Jerome Glaser lectureship. The role of food allergy and mediator release in atopic dermatitis

Atopic Dermatitis and Food Allergy: Best Practices and Knowledge Gaps-A Work Group Report from the AAAAI Allergic Skin Diseases Committee and Leadership Institute Project

Allergists are often asked to evaluate children with atopic dermatitis (AD) for allergen triggers to disease. Testing, particularly for food triggers, often leads to elimination diets in an effort to improve AD control. However, the dual exposure hypothesis suggests that oral tolerance to food antigens is promoted through high-dose oral exposure, where sensitization occurs through lower dose cutaneous exposure. This suggests that strict elimination diets may pose some risks in children with AD. In addition, emerging evidence suggests an important role of skin inflammation in further allergic disease and the importance of dietary exposure to maintain oral tolerance. This work group report reviews current guidelines-based management for children with moderate-to-severe AD, the evidence for current recommendations for the evaluation and management of these children, provides a nuanced examination of these studies, and addresses current knowledge gaps in the care of these children.

Are avoidance diets still warranted in children with atopic dermatitis?

Nearly 40% of children with moderate-to-severe atopic dermatitis (AD) have IgE-mediated food allergy (FA). This clinical observation has been extensively documented by experimental data linking skin inflammation in AD to FA, as well as by food challenges reproducing symptoms and avoidance diets improving AD. Although food avoidance may improve AD, avoidance diets do not cure AD, may even have detrimental effects such as progression to immediate-type allergy including anaphylactic reactions, and may significantly reduce the quality of life of the patient and the family. AD care should focus upon optimal medical management, rather than dietary elimination. Food allergy testing is primarily indicated when immediate-type allergic reactions are a concern. In recalcitrant AD, if food is being considered a possible chronic trigger, a limited panel of foods may be tested. An avoidance diet is only indicated in patients clearly identified as food allergic by an appropriate diagnostic food challenge, and after adequately informing the family of the limited benefits, and possible harms of an elimination diet.

A comprehensive review of sensitization and allergy to soy-based products

Since 1943, cases of sensitization or allergy to soy-based formulas (SBFs) have been described without any consensus on their real prevalence. We identified the adjusted prevalence of IgE-mediated soy allergies in children and performed a secondary analysis of the impact of age (less than and more than 6 months). We performed a systematic review with meta-analysis of studies published from 1909 to 2013 in PubMed, Embase, LILACS, ARTEMISA, Cochrane, Bandolier, DARE and the GRADE system for grading quality. Results are presented in tables and graphs using a forest plot. The 40 studies identified established weighted prevalence of soy allergies of 0 to 0.5 % (0.27) for the general population, 0.4 to 3.1 % (1.9) for the referred population, and 0 to 12.9 % (2.7) for allergic children. Prevalence of sensitization after the use of SBFs is 8.7 and 8.8 %, depending on the method used. The prevalence of allergies to soy and IgE sensitization to the use of SBFs is less than reported. Not enough evidence exists to show a higher risk of allergy in infants younger than 6 months. The concern about soy allergy is no reason to postpone the use of SBFs in IgE-mediated cow's milk allergy infants until the age of 6 months.

Screening for hen's egg and chicken meat specific IgE antibodies in Saudi patients with allergic disorders

BACKGROUND

Allergy to hen's egg and meat contributes significantly to the manifestations of food allergy all over the world.

OBJECTIVES

This study was performed to assess the presence of hen's egg and meat specific IgE antibodies among patients investigated for various allergic disorders.

METHODS

This is a retrospective study performed at King Khalid University Hosptial, Riyadh. Data from 421 patients with allergic disorders screened for food specific IgE antibodies between January 2009 and March 2011 were analyzed. Sixty (14.25%) patients including 42 males and 18 females with the mean age (sd) of 7.5 (7.4) years were found to have specific IgE antibodies against hen's egg and chicken meat. There were 56 (93.3%) children and 4 (6.7%) adult patients. Specific IgE antibodies were measured by radioallergosorbent test (RAST) using Pharmacia ImmunoCAP 250 analyzer.

RESULTS

Atopic dermatitis was the most common (55%) clinical condition. Out of the total 60 patients harboring hen's egg and chicken meat specific IgE antibodies high levels of egg white, yolk and chicken meat specific IgEs were detected in 58 (96.6%), 37 (61.6%) and 6 (10%) patients respectively. Both the egg white and yolk antibodies coexisted in 35 (58.3%) patients.

CONCLUSION

Sensitization against hen's egg was higher compared to the chicken meat. Egg white sensitization higher than the egg yolk particularly in Saudi children with food related allergic disorders.

Food hypersensitivity in patients over 14 years of age suffering from atopic dermatitis

BACKGROUND

Patients suffering from atopic dermatitis often describe food hypersensitivity. Rising prevalence of food hypersensitivity and severe allergic reactions to foods have been reported, but the data are scarce.

AIMS AND OBJECTIVES

Evaluation of food hypersensitivity reactions in patients suffering from atopic dermatitis.

MATERIALS AND METHODS

The dermatological examination was performed in patients of age 14 years and above and the detailed history was taken concerning the food hypersensitivity.

RESULTS

A total of 228 patients were examined-72 men, 156 women, average age 26.2 (SD 9.5) years. The food hypersensitivity reactions were recorded in 196 patients from 228 (86%), no reactions were recorded in 32 patients (24%). Foods with the most often recorded reactions are: Nuts (in 35% of patients), tomatoes (in 20%), and kiwi (in 17, 5%), apples and spices (in 16%), tangerines and oranges (in 15%), capsicum (in 13%), fishes (in 12%), celery (in 9%), and chocolate (in 7%).

