Role of food allergy in childhood atopic dermatitis

The interplay between atopic dermatitis (AD) and food allergy is complex and subject to significant misconceptions both by the general public and the medical community. Childhood AD is a very prevalent disorder. In its moderate and severe forms, AD is a challenging disorder to manage from the perspective of the child, parent and treating doctor. As AD is one of the disease manifestations of atopy, it is unsurprising that many children with AD also have a coexisting IgE‐mediated food allergy. It is a common misconception that food allergy is causal in the setting of AD. However, in a proportion of sufferers, food allergy does play a role in triggering or exacerbating pre‐existing AD by immune‐mediated mechanisms and potentially by non‐immune mechanisms. It is, therefore, important to differentiate causality, co‐existent disease and disease modifiers in this context. This paper seeks to clarify the role of food allergy in childhood AD, and to outline a rational framework for the diagnosis and approach to food allergy in the context of the management of a child with problematic AD.     

Ass''s milk in children with atopic dermatitis and cow''s milk allergy: Crossover comparison with goat''s milk

Cow milk allergy is a common disease of infancy, often associated with atopic dermatitis (AD). Avoidance of cow milk (CM) implies the use of alternative dietary supports such as mammalian milks. In this study, we assessed the tolerability and clinical effect of ass's milk (AM), when compared with the largely used goat's milk (GM) in a single-blind, controlled, randomized crossover. Twenty-eight children with AD and ascertained allergy to CM were enrolled. The children were randomized to AM or GM for 6 months, then switched to the other milk for further 3 months. The SCORAD index (SI) and a visual analog scale (VAS) were evaluated blindly. After termination of the study, food challenges with GM and AM were performed. An SDS-PAGE analysis of different milks was performed. Two children from the GM group dropped out after randomization and 26 completed the study. Ass milk invariantly led to a significant improvement of SI and VAS of symptoms (p < 0.03 vs. baseline and inter-group), whereas GM had no measurable clinical effect. At the end of the study 23 of 26 children had a positive food challenge with GM and one of 26 with AM. Ass's milk had a protein profile closer to human milk than GM. Ass milk is better tolerated and more effective than GM in reducing symptoms of AD. It may represent a better substitute of CM than the currently used GM.     

Food hypersensitivity in two groups of children and young adults with atopic dermatitis evaluated a decade apart

There is an impression that children today are experiencing allergic reactions to an increasing variety of foods. We compared two separate groups of children and young adults with atopic dermatitis evaluated a decade apart and found no difference in sensitization rates or overall clinical reactivity to a variety of foods. Allergies to egg, milk, wheat, soy, peanut, tree nuts, and seafood continue to account for ≈ 90% of food‐allergic reactions over the past decade.     

特应性皮炎婴幼儿IgE介导食物过敏的随访研究

目的探讨IgE介导的食物过敏在特应性皮炎中的作用及其转归。方法对86例深圳地区特应性皮炎患儿进行混合食物组过敏原筛查(fx5E)检测,阳性者进一步检测6种常见食物(鸡蛋白、牛奶、鱼、小麦、花生、大豆)过敏原特异性IgE(sIgE)。对sIgE阳性患儿建议采取过敏食物回避措施,随访6个月和2年。结果 86例患儿中,36例(42%)有IgE介导的食物过敏,牛奶和(或)鸡蛋白为主要过敏原,分别占70%和64%。31例患儿完成了2年随访,食物sIgE检测为1级的13例患儿目前均无过敏症状;13例2级患儿再次进食过敏食物,仍有5例出现症状;7例3级以上过敏患儿,目前再次进食过敏食物,均出现症状。结论 IgE介导的食物过敏是引起婴幼儿特应性皮炎的重要原因,牛奶和(或)鸡蛋白是主要的过敏食物。回避过敏食物可以明显缓解症状,轻度过敏者症状随年龄增长可以消失,过敏程度越高,再次接触过敏食物出现症状的可能性越大。     

Food allergy as a risk factor for nutritional rickets

The case of a 14-month-old boy with vitamin D deficiency rickets as a result of unsupervised dietary manipulation in the context of cow's milk allergy is presented. Adequate supervision by a qualified dietician, coupled with appropriate supplementation, is essential if nutritional compromise is to be avoided in children with food allergy.     

