Etiologic implication of foods in atopic dermatitis: evidence against

Atopic dermatitis is a typical chronic inflammatory skin disease that usually occurs in individuals with a personal or family history of atopy. Children with atopic dermatitis frequently present IgE-mediated food sensitization, the most commonly involved foods being egg and cow's milk. However, controversy currently surrounds whether food allergy is an etiological factor in atopic dermatitis or whether it is simply an associated factor, accompanying this disease as one more expression of the patient's atopic predisposition. Approximately 40 % of neonates and small children with moderate-to-severe atopic dermatitis present food allergy confirmed by double-blind provocation tests but this allergy does not seem to be the cause of dermatitis since in many cases onset occurs before the food responsible for allergic sensitization is introduced into the newborn's diet.Studies of double-blind provocation tests with food in patients with atopic dermatitis demonstrate mainly immediate reactions compatible with an IgE-mediated allergy. These reactions occur between 5 minutes and 2 hours and present mainly cutaneous symptoms (pruritus, erythema, morbilliform exanthema, wheals) and to a lesser extent, digestive manifestations (nausea, vomiting, abdominal pain, diarrhea), as well as respiratory symptoms (wheezing, nasal congestion, sneezing, coughing). However, these reactions do not indicate the development of dermatitis.Some authors believe that responses to the food in provocation tests may also be delayed, appearing mainly in the following 48 hours, and clinically manifested as exacerbation of dermatitis. However, delayed symptoms are difficult to diagnose and attributing these symptoms to a particular foodstuff may not be possible.Delayed reactions have been attributed to a non-IgE-mediated immunological mechanism and patch tests with food have been proposed for their diagnosis. In our experience and in that of other authors, the results of patch tests with cow's milk do not seem very specific and could be due, at least in part, to the irritant effect of these patches on the reactive skin of children with atopic dermatitis.The involvement of foods in atopic dermatitis will always be difficult to demonstrate given that an exclusion diet is not usually required for its resolution. Food is just one among several possible exacerbating factors and consequently identification of its precise role in the course of the disease is difficult. Further double-blind prospective studies are required to demonstrate the effectiveness of exclusion diets in the treatment of atopic dermatitis.Apart from the controversy surrounding the etiological role of foods, the most important point in atopic dermatitis is to understand that the child is atopic, that is, predisposed to developing sensitivity to environmental allergens; in the first few years of life to foods and subsequently to aeroallergens. Consequently, possible allergic sensitization to foods should be evaluated in children with atopic dermatitis to avoid allergic reactions and to prevent the possible development of allergic respiratory disease later in life.     

Quoi de neuf en allergologie pédiatrique en 2005 ? Partie 4. Allergie cutanée,alimentaire, médicamenteuse et aux insectes (Une revue de la littérature internationale d'octobre 2004 à octobre 2005)

Allergological work-up and treatment of french children with atopic dermatitis have been the subject of a recent consensus. Food avoidance is useless for prevention of atopic dermatitis, and should be indicated in children with severe atopic dermatitis associated with food allergy only. Exposure, sensitization and allergy rates to nuts increase with age, and avoidance of nuts (even tolerated) is recommended in young children allergic to one or several nuts to prevent the risk of sensitization and allergy to an increasing number of nuts. Threshold values of skin prick-tests and specific IgE determinations with a 90-100% predictive value for food allergy are highly variable from one study to another one, and depend on numerous factors such as age of the children, the allergens used, etc. The diagnostic value of patch-tests and skin application food tests remains controversial. Treatment of food allergy is based on the eviction of the allergenic foods. However, probiotics and « desensitization » to foods may be efficacious in some patients. In children that have outgrown their food allergy, tolerance should be maintened by regular consumption of the foods. However, the parents should be informed that relapses requiring an emergency treatment may occur. Finallly, in children as in adults, repeated mosquito bites induce a desensitization, and most children outgrow their allergy between five to fourteen years.     

