Food allergy and anaphylaxis

Alpha-Gal Syndrome: A Novel and Increasingly Common Cause of Anaphylaxis

The alpha-gal syndrome is a recently described cause of anaphylaxis to red meat that has been increasing in frequency over time. It is related to Lone Star tick bites in the United States and occurs in many other parts of the world. It is especially common in the southeastern United States. In addition to the usual symptoms of anaphylaxis, gastrointestinal symptoms are prominent. Another unusual feature is the delay of several hours between eating meat and the development of symptoms. Diagnosis can be made by a blood test for the immunoglobulin E antibodies to a specific oligosaccharide. As many as 10% of patients diagnosed with idiopathic anaphylaxis have alpha-gal syndrome in some parts of the United States. The only current treatment is a meat-free diet. Clinician awareness of alpha-gal syndrome is low, and because severe recurrent life-threatening episodes can occur, it is an important condition for emergency clinicians to be aware of.

Evaluation and Management of Food Allergies in the Emergency Department

Food allergies are a common and serious cause of illness, accounting for an increasing number of emergency department visits annually. Although definite diagnosis lays outside of an emergency department visit, the clinical management of the most serious food allergies highlights emergency care. The staple of acute care remains epinephrine in association with antihistamines and steroids. The greatest threat remains undertreatment for this group of disorders and underutilization of epinephrine. Those who have been treated for a food allergy need a follow-up allergist evaluation, guidance of food avoidance, and avoidance of foods with cross-sensitivities as well as ready access to epinephrine.

Evaluation and Management of Food Allergies in the Emergency Department

Food allergies are a common and serious cause of illness, accounting for an increasing number of emergency department visits annually. Although definite diagnosis lays outside of an emergency department visit, the clinical management of the most serious food allergies highlights emergency care. The staple of acute care remains epinephrine in association with antihistamines and steroids. The greatest threat remains undertreatment for this group of disorders and underutilization of epinephrine. Those who have been treated for a food allergy need a follow-up allergist evaluation, guidance of food avoidance, and avoidance of foods with cross-sensitivities as well as ready access to epinephrine.

Gastrointestinal Food Allergies and Intolerances

Adverse reactions to food include immune-mediated food allergies, celiac disease, and nonimmune-mediated food intolerances. Differentiating between these many disorders is important to guide us toward appropriate testing and management. Double-blind placebo-controlled food challenges are the gold standard for food allergy diagnosis but are difficult and time-consuming. In place of this, strong clinical history, other supportive tests, and oral food challenges are helpful. Some commonly available tests for food allergy and intolerances lack sufficient evidence for efficacy. Food intolerance diagnosis is largely based on history and supported by symptom improvement with appropriate dietary manipulation.

Sensitization profiles to hazelnut allergens across the United States

BACKGROUND

Measurement of IgE antibody to hazelnut components can aid in the prediction of allergic responses to the food.

OBJECTIVE

To investigate the association between patient demographics (age, location) and patterns of allergic sensitization to hazelnut components across the United States and to investigate the degree of correlation between hazelnut sensitization with sensitization to other tree nuts, peanuts, and their components.

METHODS

Serum samples from 10,503 individuals with hazelnut extract specific IgE (sIgE) levels of 0.35 kU_A/L or higher were analyzed for IgE antibodies to Cor a 1, 8, 9, and 14 by ImmunoCAP. A subset of these patients were analyzed for IgE antibodies to peanut, walnut, and cashew nut IgE along with associated components.

RESULTS

Among hazelnut sensitized individuals, children (<3 years old) were predominantly sensitized to Cor a 9 and Cor a 14. Conversely, Cor a 1 sIgE sensitization was much higher in adults than children, especially in the Northeastern United States. Cor a 8 sensitization was relatively constant (near 10%) across all ages. Cosensitization of hazelnut with other tree nuts and peanuts was related to correlation of IgE concentrations of individual component families.

CONCLUSION

We conclude that sensitization to individual hazelnut components is highly dependent on age and/or geographic location. Component correlations suggest that cosensitization to hazelnut and walnut may be caused by their pathogenesis-related protein 10 allergens, nonspecific lipid transfer proteins, or seed storage proteins, whereas hazelnut and peanut cosensitization is more often caused by cross-reactivity of pathogenesis-related protein 10 (Cor a 1 and Ara h 8) and nonspecific lipid transfer proteins (Cor a 8 and Ara h 9).