Food allergy and atopic dermatitis in infancy: an epidemiologic study

Atopic dermatitis is common in infancy. The role of food allergy in atopic dermatitis of infancy is unclear. We examined the relationship between atopic dermatitis and immunoglobulin E (IgE)-mediated food allergy in infancy. A birth cohort of 620 infants with a family history of eczema, asthma, hayfever or immediate food allergy in a parent or sibling: 487 children had complete data including skin prick tests (SPTs) to evaluate IgE-mediated food allergy to cow milk, egg and peanut. Participants were grouped as no atopic dermatitis (Gp 0) or in quartiles of increasing severity of atopic dermatitis (Gps 1-4) quantified by days of topical steroid use as reported monthly. Adverse reactions to foods were recorded. The cumulative prevalence of atopic dermatitis was 28.9% to 12 months (10.3% of the cohort of moderate severity). As atopic dermatitis severity increased so did the prevalence of IgE-mediated food allergy (Gp 0, 40/346 vs. Gp 1, 6/36 vs. Gp 2, 8/35 vs. Gp 3, 12/35 vs. Gp 4, 24/35; chi(2) = 76; p < 10(-6)), and the frequency of reported adverse food allergy reactions (Gp 0, 43/346 vs. Gp 1, 4/36 vs. Gp 2, 8/35, vs. Gp 3, 5/35, vs. Gp 4, 13/35; chi(2) = 17; p = 0.002). The relative risk of an infant with atopic dermatitis having IgE-mediated food allergy is 5.9 for the most severely affected group. Atopic dermatitis is common in infancy. There is a strong association between IgE-mediated food allergy and atopic dermatitis in this age group.     

Food allergy and atopic dermatitis: Prediction,progression, and prevention

The rising burden of allergic diseases in childhood requires a compelling need to identify individuals at risk for atopy very early in life or even predict the onset of food allergy and atopic dermatitis since pregnancy. The development and clinical phenotypes of atopic diseases in childhood depend on a complex interaction between genetic and environmental factors, such as allergen exposure, air pollution, and infections. Preventive strategies may include avoidance measures, diet supplements, and early complementary food introduction. Overall, the management of allergic diseases has been improving to date toward a patient's tailored approach. This review will cover the current understanding of risk factors, prediction, and management of food allergy and atopic dermatitis in childhood and discuss how these may contribute to the modification of the natural history of food allergy and atopic dermatitis.     

Helicobacter pylori seropositivity in children with atopic dermatitis as sole manifestation of food allergy

A positive association between Helicobacter pylori antibodies and food allergy presenting with gastrointestinal symptoms has recently been reported. A subset of a H. pylori strain possesses an antigen, CagA, as a virulence factor. Anti‐ H. pylori and anti‐CagA IgG titre have been determined in children with atopic dermatitis (AD) as the sole clinical manifestation of food allergy. In this study, thirty patients with AD as the sole clinical manifestation of food allergy were examined (group A). For comparative purposes, 30 patients affected by food allergy with gastrointestinal symptoms (group B) and 30 affected by atopic asthma (group C) were studied. Anti‐ H. pylori and anti‐CagA immunoglobulin G (IgG) were determined in all individuals by means of the enzyme‐linked immunosorbent assay. The anti‐ H. pylori IgG titre was significantly higher in group A and group B vs. group C (p < 0.05); no significant difference was detected between group A and group B (p > 0.05). No significant difference in anti‐CagA titre was found between the groups. These data demonstrate a positive association between H. pylori antibodies and AD as the sole manifestation of food allergy. Further investigations are needed to evaluate the cause–effect relationship between H. pylori seropositivity and AD.     

The spectrum of cow''s milk allergy

Childhood cow's milk allergy is a diagnosis encompassing various syndromes. Antigen-immunoglobulin E (IgE) antibody interaction is classically involved in mast cell degranulation in IgE-mediated food allergy, while non-IgE mediated cow's milk allergy is mostly mediated by cellular mechanisms. The diagnosis of cow's milk allergy largely relies on a good knowledge of the clinical expression of the disease. In this educational review series, we describe three cases of cow's milk allergy, first a 7-yr-old girl with persisting IgE-mediated cow's milk allergy, second a 8-month-old boy with cow's milk induced flares of atopic dermatitis, and third a 6-yr-old boy with sheep and goat milk allergy, in the absence of cow's milk allergy. The cases are discussed and summarized with more general recommendations for the clinical management of cow's milk allergy.     

Proposal for a standardized interpretation of the atopy patch test in children with atopic dermatitis and suspected food allergy

The interpretation of the atopy patch test (APT) to foods is not standardized. This study aimed to validate the reading of the APT in terms of the diagnostic accuracy of individual skin signs. Eighty-seven children (mean age 2.4 +/- 2.5 yr, range 0.5-13.5; 57 male) with atopic dermatitis (AD) and suspected food allergies underwent APT to cow's milk, hen's egg, wheat and soy. Twelve-millimetre Finn chambers were applied for 48 h, and results were read after 48 and 72 h. Skin changes were graded for erythema, induration, papule formation and 'crescendo' phenomenon (increase of skin sign severity from 48 to 72 h). Food allergy was assessed by double blind, placebo-controlled food challenges (DBPCFC). Sensitivity, specificity and predictive values were calculated for each skin signs in relation to challenge outcome. Of 165 DBPCFC children, 75 (45%) were positive. The combination of any skin induration plus papules (seven or more), or of moderate erythema plus any induration plus seven or more papules had a positive predictive value (PPV) and specificity for the challenge outcome of 100%; however, the sensitivity was low (8% and 15%). The best diagnostic accuracy for single signs was found for induration beyond the Finn chamber margin (PPV 88%, specificity 99%, sensitivity 9%) and presence of at least seven papules (PPV 80%, specificity 96% sensitivity 21%). Presence of both induration and of at least seven papules at 72 h were the APT skin signs with the greatest diagnostic accuracy for food allergy in children with AD.     

