Outcome of double-blind, placebo-controlled food challenge tests in 107 children with atopic dermatitis

Atopy patch test (APT) in the diagnosis of food allergy in children with atopic dermatitis

BACKGROUND

Atopic Dermatitis is a chronic inflammatory skin disease. Food allergens are important in the pathogenesis in 1/3 of the cases. Several mechanisms are involved in the pathogenesis of Atopic Dermatitis. Immediate reactions are identified by both measurement of specific IgE and skin prick test. Atopy Patch Test seems to be relevant in the investigation of patients with suspected delayed-type reactions.

OBJECTIVES

To evaluate the standardization of this method concerning allergen concentration, occlusion time and interpretation, and determine the specificity and sensitivity of the Atopy Patch Test according to the skin prick test and specific IgE levels in food allergy diagnosis in children with Atopic Dermatitis.

METHODS

Seventy-two children, aged 2-12 years were selected and followed at the allergy clinic of the Hospital São Zacharias. Skin prick test, specific IgE and food Atopy Patch Test (cow's milk, egg, soy and wheat) were carried out. Three groups were submitted to the Atopy Patch Test: (1) Atopic Dermatitis with or without Rhinitis and Asthma; (2) Rhinitis and or Asthma without AD; (3) Healthy individuals.

RESULTS

In group 1, 40% of the patients presented positive reactions. The longer the exposure time (48h and 72h), the higher the sensitivity. In group 2, the test was more specific than sensitive for all the extracts, with increased sensitivity the longer the time of exposure (72h). In group 3, 8.3% presented positive tests.

CONCLUSION

APT evidenced a great diagnostic value in late-phase reactions to food, with high specificity. It showed to be a specific and reliable tool in comparison with the healthy group's results.

Evaluation of cow's milk allergy in a large group of adolescent and adult patients with atopic dermatitis

Few studies concerning the occurrence of cow's milk allergy with the use of double-blind, placebo controlled food challenge test in adolescents and adult patients suffering from atopic dermatitis exist.

AIM

To evaluate the occurrence of cow's milk allergy in adolescents and adults suffering from atopic dermatitis.

METHOD

Altogether 179 persons suffering from atopic dermatitis were included in the study: 51 men and 128 women entered the study with the average age of 26.2 (s.d. 9.5 years). Complete dermatological and allergological examinations were performed.

RESULTS

The positive results in specific IgE and in skin prick tests were recorded in 12% of patients. According to the open exposure tests and double-blind, placebo controlled food challenge tests these patients are only sensitized to cow's milk without clinical symptoms of allergy. Double-blind, placebo controlled food challenge test confirmed food allergy to cow milk only in one patient (worsening of atopic dermatitis), the oral allergy syndrome was observed in another one patient, occurrence of this allergy was altogether 1.1%.

CONCLUSION

Cow's milk allergy rarely plays a role in the worsening of atopic dermatitis in adolescent and adult patients.

Skin prick test and specific serum IgE in the diagnostic evaluation of suspected cow's milk and hen's egg allergy in children: does one replace the other?

BACKGROUND

The measurement of specific serum immunoglobulin E (sIgE) and the skin prick test (SPT) are accepted tools in the diagnostic work-up of suspected food allergy. Often only one of the methods is used to determine sensitization; however, it is still under debate whether these two methods can be used interchangeably.

OBJECTIVES

To investigate the concordance of SPT and sIgE serum assays with regard to suspected food allergy.

METHODS

In 395 children referred to our clinic with suspected cow's milk allergy and in 268 children with suspected hen's egg allergy specific immunoglobulin E (IgE) was measured, a SPT and an oral food challenge performed. A weal size ≥ 3 mm and sIgE ≥ 0.35 kU/L were considered positive. The weal size of the SPT and the level of food-specific IgE were tested for correlation for each allergen.

RESULTS

Of the 395 (23%) children orally challenged with cow's milk, 92 showed no corresponding results for SPT and sIgE as either positive or negative. For hen's egg, in 27 of 268 (10%) children differing test results for SPT and sIgE in serum were obtained. Moreover, regarding the quantitative values for sIgE and SPT in children with or without clinically relevant food allergy, sIgE and SPT correlated badly.