Sensitization profiles to peanut allergens across the United States

BACKGROUND

Measurement of IgE antibody to peanut components can aid in the prediction of allergic responses the food.

OBJECTIVE

To investigate the association between patient demographics (age, location) and allergic sensitization to peanut components across the United States.

METHODS

Serum samples from 12,155 individuals with peanut extract specific IgE levels of 0.35 kUA/L or higher were analyzed for IgE antibodies to Ara h 1, 2, 3, 8, and 9 by ImmunoCAP.

RESULTS

Among this population of peanut sensitized individuals, 79.1% of children (<3 years old) were sensitized to one or more peanut storage proteins (Ara h 1, 2, and/or 3), in contrast to 64.2% of adolescents (12-15 years old) and 22.1% of adults (>20 years old). Although sensitization was more prevalent to Ara h 2 than to the other storage proteins, a sizable fraction of patients were sensitized to Ara h 1 and/or 3 but not to Ara h 2 (eg, 13% of children <3 years old). Moreover, 9.6% of children, 10.2% of adolescents, and 10.5% of adults were sensitized to Ara h 9, whereas 2.4% of children, 49.4% of adolescents, and 42.9% of adults produced IgE to Ara h 8 (pathogenesis-related protein 10). Sensitization to Ara h 8 alone was markedly higher in the Northeastern United States relative to other regions of the country.

CONCLUSION

We conclude that sensitization to individual peanut components is highly dependent on age and geographic location. Given that a severe allergic reaction to peanut is unlikely in individuals with isolated sensitization to Ara h 8, a sizable fraction of patients, in particular adolescents and adults, may be at lower risk than anticipated based only on demonstration of sensitization to whole peanut extract.

Evaluation of Anaphylaxis Management in a Pediatric Emergency Department

OBJECTIVE

In 2006, the National Institute of Allergy and Infectious Disease established evidence-based treatment guidelines for anaphylaxis. The purpose of our study was to evaluate provider adherence to guidelines-based management for anaphylaxis in a tertiary care pediatric emergency department (ED).

METHODS

Retrospective chart review was conducted of patients (0-18 years) presenting to the Arkansas Children Hospital ED from 2004 to 2011 for the treatment of anaphylaxis using International Classification of Diseases, Ninth Edition, codes. Multiple characteristics including demographics, clinical features, allergen source, and anaphylaxis management were collected. Fisher exact or χ tests were used to compare proportion of patients treated with intramuscular (IM) epinephrine in the preguideline versus postguideline period. Relative risk (RR) statistics were computed to estimate the ratio of patients who received self-injectable epinephrine prescription and allergy follow-up in the preguideline and postguideline groups.

RESULTS

A total of 187 patients (median [range] age, 7 [1-18] years; 67% male; 48% African American) were evaluated. Food (44%) and hymenoptera stings (22%) were commonly described culprit allergens, whereas 29% had no identifiable allergen. Only 47% (n = 87) received epinephrine in the ED and 31% (n = 27) via the preferred IM route. Comparing postguideline (n = 126) versus preguideline (n = 61) periods demonstrated increase in the usage of the IM route (46% postguideline vs 6% preguideline; risk ratio (RR), 7.64; 95% confidence interval [CI], 2.04-46.0; P < 0.001). Overall, 61% (n = 115) of the patients received self-injectable epinephrine upon discharge, and there were no significant differences between the groups (64% postguideline vs 56% preguideline, P = 0.30). Postguideline patients were more likely to receive a prescription compared with preguideline patients (64% postguideline vs 56% preguideline; RR, 1.15; 95% CI, 0.89-1.55; P = 0.30). Only 45% (n = 85) received an allergy referral. Postguideline patients were more likely to receive an allergy referral than preguideline patients (48% postguideline vs 41% preguideline; RR, 1.16; 95% CI, 0.81-1.73; P = 0.40).

CONCLUSIONS

Provider use of IM epinephrine has improved since anaphylaxis guidelines were published. However, more provider education is needed to improve overall adherence of guidelines in a tertiary care pediatric ED.