CONCLUSION

Food hypersensitivity reactions are recorded in 86% of patients suffering from atopic dermatitis. Nuts, tomatoes, and pollen-associated foods play a role in the majority of patients suffering from atopic dermatitis.

Safety of soya-based infant formulas in children

Soya-based infant formulas (SIF) containing soya flour were introduced almost 100 years ago. Modern soya formulas are used in allergy/intolerance to cows' milk-based formulas (CMF), post-infectious diarrhoea, lactose intolerance and galactosaemia, as a vegan human milk (HM) substitute, etc. The safety of SIF is still debated. In the present study, we reviewed the safety of SIF in relation to anthropometric growth, bone health (bone mineral content), immunity, cognition, and reproductive and endocrine functions. The present review includes cross-sectional, case-control, cohort studies or clinical trials that were carried out in children fed SIF compared with those fed other types of infant formulas and that measured safety. The databases that were searched included PubMed (1909 to July 2013), Embase (1988 to May 2013), LILACS (1990 to May 2011), ARTEMISA (13th edition, December 2012), Cochrane controlled trials register, Bandolier and DARE using the Cochrane methodology. Wherever possible, a meta-analysis was carried out. We found that the anthropometric patterns of children fed SIF were similar to those of children fed CMF or HM. Despite the high levels of phytates and aluminium in SIF, Hb, serum protein, Zn and Ca concentrations and bone mineral content were found to be similar to those of children fed CMF or HM. We also found the levels of genistein and daidzein to be higher in children fed SIF; however, we did not find strong evidence of a negative effect on reproductive and endocrine functions. Immune measurements and neurocognitive parameters were similar in all the feeding groups. In conclusion, modern SIF are evidence-based safety options to feed children requiring them. The patterns of growth, bone health and metabolic, reproductive, endocrine, immune and neurological functions are similar to those observed in children fed CMF or HM.

Diagnostic accuracy of atopy patch tests for food allergy in children with atopic dermatitis aged less than two years

BACKGROUND

Atopy patch tests (APT) have been introduced as a valuable tool for the diagnosis of food allergy. However, interpretation of the readout of APT requires further clarification.

OBJECTIVE

To investigate the accuracy of APT in identifying atopic sensitisation to hen's eggs (HE), cow's milk (CM), soybean and wheat in Chinese children with atopic dermatitis (AD) aged less than two years and to evaluate skin signs of APT for accurate diagnosis of food allergy.

METHODS

APT was performed and food allergy confirmed by open oral food challenges with HE, CM, soybean and wheat in 150 Chinese AD children aged less than two years. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, positive (LR+) and negative likelihood ratio (LR-) of APT were calculated.

RESULTS

Erythema and infiltration were not sufficiently indicative of a positive APT. The PPV increased with the appearance of indurations and the number of papules. The true positive APT rate increased from scores of + to +++. The PPV and specificity were 100% while APT scores of +++ were obtained with HE, CM and wheat. The sensitivity of APT with HE, CM, soybean and wheat allergy ranged from 59.6% to 90.5%, while the specificity ranged from 82.1% to 92.4%.

CONCLUSION

The APT is a suitable method for the diagnosis of AD in Chinese children aged less than two years with food allergies. Erythema and infiltration are not sufficient indicators of APT positivity. The PPV increases with indurations and the number of papules.

Sensitization to Malassezia in children with atopic dermatitis combined with food allergy

BACKGROUND

The yeast Malassezia belongs to our normal cutaneous flora, but is capable of sensitizing individuals with atopic dermatitis (AD). Our objective was to investigate the prevalence of sensitization to Malassezia with a 10-yr follow-up among children suffering from AD combined with food allergy (FA) in relation to the extent of AD in infancy.

METHODS

One hundred and eighty seven infants diagnosed with AD and milk/wheat allergy before 1 yr of age were included in the study. The area of AD was estimated from patient records of the first visit and measured with SCORAD at the 10-yr follow-up. Specific IgE against Malassezia was determined with ImmunoCAP™ at 11 yr of age.

RESULTS

In infancy, 24 children (13%) were allergic to milk, 71 (38%) to wheat, and 92 (49%) to both milk and wheat, and 94 (50%) children had mild, 57 (30%) moderate and 36 (19%) severe AD. At the 10-yr follow-up visit, 19 (10%) of the children had ongoing milk and/or wheat allergy; 147 children (79%) had mild AD and 30 (16%) had SCORAD index of 0. Specific IgE against Malassezia mix was positive (≥0.35 kU/l) in 27% and specific IgE against M. sympodialis in 20% of the 187 children. The area of AD in infancy was associated with a greater risk of having allergen-specific IgE to Malassezia at the 10-yr follow-up. The risk ratio for FA was 3.11 (95% CI: 2.05-4.72; p < 0.001) if specific IgE to Malassezia was positive.

CONCLUSIONS

Infants with severe AD and FA seem to have a greater risk of becoming sensitized to Malassezia during a 10-yr follow-up.

