Anaphylaxis to foods

A new framework for the interpretation of IgE sensitization tests

IgE sensitization tests, such as skin prick testing and serum-specific IgE, have been used to diagnose IgE-mediated clinical allergy for many years. Their prime drawback is that they detect sensitization which is only loosely related to clinical allergy. Many patients therefore require provocation tests to make a definitive diagnosis; these are often expensive and potentially associated with severe reactions. The likelihood of clinical allergy can be semi-quantified from an IgE sensitization test results. This relationship varies though according to the patients' age, ethnicity, nature of the putative allergic reaction and coexisting clinical diseases such as eczema. The likelihood of clinical allergy can be more precisely estimated from an IgE sensitization test result, by taking into account the patient's presenting features (pretest probability). The presence of each of these patient-specific factors may mean that a patient is more or less likely to have clinical allergy with a given test result (post-test probability). We present two approaches to include pretest probabilities in the interpretation of results. These approaches are currently limited by a lack of data to allow us to derive pretest probabilities for diverse setting, regions and allergens. Also, cofactors, such as exercise, may be necessary for exposure to an allergen to result in an allergic reaction in specific IgE-positive patients. The diagnosis of IgE-mediated allergy is now being aided by the introduction of allergen component testing which may identify clinically relevant sensitization. Other approaches are in development with basophil activation testing being closest to clinical application.

Prevalence and Clinical Impact of IgE-Mediated Food Allergy in School Children With Asthma: A Double-Blind Placebo-Controlled Food Challenge Study

Purpose

Recent studies indirectly suggest a possible link between food allergy (FA) and asthma. Most of them have evaluated the occurrence of FA in asthmatic children, especially in the first year of life, using questionnaire-based studies or specific IgE (sIgE) assay. The aim of this study was to evaluate the prevalence and clinical impact of IgE-mediated FA in school children with asthma using a double-blind placebo-controlled food challenge (DBPCFC).

Methods

The study group consisted of school children with atopic asthma who were admitted to the Department of Pediatric Allergology, Gastroenterology and Nutrition, Medical University of Lodz, for the evaluation of food hypersensitivity. The diagnosis of FA was established using questionnaires, sIgE analysis, and the DBPCFC. Asthma severity and asthma control state were also assessed.

Results

A relationship between consumed food and complaints was reported in 180 children (49.7%). Seventy children (19.3%) were sensitized to food allergens. IgE-mediated FA was confirmed in 24 children (6.6%), while 11 children (3%) demonstrated respiratory symptoms. Food-induced asthma exacerbations were observed in 9 patients (2.5%). Statistically significant differences in the prevalence of atopic dermatitis (P<0.002), urticaria (P<0.03), digestive symptoms (P<0.03), rhinitis (P<0.02), sIgE level (P<0.001), positive family history of atopy (P<0.001) and FA in history (P<0.001) were found between asthmatic children with FA and those without. Children with food-induced asthma exacerbations demonstrated significantly greater severity, poorer controls, and worse morbidity compared to those without.

Conclusions

Although food-induced respiratory reactions in children with asthma were rare, they were classified as severe and associated with worse morbidity, greater severity, and poorer control. As the most commonly observed symptoms were coughing and rhinitis, which can be easily misdiagnosed, a proper diagnosis is essential for improving the management of both clinical conditions.

A surface-enhanced Raman scattering strategy for detection of peanut allergen Ara h 1 using a bipyramid-shaped gold nanocrystal substrate with an improved synthesis

We report an improved synthesis of branched gold nanocrystals for detection of peanut allergen Ara h 1 through use of sodium dodecylbenzene sulfonate. The method allows reduction of CTAB to 0.05 M and accelerates growth of gold seeds.

The two faces of mast cells in food allergy and allergic asthma: the possible concept of Yin Yang

The purpose of this review is to discuss the role of mast cells in allergic inflammation. We have focused on inflammation associated with allergic asthma and food allergy. Mast cells are 'first line of defense' innate/adaptive immune cells and are widely distributed in tissues in surfaces exposed to the environment. Especially in allergic settings mast cells are extensively studied, as they can be activated to release a wide range of mediators by allergen-IgE specific triggers. In addition, in allergic inflammation mast cells can also be activated non-allergic triggers. Recent studies revealed that mast cells, besides the classical role of pro-inflammatory effector cell, have also emerged as modulators of allergic sensitization and down-regulators of allergic inflammation. Therefore, mast cells can be regarded as 'Ying Yan' modulators in allergic responses in intestinal tract and airways. This article is part of a Special Issue entitled: Mast Cells in Inflammation.

