Frequent Food Allergens Research Articles

Point-of-care personalized rapid diagnosis of allergies using peptide epitopes and SPR multiplexed detection

Allergy is the most common chronic disease in Europe. Up to 20 % of patients with allergies live with a severe debilitating form of their condition, struggling with the fear of a possible asthma attack, anaphylactic shock, or even death from an allergic reaction. Allergic reactions vary among different patients, due to the presence of different antibodies, which may also define the severity of the allergic reaction. Diagnostic tools are still suboptimal, as they require an oral food challenge for diagnostic, which is personnel, time, and cost consuming and bear the risk of severe allergic reactions for the patient. Also, there is a major gap in food allergy diagnosis to easily distinguish between sensitization and allergy. Therefore, a fast point-of-care multiplexed analytical platform for allergy assessment, supporting low-risk minimally invasive personalized diagnostics and treatment monitoring is advanced. The novel portable Surface Plasmon Resonance system integrates microfluidics and a low-fouling, multiple-ligand biosensor based on recently identified peptide epitopes for appraising allergen-specific serum antibodies. Aiming at personalized diagnosis of allergy, we successfully tested and validated the platform on hazelnuts and peanuts, two of the most threatening and frequent food allergens. Moreover, in contrast to the conventional SPR analysis and ELISA, by using an innovative analysis of the entire sensing area where the peptides are immobilized, it was even possible to discern different sera related to the same allergen.

Public health aspects of food allergy and food intolerance: Literature review

Aim of the paper was to make a review of available evidence for food allergies and food intolerance, to make a distinction between allergy and intolerance, and to emphasize the current knowledge about the prevalence and preventive measures. We made a search through PubMed and Google scholar, using the search terms "food", "allergy", "intolerance", "prevalence", "prevention" and "measures" for the period from 2000 to 2020, in order to find appropriate papers and publications. Food intolerance is defined as a non-immunological reaction to certain natural food ingredients or food additives that causes pharmacological, metabolic and gastro-intestinal reactions to food or food compounds. Food allergy is defined as an immune-mediated reaction to food, that is almost always mediated by immunoglobulin E (IgE). The worldwide prevalence of IgE-mediated allergic reactions is not exactly known. It is believed that about 1-2% of adults and between 5-7% of the children suffer from some type of food allergy and this number is growing. The most frequent specific food allergens are eggs, fish, peanuts, nuts, cow's milk, cereals containing gluten, (such as wheat, rye, barley, oats) seafood, soybeans, sesame, celery and mustard. Food intolerance can sometimes be controlled by limiting the amount of a certain type of food that is consumed, but when it comes to food allergies, much stricter avoidance of the food is required. Only food allergy, not food intolerance, can lead to a potentially fatal anaphylaxis reaction. In order to avoid food allergy, it is necessary to label the products for the presence of allergens.

Food-induced anaphylaxis in early childhood and factors associated with its severity.

Background: Several factors that increase the risk of severe food-induced anaphylaxis have been identified. Objective: We aimed to determine the demographic, etiologic, and clinical features of food-induced anaphylaxis in early childhood and also any other factors associated with severe anaphylaxis. Methods: We carried out a medical chart review of anaphylaxis cases from 16 pediatric allergy and immunology centers in Turkey. Results: The data of 227 patients with 266 food-induced anaphylaxis episodes were included in the study. The median (interquartile range) age of the first anaphylaxis episode was 9 months (6-18 months); 160 of these patients were boys (70.5%). The anaphylaxis episodes were mild in 75 cases (28.2%), moderate in 154 cases (57.9%), and severe in 37 cases (13.9%). The most frequent food allergens involved were cow's milk (47.4%), nuts (16.7%), and hen's egg (15.8%). Epinephrine was administered in only 98 (36.8%) of these anaphylaxis episodes. A logistic regression analysis revealed two statistically significant factors that were independently associated with severe anaphylaxis: the presence of angioedema and hoarseness during the anaphylactic episode. Urticaria was observed less frequently in patients who developed hypotension. In addition, confusion and syncope were associated with 25.9- and 44.6-fold increases, respectively, in the risk of concomitant hypotension. Conclusion: Cow's milk, nuts, and hen's egg caused the majority of mild and moderate-to-severe anaphylaxis episodes. The presence of angioedema and hoarseness in any patient who presents with a history of food-induced anaphylaxis should alert clinicians that the reaction may be severe. In addition, the presence of confusion, syncope, or stridor probably indicates concomitant hypotension.