Management of difficult-to-treat atopic dermatitis

Atopic dermatitis is a complex disorder caused by the interplay between multiple genetic and environmental factors. Particularly in patients with severe disease, the effect is not just an itchy rash but also the secondary effects on the psychological well-being of the patient and their carers, particularly disturbed sleep. The aim of this review is to provide health care professionals with a holistic approach to the management of difficult-to-treat atopic dermatitis, defined as atopic dermatitis seemingly unresponsive to simple moisturizers and mild potency (classes VI and VII) topical corticosteroids. The critical importance of education and advice is emphasized, as is the seminal role of secondary bacterial infection and polyclonal T-cell activation in causing acute flares in patients with severe, generalized disease. In atypical cases or those that do not respond to treatment, alternative diagnoses should be considered.

Use of soy protein-based formulas in infant feeding

Soy protein-based formulas have been available for almost 100 years. Since the first use of soy formula as a milk substitute for an infant unable to tolerate a cow milk protein-based formula, the formulation has changed to the current soy protein isolate. Despite very limited indications for its use, soy protein-based formulas in the United States may account for nearly 25% of the formula market. This report reviews the limited indications and contraindications of soy formulas. It will also review the potential harmful effects of soy protein-based formulas and the phytoestrogens contained in these formulas.

Food Allergy in Dogs and Cats: A Review

Food allergy (FA) is defined as "all immune-mediated reactions following food intake," in contrast with food intolerance (FI), which is non-immune-mediated. Impairment of the mucosal barrier and loss of oral tolerance are risk factors for the development of FA. Type I, III, and IV hypersensitivity reactions are the most likely immunologic mechanisms. Food allergens are (glyco-)proteins with a molecular weight from 10-70 kDa and are resistant to treatment with heat, acid, and proteases. The exact prevalence of FA in dogs and cats remains unknown. There is no breed, sex or age predilection, although some breeds are commonly affected. Before the onset of clinical signs, the animals have been fed the offending food components for at least two years, although some animals are less than a year old. FA is a non-seasonal disease with skin and/or gastrointestinal disorders. Pruritus is the main complaint and is mostly corticoid-resistant. In 20-30% of the cases, dogs and cats have concurrent allergic diseases (atopy/flea-allergic dermatitis). A reliable diagnosis can only be made with dietary elimination-challenge trials. Provocation testing is necessary for the identification of the causative food component(s). Therapy of FA consists of avoiding the offending food component(s).

Prevalence of atopic dermatitis and serum IgE values in nursery school children in Ishigaki Island, Okinawa, Japan

There have been many studies of the prevalence of atopic dermatitis (AD), but few population-based epidemiologic studies measure the prevalence in Japan among children aged 5 years and younger. We examined the prevalence of AD, serum total IgE levels and specific IgE antibodies to 10 common allergens among children in Ishigaki Island, Okinawa, Japan in 2001. We also obtained information on the predictability of the U.K. Working Party diagnostic questionnaire criteria for AD in this population. Five hundred and sixty five children aged 5 years and younger were enrolled in this study with informed consent from their parents. The questionnaire of the U.K. Working Party diagnostic criteria for AD was translated into Japanese, and the parents completed the questionnaire sheet. Physical examination and blood sampling were done for all children. Thirty-nine out of the 565 (6.9%) children were diagnosed with AD by physical examination. The total and specific IgE levels were significantly higher in the children with AD than in those without AD. High levels of total IgE were found in 33.3% of the children with AD. A specific IgE to one or more allergens was detected in 64.1% of children with AD. However, a substantial population of children without AD also had high levels of total IgE (12.7%) and a specific IgE to one or more allergens (30.2%), and the increment of total and specific IgE levels was significantly associated with age. The percentage of positive answers to the questionnaire of the U.K. Working Party diagnostic criteria for AD was significantly higher in children with AD (59.0%) than in children without AD (5.3%) (P<0.0001). Its specificity was 94.7%. The false negative rate was 41%. In conclusion, the prevalence of AD was relatively low in children in Ishigaki Island. High levels of total IgE were found in only one third of children with AD under 5 years of age. The Japanese translated form of the questionnaire of the U.K. Working Party diagnostic criteria for AD should be refined to improve its sensitivity.

Role of food allergy in atopic dermatitis

PURPOSE OF REVIEW

Food allergy and atopic dermatitis often occur in the same patient. Based on clinical data from the past few decades, it is clear that foods such as cow's milk and hen's eggs can directly provoke flares of atopic dermatitis particularly in sensitized infants, whereas inhaled allergens and pollen-related foods are of greater importance in older children, adolescents and adults. Because the role and immunology of food allergy in atopic dermatitis remain controversial, here we review data that mainly focus on skin eczema and food allergy.

RECENT FINDINGS

Clinical studies have revealed that more than 50% of all children with atopic dermatitis that can be exacerbated by certain foods will react with a worsening of skin eczema alone or in addition to immediate symptoms. Adolescents and adults also react to foods, but reactions to 'classical' food allergens such as hen's eggs and cow's milk are not as common as in childhood. Subgroups of children and of adults with atopic dermatitis do, however, react to pollen-associated foods. Both immunoglobulin E associated and independent T-cell mediated responses appear to be involved in clinical eczematous reactions.

SUMMARY

Food-induced eczema should be diagnosed only by a thorough diagnostic procedure, taking into account the patient's history, the degree of sensitization and the clinical relevance of the sensitization. More clinical and immunological studies are needed to unravel the pathophysiology and the different rates of clinical responsiveness to different foodstuffs in patients with atopic dermatitis.