Japanese Guideline for Food Allergy 2014

A food allergy is defined as "a phenomenon in which adverse reactions are caused through antigen-specific immunological mechanisms after exposure to given food."Various symptoms of food allergy occur in many organs. Food allergies are classified roughly into 4 clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type food allergy (urticaria, anaphylaxis, etc.), and (4) food dependent exercise-induced anaphylaxis and oral allergy syndrome (i.e., specific forms of immediate food allergy).The therapy for food allergies includes treatment of and prophylactic measures against hypersensitivity such as anaphylaxis. A fundamental prophylactic measure is the elimination diet. However, elimination diets should be used only if necessary because of the patient-related burden. For this purpose, it is very important that causative foods be accurately identified. There are a number of means available to identify causative foods, including the history taking, a skin prick test, detection of antigen-specific IgE antibodies in the blood, the basophil histamine release test, the elimination diet test, and the oral challenge test, etc. Of these, the oral challenge test is the most reliable. However, it should be conducted under the supervision of experienced physicians because it may cause adverse reactions, such as anaphylaxis.     

Intérêt des tests épicutanés dans la dermatite atopique du nourrisson

The diagnostic workup of allergy is adapted to the age of the child, the clinical features and the suspected allergen. Patch tests investigate delayed hypersensitivity and so theoretically they are indicated in atopic dermatitis of the infant. Nevertheless, not all cases of atopic dermatitis are allergic in origin. Patch tests are recommended in the infant with moderate to severe atopic dermatitis which recurs with topical corticosteroids and in particular circumstances revealed by the history. Elimination procedures in accordance with the results of the allergological investigation always result in improvement in the infant with atopic dermatitis and may modify the natural history of the condition. In the absence of a reference test such as challenge tests in food allergy, the positivity of patch tests is always correlated with their clinical relevance. Patch tests are carried out for contact allergens, inhalant allergens and foods. The food extracts used for these tests should be standardized to allow routine use. Studies are currently being carried out to validate the use of a simplified patch test series in the infant.     

Japanese Guideline for Food Allergy

Food allergy is defined as “a phenomenon in which adverse reactions (symptoms in skin, mucosal, digestive, respiratory systems, and anaphylactic reactions) are caused in living body through immunological mechanisms after intake of causative food.”Various symptoms of food allergy occur in many organs. Food allergy falls into four general clinical types; 1) neonatal and infantile gastrointestinal allergy, 2) infantile atopic dermatitis associated with food allergy, 3) immediate symptoms (urticaria, anaphylaxis, etc.), and 4) food-dependent exercise-induced anaphylaxis and oral allergy syndrome (i.e., specific forms of immediate-type food allergy).Therapy for food allergy includes treatments of and prophylactic measures against hypersensitivity like anaphylaxis. A fundamental prophylactic measure is the elimination diet. However, elimination diets should be conducted only if they are inevitable because they places a burden on patients. For this purpose, it is highly important that causative foods are accurately identified. Many means to determine the causative foods are available, including history taking, skin prick test, antigen specific IgE antibodies in blood, basophil histamine release test, elimination diet test, oral food challenge test, etc. Of these, the oral food challenge test is the most reliable. However, it should be conducted under the supervision of experienced physicians because it may cause adverse reactions such as anaphylaxis.     

Food allergy and the respiratory tract

Previous studies have confirmed that IgE-mediated, food allergy-induced respiratory tract symptoms occur, typically accompanied by cutaneous or gastrointestinal symptoms. The possibility that respiratory tract symptoms are food allergy induced should be considered in patients who have a current or past history of one or more of the following: atopic dermatitis, wheezing (or experiencing anaphylactic symptoms) after ingesting a particular food or foods, and confirmed food allergy. Moreover, the work-up of food allergy in asthma should be considered in patients in whom asthma is poorly controlled despite persistent use of appropriate asthma medications. A definitive diagnosis of food allergy should be based on clinical history, appropriate laboratory testing, and, when indicated, well-controlled oral food challenges. Treatment is based on establishing a safe elimination diet and an emergency plan for managing reactions caused by accidental ingestion.     