What are the 'ideal' features of an adrenaline (epinephrine) auto-injector in the treatment of anaphylaxis?

Anaphylaxis is a systemic allergic reaction that often involves respiratory symptoms and cardiovascular collapse, which are potentially life-threatening if not treated promptly with intramuscular adrenaline. Owing to the unpredictable nature of anaphylaxis and accidental exposure to allergens (such as peanuts and shellfish), patients should be prescribed intramuscular adrenaline auto-injectors and carry these with them at all times. Patients also need to be able to use their auto-injectors correctly while under high stress, when an anaphylactic attack occurs. Despite this, an alarming number of patients fail to carry their auto-injectors and many patients, carers of children with known anaphylaxis and healthcare professionals do not know how to use the device correctly, despite having had training. Currently available auto-injector devices have various limitations that may impede their use in the management of anaphylaxis. There is also a lack of validated assessment criteria and regulatory requirements for new devices. This review describes the different delivery systems used in currently available auto-injectors and discusses the key barriers to the use of adrenaline auto-injectors, with the goal of identifying the 'ideal' features/characteristics of such devices in the emergency treatment of anaphylaxis that will ensure ease of use, portability and accurate delivery of a life-saving drug.

Food allergy prevalence in children of opisthorchiasis world region

The study of the food allergy prevalence in children of Tomsk city and rural areas with high and low opisthorchiasis level was performed. It was revealed that the food allergy prevalence in children is associated with chronic opisthorchiasis level.

Establishing the diagnosis of peanut allergy in children never exposed to peanut or with an uncertain history: a cross-Canada study

The diagnosis of peanut allergy (PA) can be complex especially in children never exposed to peanut or with an uncertain history. The aim of the study is to determine which diagnostic algorithms are used by Canadian allergists in such children. Children 1-17 yrs old never exposed to peanut or with an uncertain history having an allergist-confirmed diagnosis of PA were recruited from the Montreal Children's Hospital (MCH) and allergy advocacy organizations. Data on their clinical history and confirmatory testing were compared to six diagnostic algorithms: I. Skin prick test (SPT) >or=8 mm or specific IgE >or=5 kU/l or positive food challenge (+FC); II. SPT >or=8 or IgE >or=15 or +FC; III. SPT >or=13 or IgE >or=5 or +FC; IV. SPT >or=13 or IgE >or=15 or +FC; V. SPT >or=3 and IgE >or=5 or IgE >or=5 or +FC; VI. SPT >or=3 and IgE >or=15 or IgE >or=15 or +FC. Multivariate logistic regression analysis was used to identify factors associated with the use of each algorithm. Of 497 children recruited, 70% provided full data. The least stringent algorithm, algorithm I, was applied in 81.6% (95% CI, 77-85.6%) of children and the most stringent, algorithm VI, in 42.6% (95% CI, 37.2-48.1%).The factor most associated with the use of all algorithms was diagnosis made at the MCH in those never exposed to peanut. Other factors associated with the use of specific diagnostic algorithms were higher paternal education, longer disease duration, and the presence of hives, asthma, eczema, or other food allergies. Over 18% (95% CI, 14.4-23.0%) of children were diagnosed with PA without fulfilling even the least stringent diagnostic criteria.