Oral food challenge in IgE mediated food allergy in eastern Mediterranean children.

The oral food challenge (OFC) in IgE mediated food allergy causes anxiety both in parents and in patients due to its inherent risks. Documentation of the rate, spectrum, and predictors of positive reactions is instructive. Children, who underwent OFC between January 1, 2017 and December 31, 2019 were analyzed. A total of 1361 OFCs in 613 cases were reviewed. Most of them were performed in preschool children (≤2 years 50%) and 55% of them had more than one OFC. Mainly considered food groups were cow's milk (31.8%), hen's egg (28.5%), tree nuts (20%), legumes (7%), seeds (4.9%), and wheat (2.7%). The overall OFC positivity was 9.6%, whereas 6.7% with cow's milk, 4.9% with hen's egg, 16.1% with tree nuts, 21.6% with wheat, and 32.8% with seeds. The severity scoring revealed grade I (24.4%), II (45.8%), and III (29.7%) reactions. Fifty (38%) cases required epinephrine and four cases required hospitalization. OFCs with sesame seeds (odds ratio [OR]: 7.747, [confidence interval (CI) 95%: 4.03-14.90]), wheat (OR: 3.80, [CI: 1.64-8.84]), and tree nuts (OR: 2.78, [CI: 1.83-4.23]) predicted a positive OFC while a concomitant asthma (OR: 3.61 [CI: 1.27-10.28]) was more likely to elicit anaphylaxis. In OFC practice, priority is given to basic nutritional sources and the most frequent food allergens, where preschool children with multiple sensitizations are the primary subjects. Increased risks of positive reactions with sesame, tree nut, and wheat and increased risk of anaphylaxis with concomitant asthma should be considered while performing OFC.

Most frequent food allergens and prevalence of food allergy IgE mediated by parental report in schoolchildren in Santa Fe city

Introduction: food allergy (FA) is an immune disorder triggered by the ingestion of an allergen food, whose symptoms are specific and reproducible. Although in developed countries the prevalence of FA has been documented in 6-8% of the child population, data from the most of Latin American countries remain unknown. Objectives: to evaluate the prevalence of FA immunoglobulin E (IgE) mediated by parental report and to determine the most frequent food allergens in schoolchildren from 5 to 14 years of the city of Santa Fe, Argentina, in 2018. Materials and methods: a cross-section quantitative, descriptive, observational, retrospective study was performed collecting data by using a validated survey in Argentine Spanish to determine the most frequent food allergens and FA prevalence among schoolchildren. The sample consisted of 4,059 schoolchildren from nine schools; 1,493 schoolchildren returned the questionnaire (response rate of 36.78%) and 1,431 were considered as valid. Results: the prevalence of FA IgE mediated by parental report in schoolchildren from 5 to 14 years of age was 5.03%. The most frequently reported allergenic foods in this population were chocolate (23.58%), chilli and milk (both 16.04%). Conclusions: the prevalence of FA IgE mediated by parental report in schoolchildren was 5.03%. The most frequently reported allergenic foods in schoolchildren were chocolate, chilli and milk. Correct identification of FAs is important to avoid unnecessary exclusion of foods that can harm the growth and development of children, especially during the first years old. Key words: food allergy; schoolchildren; parental report.

Frequency and Pattern of IgE-mediated Sensitization to Aero and Food Allergens in Ahvaz, Province of Khuzestan in Southwestern Iran.

