactivities regarding specificity, abundance, reactivity, or interaction. Improved functional tests might enable reliable estimation of the clinical relevance of IgE sensitizations at justifiable expenses.

Thresholds for food allergens and their value to different stakeholders

Thresholds constitute a critical piece of information in assessing the risk from allergenic foods at both the individual and population levels. Knowledge of the minimum dose that can elicit a reaction is of great interest to all food allergy stakeholders. For allergic individuals and health professionals, individual threshold data can inform allergy management. Population thresholds can help both the food industry and regulatory authorities assess the public health risk and design appropriate food safety objectives to guide risk management. Considerable experience has been gained with the double-blind placebo-controlled food challenge (DBPCFC), but only recently has the technique been adapted to provide data on thresholds. Available data thus vary greatly in quality, with relatively few studies providing the best quality individual data, using the low-dose DBPCFC. Such high quality individual data also form the foundation for population thresholds, but these also require, in addition to an adequate sample size, a good characterization of the tested population in relation to the whole allergic population. Determination of thresholds at both an individual level and at a population level is influenced by many factors. This review describes a low-dose challenge protocol developed as part of the European Community-funded Integrated Project Europrevall, and strongly recommends its wider use so that data are generated that can readily increase the power of existing studies.

Predictive value of the sulfidoleukotriene release assay in oral allergy syndrome to celery, hazelnut, and carrot

BACKGROUND

Patients sensitized to birch pollen frequently suffer from a food allergy to plant foods such as celery, carrots, or hazelnut. One of the main manifestations of birch pollen-related food allergy is the oral allergy syndrome. Skin tests and allergen-specific immunoglobulin (Ig) E determinations are poor predictors of such reactions when assessed by double-blind placebo-controlled food challenge (DBPCFC).

OBJECTIVE

To investigate whether a cellular test based on leukotriene release from basophils, the cellular antigen stimulation test in combination with enzyme-linked immunosorbent assay (CAST-ELISA), is predictive of pollen-related food allergy.

METHODS

Birch pollen-sensitized patients with positive DBPCFC to celery (n=21), hazelnut (n=15), and carrot (n=7) underwent skin tests along with determination of specific IgE and CAST-ELISA for the respective allergens. The results were compared with those of 24 birch pollen-sensitized patients with negative open food challenge to celery, hazelnut, and carrot.

RESULTS

While skin prick tests had a sensitivity of 85%, 80%, and 29% for commercial extracts of celery, hazelnut, and carrot, respectively, prick testing with self-prepared extracts yielded sensitivities of 100%, 80%, and 100%, respectively. For specific IgE determinations, sensitivities were 71%, 73%, and 57%, respectively, and the respective specificities were 67%, 73%, and 60%. For CAST-ELISA with various sources and doses of allergens, the sensitivity varied from 71% to 95% for celery, 73% to 80% for hazelnut, and 43% to 86% for carrot. The respective specificities were 67% to 92%, 75% to 88%, and 77% to 91%. Analysis of the predictive value of CAST-ELISA with receiver operating characteristic curves showed that the results of the tests were more predictive of pollen-related food allergy than quantitative allergen-specific IgE determinations.

CONCLUSIONS

CAST-ELISA is more specific than routine diagnostic tests for the diagnosis of pollen-related food allergy to celery, hazelnut, and carrot.

Strategy for allergenicity assessment of 'natural novel foods': clinical and molecular investigation of exotic vegetables (water spinach, hyacinth bean and Ethiopian eggplant)

BACKGROUND

Foods not commonly consumed in the European Union must be proven safe before being brought to market, including an assessment of allergenicity. We present a three-stepwise strategy for allergenicity assessment of natural novel foods using three novel vegetables, namely, water spinach, hyacinth bean, Ethiopian eggplant.

METHODS

First, vegetable extracts were analyzed for the presence of pan-allergens [Bet v 1 homologous proteins, profilins, nonspecific lipid transfer proteins (LTP)] by immunoblot analysis with specific animal antibodies. Secondly, the IgE-binding of the food extracts was investigated by EAST (Enzyme-allergosorbent test) and immunoblot analysis using sera with IgE-reactivity to known pan-allergens or to phylogenetically related foods from subjects (i) allergic to birch, grass and mugwort pollen, (ii) with food allergy to soy, peanut, tomato, multiple pollen-related foods and (iii) sensitized to LTP. Thirdly, the clinical relevance of IgE-binding was assessed in vivo by skin prick testing (SPT) and open oral food challenges (OFC).

RESULTS

Profilin and LTP were detected by animal antibodies in all vegetables, a Bet v 1 homologue selectively in hyacinth bean. IgE-binding to LTP, profilin and a Bet v 1 homologue was proven by immunoblot analysis and EAST. Positive SPT and OFC results were observed for all vegetables in pollen-allergic patients.

CONCLUSIONS

Our stepwise procedure confirmed the presence and IgE-binding capacity of novel vegetable proteins homologous to known allergens in endemic vegetable foods. In vivo testing proved the potential of the novel vegetables to elicit clinical allergy. Hence, our described algorithm seems to be applicable for allergenicity testing of natural novel foods.

Enhancement of hazelnut extract for IgE testing by recombinant allergen spiking

BACKGROUND

Hazelnuts are a common cause of food allergic reactions. Most hazelnut allergic individuals in central and northern Europe are sensitized to Cor a 1, a member of the PR-10 protein family, while the lipid transfer protein Cor a 8 acts as a major allergen in the south of Europe. Other allergens, including profilin and seed storage proteins, may be important in subgroups of patients. Reliable detection of specific IgE in the clinical diagnosis of food allergy requires allergen reagents with a sufficient representation of all relevant allergen components. Some reported observations suggest that natural hazelnut extract may not be fully adequate in this respect.

METHODS

The capacity of immobilized natural hazelnut extract to bind Cor a 1-, Cor a 2- and Cor a 8-specific IgE and IgG antibodies was investigated by serum adsorption and extract dilution experiments and by the use of allergen specific rabbit antisera. All measurements were performed with the ImmunoCAP assay platform.

RESULTS

The experimental results revealed an incomplete capacity of immobilized hazelnut extract to capture IgE antibodies directed to the major allergen Cor a 1. Spiking of hazelnut extract with recombinant Cor a 1.04 prior to solid phase coupling gave rise to significantly enhanced IgE antibody binding from Cor a 1 reactive sera. The spiking did not negatively affect the measurement of IgE to extract components other than Cor a 1.

CONCLUSION

A hazelnut allergen reagent with enhanced IgE detection capacity can be generated by supplementing the natural food extract with recombinant Cor a 1.04.