Sensitization to turnip rape and oilseed rape in children with atopic dermatitis: a case-control study

Turnip rape and oilseed rape 2S albumins are new allergens in children with atopic dermatitis suspected for food allergy. We recently found that 11% (206/1887) of these children had a positive skin prick test to seeds of oilseed rape ( Brassica napus ) and/or turnip rape ( Brassica rapa ). In the present case-control study we examined how the children with atopic dermatitis sensitized to turnip rape and oilseed rape had been breast-fed and whether they had some common sensitization pattern to certain foods or pollens. A total of 64 children with atopic dermatitis and a positive skin prick test to turnip rape and/or oilseed rape (≥5 mm) were examined. Sixty-four age- and sex-matched children with atopic dermatitis but negative skin prick tests to turnip rape and oilseed rape served as case controls. The turnip rape and/or oilseed rape sensitized children with atopic dermatitis had significantly more often positive skin prick tests reactions and IgE antibodies to various foods (cow's milk, egg, wheat, mustard; p < 0.01) and pollens (birch, timothy, mugwort; p < 0.01) than the control children. They had been exclusively breast-fed for a longer period (median 4 months; p < 0.05) and had more often associated asthma (36%) and allergic rhinitis (44%). Children with atopic dermatitis sensitized to oilseed rape and turnip rape had high frequency of associated sensitizations to all foods and pollens tested showing that oilseed plant sensitization affects especially atopic children who have been sensitized to multiple allergens.     

Risks of milk formulas containing peanut oil contaminated with peanut allergens in infants with atopic dermatitis

Four cases of infants with atopic dermatitis are reported. In all cases, a sensitization to peanut is demonstrated. Any ingestion of peanuts can be excluded, with the exception of a daily consumption of peanut oil, contained in milk formulas. Oral challenges with peanut oil induce a rash, and elimination of these brands is followed by the disappearance of eczematous lesions. The presence of residual allergenic proteins in peanut oil is thus suspected. Owing to the growing incidence of peanut hypersensitivity, the elimination of peanut oil from all milk formulas, food for babies, and ointments, seems to be highly advisable.     

Diagnosis of IgE‐mediated food allergy among Swiss children with atopic dermatitis

Diagnosis of food allergy in children with atopic dermatitis (AD) relies on a good knowledge of the prevalence of the disease and of the foods most frequently involved. Our objective was to define these characteristics in a population of Swiss children with AD. Patients referred to a pediatric allergist or a dermatologist for AD were routinely tested by skin‐prick test (SPT) to seven common food allergens (milk, egg, peanut, wheat, soy, fish, and nuts), and to all other foods suspected by history. Patients with positive SPTs were further evaluated for specific serum immunoglobulin E (IgE) antibodies (by using the CAP System FEIA^?). CAP values were interpreted following previously published predictive values for clinical reactivity. Patients with inconclusive results (between the 95% negative predictive value [NPV] and the 95% positive predictive value [PPV]) were challenged with the suspected food. A total of 74 children with AD were screened for food allergies. Negative SPTs excluded the diagnosis in 30 subjects. Nineteen patients were diagnosed by histories suggestive of recent anaphylactic reactions to foods and/or CAP values above the 95% PPV. Forty‐three food challenges (35 open challenges and eight double‐blind, placebo‐controlled in children with persistent lesions of AD despite aggressive topical skin treatment) were performed in patients with positive SPTs but with inconclusive CAP values. Six patients were diagnosed as positive to 15 foods. Challenges were not performed to high‐allergenic foods in young children (under 12 months of age for egg and fish, and under 3 years of age for peanuts and nuts). Altogether, 33.8% (25 of 74) of the AD patients were diagnosed with food allergy. The prevalence of food allergy was 27% (seven of 25) in the group referred to the dermatologist for primary care of AD. The foods most frequently incriminated were egg, milk, and peanuts. The prevalence of food allergy in our population was comparable to that in other westernized countries, suggesting an incidence of food allergy in approximately one‐third of children with persistent lesions of AD. Together with milk and eggs, peanuts were most frequently involved in allergic reactions.