Efficient diagnosis of allergy and proper treatment need identification of the causative allergens eliciting clinical symptoms. The present study was performed to identify the most common aero- and food allergens and determine the pattern of sensitization among people of Ahvaz (southwestern Iran), one of the most polluted cities worldwide. Based on the physical examination and medical records, patients were referred to the Allergy laboratory for "in vitro" IgE determination. Specific and total IgE was determined by the ImmunoCAP system (Thermo Fisher-Phadia, Uppsala, Sweden). A total of 666 consecutive patients (51.1% female) were tested for 202 different allergens. The majority of requests (57%) belonged to food allergens. Sensitization to at least one allergen was found in 47.6% of patients. In a selected group of allergens for which specific IgE had been tested in at least 100 patients, the most common sensitizing aeroallergens were Russian thistle, grass pollen, and willow; while wheat, honey, and shrimp were the most frequent food allergens, respectively. Sensitization profiles based on measurement of specific IgE indicated that Russian thistle, grasses, and wheat were the most prevalent allergens in people with allergic symptoms living in Ahvaz.

Asthma, Eczema, and Food Allergy in Children Following Liver Transplantation

To describe the prevalence and the relationship between asthma, eczema, food allergy, and rhinitis in children after liver transplantation. Children who were liver transplant recipients were investigated to assess whether the high prevalence of food allergies was accompanied by eczema, rhinitis, and asthma. Furthermore, we included 56 children with chronic liver disease to explore the risk of allergy, eczema, and asthma in this group. After liver transplantation, children had higher prevalence of allergic reactions to food as compared with children with chronic liver disease (P < .001). Current asthma (P = .04) and eczema (P < .02) were observed more frequently in transplanted children as compared with children with chronic liver disease. For transplanted children who had ever received tacrolimus the relative risk (RR) of asthma was 1.7 (95% CI, 1.2-2.4; P = .02) as compared with children with chronic liver disease. Transplanted children with asthma had higher rates of sensitization to food allergens than those without asthma (RR, 3.6; 95% CI, 1.3-10.3; P = .01). The most frequent food allergens associated with asthma in transplanted children were milk (RR for asthma, 3.9; 95% CI, 1.6-9.4; P < .01), eggs (RR, 2.9; 95% CI, 1.2-7.0; P = .03), and peanuts (RR, 3.7; 95% CI, 1.6-8.3; P < .01). Food allergies occurred earlier than asthma, at 1.5 years after transplantation (IQR, 0.5-3.0 years) vs 2.5 years after transplantation (IQR, 1.0-4.5 years; P < .05). Food allergies were also associated with eczema, but not with sensitization to aero-allergens or rhinitis. The high risk of food allergies in children who were liver transplant recipients was associated with eczema and asthma, but not rhinitis. The most frequent food allergens associated with asthma were milk, eggs, and peanuts.

Evaluating the associations of race, ethnicity, and food allergens in the development of childhood asthma: Re-analysis of publicly available retrospective cross-sectional cohort data

Asthma is among the most prevalent chronic diseases affecting children worldwide. Sociodemographic factors, such as race and ethnicity, as well as food allergens and their association with asthma, have been extensively studied in an individual manner. Less is known about how food allergens can influence the effect of sociodemographic factors on childhood asthma prevalence. In this study, we re-analyzed a publicly available retrospective cross-sectional cohort dataset of childhood asthma. Multiple logistic regression of asthma by race and ethnicity, before and after adjustment by the most prevalent allergens, was implemented to the dataset. Hispanic individuals showed a higher odds risk (ORs; 1.30, CI 1.26 – 1.35) of asthma than Non-Hispanic individuals (0.24, CI 0.23 – 0.25), but after adjustment by most frequent food allergens reactivities (shellfish, peanut, and milk), the asthma odd risks were comparable (Hispanic, 3.62 [CI 3.49 – 3.76]; Non-Hispanic, 3.51 [3.47 – 3.52]). When considering race, Black individuals (1.90, CI 1.87 – 1.94) had higher ORs of asthma than White individuals (0.21, CI 0.20 – 0.22), Asian/Pacific Islander individuals (1.00, CI 0.95 – 1.05), and Other/Unknown races (1.14, CI 1.11 – 1.27). Although the ORs increased by three to four times for all races after adjusting for the most frequent food allergen reactivities, the same pattern of childhood asthma remained when considering races (in this order, Black, Other/Unknown, Asian/Pacific Islander, and White). In the dataset evaluated in this study, food allergens modified the association of race and ethnicity with the development of asthma. Therefore, public health interventions that gear towards the incidence of childhood asthma should contemplate the interplay and differences in nutrition among races and ethnicities.