Teenagers' experiences of living with food hypersensitivity: a qualitative study

Teenagers are a high-risk group for food-hypersensitivity fatalities, engage in risk-taking behaviours and may experience impaired quality of life. Understanding their experience is important to inform their care. This study aimed to describe the lived experiences of teenagers with food hypersensitivity. Individual semi-structured interviews were conducted with 21 teenagers (13-18 yr) with food hypersensitivity to a variety of foods and analysed using a phenomenological approach. Teenagers described living with (or coming to know) food hypersensitivity (FHS) as a way of life but still found living with food hypersensitivity to be burdensome. A necessary part of living with food hypersensitivity was coping with associated burden; a variety of coping strategies were employed to this effect. Teenagers described ways in which the burden of living with food hypersensitivity was alleviated or exacerbated by others. Management of food hypersensitivity was based on an assessment of acceptable risk resulting in varying levels of precaution taking. Teenagers' understanding of their FHS and ability to cope with it needs to be regularly assessed. Educational support may be required to ensure they take an appropriate level of precautions to minimize the chance of future reactions while not over compromising their quality of life. Psychological support may be required to help them to utilize healthy adaptive strategies to cope with the stresses of living with FHS. This approach is also likely to facilitate the smooth handover of responsibility from parent to teenager.

Lupine, a source of new as well as hidden food allergens

The present review summarizes current knowledge about lupine allergy, potential sensitization routes, cross-reactions between lupine and other legumes, and the respective IgE-binding proteins. Since the 1990 s, lupine flour is used as a substitute for or additive to other flours, mostly wheat flour, in several countries of the EU. In 1994, the first case of an immediate-type allergy after ingestion of lupine flour-containing pasta was reported. Since then, the number of published incidents following ingestion or inhalation of lupine flour is rising. So far, the Lupinus angustifolius beta-conglutin has been designated as the allergen Lup an 1 by the International Union of Immunological Societies Allergen Nomenclature Subcommittee. Initially, publications focussed on the fact that peanut-allergic patients were at risk to develop anaphylaxis to lupine due to cross-reactivity between peanut and lupine. At present, however, the ratio between cases of pre-existing legume allergy (mostly peanut allergy) to de novo sensitization to lupine seed is nearly 1:1. Although in December 2006, lupine and products thereof were included in the EU foodstuff allergen list according to the Commission Directive 2006/142/EC amending Annex IIIA of Directive 2000/13/EC in order to prevent severe reactions caused by "hidden food allergens", the majority of patients and medical personnel are still not aware of raw lupine seed as potentially dangerous food allergen.

Reported symptoms to peanut between 4 and 8 years among children sensitized to peanut and birch pollen - results from the BAMSE birth cohort

BACKGROUND

Specific IgE tests are sometimes difficult to interpret due to structural similarities between certain food and pollen allergens. This may be the reason why concomitant sensitization to peanut and birch pollen is frequently seen. The aim of this study was to investigate reported symptoms to peanut- and birch pollen in relation to sensitization.

METHODS

The data originate from 1928 children in the BAMSE birth cohort. Background factors and clinical parameters were obtained and the levels of IgE antibodies to peanut and birch pollen measured at 4 and 8 years.

RESULTS

IgE antibodies to peanut were found in 5.5% and 7.4% of the children at 4 and 8 years, respectively. The IgE antibody levels to peanut were higher in children sensitized to peanut but not birch than in children sensitized to peanut and birch among both 4- and 8-year-olds (P = 0.093 and P = 0.003, respectively). Eight-year-olds sensitized to peanut but not birch, more often reported symptoms to peanut than children sensitized to both peanut and birch pollen (76%vs 46%, P = 0.002). The probability of reported symptoms to peanut increased significantly with increasing IgE levels to peanut, especially in 8-year-olds not sensitized to birch.

CONCLUSIONS

Children sensitized to both peanut and birch pollen are less likely to report symptoms to peanut than children sensitized to peanut but not to birch pollen at 8 years. This is likely due to cross reactions between birch pollen and peanut and can explain the high sensitization rate to peanut in areas where birch trees are common.