The Effect of Wheat Allergy on the Course of Atopic Eczema in Patients over 14 Years of Age

Few studies concerning the importance of wheat allergy affecting the course of atopic eczema in adolescents and adult patients exist. Aim: The evaluation if wheat allergy can deteriorate the course of atopic eczema. Follow-up of patients with confirmed food allergy to wheat. Method: Altogether 179 persons suffering from atopic eczema were included in the study: 51 men and 128 women entered the study with an average age of 26.2 (s.d. 9.5 years) Dermatological and allergological examinations were performed, including skin prick tests, atopy patch tests, and specific serum IgE for wheat, open exposure test and double-blind, placebo-controlled food challenge test with wheat flour. Results: Wheat allergy affecting the coures of atopic eczema was confirmed in eight patients (4.5%) out of 179 patients enrolled in this study by double-blind, placebo controlled food challenge test. The course of atopic eczema showed a positive trend in patients with confirmed food allergy at 3, 6, 9, 12 month follow-up (statistical evaluation with paired t-test) after the elimination of wheat flour. Conclusion: Wheat allergy may play an important role in the worsening of atopic eczema (acting as a triggering exacerbating factor) only in a minority of adolescents and adult patients (4.5% in our study). The diagnostic methods (skin prick test, specific IgE, atopy patch test, history) cannot be used as separated tests for the determination of food allergy to wheat in patients with atopic eczema.Open exposure tests and double-blind, placebo-controlled food challenge should be used for the confirmation of wheat allergy affecting the course of atopic eczema.

Managing nut-induced anaphylaxis: challenges and solutions

The prevalence of peanut and tree nut allergy in the USA has increased, especially in the pediatric population. Nut allergy remains the leading cause of fatal anaphylactic reactions. Management of anaphylaxis includes not only treatment of symptoms during a reaction, but strict dietary avoidance and education on potential situations, which may place the patient at high risk for accidental exposure. Cross-reactivity between various nuts along with various cross-contamination sources should be discussed with all nut-allergic individuals. Exciting research continues to emerge on other potential treatments for patients allergic to nuts, including allergen immunotherapy. Results of such interventions have been encouraging, though further studies are needed regarding safety and long-term outcomes before these can be applied to clinical practice.

Loss of IL-4Rα-mediated PI3K signaling accelerates the progression of IgE/mast cell-mediated reactions

Clinical and experimental evidence indicate that polymorphisms within the interleukin 4 (IL‐4) receptor (IL‐4R) chain are sufficient for altered strength of IL‐4/IL‐13 signaling, leading to an exaggerated allergic inflammatory response and increase susceptibility to allergic phenotypes. In the present study, we show that ablation of IL‐4Rα–induced phosphatidylinositol 3‐kinase (PI3K) activating signal by germline point mutation within the IL‐4Rα motif (Y500F) did not alter susceptibility to IgE‐mediated, food‐induced experimental anaphylaxis. Moreover, diarrhea occurrence, antigen‐specific IgE and intestinal mastocytosis were comparable between WT and IL‐4Rα^Y500F mice. However, mice unable to stimulate IL‐4Rα–mediated PI3K signaling had accelerated disease progression. Notably, the accelerated anaphylactic response was associated with more rapid histamine‐induced hypovolemia. Mechanistic in vitro and in vivo analyses revealed that endothelial IL‐4Rα PI3K signaling negatively regulates the histamine‐induced endothelial leak response. These results define an unanticipated role for IL‐4Rα–mediated PI3K signaling in negative regulation of IgE‐mediated anaphylactic reactions.

Review article: the diagnosis and management of food allergy and food intolerances

BACKGROUND

Adverse reactions to food include immune mediated food allergies and non-immune mediated food intolerances. Food allergies and intolerances are often confused by health professionals, patients and the public.

AIM

To critically review the data relating to diagnosis and management of food allergy and food intolerance in adults and children.

METHODS

MEDLINE, EMBASE and the Cochrane Database were searched up until May 2014, using search terms related to food allergy and intolerance.

RESULTS

An estimated one-fifth of the population believe that they have adverse reactions to food. Estimates of true IgE-mediated food allergy vary, but in some countries it may be as prevalent as 4-7% of preschool children. The most common food allergens are cow's milk, egg, peanut, tree nuts, soy, shellfish and finned fish. Reactions vary from urticaria to anaphylaxis and death. Tolerance for many foods including milk and egg develops with age, but is far less likely with peanut allergy. Estimates of IgE-mediated food allergy in adults are closer to 1-2%. Non-IgE-mediated food allergies such as Food Protein-Induced Enterocolitis Syndrome are rarer and predominantly recognised in childhood. Eosinophilic gastrointestinal disorders including eosinophilic oesophagitis are mixed IgE- and non-IgE-mediated food allergic conditions, and are improved by dietary exclusions. By contrast food intolerances are nonspecific, and the resultant symptoms resemble other common medically unexplained complaints, often overlapping with symptoms found in functional disorders such as irritable bowel syndrome. Improved dietary treatments for the irritable bowel syndrome have recently been described.

