Food allergy diagnosis

The diagnosis of food allergies (FA) relies upon the sequential use of different means and tools, according to a decision tree. Ten clinical characteristics point to a potential FA. A diary for food consumption during a week surveys all labellings, in order to detect masked food allergens. The second step is based on skin prick tests to natural foods, and epicutaneous tests to a few proteins (casein, gluten...). Biological tests using multi detection tests of specific IgEs to numerous allergens are not advised owing to the frequency of clinically not relevant in vitro cross-reactivity. Single determination of specific IgEs, have a 95% predictive positive value of high levels in cases of allergy to milk, egg, fish and peanut, and can spare oral challenges. The primary use of biological tests is not currently advised but may be of interest in litigious cases. Standardized oral challenges are the golden standard. Eviction regimens are an alternative used for cow's milk allergy in infancy, or for suspected digestive allergies in adults.     

Component-Resolved Diagnosis for Phleum Allergy: The Role of Recombinants

Background. Conventional diagnostic tests (such as radioallergosorbent test [RAST] and skin prick test [SPT]) use native raw pollen allergen extracts to establish allergy. However, recombinant allergens may offer important advantages compared with their natural counterparts. Objective. This study evaluated serum immunoglobulin E (IgE) in patients with grass-induced allergic rhinitis (AR) or AR with asthma (ARA), comparing assays with natural or recombinant grass allergens. Methods. Sixty patients (33 AR, 27 ARA) positive with SPT and serum IgE for Phleum pratense were enrolled in the study. Serum IgE specific for conventional and recombinant Phleum pratense: rPhl p 1, rPhl p 2, nPhl p 4, rPhl 5b, rPhl p 6, rPhl p 7, rPhl p 11, rPhl p 12, were measured by the IFMA procedure (ImmunoCAP, Phadia, Uppsala, Sweden). Data were expressed as the median (md) and percentiles. Recombinant allergen results were expressed also as the percentage of positive concentrations. The Wilcoxon test was used to compare samples. Because diagnosis is a binary variable (AR/ARA), logistic regression analysis was performed to identify possible correlates. Results. IgE concentrations assessed with recombinant allergens were significantly higher in ARA patients (p = .05) than in AR patients. A value >5.8 kU/L is the optimal cut-off to discriminate AR and ARA patients. Model specificity was 76%, sensitivity 78%, and efficiency 77%. Conclusion. This study shows that IgEs for natural and recombinant grass pollen allergens are significantly higher in patients with AR and asthma. Moreover, using recombinant allergens it is possible to define a prediction model for diagnosis with 77% efficiency. Therefore, this study may suggest that there are advantages of using recombinant or purified, native allergens over crude extracts.     

Adult food allergy

Adult food allergy is estimated at approximately 3.2% worldwide. The persistence of childhood food allergy is unusual, peanut allergies excepted. Once established in adults, food allergy is rarely cured. Factors favoring the acquisition of allergy could be sensitization to pollens, occupational sensitization by inhalation, drugs (such as tacrolimus), and sudden dietary changes. Severe anaphylaxis and oral allergy syndrome are frequent. The fatality risk is estimated at 1% in severe anaphylaxis. Risk factors for severe anaphylaxis are agents causing increased intestinal permeability, such as alcohol and aspirin. β-blockers, angiotensin-converting enzyme (ACE) inhibitors, and exercise are other factors. Gastrointestinal food allergy remains, to a large extent, undiagnosed in adults. Food allergens are mainly fruit and vegetable, related to pollen sensitizations, or to latex allergy. Wheat flour allergy is increasing. The diagnosis relies on prick skin tests, detection of specific IgEs, and standardized oral challenges. Strict avoidance diets are necessary. Specific immunotherapy to pollens may be efficient for cross-reactive food allergies.     

Importance of recombinant k82 in the diagnosis of latex allergy

Measurement of IgEs keeps a predominant place in the diagnosis of allergy and in particular in certain pathologies such as those induced by dangerous allergens like, for example, latex. The contribution of recombinant allergens is a significant element in the measurement of IgEs and we have observed this for latex. Sensitivity of recombinant k82 is significantly greater than that of k82. It permits better detection of patients who are sensitised to latex and thus a better prevention by absence of frequent contact with latex gloves and detergents.     

Cellular allergen stimulation test (CAST) 2003, a review.