CONCLUSIONS

The concordance between SPT and sIgE is surprisingly low for cow's milk and hen's egg on an individual basis. Therefore, the tests should not be used interchangeably. Especially in children who receive a negative test result the alternative test should also be used. Furthermore, our data indicate again that oral food challenges are still the method of choice to diagnose food allergies.

The influence of the time and temperature of heat treatment on the allergenicity of egg white proteins

PURPOSE

The present study was performed to determine the factor, either duration or the temperature of heat treatment, exerting maximal and significant influence on the composition and allergenicity of egg white (EW) proteins.

METHODS

Raw EW and 4 kinds of heated EW (fried EW, boiled EW for 10 minutes, boiled EW for 30 minutes, and baked EW for 20 minutes at 170℃) were prepared, and subsequently protein extraction was carried out. The proteins were separated by SDS-PAGE, and then immunoglobulin E (IgE) immunoblots were performed with the sera of 7 egg-allergic patients. Furthermore, the antigenic activities of ovalbumin (OVA), ovomucoid (OM), and ovotransferrin (OT) in different EW samples were measured by inhibition enzyme-linked Immuno-sorbent assay (ELISA).

RESULTS

In SDS-PAGE analysis, the intensity of the protein band at 45 kD (corresponding to OVA) decreased significantly in boiled EW (30 minutes) and baked EW, but no change was observed in the case of boiled EW for 10 minutes. In IgE immunoblots, the IgE response to 34-50 kD (OM and OVA) in boiled EW for 30 minutes decreased significantly, when compared with raw EW and other heated EWs. In inhibition ELISA, a significant decrease in the OVA antigenic activity was observed in boiled EW for 30 minutes amongst other heated EW samples. However, OM antigenic activity in all kinds of heated EW including boiled EW for 30 minutes did not reduce after heat treatment. The OT antigenic activity nearly disappeared in heated EWs except in the case of boiled EW for 10 minutes.

CONCLUSIONS

Amongst 4 kinds of heated EWs, the boiled EW for 30 minutes showed the most significant changes both in composition and reduction in allergenicity. Our results revealed that the duration of heat treatment had more influence on the composition and allergenicity of EW proteins than the temperature.

The influence of the presence of wheat flour on the antigenic activities of egg white proteins

Purpose

It is known that ovomucoid, an egg allergen, is heat resistant and remains soluble after heating. However, a recent study showed that the antigenic activity of ovomucoid could be reduced by heating when egg white (EW) was mixed with wheat flour. This study was performed to determine the influence of wheat flour on the antigenic activities of EW proteins when EW is heated, and the influence of the duration of heat treatment.

Methods

A mixture of EW and wheat flour was kneaded for 10 minutes and then baked at 180℃ for 10 minutes and 30 minutes. The EW without wheat flour was also heated at 180℃ for 10 minutes and 30 minutes. The proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and IgE immunoblotting was performed with the pooled sera of 5 egg-allergic patients. The antigenic activities of ovomucoid in different EW samples were measured by inhibition enzyme-linked immunosorbent assay (ELISA).

Results

1) SDS-PAGE: the intensity of the 37-50 kD bands (overlapped bands of ovomucoid and ovalbumin) decreased significantly in the mixture of EW and wheat flour baked for 30 minutes, compared with the mixture baked for 10 minutes, heated EW and raw EW. 2) IgE immunoblot: in the mixture of EW and wheat, a remarkable decrease of IgE reactivity to 37-50 kD was observed when baked for 30 minutes. 3) Inhibition ELISA: the antigenic activity of ovomucoid decreased significantly in the mixture of EW and wheat baked for 30 minutes, but not in the heated pure EW.

Conclusions

This study showed that the antigenic activity of ovomucoid can be reduced by baking EW with wheat flour. The decrease in ovomucoid antigenicity in the baked mixture of EW and wheat flour was dependent on the time of heat treatment, indicating that heating should be prolonged to achieve a reduction in ovomucoid antigenic activity.