CONCLUSIONS

Food allergies are more common in children, can be life-threatening and are distinct from food intolerances. Food intolerances may pose little risk but since functional disorders are so prevalent, greater efforts to understand adverse effects of foods in functional disorders are warranted.

Anaphylaxis avoidance and management: educating patients and their caregivers

Anaphylaxis is an increasingly prevalent problem in westernized countries. Therefore, it is of utmost importance that the increasing numbers of patients at risk for anaphylaxis receive proper education on the etiology and risk factors as well as appropriate treatment of anaphylaxis with epinephrine. The physician’s role is crucial in order to educate the patients and care takers on effective measures to prevent anaphylaxis and empower them to take charge of early recognition and proper management of an anaphylactic reaction to prevent poor outcomes. This review summarizes the clinical presentation, triggers, avoidance, and management of anaphylaxis.

Remission of food allergy by the Janus kinase inhibitor ruxolitinib in mice

To clarify the role of Janus kinase (JAK) in and the efficacy of JAK inhibitors on food allergy, we investigated the effect of the clinically available JAK inhibitor ruxolitinib on mouse food allergy and the functions of cultured mast cells in vitro. Anaphylactic symptoms including diarrhea and decreases in body temperature pursuant to oral ovalbumin (OVA) challenges in food allergy mice were attenuated by the daily oral administration of ruxolitinib. This drug inhibited increases in mouse mast cell protease-1 concentrations in the serum and mast cell numbers in the intestines of these mice as well as degranulation, IL-13 production, and the spontaneous and IL-9-dependent survival of mouse bone marrow-derived mast cells in spite of the absence of an effect of ruxolitinib on passive systemic anaphylaxis. Anti-OVA IgG2a, IgE, and IgG1 serum levels and the release of IFN-γ, IL-4, IL-9, and IL-10 from the OVA-restimulated splenocytes of food allergy mice were also decreased by the treatment. Moreover, ruxolitinib administration to mice that had already exhibited anaphylactic responses to previous challenges reduced anaphylactic responses to further oral OVA challenges, which suggested that ruxolitinib has a therapeutic potential on food allergy. Our results showed that ruxolitinib remitted food allergy in mice mainly through immunosuppression and the prevention of mast cell hyperplasia, and partially through the inhibition of mast cell activation. We consider JAK inhibition to be a promising strategy for the prevention of food allergy, and ruxolitinib along with its derivatives inhibiting JAK as good candidates for therapeutic drugs to treat food allergy.

Clinical predictors for favorable outcomes in an oral immunotherapy program for IgE-mediated cow's milk allergy

BACKGROUND

Avoidance strategies in patients with cow's milk allergy occasionally fail to protect these patients from inadvertent exposures, leading to life-threatening reactions.

OBJECTIVE

To assess the safety and efficacy of milk oral immunotherapy as an alternative therapeutic strategy.

METHODS

Patients (n = 280, >4 years old) with IgE-mediated cow's milk allergy were enrolled into a milk oral immunotherapy program at a single hospital center. High-risk patients were not excluded. The treatment protocol consisted of 3 rounds of oral induction performed every 4 weeks. On day 1, a patient's reaction threshold was determined. On days 2 and 3, a tolerated starting dose below the threshold was confirmed. Day 4 mimicked the home treatment, which continued until the next induction.

RESULTS

The median initial starting dose was 52.5 mg of cow's milk protein. Excluding those whose treatment failed in the first week (n = 5) or are still undergoing treatment (n = 15), 61.5% (160 of 260 patients) achieved 7,200 mg and 85.4% of patients were consuming at least 180 mg of milk protein. Reactions at home requiring the use of injectable epinephrine occurred in 15.7% of patients (44 of 280) and in 0.075% (58 of 77,098) of doses administered. Predictors for achieving a full dose in multivariate analysis included a starting dose higher than 30 mg of milk protein (odds ratio 4.6, P < .001), not requiring epinephrine during induction (odds ratio 5.2, P < .001) or home treatment (odds ratio 2.6, P = .037), and the lack of nonanaphylactic type symptoms (odds ratio 15.6, P < .001).