Specific diagnosis of immediate type allergies, such as rhinoconjunctivis, asthma, urticaria/angioedema and anaphylaxis, particularly when IgE-mediated, traditionally rests on prick and/or intradermal skin tests and, since about 30 years, on the determination of allergen specific IgEs. Some cellular tests, i.e. tests determining the reactivity of blood cells in vitro, particularly basophils, to allergens, have been available for many years. The determination of histamine release has been widely used in allergy pathophysiological research but its routine application in allergy diagnosis has been restricted to few groups. Basophil degranulation, as determined by microscopic examination, was promoted by some groups in the 1980's but has been largely abandoned since around 10 years ago; an alternative cellular test, based on the determination of sulfidoleukotrienes (LTC4, LTD4, LTE4) produced by IL-3 primed basophils stimulated by allergens in vitro, has been proposed. This test became available commercially in 1993 under the name of CAST (Bühlmann Laboratories, Allschwil, Switzerland). The CAST assay has been used in allergy diagnosis in a variety of indications, such as inhalation allergies, allergies to insect venoms, foods, occupational allergens and various drugs. A large number of reports on CAST diagnostic value, however, have been anecdotal. A meta-analysis of validated and well controlled studies encompasses 37 studies, 1614 patients and 1145 controls. This should definitely establish the value of this diagnostic test, particularly in instances where other in vitro or in vivo diagnostic tests are not reliable, such as food or drug allergies, as well as in non-IgE-mediated immediate hypersensitivity reactions. However, a number of questions about the CAST diagnostic assay are still open or have not been systematically explored. This may explain, in addition to the practical limitations inherent to all allergy cellular tests, why CAST has not yet become a very widely used assay worldwide, having gained broad acceptance in some countries but not in others.     

Les allergènes recombinants : leur apport à l’allergologie en 2006

Advances in molecular biology techniques have led to the production of recombinant allergens, about thirty of them now being available for measurements (DIAGNOSIS?) in vitro. These recombinant allergens correspond to a precise molecular variant of a natural allergen, and their biological activity has to be evaluated in comparison with the corresponding natural allergen. The advantages of recombinant allergens are essentially the creation of allergenic preparations having constant pharmaceutic properties, which allows determination of specific IgE directed against different molecular components of an allergenic source, for example, pollen, mites, etc. The main consequences of these biological advances are the following: evaluation of sensitivities to allergen molecules in different populations (molecular epidemiology), improvement of extracts used for diagnosis by selection of the most pertinent allergenic sources and in quantifying their major allergen content, definition of the spectrum of recognition of specific IgE vis-à-vis different molecular components (spectrotype), quantitative evaluation of IgE responses, establishing the molecular basis of cross-reactions between different inhaled allergens, between different food allergens, and between inhaled allergens and food allergens. As regards allergy practice, this new diagnostic tool can lead to better interpretation of polysensitivities, observed by skin tests and in vitro tests. Some examples of particular clinical cases associated with specific sensitivities vis-à-vis certain recombinant allergens will be presented.     

Intérêt des allergènes recombinants dans le diagnostic de l’allergie alimentaire

To date, neither in vitro nor in vivo tests can establish with reliability the diagnosis of food allergy. The availability of recombinant allergens (RA) has led to improvement in the standardization of allergenic extracts and enrichment of natural extracts, resulting in more sensitive screening tests. These biotechnological advances facilitate the diagnostic approach which now rests on an individual reaction profile (component resolved diagnosis) with well-characterized allergens classified on a molecular basis. Development of diagnostic tests using RA or peptides expressing some distinctive epitopes of interest may improve the prediction of severe and/or persistent food allergies and guide the choice of the therapeutic measures that follow.     

The role of allergy evaluation in children with eosinophilic esophagitis

Background

To our knowledge, in Asia, data on utility of allergy tests in management of eosinophilic esophagitis are lacking. The objective of our study was to determine the role of allergy evaluation in management of Saudi children with eosinophilic esophagitis.

Methods

Children diagnosed as having eosinophilic esophagitis during the period from 2009 to 2012 were referred to an allergist for allergy evaluation. The allergy evaluation consisted of total IgE level, radio-allergosorbent assay, and skin prick test. Depending on the results of the allergy tests, a restricted or elemental diet was established. Swallowed fluticasone inhaler was prescribed to patients who rejected or failed to respond to the diet. Clinical, endoscopic, and histological evaluation was performed in 8 weeks to assess response.