Interactions between FLG mutations and allergens in atopic dermatitis

Filaggrin gene (FLG) mutations and sensitization in patients with atopic dermatitis (AD) have been well documented. However, whether an interaction exists between these mutations and specific sensitization in AD patients is still unknown. The aim of the study was to explore the interaction between FLG mutations and specific sensitization in AD patients. A total of 249 AD outpatients were recruited in the current study. Skin prick tests were conducted to assess the patient's sensitization to specific allergens. FLG mutations were analyzed through comprehensive sequencing. Logistic regression analyses were conducted to determine the interactions between FLG mutations and sensitization present. The mean age of the patients was 3.5 years, and the mean age of onset of AD was 9.6 months. The mean SCORAD of the patients was 25.8. Fourteen types of mutations were identified in the FLG of 64 patients. A total of 24 (9.6 %) and 29 (11.6 %) cases were mutated with 3321delA and K4671X, respectively. Sensitization to at least one type of allergen was detected in 118 patients (47.4 %). Logistic regression analyses showed that FLG mutations presented an interaction with sensitization to peanut and did not interact with the other detected allergens among AD patients. Sensitization to peanut allergens would have an interaction with the mutation of K4671X and the combined mutations in FLG in patients with atopic dermatitis. However, sensitization to the other common allergens might not interact with FLG mutations in the development of atopic dermatitis.

Food allergy testing in infantile eczema: a clinical approach and algorithm

The complex relationship between food allergy and infantile eczema has prompted divergent approaches to investigating potential food triggers in eczematous patients. It is well recognised that a significant proportion of infants with eczema have immunoglobulin E-mediated food allergy, reported to range between 20-80%. Determining whether certain foods trigger an eczematous flare in individual infants with eczema is difficult. For all infants with eczema, good skin care is the mainstay of treatment but identifying and avoiding triggers (both allergic and non-allergic) is important in some infants. Given this, we have a developed an algorithm that can be used by dermatologists in the investigation and management of food allergies in infantile eczema. Issues such as patient selection, investigation and elimination diets are addressed, with reference to relevant evidence in the literature. Our aim is to provide dermatologists with a framework to manage food allergies in infantile eczema, allowing the problem to be addressed with confidence.

Dissecting the causes of atopic dermatitis in children: less foods, more mites

Atopic dermatitis (AD) is a common, chronic or chronically relapsing, multifactorial skin disease that mainly occurs in children but affects also adults. AD usually begins early in life and often concerns people with a personal or family history of asthma and allergic rhinitis. AD is characterized by eczematous changes in the epidermis and originates from a late, T-cell mediated reaction associated to the formation and production of memory T-cell of TH2 type, occurrence of homing receptor at skin level and cutaneous lymphocyte-associated (CLA) antigens. Extrinsic or allergic AD, but not intrinsic AD, shows high total serum IgE levels and the presence of specific IgE for environmental and food allergens. A pivotal role in the pathogenesis of AD is played by filaggrin, a protein contained in the granular layer of the epidermis regulating the aggregation of keratin filaments. Mutation in the filaggrin gene causes decreased barrier function of the corny layers of the epidermis. This favours the enter through the skin of environmental allergens, especially the house dust mite, that further facilitates such entering by the proteolytic activity of its major allergen Der p 1. In fact, recent advances suggest that the dust mite, more than foods, is the major cause of allergic AD. As far as the causal diagnosis of AD is concerned, there is notable evidence supporting the capacity of the atopy patch test (APT) to reproduce the pathophysiologic events of AD. This makes APT a valuable diagnostic tool for AD.

Management of itch in atopic dermatitis

Atopic dermatitis is a common, pruritic, inflammatory skin disorder. Chronic, localized, or even generalized pruritus is the diagnostic hallmark of atopic dermatitis, and its management remains a challenge for physicians. The threshold for itch and alloknesis is markedly reduced in these patients, and infections can promote exacerbation and thereby increase the itch. Modern management consists of anti-inflammatory, occasionally antiseptic, as well as antipruritic therapies to address the epidermal barrier as well as immunomodulation or infection. Mild forms of atopic dermatitis may be controlled with topical therapies, but moderate-to-severe forms often require a combination of systemic treatments consisting of antipruritic and immunosuppressive drugs, phototherapy, and topical compounds. In addition, patient education and a therapeutic regimen to help the patient cope with the itch and eczema are important adjuvant strategies for optimized long-term management. This review highlights various topical, systemic, and complementary and alternative therapies, as well as provide a therapeutic ladder for optimized long-term control of itch in atopic dermatitis.