Specific IgE to Common Food Allergens in Children with Atopic Dermatitis

Background: Atopic dermatitis is a major public health problem, often starting in early childhood and sometimes followed by other allergic diseases. Although hypersensitivity to foods is assumed to play an essential role in the development of atopic dermatitis in some patients, little is known about common food allergens in Iranian children with atopic dermatitis. Objectives: This study was designed to identify probable food allergens in Iranian children with atopic dermatitis and find the relationship between food sensitization and the severity of atopic dermatitis. Methods: This study included 90 children aged 2-48 months with atopic dermatitis. Skin prick tests for cow's milk, hen's egg, almond, potato and soybean were done. Serum specific IgE to 20 food allergens was also screened. Results: Among children with atopic dermatitis, the frequency of food sensitization was 40% by skin prick test and 51% by food-specific IgE. Children with atopic dermatitis were most commonly sensitized to cow's milk (31%), hen's egg (17.7%), tree nuts (17.7%), wheat (12.2%), potato (11.1%), tomato (8.8%) and peanut (8.8%). In 42 children with moderate to severe eczema, sensitivity to food allergens was 78.5% by skin prick test and 88% by serum specific IgE evaluation. Conclusion: Our results showed that cow's milk, hen's egg and tree nuts were the most common food allergens in Iranian children with atopic dermatitis. Sensitization to foods was much higher in patients with moderate to severe atopic dermatitis. Determining specific IgE in children with atopic dermatitis can be helpful in managing these patients.     

Recent advancement to prevent the development of allergy and allergic diseases and therapeutic strategy in the perspective of barrier dysfunction

Therapeutic strategy in late 20th century to prevent allergic diseases was derived from a conceptual framework of allergens elimination which was as same as that of coping with them after their onset. Manifold trials were implemented; however, most of them failed to verify the effectiveness of their preventive measures. Recent advancement of epidemiological studies and cutaneous biology revealed epidermal barrier dysfunction plays a major role of allergen sensitization and development of atopic dermatitis which ignites the inception of allergy march. For this decade, therapeutic strategy to prevent the development of food allergy has been confronted with a paradigm shift from avoidance and delayed introduction of allergenic foods based on the theoretical concept to early introduction of them based on the clinical and epidemiological evidences. Especially, prevention of peanut allergy and egg allergy has been established with the highest evidence verified by randomized controlled trials, although application in clinical practice should be done with attention. This paradigm shift concerning food allergy was also due to the discovery of cutaneous sensitization risk of food allergens for an infant with eczema revealed by prospective studies. Here we have recognized the increased importance of prevention of eczema/atopic dermatitis in infancy. Two randomized controlled trials using emollients showed successful results in prevention of atopic dermatitis in infancy; however, longer term safety and prognosis including allergy march should be pursued. To establish more fundamental strategy for prevention of the development of allergy, further studies clarifying the mechanisms of interaction between barrier dysfunction and microbial milieu are needed with macroscope to understand the relationship between allergic diseases and a diversity of environmental influences.     

Common respiratory manifestations of food allergy: A critical focus on otitis media

Previous investigations have established the pathogenic role of food allergy in respiratory tract symptoms, which rarely occur in isolation. Specific foods have been implicated in these reactions. The role of food allergy in otitis media is controversial, probably uncommon, and further studies are needed. Food-induced asthma is more common in young pediatric patients, especially those with atopic dermatitis. Asthma induced by food allergy is considered a risk factor for fatal and near-fatal anaphylactic reactions. Moreover, food allergy can elicit airway hyperreactivity and asthmatic responses. Therefore, evaluation for food allergy should be considered among patients with recalcitrant or otherwise unexplained acute severe asthma exacerbations; asthma triggered by ingestion of particular foods; and asthma and other manifestations of food allergy (eg, anaphylaxis, moderate to severe atopic dermatitis).     

Quoi de neuf en allergologie pédiatrique en 2004 ? Partie 3 : allergie cutanée,alimentaire, médicamenteuse et aux venins d'insectes (Une revue de la littérature internationale d'octobre 2003 à septembre 2004)

Severity and risk of persistence/relapse of atopic dermatitis are correlated with total IgE levels and food sensitization. Weaning to hypoallergenic formula improves SCORAD and gut barrier function in breastfed infants with persistent atopic dermatitis. Risk of anaphylaxis is high in children with cold-induced urticaria, and these children should be provided with an epinephrine autoinjector. Occult sensitizations are important risk factors for food allergy. The predictive values of serum egg-specific IgE levels are debated. The diagnostic value of atopy patch-tests with foods is confirmed in children with non-immediate food hypersensitivity reactions. Risk of persistence of food allergy is high in children with high specific IgE levels and/or with a low rate of decrease in food-specific IgE levels. Oral desensitization induces tolerance in children with persistent cow's milk allergy, except for children with very high levels of specific IgE. However, tolerance to anaphylactogenic food may be temporary, with the occurence of severe relapses after a few months. Ten per cent of children treated with penicillins are sensitized to these antibiotics. However, only a few of these children are at risk of developing allergy to penicillins. Non allergic hypersensitivity to non steroidal anti-inflammatory drugs is frequent in children. Sublingual immunotherapy may be efficient in children with latex hypersensitivity. A clinically important number of non-hyposensitized children do not outgrow hymenoptera venom allergy. In contrast, venom immunotherapy leads to a significantly lower risk of systemic reaction to stings. Thus, children with moderate to severe allergic reactions to hymenoptera stings should receive specific immunotherapy.     