CONCLUSION

Milk oral immunotherapy, carried out in a highly controlled setting, is successful in protecting the overwhelming majority of patients from accidental exposures to cow's milk protein.

Specific detection by the polymerase chain reaction of potentially allergenic salmonid fish residues in processed foods

Salmonid fish is one of the allergenic items that are recommended to be labeled in the Japanese allergen-labeling system. This study develops a salmonid-specific polymerase chain reaction (PCR) method. A new primer pair, SKE-F/SKE-R, was designed to specifically detect the salmonid fish gene encoding mitochondrial DNA cytochrome b. Genomic DNAs extracted from 58 kinds of seafood and 11 kinds of processed food were individually subjected to PCR by using the primer pair, and a salmonid-specific fragment of 212 bp was only amplified in the salmonid samples and salmonid-containing processed foods. The detection limit of the PCR method was as low as 0.02 fg/µL of salmonid fish DNA (corresponding to 10 copies). There is no ELISA method for salmonid fish, making our PCR method the only reliable measure for detecting salmonid fish in processed foods.

Structural and immunologic characterization of Ara h 1, a major peanut allergen

Allergic reactions to peanuts and tree nuts are major causes of anaphylaxis in the United States. We compare different properties of natural and recombinant versions of Ara h 1, a major peanut allergen, through structural, immunologic, and bioinformatics analyses. Small angle x-ray scattering studies show that natural Ara h 1 forms higher molecular weight aggregates in solution. In contrast, the full-length recombinant protein is partially unfolded and exists as a monomer. The crystal structure of the Ara h 1 core (residues 170-586) shows that the central part of the allergen has a bicupin fold, which is in agreement with our bioinformatics analysis. In its crystalline state, the core region of Ara h 1 forms trimeric assemblies, while in solution the protein exists as higher molecular weight assemblies. This finding reveals that the residues forming the core region of the protein are sufficient for formation of Ara h 1 trimers and higher order oligomers. Natural and recombinant variants of proteins tested in in vitro gastric and duodenal digestion assays show that the natural protein is the most stable form, followed by the recombinant Ara h 1 core fragment and the full-length recombinant protein. Additionally, IgE binding studies reveal that the natural and recombinant allergens have different patterns of interaction with IgE antibodies. The molecular basis of cross-reactivity between vicilin allergens is also elucidated.

NIAID-sponsored 2010 guidelines for managing food allergy: applications in the pediatric population

Data from many studies have suggested a rise in the prevalence of food allergies during the past 10 to 20 years. Currently, no curative treatments for food allergy exist, and there are no effective means of preventing the disease. Management of food allergy involves strict avoidance of the allergen in the patient's diet and treatment of symptoms as they arise. Because diagnosis and management of the disease can vary between clinical practice settings, the National Institute of Allergy and Infectious Diseases (NIAID) sponsored development of clinical guidelines for the diagnosis and management of food allergy. The guidelines establish consensus and consistency in definitions, diagnostic criteria, and management practices. They also provide concise recommendations on how to diagnose and manage food allergy and treat acute food allergy reactions. The original guidelines encompass practices relevant to patients of all ages, but food allergy presents unique and specific concerns for infants, children, and teenagers. To focus on those concerns, we describe here the guidelines most pertinent to the pediatric population.

Cloning and characterization of an 11S legumin, Car i 4, a major allergen in pecan

Among tree nut allergens, pecan allergens remain to be identified and characterized. The objective was to demonstrate the IgE-binding ability of pecan 11S legumin and characterize its sequential IgE-binding epitopes. The 11S legumin gene was amplified from a pecan cDNA library and expressed as a fusion protein in Escherichia coli. The native 11S legumin in pecan extract was identified by mass spectrometry/mass spectrometry (MS/MS). Sequential epitopes were determined by probing the overlapping peptides with three serum pools prepared from different patients' sera. A three-dimensional model was generated using almond legumin as a template and compared with known sequential epitopes on other allergenic tree nut homologues. Of 28 patients tested by dot blot, 16 (57%) bound to 11S legumin, designated Car i 4. MS/MS sequencing of native 11S legumin identified 33 kDa acidic and 20-22 kDa basic subunits. Both pecan and walnut seed protein extracts inhibited IgE binding to recombinant Car i 4, suggesting cross-reactivity with Jug r 4. Sequential epitope mapping results of Car i 4 revealed weak, moderate, and strong reactivity of serum pools against 10, 5, and 4 peptides, respectively. Seven peptides were recognized by all three serum pools, of which two were strongly reactive. The strongly reactive peptides were located in three discrete regions of the Car i 4 acidic subunit sequence (residues 118-132, 208-219, and 238-249). Homology modeling of Car i 4 revealed significant overlapping regions shared in common with other tree nut legumins.

