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.     

Atopic allergy: asthma and atopic dermatitis.

During the past 2 years much progress has been made in our understanding of allergic diseases: there is now increasing evidence for a direct causal relationship between exposure to allergen and the chronic diseases, asthma and atopic dermatitis; furthermore, it seems very likely that exposure to indoor allergens is the most common cause of the inflammation of the lungs that is characteristic of asthma.     

Antigliadin IgE--indicator of wheat allergy in atopic dermatitis

BACKGROUND: Cereal grains are recognized as the cause of adverse reactions in some patients exposed to grain or flour by either inhalation or ingestion. Cereal-related diseases, such as celiac disease and baker's asthma, have been well studied and the causative cereal proteins have been characterized. Although cereals form an essential part of daily nutrition, the allergenic proteins causing symptoms on ingestion in atopic dermatitis (AD) have remained obscure. In this study, we have investigated the allergenic fraction of wheat in AD. METHODS: Skin prick tests (SPT) with a NaCl wheat suspension and the ethanol-soluble wheat gliadin were performed on 18 wheat-challenge-positive or -negative children with AD, six adult AD patients with suspected cereal allergy, and one adult with wheat-dependent exercise-induced urticaria/anaphylaxis. Serum total IgE and specific IgE-antibody levels to wheat and gluten were measured with the radioallergosorbent test (RAST) simultaneously. In addition serum samples of all 25 patients were analyzed by IgE immunoblotting with the ethanol-soluble wheat-protein extract. RESULTS: Thirteen of the AD children were wheat-challenge-positive, 11/12 of them appeared to be positive with gliadin SPT, and all had an elevated gluten RAST value. Those challenge-negative were negative with both gliadin SPT and gluten RAST. Positive wheat SPT and RAST alone were not associated with positive challenges. Four of the adult patients responded to a cereal-free diet, although only two of them appeared to be positive with gliadin SPT and gluten RAST. A broad and intensive staining of gliadin peptides in IgE-immunoblotting studies was seen in challenge-positive children with positive gliadin SPT and/ or gluten RAST. Besides staining of peptides in the main gliadin area of 30-46 kDa, a characteristic finding was the staining of small, <14-kDa proteins with sera of challenge- and gliadin-SPT-positive patients. CONCLUSIONS: We found that wheat-allergic AD patients have IgE antibodies against gliadin that can be detected by both SPT and the sensitive immunoblotting method. This suggests that gliadin peptides are important allergens, and ingestion of wheat causes symptoms of AD. A broad and intensive IgE staining was seen of gliadin peptides against both the previously characterized peptides in the main gliadin area and small, previously uncharacterized peptides of less than 14 kDa. The gliadin SPT and gluten RAST are good screening methods. Further characterization of the IgE-stained gliadin proteins is needed.     

The incidence of food allergy in atopic dermatitis]

To clarify the incidence of food allergy in atopic dermatitis, non-selected 226 cases with atopic dermatitis visited in our hospital were evaluated by oral food challenge tests based on masked food allergy. 181 of 200 cases except 26 cases dropped out showed a positive reaction to at least one challenge test, after their skin manifestations had been relieved by environmental control and elimination diets. In conclusion, the incidence of food allergy in atopic dermatitis was 90.5%, and egg allergy, cow's milk allergy, soy bean allergy, wheat allergy, rice allergy were 83.5%, 51.5%, 33.5%, 20.0%, 2.5% respectively in 200 cases.     