In vivo transfection of a cis element 'decoy' against signal transducers and activators of transcription 6 (STAT6)-binding site ameliorates IgE-mediated late-phase reaction in an atopic dermatitis mouse model

Signal transducers and activators of transcription 6 (STAT6) play a crucial role in the transactivation of IL-4 and IL-13, which might be involved in the pathogenesis of atopic dermatitis (AD). We herein reported that the IgE-mediated late-phase reaction significantly decreased in STAT6-deficient (STAT6(-/-)) mice in AD model mice induced by intravenous injection of monoclonal anti-dinitrophenyl (DNP)-IgE antibody and subsequent skin testing with dinitrofluorobenzene. We therefore hypothesized that synthetic double-stranded DNA with a high affinity for STAT6 could be introduced in vivo as decoy cis elements to bind the transcriptional factor and block the gene activation contributing to the onset and progression of AD, thus providing effective therapy for AD. Treatment by the transfection of STAT6 decoy oligodeoxynucleotides (ODNs), but not scramble decoy ODN after sensitization by anti-DNP-IgE antibody, had a significant inhibitory effect on not only STAT6 binding to nuclei but also on the late-phase response. A histological analysis revealed that both edema and the infiltration of neutrophils and eosinophils significantly decreased in STAT6 decoy ODN-transfected mice. To examine the mechanism of the in vivo effect of STAT6 decoy ODN, we employed an in vitro mast cells culture system. After IgE receptor engagement, mast cells transfected by STAT6 decoy ODN exhibited normal histamine release, but their cytokine release (TNF-alpha, IL-6) markedly decreased. We herein report the first successful in vivo transfer of STAT6 decoy ODN to reduce the late-phase reaction, thereby providing a new therapeutic strategy for AD.

Late eczematous reactions to food in children with atopic dermatitis

BACKGROUND

Food allergy is a common problem in patients with atopic dermatitis (AD), particularly in children. While immediate reactions to food are well characterized, the importance of food as a provocation factor for late eczematous reactions has been a subject of debate for several decades.

OBJECTIVE

To investigate the importance of food for the induction of late eczematous reactions in children with AD and to correlate the clinical outcome to the results of specific IgE determinations and atopy patch tests (APTs).

METHODS

One hundred and six double-blind placebo-controlled food challenges (DBPCFCs) to cow's milk, hen's egg, wheat and soy in 64 children with AD (median age 2 years) were analysed retrospectively. Total and food-specific IgE were determined by CAP RAST FEIA and APTs with native foodstuff were performed. The diagnostic values of specific IgE and APT results were calculated.

RESULTS

Forty-nine (46%) of the challenges were related to a clinical reaction. An exacerbation of AD (late eczematous reaction) commonly occurred 24 h after the ingestion of food. Isolated late eczematous reactions were seen in 12% of all positive challenges. Forty-five percent of the positive challenges were associated with late eczematous responses, which followed immediate-type reactions. The sensitivity of food-specific IgE and the APT was 76% and 70%, respectively. Specific IgE and APT were often false positive, which resulted in low positive predictive values (64% and 45%, respectively).

CONCLUSIONS

Late eczematous reactions may often be observed upon food challenge in children with AD. Due to the poor reliability of food-specific IgE and APT results DBPCFCs have still to be regarded as the gold standard for the appropriate diagnosis of food responsive eczema in children with AD.

IgE and non-IgE food allergy

BACKGROUND

Food allergy (FA) is characterized by an abnormal immunologic reactivity to food proteins. The gastro-intestinal tract serves not only a nutritive function but also is a major immunologic organ. Although previously thought to be triggered primarily by an IgE-mediated mechanism of injury, considerable evidence now suggests that non-IgE mechanisms may also be involved in the pathogenesis of FA.

OBJECTIVE

To review the immunologic disturbances that occur in FA and to correlate these with the clinical manifestations expressed in affected target organs based upon a classification of IgE and non-IgE mechanisms.

METHODS

Data collected from a computerized MEDLINE search were used for the analysis of the following topics: immediate GI hypersensitivity, oral allergy syndrome, acute urticaria and angioedema, acute bronchospasm, celiac disease, cow's milk enteropathy, dietary protein enterocolitis, breast milk colitis, proctolitis, proctitis, dermatitis herpetiformis, Heiner syndrome, eosinophilic gastroenteritis, atopic dermatitis, asthma, attention-deficit-hyperactivity disorder and behavioral disorders, as well as systems affected by mucosal associated lymphoid tissue-mediated injury of associated lymphoid tissues and the immunologic deviation to Th1 or Th2 mechanisms of FA.

CONCLUSIONS

The results of this review allow the construction of a central, unifying hypothesis for a new classification of FA as follows: the clinical manifestations of FA, expressed in affected target organs, may be the result of immunologic injury mediated by interaction of food antigens with contiguous elements of mucosal associated lymphoid tissue. These appear to be modulated by relative imbalances of the Th1/Th2 paradigm, which may be the ultimate determinant governing the expression of FA as IgE-mediated, non--IgE-mediated, or mixed forms of IgE/non-IgE mechanisms of FA.

Gastroesophageal reflux and cow milk allergy: is there a link?

Gastroesophageal reflux (GER) and cow milk allergy (CMA) occur frequently in infants younger than 1 year. In recent years, the relation between these 2 entities has been investigated and some important conclusions have been reached: in up to half of the cases of GER in infants younger than 1 year, there may be an association with CMA. In a high proportion of cases, GER is not only CMA associated but also CMA induced. The frequency of this association should induce pediatricians to screen for possible concomitant CMA in all infants who have GER and are younger than 1 year. With the exception of some patients with mild typical CMA manifestations (diarrhea, dermatitis, or rhinitis), the symptoms of GER associated with CMA are the same as those observed in primary GER. Immunologic tests and esophageal pH monitoring (with a typical pH pattern characterized by a progressive, slow decrease in esophageal pH between feedings) may be helpful if an association between GER and CMA is suspected, although the clinical response to an elimination diet and challenge is the only clue to the diagnosis. This article reviews the main features of GER and CMA, focusing on the aspects in common and the discrepancies between both conditions.