Egg allergy in patients over 14 years old suffering from atopic eczema

OBJECTIVE

The aim of this study was to evaluate the occurrence of egg allergy in patients over 14 years old suffering from atopic eczema and especially to evaluate if egg allergy can deteriorate the course of atopic eczema in this group of patients.

MATERIALS AND METHODS

Altogether 179 patients suffering from atopic eczema were included in the study: 51 men and 128 women, with an average age of 26.2 years (SD 9.5 years), with median SCORAD 31.6 (SD 13.3) points. A complete allergological and dermatological examination was performed on all patients, including diagnostic work-up of food allergy to egg [skin prick tests, atopy patch tests (APTs), measurement of specific IgE level to egg yolks or whites]. Open exposure test (OET) with egg was performed in patients with positive results in some of these diagnostic methods. Food allergy to egg was determined according to positive results in the OET or according to sufficient anamnestical data about the severe allergic reaction after the ingestion of an egg.

RESULTS

An allergy to egg was confirmed in 11 patients out of 179 (6%). Of these patients, only six (3.3%) had a clear improvement in the SCORAD after the elimination of egg. Other triggering factors may cause exacerbation of the atopic eczema in the patients enrolled in the study. Twenty-eight percent of patients were only sensitized to egg without clinical symptoms. ATPs were a useful tool in the diagnosis of food allergy to egg in patients without IgE reactivity.

CONCLUSION

Egg allergy may play an important role in the worsening of atopic eczema acting as a triggering-exacerbating factor in a minority of patients. The diagnostic work-up may comprise the challenge tests to confirm the food allergy to egg.

Molecular diagnosis of egg allergy

PURPOSE OF REVIEW

Allergy to hen's egg is common in infancy and childhood. Oral food challenges are often required to diagnose egg allergy, because of the limitation in the diagnostic accuracy of skin test and specific IgE to egg white. New molecular diagnostic technologies have been recently introduced into allergological research. In this article, we will review the recent literature regarding the potential value of these tests for the clinical management of egg-allergic patients.

RECENT FINDINGS

Component-resolved diagnosis that can be combined with the microarray technology is promising as measurement of specific IgE antibodies to individual egg white components has been shown to predict different clinical patterns of egg allergy. Specific IgE to ovomucoid has been identified as a risk factor for persistent allergy and could indicate reactivity to heated egg. Ovomucoid and ovalbumin IgE and IgG4-binding epitope profiling could also help distinguish different clinical phenotypes of egg allergy. Particularly, egg-allergic patients with IgE antibodies reacting against sequential epitopes tend to have more persistent allergy.

SUMMARY

Using recombinant allergens, IgE-binding epitopes, and microarrays, molecular-based technologies show promising results. However, none of these tests is ready to be used in clinical practice and oral food challenge remains the standard for the diagnosis of egg allergy.

Milk and soy allergy

Cow's milk allergy (CMA) affects 2% to 3% of young children and presents with a wide range of IgE and non-IgE-mediated clinical syndromes, which have a significant economic and lifestyle effect. It is logical that a review of CMA would be linked to a review of soy allergy because soy formula is often an alternative source of nutrition for infants who do not tolerate cow's milk. This review examines the epidemiology, pathogenesis, clinical features, natural history, and diagnosis of cow's milk and soy allergy. Cross-reactivity and management of milk allergy are also discussed.

Current understanding of egg allergy

Egg is one of the most important allergens in childhood feeding, and egg allergy can pose quality-of-life concerns. A clear clinical history and the detection of egg white-specific immunoglobulin E (IgE) will confirm the diagnosis of IgE-mediated reactions. Non-IgE-mediated symptoms, such as those of eosinophilic diseases of the gut, might also be observed. Egg avoidance and education regarding the treatment of allergic reactions are the cornerstones of management of egg allergy. This article discusses epidemiology, risk factors, diagnosis, treatment, and natural history of egg allergy.

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.