Troubles des conduites alimentaires et allergies alimentaires

Many eating disorders are observed in food allergy practice. It is common to see patients avoiding many foods because they have been poorly informed of cross-reactions that are not clinically relevant. For children, parental anxiety may multiply irrational avoidance. The diagnosis of Münchausen syndrome by proxy should be envisaged, although it is rare. Abnormal eating behavior in children can be related to a Pavlovian reaction of disgust, to anxiety or depression, a perturbed relationship with the mother or simply due to an aversion to new foods. In adults, food avoidance is linked to poor interpretation of positive laboratory tests indicating cross-reactions that are clinically irrelevant. Irritable bowel syndrome results in food avoidance even where food allergy is poorly documented. Fibromyalgia also leads to unnecessary avoidance diets. True neurosis (obsession and anxiety neurosis) may occur. Patients taking alternative medicines or belonging to certain sects often follow aberrant avoidance diets. All patients should undergo a nutritional evaluation. Psychologists, psychiatrists and dieticians should also be involved in treatment. Allergists should not limit themselves to simply eliminating food allergy to a given food allergy, but should make patients aware that problems arise from “not” eating different foods. Accurate tests, detailed information and careful monitoring of proposed changes in diet should result in more rational eating habits. Established neurosis will not improve, since patients are in denial about these disorders, psychiatrists know little about them.     

Quoi de neuf en allergologie pédiatrique en 2000 ?Revue de la littérature internationale dˈoctobre 1999 à octobre 2000

The relation between maternal and childhood atopy may result from an increased intrauterine Th2 environment and high levels of Th2 cytokines in the milk of atopic mothers. The value of in vitro tests for early prediction of atopy is low, but high levels of eosinophil-derived proteins in nasal secretions of neonates may predict respiratory allergy. The prevalence of respiratory allergy has decreased in children living in rural areas, especially on farms. This may be related to exposure to mycobacterias, but the development of allergic conditions is independent of tuberculin reactivity and history of tuberculosis infection; however, the prevalence of asthma is decreased in young adults infected by Mycobacterium tuberculosis during childhood. High levels of eosinophils in the blood of children with bronchiolitis predict the development of persistent wheezing and asthma. Inhaled, oral and intravenous corticosteroids do not prevent relapses of bronchiolitis and persistent wheezing, but early hyposensitization has long-term beneficial effects on asthmatic symptoms. Results of prick-tests and specific IgE determinations are correlated with the severity of food allergy, and several studies confirm the diagnostic value of patch-tests with foods in children with atopic dermatitis associated with food allergy. Interesting cases of unexpected food allergies are reported (carob-induced anaphylaxis, and exercise-induced anaphylaxis to snails). Finally, children with spina bifida demonstrate a progressive sensitization to latex, in spite of a latex-free environment after the first surgical procedure(s), and the gelatin included in vaccines is highly immunogenic and allergenic.     

Japanese guidelines for food allergy 2020

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.     

Japanese guidelines for food allergy 2017

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.     

Management of atopic dermatitis: practical guidelines suggested by the conclusion of systematic assessment in 500 children

Allergic management of AD may be worthwhile since allergy may trigger the disease. A systematic evaluation of sensitizations overtime and study of their clinical involvement in 500 children with AD was carried out, including minor, moderate, and severe patients (defined by clinical scores). Standardized methods assessed the possibility of contact dermatitis as well as IgE dependant allergies. Contact dermatitis concerned fragrances and nickel. Contact dermatitis was observed in minor and moderate AD with a progressive increase: 11% of children under 2 years and 58% in those over 15 years of age. Later in older children, sensitization to cosmetics and occupational allergens occurred in close connection with the specific environment. As for IgE sensitization, investigation should be electived advised in moderate and severe AD. Inhalant allergen sensitization was observed in 66% in moderate AD and 93% in severe AD in the group of 7 or 15 years. Clinical confrontation was a better indicator of cutaneous involvement than atopen patch-test. It mainly concerned respiratory symptoms. In severe AD, food allergy was constantly observed and presented as a marker for severe atopic dermatitis. The main trophallergen differ according to the age and cultural habits: in children under 2 years of age, eggs, peanuts, milk, fish were the main offending agents. Later, main trophallergens were wheat flour, shellfish. Although spontaneous decrease of food allergy is sometimes observed, it must be pointed out that food allergy may still persist as a triggering factor in teenagers as well as in adult-hood. The allergologic diagnosis of atopic dermatitis should not focus on IgE dependent sensitization without patch testing.     