Atopic diseases of childhood

The atopic diseases of childhood consist of the triad of asthma, allergic rhinitis, and atopic dermatitis. All share a common pathogenesis, being mediated by IgE, and are frequently present together in the same individual and family. These disorders and their comorbidities comprise a large component of general pediatric practice and their incidence in developed countries has been increasing over the past few decades. They are a leading reason for clinic and emergency room visits, as well as hospital admissions. They have the potential to interfere with education, physical activity, socialization, and self-esteem. Fortunately, we now have a reasonable armamentarium of maintenance medications available to help control these disorders and improve the quality of life for children suffering from them. In addition, early diagnosis and aggressive management of these disorders seem to offer the possibility of altering their natural history. As such, developing a sensible approach to the diagnosis and treatment of these disorders in an outpatient setting is essential. In this review, I summarize the most current literature and provide a framework for effectively diagnosing and managing these disorders.

Allergy to cooked white potatoes in infants and young children: A cause of severe, chronic allergic disease

BACKGROUND

Cases of allergy to cooked potato in children have been reported, some with immediate and others with late reactions. The clinical effects of chronic allergic reactions to potato and the effectiveness of diet on such reactions have not been described previously.

OBJECTIVE

We sought to evaluate the importance of cooked potato as an allergenic food in individual cases of atopy in children.

METHODS

Eight atopic children were selected on the basis of suspicion of allergy to cooked potatoes: all had potato-specific IgE, 2 of 8 had experienced immediate allergic reactions, and 6 of 8 had eczema that improved with a potato-elimination diet (decrease in severity scoring of atopic dermatis [SCORAD] index of >50%). The patients were evaluated by using skin prick tests with homemade cooked and noncooked potato extracts and with a commercial extract and by using IgE immunoblots from SDS-PAGE patterns of potato extract. Seven patients were challenged with cooked potato. The control group consisted of 9 age-matched atopic children, 8 of them with eczema.

RESULTS

The mean SCORAD index decreased from 43.3 before to 11.5 after elimination of potato from the diet. Potato CAP values ranged from 3.71 to greater than 100 kUa/L. Potato challenge results were positive in 7 of 7 patients. Skin prick test responses were positive for cooked potato extracts in 7 of 7 patients, for noncooked extracts in 7 of 7 patients, and for the commercial extract in 8 of 8 patients compared with in 0 of 9, 1 of 9, and 1 of 9 subjects in the control group, respectively. During immunoblotting, 8 of 8 patient sera recognized one or more protein bands compared with 0 of 9 control subject sera.

CONCLUSION

Allergy to cooked potatoes is a cause of severe allergic disease, with immediate reactions and eczema in some atopic infants and young children.

Hidden peanut allergens detected in various foods: findings and legal measures

BACKGROUND

Undeclared allergens in foodstuffs represent a major health problem for sensitized persons. Until recently, most food control authorities were not in the position to monitor hidden allergens and to take legal measures against their presence in foodstuffs.

METHODS

In this study, we employed human sera-based immunoassay techniques, enabling semiquantitative detection and identification of peanut allergens in a variety of foodstuffs.

RESULTS

This study showed the presence of undeclared allergens in products belonging to various food categories, such as cereals, cookies, cakes, and snacks. The detection limit for peanut contamination was in most instances less than 50 mg peanut material per kg, i.e., less than about 5 mg peanut allergens per kg. We legally objected to products with more than one part per thousand or 1000 mg/kg of peanut contamination.

CONCLUSIONS

In most cases, food producers, confronted with our results, were able to detect and eliminate the sources of the contamination. They implemented measures to prevent the presence of hidden peanut allergens in their products, increasing food safety for sensitized persons and overall food quality.

Systematic review of evidence for the prevalence of food sensitivity in dogs

Twelve papers giving original data on canine food sensitivity in an acceptable form were reviewed, and the disorder was confirmed in 390 dogs. Most of the papers did not give either the criteria by which dogs were included in a trial, or information about dogs which had undergone a trial with a restricted diet but in which food sensitivity had not been observed. Only one author indicated how the degree of pruritus of the dogs in the study was assessed. The question of owner compliance in conducting a diet trial was not considered in any of the papers. The best available evidence comes from three of the studies covering 534 dogs in total, of which 93 (17 per cent) suffered food sensitivity.

Atopic dermatitis in infants and children. An update

The goal in treating patients with atopic dermatitis is to maintain adequate hydration while decreasing pruritus and inflammation. It is also important to recognize factors that are responsible for flares. Although the etiology of atopic dermatitis remains unknown, therapies are being developed targeting immunologic defects in this disease.

Markers for early sensitization and inflammation in relation to clinical manifestations of atopic disease up to 2 years of age in 133 high-risk children

BACKGROUND

The combination of genetic susceptibility and environmental factors induce allergic sensitization and subsequently local inflammation, resulting in atopic manifestations.

OBJECTIVE

To examine whether immunological features reflecting sensitization (total and specific IgE levels, allergen-induced proliferative responses and skin tests) and markers of inflammation (plasma sE-selectin and blood eosinophils) are related to the clinical expression of atopy and whether they precede atopic disease in children up to 2 years of age.