Diagnostic tests in children with atopic dermatitis and food allergy

Background Skin testing is a common diagnostic procedure in food allergy. The skin prick test is the test of first choice for investigating the immediate IgE-mediated reaction, TTie skin application food test (SAFT) has been developed on the basis of the mechanism of the contact urticaria syndrome (CUS), Methods We studied the relevance of the SAFT in children younger than 4 years with atopic dermatitis and (suspected) food allergy as compared with the prick-prick test, the radioallergosorbent test (RAST), and the oral challenge. In the skin tests, we used fresh food, in the same state as it was consumed.
Results There was a good agreement between the SAFT and the prick-prick test. A moderate agreement was observed between the SAFT and the serologic test (RAST). Significantly more positive results in the RAST were observed than in the SAFT, There was very good agreement between the SAFT and the oral challenge (K = 0,86).
Conclusions The SAFT is a reliable and child-friendly skin test for evaluating (suspected) food allergy in children younger than 4 years with atopic dermatitis. The very good correlation with the oral challenge indicates that one may probably consider the SAFT a "skin provocation" in children younger than 4 years.     

The peanut allergy in patients suffering from atopic dermatitis

Aim. The evaluation of the occurrence of peanut allergy in adolescent and adult patients suffering from atopic dermatitis. Methods. Altogether 175 persons suffering from atopic dermatitis were included in the study. A diagnostic work-up for food allergy to peanuts was performed (specific IgE, skin prick tests, atopy patch tests, history), and the patients were also examined for pollen allergy containing Bet v 1 and Bet v 2 allergens. Results. Allergic reactions to peanuts were recorded in 23% of patients, and another 16% of patients were sensitised to peanuts. A dependency between the occurrence of pollen allergy with Bet v 1 and Bet v 2 allergens and the results of the examination for peanut allergy is confirmed in our study. Conclusion. One-fifth of patients with atopic dermatitis suffer from peanut allergy; the most common symptom is oral allergy syndrome.     

Learning from fungus allergy in atopic dermatitis patients]

It has been recognized that there are considerable variations in their skin reactivity to environmental allergens as well as in immunoreactivities, even in AD patients with similar signs and symptoms. Some AD patients have high serum IgE antibody levels, while others show low levels. There are also differences in the kinds of triggering factors that are related to the development and maintenance of AD, e.g., allergic or non-allergic. Even among AD patients with high titers of serum IgE antibodies, the kinds and number of allergens involved in the exacerbation of AD are different and can change with time. The types of the underlying allergic reactions vary as well, i.e., some show immediate reactions, while others show delayed type hypersensitivity responses to environmental allergens. Thus, even AD patients diagnosed by the established criteria may have remarkably different backgrounds. When we looked over our published data, we noticed that there were differences in levels of IgE RAST and skin reactions between AD with atopic respiratory diseases (ARD) and pure AD without ARD. Levels of IgE RAST against airborne allergens, which come into the body mainly through the respiratory tract, were higher in AD with ARD, while those against allergens such as Candida albicans and Malassezia furfur, which can colonize on the skin, were higher in pure AD. In addition to these Th2-mediated immunological abnormalities, Th1-mediated DTH reaction and lymphocyte proliferation indices against airborne allergens were remarkably low in AD with ARD, whereas those against Candida albicans and Malassezia furfur were relatively preserved, although they were lower than those found in normal subjects. We understand from these findings that routes of allergen entry are important for the outcome of the resultant allergic reactions. This point of view is important answering questions such as how AD develops and how it can be prevented from the insults of each allergen.     

Milk allergy/intolerance and atopic dermatitis in infancy and childhood

Adverse reactions to cow's milk proteins are usually indicated as cow's milk allergy/intolerance (CMPA/CMPI) because no differentiation is possible on the basis of symptoms, and there is no reliable single laboratory test available for the diagnosis of CMPA or CMPI. Elimination and challenge tests for cow's milk proteins using strict, well-defined diagnostic criteria are required for the diagnosis of CMPA/CMPI. Atopic dermatitis (AD) is one of the most common symptoms of CMPA/CMPI. Approximately one third of AD children have a diagnosis of CMPA/CMPI according to elimination diet and challenge tests, and about 40–50% of children <1 year of age with CMPA/CMPI have AD. Many children with AD and CMPA/CMPI develop a complete tolerance to CMP in a few years. Children with persisting forms of CMPA/CMPI have a more frequent history of familial atopic disease, change in CMPA/CMPI manifestations over time and very high frequency of multiple food intolerance and allergic diseases. Many children who outgrow their AD develop other allergic diseases, such as rhinitis or asthma. The simultaneous development of allergic tolerance in one organ and the intolerance or atopic disease in another organ suggest that genetic, immunologic and environmental factors play a complex role in the natural history of AD and other atopic diseases.     