Allergic triggers in atopic dermatitis

Food or environmental allergens play a significant pathogenic role in a subgroup of patients with atopic dermatitis (AD) and can trigger eczema flares. This review focuses on when and which diagnostic and allergen-avoidance measures are beneficial. Diagnosis of allergic triggers may be aided by skin-prick tests measuring serum-specific IgE and/or atopy patch tests (APT) based on the patient's history, and when necessary, oral food challenges (OFC). In a subset of patients, therapeutic measures, such as elimination of the incriminated allergen(s), can lead to marked improvement of AD; this is especially true for food allergens, but can also apply to inhalant allergens.

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.

Diagnostic Usefulness of the Serum-Specific IgE, the Skin Prick Test and the Atopy Patch Test Compared with That of the Oral Food Challenge Test

BACKGROUND

Atopic dermatitis (AD) is frequently associated with food allergies. In addition to the skin prick test (SPT) and serum-specific IgE, the atopy patch test (APT) has been introduced as a diagnostic procedure for food allergies.

OBJECTIVE

Our aim was to evaluate the diagnostic value of the APT, the SPT and the serum-specific IgE levels compared with that of oral food challenge test against milk and egg in AD patients.

METHODS

We conducted the SPT and APT, and determined the serum-specific IgE levels against milk and egg antigens for 101 patients. Oral food challenge tests were conducted for 86 out of 101 AD patients. The sensitivity, specificity and positive and negative predictable values were calculated for all the tests.

RESULTS

Twenty-five patients were positive to oral food challenges. The sensitivity of the APT for milk was 66.7%, while the figures for the SPT and the serum-specific IgE were 35.5% and 14.2%. The sensitivity of the APT for egg was 50%, while that for the SPT and serum-specific IgE were 21.4% and 6.7%.

CONCLUSION

We were able to conclude that the APT test seems to be a valuable additional tool for the diagnostic method of food allergies in AD.

Food allergy and atopic dermatitis: separating fact from fiction

The relationship between food and atopic dermatitis (AD) is complex. A common misunderstanding is that food allergies have a significant impact on the course of AD, resulting in uncontrolled attempts at elimination diets and undertreatment of the skin itself. Studies have shown that only a small portion of cutaneous reactions to food in the form of late, eczematous eruptions will directly exacerbate AD in young infants who have moderate-to-severe AD. Given the low frequency of food allergies actually inducing flares of AD, the focus should return to appropriate skin therapy, and identification of true food allergies should be reserved for recalcitrant AD in children in whom the suspicion for food allergy is high. A different relationship between food and AD involves delaying or preventing AD in high-risk infants by exclusive breastfeeding during the first 4 months of life. Finally, the skin barrier defect in AD may allow for easier and earlier sensitization of food and airborne allergens; therefore, exposure of food proteins on AD skin may act as a risk factor for development of food allergies.

Childhood Food Allergy: A Singaporean Perspective

Food allergy is defined as reaction to a food which has an immunologic mechanism. Its prevalence is increasing in children globally and is therefore of increasing clinical importance. A useful clinical approach is to distinguish food allergic reactions by the timing of clinical reaction in relation to food exposure and classified as immediate (generally IgE-mediated) and delayed (generally non-IgE-mediated), with the exception of eczema and eosinophilic gastrointestinal disease, which, when associated with food allergy may be associated with either mechanism. This review is aimed at providing the clinician with a Singaporean perspective on the clinical approach and management of these disorders. Key words: Asia, Children, Food allergy

State of the art and new horizons in the diagnosis and management of egg allergy

Egg allergy is one of the most frequent food allergies in children below the age of three. Common symptoms of egg allergy involve frequently the skin as well as the gut and in more severe cases result in anaphylaxis. Non-IgE-mediated symptoms such as in eosinophilic diseases of the gut or egg-induced enterocolitis might also be observed. Sensitization to egg white proteins can be found in young children in absence of clinical symptoms. The diagnosis of egg allergy is based on the history, IgE tests as well as standardized food challenges. Ovomucoid is the major allergen of egg, and recent advances in technology have improved the diagnosis and follow-up of patients with egg allergy by using single allergens or allergens with modified allergenic properties. Today, the management of egg allergy is strict avoidance. However, oral tolerance induction protocols, in particular with egg proteins with reduced allergenic properties, are promising tools for inducing an increased level of tolerance in specific patients.