Quoi de neuf en allergologie pédiatrique en 2006-2007 ? Partie 3: Allergie cutanée, alimentaire, médicamenteuse et aux insectes (une revue de la littérature internationale d’octobre 2005 à septembre 2007)

Most sensitizations in children with atopic dermatitis are non pathogenic. Thus, responses in prick-tests, specific IgE determinations and patch-tests should be carefully evaluated based on the clinical history of the children or responses in challenge tests. Moreover, although atopy patch-tests are highly specific, they have a low sensitivity. Food eviction is indicated in a few children only, since they may be responsible for anaphylactic reactions induced by accidental ingestion of the food or oral challenge tests. The predictive value of serum specific IgE to foods depends on the food investigated, the age of the children, their allergic disease (atopic dermatitis, urticaria/angioedema, anaphylaxis) and, may be, on their ethnical origin. The prevention of food-induced severe reactions is based on eviction. However, several studies suggest that oral desensitization to foods may be efficient. Most frequent reactions in children hypersensitive to antalgics, antipyretics and nonsteroidal antiinflammatory drugs are oedema (facial oedema especially) and urticaria. Usually, the severity of the reactions increases from one treatment to another one and with the dose of drug administered to the children. Diagnosis is based on a convincing clinical history or on challenge tests. Skin tests with vaccines should be performed according to a standardized procedure because they may give false positive responses. Most latex sensitizations detected by skin prick-tests and, especially, specific IgE determinations are non pathogenic. The prevention of reactions to latex is based on eviction. However, preliminary results suggest that sublingual desensitization with a latex extract is efficient and well-tolerated.     

Elimination diet in the treatment of selected patients with hypersensitivity vasculitis.

We have evaluated the effects of an elimination diet in 5 patients with hypersensitivity vasculitis and a personal or family history of allergy. The presence of autoimmune disorders, infections and neoplastic diseases was excluded on the basis of physical examination, clinical history and laboratory data. Three patients had elevated serum immune complexes and evidence of complement consumption before the oligoantigenic diet. In one patient food allergy was diagnosed on the basis of a positive and concordant challenge test, skin prick test and RAST. The study consisted of a 3 week elimination diet, followed by open and double blind challenge tests with specific foods and additives. Four patients achieved a complete remission and one patient experienced great improvement on the elimination diet. In three cases the vasculitis relapsed following the introduction of food additives; in one case with the addition of potatoes and green vegetables (i.e., beans and green peas) and in the last case with the addition of eggs to the diet. The offending foods and additives were subsequently eliminated from the usual diet and no relapses were observed in 2 years of follow-up. These results show that in selected patients with a history of allergy, hypersensitivity vasculitis can be triggered and sustained by food antigens or additives.     

Phenotypes of IgE-mediated food allergy in Turkish children

Data on food allergy-related comorbid diseases and the knowledge on factors associating specific food types with specific allergic outcomes are limited. The aim of this study was to determine the clinical spectrum of IgE-dependent food allergy and the specific food-related phenotypes in a group of children with IgE-mediated food allergy. Children diagnosed with IgE-mediated food allergy were included in a cross-sectional study. IgE-mediated food allergy was diagnosed in the presence of specific IgE or skin-prick test and a consistent and clear-cut history of food-related symptoms or positive open provocation test. Egg (57.8%), cow's milk (55.9%), hazelnut (21.9%), peanut (11.7%), walnut (7.6%), lentil (7.0%), wheat (5.7%), and beef (5.7%) were the most common food allergies in children with food allergy. The respiratory symptoms and pollen sensitization were more frequent in children with isolated tree nuts-peanut allergy compared with those with egg or milk allergy (p < 0.001); whereas atopic dermatitis was more frequent in children with isolated egg allergy compared with those with isolated cow's milk and tree nuts-peanut allergy (p < 0.001). Children with food allergy were 3.1 (p = 0.003) and 2.3 (p = 0.003) times more likely to have asthma in the presence of allergic rhinitis and tree nuts-peanut allergy, respectively. Interestingly, children with atopic dermatitis were 0.5 (p = 0.005) times less likely to have asthma. Asthma (odds ratio [OR], 2.3; p = 0.002) and having multiple food allergies (OR, 5.4; p < 0.001) were significant risk factors for anaphylaxis. The phenotypes of IgE-mediated food allergy are highly heterogeneous and some clinical phenotypes may be associated with the specific type of food and the number of food allergies.     