Concurrent cereal allergy in children with cow''s milk allergy manifested with atopic dermatitis

BACKGROUND: There is increasing consensus about the significance of food allergens in the pathogenesis of atopic dermatitis (AD) in infancy and childhood, with cow's milk and egg accounting for most of the reactions. Previous studies have indicated that multiple food sensitization, such as cereals, is very common in patients with cow's milk allergy (CMA). Evidence is lacking, however, as to its clinical relevance. OBJECTIVE: The purpose of this study was to determine the concurrent occurrence of cereal allergy among children with challenge-proven CMA who have residual symptoms, such as AD and/or gastrointestinal symptoms, during cow's milk elimination diet. Further, we sought to evaluate the utility of patch testing in prescreening foods other than cow's milk behind allergic symptoms in children. METHODS: The study population comprised 90 children, aged from 2.5 to 36 months (mean 1.1 years), with challenge-proven CMA. As a result of residual symptoms during meticulous cow's milk elimination diet (AD: n=80, and gastrointestinal: n=10), the children were put on a cereal elimination diet (oats, wheat, rye, and barley) and skin prick tests (SPT) and patch testing with cereals were performed. Open cereal challenge was performed to confirm cereal allergy. RESULTS: Cereal challenge was positive in 66 (73%) of the children with CMA. Of them, 17% reacted with immediate reactions and delayed-onset reactions were seen in 83% of the children. SPT was positive in 23%, patch test in 67%, and either SPT or patch test was positive in 73% of the children with cereal allergy. SPT gave the best positive predictive value, whereas SPT together with patch test gave the best negative predictive value. CONCLUSIONS: Residual symptoms, such as eczema or gastrointestinal symptoms in CMA children may be a sign of undetected allergy to other food antigens. SPT with cereals aids in diagnosing cereal allergy in small children, especially when used together with patch testing.     

Natural course of cow's milk allergy in children with atopic dermatitis

Cow's milk is one of the most common food allergens in children with atopic dermatitis (AD). This study was conducted to describe the natural course of cow's milk allergy in children with AD, and to identify factors predictive of outcome. To accomplish this, we reviewed the medical records of 115 children who were diagnosed with AD and cow's milk allergy before 24 months of age to evaluate their clinical characteristics and prognostic factors. During a follow-up period of 24 to 114 months, the median age for tolerance to cow's milk was found to be 67 months. Multivariate analysis using the Cox proportional hazard model revealed that the peak cow's milk-specific IgE level within 24 months after birth was the most important factor for prediction of the outcome of cow's milk allergy. In conclusion, half of the children younger than 24 months of age with AD and cow's milk allergy could tolerate cow's milk at 67 months of age. The peak cow's milk-specific IgE level within the first 24 months of birth is useful to predict the prognosis of cow's milk allergy in children with AD.     

Severity of atopic dermatitis in relation to food and inhalant allergy in adults and adolescents

The aim of this study is the evaluation of the relationship between the severity of atopic dermatitis (AD) and the occurrence of IgE-mediated food allergy, food sensitization, and sensitization to inhalant allergens. The complete dermatological and allergological examinations were performed and the severity of AD was evaluated with the SCORing Atopic Dermatitis index. The statistical evaluation of the relationship between the occurrence of IgE-mediated food allergy, food sensitization, sensitization to inhalant allergens, and the severity of AD was performed. Two hundred and eighty-three patients were examined, 89 men and 194 women, average age 26.2 (s.d. 9.5). The significant relation was recorded between the severity of AD and sensitization to tested inhalant allergens. The significant relation was also found between the severity of AD and IgE-mediated food allergy. It turns out that the higher time to reaction, the higher the severity of AD.