Results

Eighteen children with eosinophilic esophagitis were included (13 males; mean age 5 years, range 1–11). Sensitization to foods was demonstrated in 14 patients: 4 with a positive test for a single food (28.5 %), 1 for 2 food allergens (7 %), and 9 for ≥3 food allergens (64.5 %). The most common food allergens were milk, soybean, wheat, egg, and nuts. Three young children out of the total 14 patients responded to elemental formula. Four of the 10 older children on the allergy testing guided-dietary restriction achieved partial remission and the remaining 6 did not respond. All 10 patients responded to a swallowed fluticasone inhaler.

Conclusion

Although food sensitizations in Saudi children with eosinophilic esophagitis are common, the allergy tests had limited predictive value for the response to dietary elimination.     

Wheat flour allergy: an entire diagnostic tool for complex allergy

Wheat proteins are involved in respiratory allergy, contact allergy and food allergy. Wheat allergens involve in these pathologies are well-known. However, establishment of wheat allergy diagnostic can be sometimes difficult on account of the complex allergenic composition of skin prick test (SPT) solutions of wheat flour. Therefore, we have studied specific IgE reactivity from patient sera with wheat food allergy, and characterized allergenic composition of wheat SPT solutions by specific antibodies directed to wheat allergens. The results showed that 20 of the 25 sera analyzed contained specific IgE to at least one wheat protein fraction. Among positive sera, 75% have specific IgE to water/salt soluble fraction, 85% to native gluten fractions and 65% to wheat isolate fraction. The results showed also that SPT solutions of wheat flour contained major food allergens from each allergenic fraction. These results highlighted the importance of using fractions, which constitute the whole wheat allergenic pattern, during specific IgE reactivity analyses. Moreover, we have observed that wheat isolate extract (results of food industrial process) contained not only modified allergens (neo-allergens) involve of specific food allergy to wheat isolate but also some native allergens involve in wheat food allergy. Thus, these results showed the importance to use, for wheat in vivo diagnosis together wheat SPT solutions (gluten extract and wheat isolate) in order to differentiate wheat food allergy to specific wheat isolate allergy.     

Intérêt du dosage des IgE vis-à-vis de l'allergène recombinant rBet v 1 dans la prise en charge de la pollinose printanière

We evaluated the value of recombinant Bet v 1 (rBet v 1)-specific IgE as a new diagnostic tool in the evaluation of spring pollinosis.Methods. – Based on the results of rBet v 1-specific IgE assays, 117 patients with a variety of symptoms who had been referred to our clinic were included. The diagnosis of birch pollinosis was based on a positive clinical history with positive skin test to birch pollen extract. One hundred and five patients were asked if they had had oral allergy symptoms. Associated asthma was considered an aggravating factor. Assays for rBet v 2-specific IgE and birch pollen-specific IgE (t3) were then done in 82 and 28 of these patients, respectively.Results. – In the studied population, the sensitivity, specificity, PPV and NPV of the rBet v 1 specific-IgE assay were excellent (91%, 82%, 92% and 93%, respectively). In patients with positive t3-specific IgEs, the sensitivity and the specificity of the rBet v 1 specific-IgE assay were higher than those of the t3-specific IgE assay. Assays for rBet v 2-specific IgE carried out concomitantly were positive in 19.5% of the cases, with a median level of 2.46 KU/l. Oral allergy syndromes were more frequently found in patients with levels of rBet v 1 specific IgEs superior to 50 KU/l. On the other hand, the level of rBet v 1-specific IgE was not predictive of pollinosis-associated asthma.Conclusion. – Measurement of rBet v 1-specific IgE allows one to define the sensitization profiles of pollen-sensitive patients and may be useful as a guide for specific immunotherapy.     

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.     

Intracutaneous tests with recombinant allergens in cystic fibrosis patients with allergic bronchopulmonary aspergillosis and Aspergillus allergy

Allergic bronchopulmonary aspergillosis (ABPA), an intensive inflammatory reaction to Aspergillus fumigatus, can cause irreversible lung damage in patients with cystic fibrosis (CF). The aim of this study was to assess if intracutaneous testing with recombinant A. fumigatus allergens (rAsp f ) allowed a reliable diagnosis of ABPA. Fifty patients with CF were tested, 12 suffering from ABPA, 21 with allergy to A. fumigatus, and 17 CF control patients not sensitized to A. fumigatus. All patients with ABPA reacted to at least one of the two intracellular A. fumigatus allergens rAsp f 4, a 30-kD protein of unknown biologic function, and rAsp f 6, a 23-kD manganese superoxide dismutase, at a concentration of 10(-2) microg/ml. The intracutaneous tests were negative or only marginally positive in the patients with allergy to A. fumigatus and completely negative in the CF control patients. The differential responses to the recombinant A. fumigatus allergens were in perfect agreement with our previous serologic results, so that rAsp f 4 and rAsp f 6 can be considered specific markers for ABPA. Early diagnosis of the disease might help to prevent irreversible lung damage and minimize possible steroid-mediated side effects as a consequence of an optimized control of the disease.     