Etiologic implication of foods in atopic dermatitis: evidence in favor

Some of the immunopathologic mechanisms involved in IgE responses are currently being identified; Th2 lymphocytes are known to be activated in patients with atopic dermatitis with subsequent production of the cytokines interleukin (IL)-4 and IL-5, which are responsible for IgE production and eosinophil recruitment. Nevertheless, T cell activation in this disease takes place in two phases. In the first phase, Th2 cells are activated and IL-4, IL-5 and IL-13 are produced; this first stage is produced with the initial activation induced by the antigen. In the second phase there are chronic lesions, Th1 lymphocytes are activated and IFg is produced. This chronic phase is associated with the presence of eosinophils and macrophages that produce IL-12.Numerous articles have demonstrated food sensitization to be an etiopathogenic factor in atopic dermatitis. The prevalence of sensitization varies, depending on the patient's age and the severity of the disease. Children with moderate-to-severe atopic dermatitis have been observed to have a positive skin test and high IgE concentrations to various foods. Nevertheless, a positive skin test to foods in such children does not always implicate these foods as the cause of the clinical manifestations; moreover, in children showing subsequent tolerance to these foods, skin tests can sometimes remain positive and high levels of specific IgE can persist. It is now known that IgE not only participate in the degranulation of mastocyte cells but also in reactions mediated by T cells and other antigen-presenting cells (dendritic cells) which have high-affinity receptors for IgE.The immediate IgE response is well known but it is also known that in addition to the immediate response, a delayed response is also involved, evidenced by the presence of antigen-specific T cells to foods or other allergens such as inhalant allergens. After a strict exclusion diet, children with atopic dermatitis and sensitivity to foods such as milk, egg, flour and soya can develop tolerance; for this reason provocation tests with the food in question should be repeated every 2-3 years. In children with sensitivity to other foods such as dried fruits, fish, and shellfish, sensitivity can sometimes persist into adulthood without tolerance being achieved. In conclusion, there are two groups of children with atopic dermatitis. One group consists of those with atopic dermatitis (allergic disease), which is characterized by early development, high IgE titers, the presence of antigen-specific IgE to allergens and a family history of atopy and which is clinically moderate or severe. Early diagnosis and treatment are important in these children, as is the prevention of progression of the disease to bronchial asthma. The other group consists of children whose dermatitis is clinically atopic in terms of its localization and morphology, who have no demonstrable allergic disease and whose management differs from that in children presenting allergic disease     

"Atopy patch tests" in the diagnosis of delayed food hypersensitivity

The prevalence of atopic diseases is increasing worldwide. Food allergies are the earliest manifestation of atopy. Atopic eczema affects about 18% of infants in the first 2 years of life and the main cause is allergy to multiple foods. A strong association has been shown between atopic eczema and IgE mediated allergy to milk, egg or peanut, but more than two-thirds of patients intolerant to food proteins have no evidence of IgE sensitization to the relevant food protein. Recently, patch testing with proteins has been found to be helpful in diagnosing food allergy in cases where skin prick tests and estimation of specific antibodies have failed. The methodology of atopy patch test (APT) is unstandardized, and contradictory results have been reported. In contrast to the more standardized APT methodology with aeroallergens, the sensitivities and specificities of food allergens can easily be estimated with food challenge tests. With multiallergic children adding of APTs to the skin prick tests and specific antibody estimation tests give more information for planning a wide enough elimination diet to get the skin and gastrointestinal tract symptomless in order to perform the challenge test which remains the only reliable test for food allergy. Standardization of the APT materials and reading procedure will add to the reliability of this new test method.