METHODS

The development of these markers during the first 2 years of life was studied prospectively in 133 newborns at high risk to develop atopic disease.

RESULTS

The prevalence of atopic disease increased from 25% at 12 months to 32% at 24 months of age. The children with food allergy at 12 months, who all had atopic dermatitis (AD), turned out to have asthma-like disease in 40% and AD in 100% at the age of 24 months. Total IgE levels increased with time and from 12 months onward levels started to differ markedly between atopics and nonatopics. Food-specific IgE antibodies were significantly associated with AD (relative risk [RR] = 2.39), food (RR = 1.32) and upper-airway allergy (RR = 1.20), and house dust mite-specific IgE antibodies with upper-airway allergy (RR = 5.00). A positive skin test was significantly associated with AD (RR = 2.90) and food allergy (RR = 1.36). The inflammation markers investigated, were not related to the clinical expression or preceded atopic disease at 2 years of age in high-risk children.

CONCLUSION

Positive skin tests and specific IgE to food or inhalant allergens were related to the clinical expression of different atopic diseases. The combination of AD and food allergy at 12 months reflected the strongest risk factor in this high risk cohort for the development of asthma-like disease at 24 months of age.

Beef allergy in children

Beef allergy was poorly known before the '90s. Since then, a number of papers appeared elucidating the nature, epidemiology, and symptoms of beef allergy in children allergic to cow's milk and children suffering from atopic dermatitis. It is now clear that beef allergy is not an infrequent occurrence, with an incidence between 3. 28% and 6.52% among children with atopic dermatitis, its incidence may be as much as 0.3% in the general population. A diagnosis of beef allergy must be supported by skin prick tests, RASTs, and challenges. The specificity and sensitivity according to type of test and the type of extract, however, remains to be evaluated. Despite the fact that other allergens can be sensitizing, the major beef allergen is bovine serum albumin (BSA). Beef-sensitive children are also sensitized to ovine serum albumin, as well as to other serum albumins; therefore, the use of alternative meats in beef-allergic children must be carefully evaluated on an individual basis. Because industrial heat processing is more efficient than domestic cooking in reducing reactivity in beef-sensitive children, freeze-drying and homogenization may support the introduction of processed beef into the diet of beef-allergic children.

Identification of bovine IgG as a major cross-reactive vertebrate meat allergen

BACKGROUND

Although beef is a main source of protein in Western diets, very little has been published on allergic reactions to beef or the main allergens implicated in these reactions. The aim was to evaluate the IgE antibody response to beef in suspected meat-allergic subjects and assess cross-reactivity of beef with other vertebrate meats.

METHODS

Fifty-seven sera from suspected meat-allergic subjects were tested by grid blot for specific IgE antibodies to vertebrate meats (beef, lamb, pork, venison, and chicken), and the patterns of recognition of meat proteins were assessed by immunoblot studies.

RESULTS

A 160-kDa band, identified as bovine IgG, was detected in raw beef in 83% (10/12) of beef-allergic subjects but in only 24% of the beef-tolerant subjects. IgE reactivity to a band of similar mol. mass was detected also in lamb and venison, but rarely in pork or chicken. Complete inhibition of the IgE reactivity to the bovine IgG was obtained with lamb, venison, and milk. IgE reactivity to this band also completely disappeared when beef or lamb extracts were separated under reducing conditions, indicating conformational epitopes.

CONCLUSIONS

Bovine IgG appears to be a major cross-reacting meat allergen that could predict beef allergy. Further studies with oral IgG challenges should be performed to document the conclusion that in vitro reactivity correlates with clinical hypersensitivity. The role of bovine IgG in other bovine products such as milk, dander, or hair must also be studied, and the hypothesis that it is a cross-reacting allergen with other mammalian products validated.

Dietary docosahexaenoic acid suppresses inflammation and immunoresponses in contact hypersensitivity reaction in mice

This study was designed to examine the immunomodulatory effects of dietary docosahexaenoic acid (DHA) in the absence of eicosapentaenoic acid (EPA). We investigated the effects of feeding dietary DHA ethyl ester (DHA-Et) (97% pure) at levels of 4.8 wt% of the total diet and of feeding EPA ethyl ester (EPA-Et) (99% pure) at 4.8 wt% on the inflammatory response in the challenge phase of the contact hypersensitivity reaction (CHR) in the ears of mice sensitized with 2,4-dinitro-1-fluorobenzene (DNFB). The effect of DHA-Et on T lymphocytes at the CHR site was examined using anti-CD4 antibodies. Furthermore, we examined the cytokines formed at the CHR site on the mRNA level. It was found that 24 h after the challenge, DHA-Et but not EPA-Et reduced the ear swelling. Infiltration of inflammatory cells, in particular, CD4-positive T lymphocytes, into the ears in the challenge phase of CHR was observed. DHA-Et reduced the infiltration of CD4-positive T lymphocytes into the ears. DHA-Et also decreased the expression of interferon-gamma, interleukin (IL)-6, IL-1beta, and IL-2 mRNA in ears. These observations suggest that DHA, but not EPA, may exert an antiinflammatory and immunosuppressive effect. The immunosuppressive effectiveness of fish oil may be attributed mainly to DHA.

Lupine-induced anaphylaxis

BACKGROUND

Legumes are one of the most common foods causing allergic reactions in children and adults. Cross-reacting antibodies are frequently demonstrated in this family but the real clinical cross-reactivity is uncommon.