Factors influencing the incidence and prevalence of food allergy

Food allergy is an increasing problem in Europe and elsewhere and severe reactions to food are also becoming more common. As food allergy is usually associated with other forms of allergic sensitisation it is likely that many risk factors are common to all forms of allergy. However the potential severity of the disease and the specific public heath measures required for food allergy make it important to identify the specific risk factors for this condition. Food allergy is unusual in that it often manifests itself very early in life and commonly remits with the development of tolerance. Hypotheses that explain the distribution of food allergy include specific genetic polymorphisms, the nature of the allergens involved and the unique exposure to large quantities of allergen through the gut. Progress has been made in developing more specific and testable hypotheses but the evidence for any of these is still only preliminary. Further collaborative research is required to develop an appropriate public health response to this growing problem.

Egg allergy in childhood: an update

PURPOSE OF REVIEW

Allergy to hen's egg is common in infancy and childhood. The management of egg allergy involves dietary avoidance of egg-containing foods, implementation of anaphylaxis precautions and ongoing monitoring for tolerance development. In this article, we review the recent literature regarding the immunology, clinical presentation, diagnosis, management and natural history of egg allergy.

RECENT FINDINGS

Retrospective studies suggest that most egg-allergic children will become tolerant over time. Regular ingestion of small quantities of cooked egg in baked products is often well tolerated and may hasten tolerance development. Influenza vaccination of egg-allergic patients remains controversial, and immunization of patients with previous significant reactions or anaphylaxis to egg is currently not recommended. In recent years, there has been increasing success in clinical trials of specific oral tolerance induction to egg, but concerns regarding the safety and long-term efficacy still preclude the use of oral immunotherapy in clinical practice.

SUMMARY

Egg allergy generally has a good prognosis. Despite recent advances in oral immunotherapy trials, the treatment of egg allergy currently relies on avoidance of egg-containing foods until tolerance has developed. It remains unclear whether the ongoing low-dose exposure to egg proteins in cooked foods improves the natural history of egg allergy.

Approach to suspected food allergy in atopic dermatitis. Guideline of the Task Force on Food Allergy of the German Society of Allergology and Clinical Immunology (DGAKI) and the Medical Association of German Allergologists (ADA) and the German Society of Pediatric Allergology (GPA)

The following guideline of the "Arbeitsgruppe Nahrungsmittelallergie der DGAKI" (Task Force on Food Allergy of the German Society of Allergology and Clinical Immunology) and the ADA ("Arzteverband Deutscher Allergologen", Medical Association of German Allergologists) and the GPA (German Society of Pediatric Allergology) summarizes the approach to be taken when food allergy is suspected in patients with atopic dermatitis (neurodermatitis, atopic eczema). The problem is clinically relevant because many patients assume that allergic reactions against foods are responsible for triggering or worsening their eczema. It is important to identify those patients who will benefit from an elimination diet but also to avoid unnecessary diets. Elimination diets (especially in early childhood) are associated with the risk of malnutrition and additional emotional stress for the patients. The gold standard for the diagnosis of food-dependent reactions is to perform placebo-controlled, double-blind oral food challenges because specific IgE, prick tests and history often do not correlate with clinical reactivity. This is particularly true in the case of delayed eczematous skin reactions. Diagnostic elimination diets should be used before an oral provocation test. If multiple sensitizations against foods are discovered in a patient, an oligoallergenic diet and a subsequent stepwise supplementation of the nutrition should be performed. If a specific food is suspected of triggering food allergy, oral provocation should be performed after a diagnostic elimination diet. As eczema-tous skin reactions may develop slowly (i. e. within one or two day), the skin be inspected the day after the provocation test and that a repetitive test be performed if the patient has not reacted to a given food on the first day of oral provocation. The guideline discusses various clinical situations for patients with atopic dermatitis to facilitate differentiated diagnostic procedures.