Predictors of a positive oral food challenge to cow's milk in children sensitized to cow's milk

Introduction and objectivesThe diagnosis of IgE-mediated cow's milk allergy (CMA) is often based on clinical history and on specific IgE levels and/or skin-prick tests (SPT), both of which are sensitive but not specific. The gold standard, oral food challenge (OFC), is expensive and time-consuming and involves a risk of severe allergic reactions. This study aimed to determine the value of specific IgEs, ratios of specific IgEs for cow's milk and its components to total IgE, and wheal size on SPT for predicting a positive OFC for CMA.Material and methodsWe retrospectively studied 72 patients [median age, four years; age range 0.75–15 years] sensitized to cow's milk who underwent OFCs to milk. predictive variables between patients with positive and negative OFCs were compared. Receiver operator characteristic (ROC) curves were uses to assess variables’ discriminatory capacity and Youden's index to determine the best cut-offs for predicting CMA.ResultsThe OFC was positive in 39 (54%) patients. Wheal size on SPT and all specific IgEs and specific-to-total IgE ratios were significantly different between patients with positive OFCs and those with negative OFCs (p < 0.001). The variable with the greatest area under the ROC curve was casein-specific IgE (0.98), followed by β-lactoglobulin-specific IgE (0.923), casein-specific-to-total-IgE ratio (0.919), and α-lactalbumin-specific IgE (0.908). Casein-specific IgE ≥0.95 kU/L yielded 88.9% sensitivity and 90.9% specificity.ConclusionsIn our center, casein-specific IgE >0.95 kU/L can obviate an OFC to cow's milk for the diagnosis of CMA in patients sensitized to cow's milk with a compatible history.     

In vitro diagnostic evaluation of patients with inhalant allergies: summary of probability outcomes comparing results of CLA- and CAP-specific immunoglobulin E test systems.

For the diagnosis of allergy, presence of allergen-specific immunoglobulin E (IgE) usually is established either by allergen skin tests or by in vitro allergen-specific IgE measurements. However, in vitro assays of specific IgE often are modified as manufacturers improve allergens or change reagents to optimize test performance, affecting the diagnostic performance of in vitro allergen-specific IgE assays. This investigation compares the diagnostic outcomes of the Hitachi Chemical Diagnostics chemiluminescent assay (CLA) and Pharmacia, capsulated hydrophilic carrier polymer (CAP) in vitro allergen-specific IgE test methods in patients with inhalant allergy to a panel of selected allergens. Sera were obtained from 60 consecutive patients who had a clinical history suggesting inhalant allergy and were evaluated by allergen skin-prick test (SPT). Only patients with clinical findings of allergic asthma or rhinoconjunctivitis were included. Sera from patients with at least one positive SPT, which clinically correlated with the case history, were used for specific IgE measurements. Sensitivity and specificity were defined as conditional probabilities describing performances of the CAP system and the CLA system in reference to a standard composed of a combination of allergen-specific symptoms and a positive SPT. A test concordance of 79% was found between the CLA and CAP test results with a correlation coefficient of 0.8. Allergen-specific IgE assay sensitivity of the CLA and CAP systems was similar and allergen dependent, ranging from 67 to 100%. Assay specificity ranged from 39 to 86% for the CLA system and from 36 to 81% for the CAP system. When comparing the specific IgE results with allergen SPTs, 75% (+/- 3%) of CLApositive patients had a positive SPT, and 92% (+/- 4%) of CAPpositive patients had a positive SPT. Eighty-four percent (+/- 4%) of CLAnegative patients had a negative SPT, whereas 69% (+/- 5%) of CAPnegative patients had a negative SPT. The overall concordance between skin tests and in vitro tests was 76% for CLA and 67% for CAP. CLA and CAP score values showed good correlation and both tests may be useful when skin tests cannot be performed to identify subjects with IgE-mediated allergy. The CLA and CAP assays for allergen-specific IgE may be useful as part of an initial allergy evaluation because of the high negative predictive value of negative test results. For the majority of allergens the sensitivity was high. However, the specificity of both in vitro tests was low, indicating that positive in vitro test results should be evaluated carefully in conjunction with clinical symptoms and allergen-specific skin tests to determine the clinical relevance of the allergen sensitization.     