Parents' attitudes when purchasing products for children with nut allergy: a UK perspective

Food avoidance remains the main strategy in prevention of anaphylaxis in children with acute food allergies. To achieve this aim, product labelling needs to be clear and accurate and parents educated on optimal avoidance measures. Food product labelling although improved often still remains ambiguous. The aim of this study was to understand and quantify the attitudes of parents of children with nut allergy towards labels informing that the product could contain nuts. An anonymous questionnaire was filled out by parents of children with nut allergy attending a tertiary paediatric allergy clinic to assess response to differing descriptive labelling of foods containing nuts. In 184 questionnaire responses, 80% of parents would not purchase a product labelled 'not suitable for nut allergy sufferers' or 'may contain nuts'. However, other labels including 'this product does not contain any nuts but is made in a factory that uses nuts', 'cannot guarantee is nut free' and 'may contain traces of nuts' were avoided by only around 50% of parents. Previous allergic reaction to nut products had no bearing on outcome. Additionally, large numbers of parents did not read labels for the presence of nuts in non-food products. A large number of patients with nut allergy continue risk-taking by either ignoring warning labels on foods or assuming that there is a gradation of risk depending on the wording of label warnings. Further tightening of labelling legislation and improved education would help to decrease the risk of anaphylaxis.

The diagnosis of IgE-mediated food allergy in childhood

IgE-mediated food allergy is a common condition in childhood and a recognized public health concern. An accurate diagnosis of food allergy facilitates the avoidance of the allergen - and cross-reactive allergens - and allows for safe dietary expansion. The diagnosis of food allergy relies on a combination of rigorous history, physical examination, allergy tests [skin prick tests (SPT) and/or serum-specific IgE] and oral food challenges. Diagnostic cut-off values for SPT and specific IgE results have improved the diagnosis of food allergy and thereby reduced the need to perform oral food challenges. This clinical case series seeks to highlight a contemporary approach to the diagnosis of food allergy in children strategies.

Utility of ovomucoid-specific IgE concentrations in predicting symptomatic egg allergy

BACKGROUND

Children with allergy to raw egg white might tolerate low amounts of heated egg. Ovomucoid-specific IgE antibodies have been suggested to be predictors of whether children could tolerate heat-treated egg.

OBJECTIVE

The aim was to evaluate the clinical usefulness and added diagnostic value of measurements of IgE antibodies to egg white, ovalbumin, and ovomucoid in children with egg allergy.

METHODS

One hundred eight patients (median age, 34.5 months) with suspected egg allergy underwent double-blind, placebo-controlled food challenges with raw and heated egg. The outcomes of the challenges were related to the serum concentration of specific IgE antibodies and total IgE by using ImmunoCAP.

RESULTS

Reactions to heated egg white were observed in 38 patients (considered allergic to raw and heated egg), 29 patients reacted to only raw egg white, and 41 patients were tolerant. Correlation was observed between the serologic parameters studied. Receiver operating characteristic analysis showed that egg white ImmunoCAP was useful in the diagnosis of allergy to raw egg white. The positive decision point, based on 95% clinical specificity, was 7.4 kU(A)/L, and the negative decision point, based on 95% clinical sensitivity, was 0.6 kU(A)/L. For reaction to heated egg white, ovomucoid ImmunoCAP was superior. The positive decision point was 10.8 kU(A)/L, and the negative decision point was 1.2 kU(A)/L.

CONCLUSIONS

Quantitative measurements of specific IgE antibodies to both egg white and ovomucoid and the evaluation against the suggested positive and negative decision points for specific IgE will be useful in the diagnosis of egg allergy.

New visions for food allergy: an iPAC summary and future trends

The spectrum of food allergy consists of a variety of different clinical pictures including immunoglobulin (Ig)E, and non-IgE food allergy as well as mixed, IgE and non-IgE disorders. In addition, eosinophilic diseases of the gastrointestinal (GI) tract with occasional IgE-type sensitization are increasingly recognized. As a consequence, the clinical picture of food allergy is pleomorphic and can range from chronic GI symptoms to severe anaphylaxis. The diagnosis of food allergy is mostly hampered by the lack of reliable in vitro tests for non-IgE-mediated diseases, and in most cases relies on a reoccurrence of symptoms upon re-exposure to the antigen; in general during a standardized food challenge. Currently, there is no safe and efficient treatment for food allergy and the treatment relies on avoidance diets. Priorities for research have been identified by iPAC (international Pediatric Allergy and Asthma Consortium) and outlined in this review. They include studies to better identify the pathogenesis of food allergy, including genetic aspects; studies to develop diagnostic and follow-up tests; studies for standardization of food challenges; as well as studies addressing a safe and efficient treatment of food allergy.