Patch test in the diagnosis of food allergy

Double-blind, placebo-controlled food challenges (DBPCFC) are the gold standard method for diagnosing food allergies. However, due to the difficulty of their performance on routine clinic, there is a need for laboratory tools in order to minimise the frequency of DBPCFC. Atopy patch test (APT) represents a promising manner of diagnosing delayed-type allergic reactions. The APT may identify patients with food allergies with negative specific IgE. However, the clinical relevance of positive APT reactions is still to be proven by standardised outcome definitions.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Does hapten exposure predispose to atopic disease? The hapten-atopy hypothesis

Contact allergy data indicates that atopics have heightened oral tolerance to haptens (chemical allergens). We speculate here, that artificially increased oral exposure to chemicals compete with dietary proteins for the development of oral tolerance, predisposing to the acquisition of food protein allergy and representing one driver for the increasing prevalence of protein allergy and/or atopy. Hapten exposure via other surfaces such as the skin and airways might also be important in promoting atopic disease. Consistent with this hypothesis it is notable that over 40 years, with the huge increase in atopic disease, there has also been an increase in dietary hapten exposure through processed food, formula milk and oral antibiotic and drug use.

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.

New visions for atopic eczema: an iPAC summary and future trends

Atopic eczema (AE) is a chronic inflammatory skin disease characterized by pruritus, dry skin and an ongoing course of exacerbations and remissions. AE is a common disorder in children with a worldwide cumulative prevalence of 15-20% in this age group. AE has a strong familial predisposition. While AE is a complex disease with multiple gene involvement, recent interest has focused on genes involved in skin barrier/epidermal differentiation and in immune response/host defense. Recent developments and future directions on pathogenesis, diagnosis, natural course and prognosis are discussed.

Safety of open food challenges in the office setting

BACKGROUND

Open food challenges are a practical alternative to double-blind, placebo-controlled food challenges in confirming clinical sensitivity or tolerance to a food, and the risks associated with open challenges are unknown.

OBJECTIVE

To examine the safety of open food challenges administered in an office setting.

METHODS

A retrospective medical record review of open food challenges, administered in a university-based pediatric allergy-immunology clinic during a 3-year period, was performed.

RESULTS

A total of 109 patients (69% male) underwent 150 open food challenges, most of which were to milk (n = 39), peanut (n = 37), and egg (n = 29). There were 40 positive challenges (27% of all challenges) in 33 patients. Reactions were mild to moderate in 92% of positive challenges. Cutaneous reactions occurred in 68% of positive challenges, followed by gastrointestinal tract reactions (45%) and upper respiratory tract reactions (38%), excluding laryngeal symptoms. No patient had cardiovascular involvement. Food specific IgE values did not correlate with reaction severity. Interventions included observation or antihistamine only in 92% of positive challenges. No patient received epinephrine or required hospitalization. For negative challenges to milk, peanut, and egg, median prechallenge food specific IgE approached previously published negative predictive values for these foods. Negative challenges in patients allowed the introduction of 19 different foods into the diet of 88 patients.

CONCLUSION

Open food challenges are a safe procedure in the office setting for patients selected based on history and food specific IgE approaching negative predictive values.

Soy allergy in perspective

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Eosinophils and allergic diseases of the gastrointestinal tract

The association between increased tissue eosinophilia and allergic disease is particularly striking in the case of the gastrointestinal tract. About 80% of individuals with eosinophilic gastrointestinal disorders (EGIDs) are atopic, while half of the patients with gastrointestinal allergy show tissue eosinophilia. The function of eosinophils in gastrointestinal allergic disorders is unclear; however, a proinflammatory action is most likely. Cytokines (interleukins 5 and 3, granulocyte-monocyte colony-stimulating factor) and chemokines (eotaxin, RANTES, etc.) released by Th2 lymphocytes, mast cells and other tissue cells have been identified as major regulators of eosinophil chemotaxis and activation, but a convincing mechanism by which eosinophils are activated in an allergen-dependent manner is still lacking. The diagnostic approach comprises both histological and laboratory methods to assess eosinophilia and eosinophil activation, as well as tools to assess the allergic disease while excluding other gastrointestinal diseases such as food intolerances, infections and tumours. Treatment of allergic EGIDs includes elimination or elemental diets and drug therapy using classical anti-allergic agents such as topical corticosteroids and new approaches such as LTD4 receptor antagonists or antibodies against IL-5 or eotaxin.

Food allergy in children suffering from atopic eczema

Whilst the association between eczema and food allergy is well established, the role of dietary manipulation in children with eczema remains controversial. These case histories highlight the differing outcomes that dietary manipulation may have in an infant with early onset, severe eczema and an older child with milder eczema. Management strategies and the evidence to support them are presented, followed by a review of clinical recommendations.