OBJECTIVE

To report a case of lupine-induced anaphylaxis and to elucidate in vivo and in vitro cross-reactivity with some legumes.

METHODS

Skin prick test (SPT) with some legumes were performed. Cap-IgE, ELISA-IgE, and immunoblotting were carried out. Open oral challenges with some legumes were performed. Cross-reactivity was studied by ELISA and immunoblotting inhibition.

RESULTS

The results demonstrated type-I hypersensitivity reactions with lupine and some other legumes. Cap-IgE with peanut was positive but the SPT and ELISA-IgE were negative and the patient tolerated a peanut challenge. ELISA inhibition revealed a partial inhibition (62%) using lupine as the solid phase. Partial inhibition was demonstrated by immunoblotting inhibition. Open oral challenge with peanut and green bean were negative but positive with pea.

CONCLUSION

We present a lupine sensitized patient with positive SPT and in vitro cross-reactivity with other legumes. Clinical cross-reactivity progressively developed over a 5-year period. Discrepancies were found between the clinical aspect and in vitro study of peanut allergy. Factors determining the wide variability in cross-reactivity among individuals are still obscure.

IgE antibody response to vertebrate meat proteins including tropomyosin

BACKGROUND

Although meat is a main source of proteins in western diets, little information is available regarding allergy to vertebrate meats or the allergens implicated in these reactions.

OBJECTIVE

To evaluate the in vitro IgE antibody response to different vertebrate meats in suspected meat-allergic subjects, as well as the possible role of tropomyosin in meat allergy and to analyze the cross-reactivity between vertebrate meats and the effect of heating on the IgE-binding to meat proteins.

METHODS

Fifty-seven sera from suspected meat-allergic subjects were tested by grid blot to extracts of beef, lamb, pork, venison, chicken, and turkey and to four mammalian tropomyosins of different origins.

RESULTS

Meat-allergic subjects have IgE antibodies to proteins in different mammalian meats (43/57 subjects); cross-reactivity with avian meat was limited: less than 50% (19/43) of meat positive sera reacted to chicken. In contrast, most of the poultry-positive sera also reacted to different mammalian meats. In general, there was stronger IgE reactivity to raw meats in comparison to cooked meats; an exception was six cases in which IgE reactivity to cooked poultry was stronger. Weak IgE reactivity to tropomyosin was detected in only 2/57 sera tested.

CONCLUSIONS

Suspected meat-allergic subjects have serum IgE directed to meat proteins. In vitro cross-reactivity among mammalian meats appears to be important, while cross-reactivity to poultry is limited indicating mammalian-specific proteins. Although cooking in general denatures meat proteins rendering them less allergenic, in some cases the process of cooking may result in the formation of new allergenic moieties. The muscle protein tropomyosin is not an important vertebrate meat allergen.

Food allergy. Part 2: diagnosis and management

Patients with food-induced allergic disorders may be first seen with a variety of symptoms affecting the skin, respiratory tract, gastrointestinal tract, and/or cardiovascular system. The skin and respiratory tract are most often affected by IgE-mediated food-induced allergic reactions, whereas isolated gastrointestinal disorders are most often caused by non-IgE-mediated reactions. When evaluating possible food-induced allergic disorders, it is often useful to categorize disorders into IgE- and non-IgE-mediated syndromes. The initial history and physical examination are essentially identical for IgE- and non-IgE-mediated disorders, but the subsequent evaluation differs substantially. Proper diagnoses often require screening tests for evidence of food-specific IgE and proof of reactivity through elimination diets and oral food challenges. Once properly diagnosed, strict avoidance of the implicated food or foods is the only proven form of treatment. Clinical tolerance to food allergens will develop in many patients over time, and therefore follow-up food challenges are often indicated. However, a number of novel immunomodulatory strategies are in the developmental stage and should provide more definitive treatment for some of these food-induced allergic disorders in the next several years.

Food allergy. Part 1: immunopathogenesis and clinical disorders

Up to 8% of children less than 3 years of age and approximately 2% of the adult population experience food-induced allergic disorders. A limited number of foods are responsible for the vast majority of food-induced allergic reactions: milk, egg, peanuts, fish, and tree nuts in children and peanuts, tree nuts, fish, and shellfish in adults. Food-induced allergic reactions are responsible for a variety of symptoms involving the skin, gastrointestinal tract, and respiratory tract and may be caused by IgE-mediated and non-IgE-mediated mechanisms. In part 1 of this series, immunopathogenic mechanisms and clinical disorders of food allergy are described.

Molecular cloning and epitope analysis of the peanut allergen Ara h 3

Peanut allergy is a significant IgE-mediated health problem because of the increased prevalence, potential severity, and chronicity of the reaction. Following our characterization of the two peanut allergens Ara h 1 and Ara h 2, we have isolated a cDNA clone encoding a third peanut allergen, Ara h 3. The deduced amino acid sequence of Ara h 3 shows homology to 11S seed-storage proteins. The recombinant form of this protein was expressed in a bacterial system and was recognized by serum IgE from approximately 45% of our peanut-allergic patient population. Serum IgE from these patients and overlapping, synthetic peptides were used to map the linear, IgE-binding epitopes of Ara h 3. Four epitopes, between 10 and 15 amino acids in length, were found within the primary sequence, with no obvious sequence motif shared by the peptides. One epitope is recognized by all Ara h 3-allergic patients. Mutational analysis of the epitopes revealed that single amino acid changes within these peptides could lead to a reduction or loss of IgE binding. By determining which amino acids are critical for IgE binding, it might be possible to alter the Ara h 3 cDNA to encode a protein with a reduced IgE-binding capacity. These results will enable the design of improved diagnostic and therapeutic approaches for food-hypersensitivity reactions.