Sensitization to food and inhalant allergens in healthy children in Van, East Turkey.

The purpose of this study was to determine the most frequent food and inhalant allergens leading to allergic sensitization in children in Van Province of Turkey. The study included 1052 serum samples with no diagnosis of allergy. The sera were tested with the Euroline Pediatric IgE test kit (EUROIMMUN, Germany). By using the EUROLineScan digital evaluation system, the intensity of bands was calculated with enzyme allergosorbent test classification. Out of the 1052 tested sera, 143 were found to be cross-reactive carbohydrate determinant-positive and were discarded from the study. Of the remaining 909 sera, 513 (56%) were from males and 296 (44%) were from females. Among the food allergens, specific IgE was most frequently found against codfish, potato, cow's milk, egg yolk, egg white, and rice, and among the inhalant allergens against cats, dogs, grass mix, Dermatophagoides pteronyssinus, and Aspergillus fumigatus, respectively. The finding of codfish being the most frequent allergen was related to the high consumption of trout in the region and endemicity of pearl mullet in Lake Van. The results obtained could contribute to determining the etiology of allergic diseases. Additionally, regular analysis of changes in allergen sensitization is important for prevention of allergic disease.

Simultaneous quantification of the food allergens soy bean, celery, white mustard and brown mustard via combination of tetraplex real-time PCR and standard addition

Abstract Food allergies are a significant public health concern throughout the world with various symptoms that range from mild to severe or even life-threatening. As the only option for the allergenic consumer is the strict avoidance of the allergenic food, in the European Union the declaration of the most frequent food allergens on the labels of products is required. However, traces of food allergens that may be present in foods due to cross-contact are not included in this regulatory provision. Therefore, thresholds above which labeling is mandatory are being discussed. The surveillance of such thresholds requires specific, sensitive and quantitative methods. For this purpose, a tetraplex real-time PCR method was established to quantify simultaneously trace amounts of the four allergens soy bean, celery, white and brown mustard. The quantification is achieved by using the standard addition method. The approach was validated with DNA extracted from lysate mixtures of boiled sausage and the standard materials at concentration levels of 1, 5, 10, 20, 40, 100 and 400 mg/kg. The parameters recovery, repeatability and robustness were evaluated and the limits of quantification of soy bean (8.5 mg/kg), brown mustard (2.6 mg/kg), celery (3.7 mg/kg) and white mustard (36.8 mg/kg) were determined. The method was applied to commercial food products labeled with one or more of the analytes or with a “may contain traces of …” statement.

Structural changes induced by heating affect ovalbumin-antigen processing and reduce allergic response in mouse model of food allergy

Background Food allergy is a serious health concern affecting about 8% of young children and about 3% of adults. The egg protein ovalbumin belongs among six frequent food allergens. Our goal was to develop the mouse model of ovalbumin food allergy and investigate how thermal processing affects its ability to induce allergic responses. Methods Effect of thermal processing (70°C and 95°C) on an ovalbumin secondary structure was characterized by circular dichroism and by kinetics of pepsin digestion with subsequent HPLC analysis. BALB/c mice were sensitized intraperitoneally and challenged intragastrically with native form or thermal processed ovalbumin (70°C). Clinical symptoms (allergic diarrhea, weight and temperature) were observed during the mice challenging. Levels of allergen-specific serum antibodies were determined by ELISA (IgA, IgG1 and IgG2a) by beta-hexosaminidase release test (IgE). Cytokine production (IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, IFN-gamma) and mast cell protease-1 activity were assessed by ELISA. The activities of brush-border hydrolases were determined in the jejunum of treated mice. Results Heating of ovalbumin caused slight irreversible changes in secondary structure and significantly decreased clinical symptoms (allergic diarrhea). The thermal processing also decreased immune allergic response on the level of IgE, IL-4, IL-5, IL-13. Furthermore, thermal-processed ovalbumin induced lower activities of serum mast cell protease-1 and enterocyte brush border membrane alkaline phosphatase as compared to native ovalbumin. On the other hand, thermal-processed ovalbumin stimulated higher IgG2a antibodies in sera and IFN-gamma secretion by splenocytes. Conclusion In our mice model of food allergy, we show that even a slight change in the secondary structure of ovalbumin after thermal processing reduces its allergenicity and induces shift towards Th1 immune responses. At present, we utilize this model for studying of food allergy in germfree mice.