Guidelines for the use of infant formulas to treat cows milk protein allergy: an Australian consensus panel opinion

Three types of infant formula (soy, extensively hydrolysed and amino acid) may be appropriate for treating cows milk protein allergy. Selection of a formula depends on the allergy syndrome to be treated. Extensively hydrolysed formula is recommended as first choice for infants under 6 months of age for treating immediate cows milk allergy (non-anaphylactic), food protein-induced enterocolitis syndrome, atopic eczema, gastrointestinal symptoms and food protein-induced proctocolitis. Soy formula is recommended as first choice for infants over 6 months of age with immediate food reactions, and for those with gastrointestinal symptoms or atopic dermatitis in the absence of failure to thrive. Amino acid formula is recommended as first choice in anaphylaxis and eosinophilic oesophagitis. If treatment with the initial formula is not successful, use of an alternative formula is recommended.

Nutritional problems related to food allergy in childhood

Food allergy is becoming an increasing problem worldwide with an estimated 6-8% of children affected at some point in their childhood. The perceived prevalence of food allergy is even higher with an estimated 20% of children adhering to some form of elimination diet. Against this background, accurate diagnosis is essential to prevent the imposition of unnecessarily restrictive diets on young children. Raising clinical awareness amongst health professionals as to the clinical characteristics, epidemiology, investigation, and management of food allergic disorders is key to tackling this growing problem. In this article, three separate cases of children with poor nutrition and secondary morbidity are presented, highlighting the varying scenarios in which these conditions can be encountered. In the first child, the features clinically displayed were hypocalcemic seizures and rickets due to prolonged breast feeding, poor weaning, and inadequate dietary supplementation. The second case reveals the dangers of complementary diagnostic allergy testing leading to poor nutrition as a consequence of an unsupervised elimination diet. The last report describes a child with multiple food allergies, failure to thrive, and protein losing enteropathy to highlight the diversity of nutritional problems faced by allergists and to underline the importance of specialist dietetic input in the management of a child with food allergy.

Differential diagnosis of food-induced symptoms

The symptoms of patients presenting with non-allergic food-related reactions may partly mimic allergic responses. Therefore, correct delineation of food allergies is often difficult and various differential diagnoses have to be considered. We describe three cases of differential diagnoses to food-induced symptoms: A 14-month-old with lactose intolerance, an 8-month-old with severe diet-induced malnutrition and subsequent development of kwashiorkor and a 12-yr-old with chronic urticaria due to colouring agents. These cases represent common symptom constellations involving food-induced reactions. A proper and correct diagnosis of food-related symptoms is particularly important for children - not only in order to find the appropriate diet but also to avoid unnecessary exclusion diets, which may lead to severe impairments in growth and development.

Guidelines for diagnosis and management of pediatric food allergy in Japan

In Japan, the prevalence of food allergy has been increasing and a variety of problems have emerged regarding what should be considered a food allergy. A treatment regimen consists of avoiding the offending food (elimination diet therapy) and receiving nourishment from alternative foods (substitutional diet therapy). There is a growing concern that confusion has resulted from the lack of a consensus on the procedures for diagnosing and treating food allergies. The Food Allergy Committee of the Japanese Society of Pediatric Allergy and Clinical Immunology established the "Guidelines for Diagnosis and Management of Pediatric Food Allergy." Definition, classification, pathophysiology, clinical disorders and management of food allergy are discussed and determined.

Egg allergy

Egg allergy is one of the most common food allergies in infants and young children. The great majority is not life-threatening and management involves exclusion of egg from the diet and regular review with the expectation that the majority of children will outgrow the allergy by school age. Judgment is required as to when the dietary elimination of egg is no longer required. This decision may be helped by demonstrating loss of sensitivity by skin prick or specific IgE testing and in some cases a supervised food challenge. Particular issues in management arise with more severe, potentially life-threatening reactions, with immunization with vaccines prepared in eggs, with the diagnosis of egg hypersensitivity as a cause of delayed exacerbations of eczema which can be non-IgE mediated, and in deciding whether a child can be allowed to ingest small amounts of cooked egg through egg-containing foods while continuing to avoid raw egg or larger amounts of whole egg. Cases which illustrate these issues are presented.