Overview of Serological-Specific IgE Antibody Testing in Children

Allergic diseases are among the most common chronic conditions in the pediatric population. Allergy diagnostic testing is an important part of the evaluation/management of allergic patients because the history may not be precise enough to identify the specific allergen sensitivity. In addition to providing information about specific sensitivities, allergy diagnostic tests have some predictive value in terms of future risk of developing an allergic condition and the severity/persistence of the allergic disease. The two most commonly used methods of confirming allergen sensitization are skin testing and measurement of serum-specific IgE. Both methods have similar diagnostic value in terms of sensitivity and specificity, with both parameters varying with the clinical scenario and allergen tested. Currently, there are three US Food and Drug Administration–cleared, serum-specific IgE assays used in the United States. The three assays report comparable analytic sensitivity, with the coefficients of variation of the precision, reproducibility, and linearity being less than 15%. However, comparative studies have demonstrated significant inter-assay variability, suggesting that they detect different populations of IgE antibody in human sera or do not measure the same antibodies with the same efficiency. Current specific IgE assays utilize allergen extract reagents. Testing with these reagents may identify sensitivity to clinically irrelevant allergens. This diagnostic limitation has spurred the development of molecular diagnostic tests, also referred to as component-resolved diagnostics, which utilize purified native or recombinant allergens to detect IgE sensitivity to individual allergen molecules. These advancements in serum IgE testing may enhance the precision of allergy diagnostic testing, which may decrease the need for oral food challenges and improve the specificity of allergen immunotherapy.     

Immunoglobulin-E Reactivity to a Glycosylated Food Allergen (Peanuts) Due to Interference With Cross-Reactive Carbohydrate Determinants in Heavy Drinkers

Background: N‐glycans in plant and invertebrate glycoproteins can induce extensive IgE cross‐reactivity therefore limiting the specificity of in vitro allergy tests. IgE sensitization to N‐glycans (cross‐reactive carbohydrate determinants, CCDs) may be increased in heavy drinkers, who therefore show IgE reactivity to aeroallergens, latex, and Hymenoptera venoms. The peanut, a CCD‐bearing allergen, is the leading cause of severe food allergic reactions in many populations. Aim of the study: To investigate the potential interference of CCDs with determinations of IgE to peanuts in heavy drinkers. Methods: We determined IgE to peanuts and IgE to a CCD marker (MUXF³, the N‐glycan from bromelain) in 41 heavy drinkers admitted to the hospital and 54 healthy controls. None of the participants reported symptoms of peanut allergy. In cases with positive (≥0.35 kU/l) IgE to peanuts, we performed inhibition assays with a neoglycoprotein consisting of MUXF³ molecules coupled to bovine serum albumin (MUXF³‐BSA) and a similar neoglycoprotein lacking xylose and fucose (MM‐BSA). In the same cases, we screened for IgE to a panel of recombinant nonglycosylated peanut allergens. SDS‐PAGE immunoblotting and inhibition assays were performed in selected cases. Results: The prevalence of positive IgE to peanuts was 22 and 3.7% in heavy drinkers and healthy controls, respectively (p < 0.001). Peanut‐IgE positivity was closely related to the presence of IgE to CCDs. In most (8/9) heavy drinkers with positive IgE to peanuts, reactivity was inhibited by preincubation with MUXF³‐BSA, but not with MM‐BSA. IgE binding to multiple bands on immunoblotting studies was also inhibited by MUXF³‐BSA preincubation. IgE to nonglycosylated recombinant peanut allergens was uniformly negative. Conclusion: Heavy drinking is associated with clinically asymptomatic IgE reactivity to peanuts, a relevant food allergen, in relation to CCD interference.     