Anaphylaxis and biphasic phase in Thailand: 4-year observation

BACKGROUND

Anaphylaxis, a severe systemic allergic reaction, can be fatal. However, its prevalence has been underestimated especially in biphasic phase, due to a lack of case awareness. This study aimed to determine the rate of anaphylaxis, describe clinical manifestations and management, and identify the causative agents and risk factors of biphasic anaphylactic reaction.

METHODS

An observational study was conducted at the Emergency Department of Thammasat University Hospital, Thailand, during the period 2004-2008.

RESULTS

Of total 208 cases of anaphylaxis identified, the median age was 20.67 years; 52.9% were male. The anaphylaxis rate was 49 per 100,000 patient-years. No fatal case was found; 58.7% had a history of atopy, and 38.5% had experienced a previous allergic reaction, of whom 8.8% had had a previous anaphylactic reaction. The causative allergens were identified in 82.2% of cases; food allergy was most common. Urticaria was the most common presentation (87%). Among 6.3% of the patients who developed biphasic reaction, a significantly longer time from onset of symptoms to administration of epinephrine was detected, with a median of 240 minutes for those with biphasic anaphylaxis, versus 70 minutes for those without (p = 0.002). The median times from onset to hospital arrival and the arrival to administration of epinephrine were also significantly longer in the biphasic group than the non-biphasic patients (p = 0.002 and p = 0.001, respectively). In multivariable regression models, the time intervals from onset and hospital arrival to administration of epinephrine continued to predict biphasic phase occurrence (p < 0.01).

CONCLUSIONS

Anaphylaxis predominantly occurs among children and young adults. Delayed administration of epinephrine was associated with the occurrence of biphasic anaphylaxis.

Recognition and management of food-induced anaphylaxis

Food-induced anaphylactic reactions are common and increasing in frequency. Despite the existence of a consensus definition of anaphylaxis, many cases are missed, recommended treatments are not given, and follow-up is inadequate. New aspects of its pathophysiology and causes, including atypical food-induced causes, are still being uncovered. Epinephrine remains the cornerstone for successfully treating anaphylaxis; H1 and H2 antihistamines, glucocorticoids, and β-agonists are ancillary medications that may be used in addition to epinephrine. Early recognition of anaphylaxis, appropriate emergency treatment, and follow up, including prescription of self-injectable epinephrine, are essential to prevent death and significant morbidity from anaphylaxis.

Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel

Food allergy is an important public health problem that affects children and adults and may be increasing in prevalence. Despite the risk of severe allergic reactions and even death, there is no current treatment for food allergy: the disease can only be managed by allergen avoidance or treatment of symptoms. The diagnosis and management of food allergy also may vary from one clinical practice setting to another. Finally, because patients frequently confuse nonallergic food reactions, such as food intolerance, with food allergies, there is an unfounded belief among the public that food allergy prevalence is higher than it truly is. In response to these concerns, the National Institute of Allergy and Infectious Diseases, working with 34 professional organizations, federal agencies, and patient advocacy groups, led the development of clinical guidelines for the diagnosis and management of food allergy. These Guidelines are intended for use by a wide variety of health care professionals, including family practice physicians, clinical specialists, and nurse practitioners. The Guidelines include a consensus definition for food allergy, discuss comorbid conditions often associated with food allergy, and focus on both IgE-mediated and non-IgE-mediated reactions to food. Topics addressed include the epidemiology, natural history, diagnosis, and management of food allergy, as well as the management of severe symptoms and anaphylaxis. These Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. They also identify gaps in the current scientific knowledge to be addressed through future research.

The safety of the H1N1 influenza A vaccine in egg allergic individuals

BACKGROUND

The safety of H1N1 vaccine is unknown in egg allergic (EA) recipients.