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

BACKGROUND AND OBJECTIVE

Little is known about late phase clinical reactions during oral food challenges and the value of specific IgE in terms of sensitivity and specificity.

METHODS

We therefore analysed retrospectively the clinical outcome of 387 oral provocations during double-blind, placebo-controlled food challenge tests in 107 children with atopic dermatitis.

RESULTS

Eighty-seven (81%) children showed a positive clinical reaction to at least one challenge. The vast majority of children (94%) showed clinical symptoms to one or two allergens. One hundred and thirty-one of 259 (51%) of verum challenges and 1/128 (0.8%) placebo challenge were assessed as positive. Oral provocations with hen's egg showed the highest percentage of positive reactions (70%). Sensitivity of specific IgE to the four allergens tested was 90%, specificity 30%. Sensitivity of the parental history as a predictive factor was 48%, specificity 72%. Ninety-two of 131 (70%) children with positive verum provocations showed early reactions, 33 (25%) late and six (5%) combined early and late reactions. In 84/131 (64%) positive provocations one organ system was involved, while in 44 (34%) provocations two and in three (2%) challenges three organ systems were involved. Skin reactions were the most frequent clinical manifestation leading to positive reactions followed by gastro-intestinal and respiratory symptoms. There was no correlation between titration dose and specific IgE. The subgroup of non-sensitized children did not differ in terms of sex, age or titration dose from the total study population.

CONCLUSION

Double-blind, placebo-controlled oral food challenges are helpful in distinguishing children with clinically manifested symptoms from those with food sensitization. Accurately identifying children with a clinical relevant food allergy may help to prescribe specific diets on a scientific basis, avoiding dietary limitations which may be unnecessary or even harmful.

Food allergy

Food allergies are immunologic reactions to food allergens or food components. Several distinct clinical entities fall under this term, including immediate-in-time allergic reactions, which are IgE-dependent and involve mast cells and basophils, and delayed-in-time reactions to foods, such as food-induced enterocolitis, which involve additional effector systems. Most food allergies are precipitated by a small number of foods. The diagnosis of these diseases depends on history, physical examination, specific diagnostic assays, and oral food challenge. The differential diagnosis of these diseases is extensive. Treatment of food allergies relies on identification of the food substance that induces the reaction and subsequent avoidance measures. When an individual inadvertently consumes food to which he or she is sensitized, pharmacologic treatment is available.

Special formulas in infant nutrition: a review

Special formulas should only be used by medical prescription and for those lactating infants with diagnosed nutritional problems. Lactose-free formulas or those based on soy are the logical choice when the exclusion of lactose from the diet is considered necessary. At present, there is no concensus on the appropriateness of soy formulas for the treatment and prevention of nutritional allergies and current opinion seems to favour hydrolyzed protein formulas. High-degree protein hydrolysate formulas are used to treat lactating infants with an allergy to cow milk proteins or with serious nutritional problems. These formulas are not without risk, as they may contain residual epitopes capable of provoking a severe allergic reaction. Before using these formulas, allergenicity tests should be performed, particularly for highly sensitive infants. The unpleasant taste and high cost of these formulas, in addition to possible nutritional problems, limit their use in the prevention of atopic disease, although their efficacy is well established. Partially protein hydrolysate formulas are only used for preventive purposes and are not suitable for lactating infants with a proven allergy to cow milk. Although these formulas can reduce the incidence or delay the appearance of certain atopic symptoms, they have not been shown to prevent IgE-mediated allergic reactions to cow's milk and so their effectiveness is open to question.

Food-induced cutaneous adverse reactions

The skin is the most frequently affected target organ in allergy or intolerance of food and food additives. The most common manifestation is acute urticaria (with or without angioedema), accounting for 40-60% of patients with IgE-mediated food allergy, whereas food additives rather aggravate chronic urticaria (intolerance provocation). The role of food allergy in the pathogenesis of atopic dermatitis is still controversial; however, there is no doubt that, particularly in infants and young children, food allergens can induce atopic dermatitis or aggravate skin lesions. In adults, food allergy as a cause or a trigger of atopic dermatitis is very rare. However, in food-allergic patients with atopic dermatitis, the ingestion of the food item can provoke the whole spectrum of IgE-mediated symptoms, from oral allergy syndrome to severe anaphylaxis. Skin symptoms can also be induced not only after food ingestion in sensitized people, but also after direct skin contact, as lipophilic food allergens can penetrate the skin via the hair follicles or when the skin barrier function is defective. Immediate contact reactions of the skin are a heterogeneous group: they include not only contact urticaria (contact urticaria syndrome) on an immunologic or nonimmunologic basis, but also allergic or nonallergic eczematous reactions caused by food proteins (protein contact dermatitis). A prototype is baker's eczema in a restricted sense with immediate-type sensitization to flour. Atopic eczema provoked by direct contact of the skin with food must also be taken into consideration. Finally, very rarely, allergic contact dermatitis that is due to type IV sensitization to food or food additives (positive delayed type reaction in the patch tests) can occur. The oral ingestion of these foods may provoke in these patients a generalized eczematous rash or dyshidrosiform reactions (vesicles) of the fingers, palms, and soles.