Axes de recherche en allergologie alimentaire : hypoallergénicité et vaccins

The frequency of food allergy in the pediatric population (8%), as well as the worrying increase of prevalence of severe anaphylaxis boost the research for means of prevention and for therapeutics alternative to the sole eviction of foods. Oral desensitization and sublingual immunotherapy, being the main part of the present clinical research are not in the scope of this review. Future trends of research focus on hypoallergenicity and vaccines. The definition of hypoallergenicity is limited to a lesser reactivity because of a lesser binding of specific IgE to modified food allergens, since the conditions of the immunogenicity leading to sensitization remain unknown. Different ways for patients, alimentary industry and agronomical research are detailed: heating and cooking, enzymatic and chemical treatment of natural foods, physical treatments (texturization, ultrafiltration,…), screening of natural varieties in order to characterize some of them with a lower level or an absence of major allergens. Bioengineering of plants with a reduced level of major allergens, and site-directed mutagenesis on B epitopes could be helpful for a safer nutrition and vaccines. Possible molecular forms aimed at vaccines are considered: recombinant natural allergens, modified recombinant allergens by dimerisation, site-directed mutagenesis, fusion with other molecules, long peptides,… Associated considerations are the choice of adjuvants promoting a Th1 response, as well as vectors for the expression of recombinant food allergens: bacteria, probiotic ones, or poorly allergenic plants. Mucosal vaccines could be especially interesting for food allergens in order to add specific mechanisms of tolerance arising in the intestinal mucosa to the reorientation towards a Th1 and TREG response. Plasmidic DNA vaccines and anti-IgE vaccines are an object of research without any application in the near future. Therapeutic vaccines for food allergens might be substituted to oral desensitization and could be applied first to peanut allergy and to cross allergy between pollens and fruit or vegetable linked to panallergens. Prophylactic vaccines might be a second step for atopic infants, insofar as more knowledge could be obtained of mechanisms and enhancing factors of oral tolerance to food allergens and the “opportunity window” for the establishment of oral tolerance.     

Food allergy: a challenge for the clinician

Adverse reactions to food resulting in gastrointestinal symptoms and due to immunologic reactions (allergy) are discussed: their pathogenesis, the prevalence of food allergens and the clinical digestive expressions of food allergy in children and adults are reviewed. In IgE-mediated food allergy, the usefulness of the biological available tests is considered, mainly CAP tests, for proceeding to the diagnosis and the monitoring of the allergic disease. Finally, the best actual diagnostic tools in food allergy are considered (clinical history, skin tests, biological tests and food oral challenges), with their limitations and indications.     

The Role of Inhalant Food Allergens in Occupational Asthma

Workers handling food products and derivatives are at increased risk of developing occupational asthma. Exposure to food allergens occurs primarily through inhalation of dust, steam, vapors, and aerosolized proteins generated during cutting, scrubbing or cleaning, cooking or boiling, and drying activities. Suspicion of the diagnosis of occupational asthma should lead to proper investigation to confirm the diagnosis objectively. Most inhaled food allergy is IgE mediated, and skin prick tests or specific IgE tests are useful tools to support the diagnosis, but objective evidence of asthma by monitoring of peak expiratory flows at and off work or specific inhalation challenges offers a better diagnostic value. This article provides a list of the various foods, food additives, and contaminants that have been associated with occupational asthma.     

Microarray based IgE detection in poly-sensitized allergic patients with suspected food allergy - an approach in four clinical cases

BackgroundComponent-resolved diagnosis and microarray technology have been recently introduced into clinical allergy practice, and may be particularly useful in poly-sensitized allergic patients.MethodsWe compare the clinical usefulness of a microarray-based IgE detection assay (ISAC^®) with skin tests and specific IgE with standard allergens (sIgE) or their monocomponents in four case reports of patients poly-sensitized to aeroallergens and food.ResultsCase 1: a woman with rhinitis, oral allergy syndrome to several fruits and anaphylaxis to cherry. Diagnostic tests supported non-specific lipid transfer proteins (nsLTPs) primary sensitization.Case 2: a woman with exercise-induced asthma, rhino-conjunctivitis and oral allergy syndrome to fresh fruits of different families. A diagnosis of primary grass and weed pollen allergy with profilin and pathogenesis-related protein family 10 (PR-10) cross-reactive food allergy was proposed.Case 3: a man with atopic eczema, asthma, rhinitis, and multiple anaphylactic episodes with cashew nuts and oral allergy syndrome to fruits. The diagnostic workup supported a primary birch pollen allergy with PR-10 and nsLTPs cross-reactive food allergy.Case 4: a woman with rhino-conjunctivitis, per-operative anaphylaxis due to latex and recent pharyngeal angio-oedema episodes. The diagnosis was a primary grass and weed pollen allergy with equivocal profilin sensitization and no obvious cross-reactivity mediated by nsLTPs sensitization.ConclusionsThe possibility to carry out multiple sIgE measurements with single protein allergens, in particular with the microarray technique, is a useful, simple and non-invasive diagnostic tool in complex poly-sensitized allergic patients.