OBJECTIVES

To establish the safety of administering H1N1 vaccine and to evaluate the predictability of H1N1 skin testing in EA patients.

METHODS

In a controlled, prospective trial, H1N1 skin testing and vaccination was compared between EA patients (n = 105) and non-EA controls (n = 19). Those with negative H1N1 skin test results received a full H1N1 dose; those with a positive skin test result received a graded challenge (10%, 90%). Booster vaccine, if required, was given as a single dose from a different lot without prior testing.

RESULTS

Prick and intradermal test results were positive in 3 (2.4%) of 124 and 41 (33.1%) of 124 study participants, respectively. Forty-one individuals received a 2-step graded vaccine challenge, including 13 of 25 with a history of egg anaphylaxis. No significant allergic reactions resulted from either method of vaccination or from subsequent booster doses.

CONCLUSION

All study participants received the H1N1 vaccine without significant allergic reactions. Skin testing is unnecessary and does not predict vaccine tolerance. All study participants who received a graded challenge tolerated a single dose booster from a different, untested lot, including 7 individuals with a history of egg-induced anaphylaxis. We recommend administration of H1N1 vaccine to EA children without prior skin testing or graded challenge dosing.

Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel

Food allergy is an important public health problem that affects children and adults and may be increasing in prevalence. Despite the risk of severe allergic reactions and even death, there is no current treatment for food allergy: the disease can only be managed by allergen avoidance or treatment of symptoms. The diagnosis and management of food allergy also may vary from one clinical practice setting to another. Finally, because patients frequently confuse nonallergic food reactions, such as food intolerance, with food allergies, there is an unfounded belief among the public that food allergy prevalence is higher than it truly is. In response to these concerns, the National Institute of Allergy and Infectious Diseases, working with 34 professional organizations, federal agencies, and patient advocacy groups, led the development of clinical guidelines for the diagnosis and management of food allergy. These Guidelines are intended for use by a wide variety of health care professionals, including family practice physicians, clinical specialists, and nurse practitioners. The Guidelines include a consensus definition for food allergy, discuss comorbid conditions often associated with food allergy, and focus on both IgE-mediated and non-IgE-mediated reactions to food. Topics addressed include the epidemiology, natural history, diagnosis, and management of food allergy, as well as the management of severe symptoms and anaphylaxis. These Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. They also identify gaps in the current scientific knowledge to be addressed through future research.

Wheat allergy

PURPOSE OF REVIEW

This review describes the diverse clinical manifestations of IgE-mediated allergy to ingested wheat and summarizes recent advances in characterization of clinically significant allergens and diagnostic workup.

RECENT FINDINGS

Recent population-based studies have shown the prevalence of wheat allergy and sensitization more precisely than past studies among small populations and in hospital settings. Intensive research has demonstrated the diverse profile of both water/salt-soluble and insoluble allergens involved in clinical types of wheat allergies determined depending on the patient age, the sensitization route, and the protein state during the exposure. Consequently, some new allergens, including nonspecific lipid transfer protein (Tri a 14), have been identified. For diagnosis, the role of water/salt-insoluble gliadins, particularly omega-5 gliadin, a major allergen of wheat-dependent, exercise-induced anaphylaxis, was assessed as compared with the results of oral challenges. The mechanisms of eliciting anaphylactic symptoms by exercise in wheat-dependent, exercise-induced anaphylaxis were speculated upon; one is the allergenicity strengthened by activated tissue transglutaminase and another is the increased absorption of allergens through the gastrointestinal tract.

SUMMARY

Findings of the recent studies show potential for more precise diagnosis in each clinical type of wheat allergies.

Food allergy and food allergy attitudes among college students

BACKGROUND

Little information is known about food allergy among college students.

OBJECTIVE

We sought to assess food allergy trends and behavioral attitudes on a large university campus.

METHODS

An online survey was distributed by e-mail to local university undergraduate students. Symptom severity was determined based on previously published criteria for anaphylaxis.

RESULTS

A total of 513 individuals responded, with 57% reporting an allergic reaction to food. Of this group, 36.2% reported symptoms consistent with anaphylaxis, and these reactions frequently occurred while enrolled. Allergy to milk (P = .032), tree nut (P < .0001), shellfish (P < .0001), and peanut (P < .0001) was significantly associated with having symptoms of anaphylaxis. Some form of emergency medication was reportedly maintained in 47.7%, including self-injectable epinephrine (SIE; 21%), although only 6.6% reported always carrying this device. Medication maintenance was significantly lower among students who had not had a reaction while enrolled (P < .0001). Only 39.7% reported always avoiding foods to which they were allergic. Within the group that reported intentionally consuming known allergens, there were significantly lower numbers of individuals who reported carrying SIE (P < .0001) and significantly higher numbers of individuals with a history of a reaction that had not resulted in symptoms of anaphylaxis (P = .026).

CONCLUSION

Potentially life-threatening anaphylactic reactions to foods are occurring on college campuses. Only 39.7% of students with food allergy avoided a self-identified food allergen, and more than three fourths did not maintain SIE. Such behaviors might place these students at increased risk for adverse events.

A sensitive and robust competitive enzyme-linked immunosorbent assay for Brazil nut ( Bertholletia excelsa L.) detection

Undeclared Brazil nut residue in food products is of great concern because it can trigger life-threatening allergic reactions in sensitive patients. A rabbit polyclonal antibody-based competitive ELISA (IC(50) = 23.2 +/- 9 ng/mL, n = 76) with good sensitivity, detection range of 10-90 ng/mL, was developed. The ELISA could detect Brazil nut seed proteins over a pH range of 5-12. The optimal pH range for the detection assay was 7-10. Among the 66 tested foods/ingredients, only cinnamon exhibited statistically significant interference (1.36%, p = 0.05). Exposing Brazil nut seeds to processing did not adversely affect the nut seed protein detection using the assay. Brazil nut seed protein recovery from 100 mg of foods spiked with 10 and 1 microg of soluble Brazil nut proteins or 100 and 10 microg of defatted Brazil nut flour exhibited a wide recovery range, 63-315%, indicating protein-food matrix interaction.

Identification of tropomyosins as major allergens in antarctic krill and mantis shrimp and their amino acid sequence characteristics

Tropomyosin represents a major allergen of decapod crustaceans such as shrimps and crabs, and its highly conserved amino acid sequence (>90% identity) is a molecular basis of the immunoglobulin E (IgE) cross-reactivity among decapods. At present, however, little information is available about allergens in edible crustaceans other than decapods. In this study, the major allergen in two species of edible crustaceans, Antarctic krill Euphausia superba and mantis shrimp Oratosquilla oratoria that are taxonomically distinct from decapods, was demonstrated to be tropomyosin by IgE-immunoblotting using patient sera. The cross-reactivity of the tropomyosins from both species with decapod tropomyosins was also confirmed by inhibition IgE immunoblotting. Sequences of the tropomyosins from both species were determined by complementary deoxyribonucleic acid cloning. The mantis shrimp tropomyosin has high sequence identity (>90% identity) with decapod tropomyosins, especially with fast-type tropomyosins. On the other hand, the Antarctic krill tropomyosin is characterized by diverse alterations in region 13-42, the amino acid sequence of which is highly conserved for decapod tropomyosins, and hence, it shares somewhat lower sequence identity (82.4-89.8% identity) with decapod tropomyosins than the mantis shrimp tropomyosin. Quantification by enzyme-linked immunosorbent assay revealed that Antarctic krill contains tropomyosin at almost the same level as decapods, suggesting that its allergenicity is equivalent to decapods. However, mantis shrimp was assumed to be substantially not allergenic because of the extremely low content of tropomyosin.

Pathophysiology of food-induced anaphylaxis

Food-induced anaphylaxis is a steadily increasing problem in westernized countries and now represents the leading cause of anaphylaxis in the outpatient setting, particularly in children. Much of our knowledge of the pathophysiology of food-induced anaphylaxis comes from animal studies. Food anaphylaxis in humans is thought to be entirely IgE mediated. Several features appear to be unique to these reactions; factors such as exercise can lower the "threshold" for anaphylaxis in certain susceptible individuals. Different methods of thermal processing can modify the allergenicity of food proteins. Alteration of stomach pH can allow for incomplete digestion of food proteins, leading to increased absorption of intact food allergens. Low serum platelet-activating factor acetylhydrolase may predispose to fatal food-induced anaphylaxis. With a greater understanding of the pathophysiology of food-induced anaphylaxis, novel approaches not only to identify those at risk, but to treat and ultimately prevent food-induced anaphylaxis, are on the horizon.