Diagnosis of Food Allergy

Diagnosis of food allergy can be challenging. Given the limited specificity of available allergy tests, these need to be interpreted in light of pre-test probability that is determined by a careful history. Using likelihood ratios calculated from previous publication may allow a more individualized assessment. This approach is likely to be most useful in patients with low to moderate results, below the 95% positive predictive value for that food. This review covers the diagnostic approach of immunoglobulin E-mediated food allergy. We first focus on the pre-test clinical assessment of a patient with a suspected food allergy. We then compare currently available diagnostic tests and discuss their performance for frequent food allergens. Finally, we conclude with the interpretation of allergy tests in light of the pre-test assessment to determine final probability of food allergy and indications for referral to an allergy specialist for food challenge.

Heat-Induced Structural Changes Affect OVA-Antigen Processing and Reduce Allergic Response in Mouse Model of Food Allergy

Background and AimsThe egg protein ovalbumin (OVA) belongs to six most frequent food allergens. We investigated how thermal processing influences its ability to induce allergic symptoms and immune responses in mouse model of food allergy.Methodology/Principal FindingsEffect of increased temperature (70°C and 95°C) on OVA secondary structure was characterized by circular dichroism and by the kinetics of pepsin digestion with subsequent HPLC. BALB/c mice were sensitized intraperitoneally and challenged with repeated gavages of OVA or OVA heated to 70°C (h-OVA). Levels of allergen-specific serum antibodies were determined by ELISA (IgA and IgGs) or by β-hexosaminidase release test (IgE). Specific activities of digestive enzymes were determined in brush border membrane vesicles of jejunal enterocytes. Cytokine production and changes in regulatory T cells in mesenteric lymph nodes and spleen were assessed by ELISA and FACS. Heating of OVA to 70°C caused mild irreversible changes in secondary structure compared to boiling to 95°C (b-OVA), but both OVA treatments led to markedly different digestion kinetics and Tregs induction ability in vitro, compared to native OVA. Heating of OVA significantly decreased clinical symptoms (allergic diarrhea) and immune allergic response on the level of IgE, IL-4, IL-5, IL-13. Furthermore, h-OVA induced lower activities of serum mast cell protease-1 and enterocyte brush border membrane alkaline phosphatase as compared to native OVA. On the other hand h-OVA stimulated higher IgG2a in sera and IFN-γ secretion by splenocytes.ConclusionsMinor irreversible changes in OVA secondary structure caused by thermal processing changes both its digestion and antigenic epitopes formation, which leads to activation of different T cell subpopulations, induces shift towards Th1 response and ultimately reduces its allergenicity.

IgE-mediated food allergies in Swiss infants and children

To determine the most frequent food allergens causing immediate hypersensitivity reactions in Swiss children of different age groups and to investigate the clinical manifestation of IgE-mediated food allergies in young patients. The study was a prospective analysis of children referred for assessment of immediate type I food hypersensitivity reactions. The diagnostic strategy included a careful history, skin prick tests with commercial extracts and native foods, in vitro determination of specific IgE to food proteins and food challenges when appropriate. A total of 278 food allergies were identified in 151 children with a median age of 1.9 years at diagnosis. Overall, the most frequent food allergens were hen's egg (23.7%), cow's milk (20.1%), peanut (14.0%), hazelnut (10.4%), wheat (6.1%), fish (4.3%), kiwi and soy (2.2% each). In infancy, cow's milk, hen's egg and wheat were the most common allergens. In the second and third year of life however, the top three food allergens were hen's egg, cow's milk and peanut, whereas above the age of 3 years, peanut was number one, followed by hen's egg and fish. Overall, urticaria (59.0%) and angioedema (30.2%) were the most frequent clinical manifestations. Gastrointestinal symptoms were found in 25.9% and respiratory involvement in 25.2%. There were 13 cases (4.7%) of anaphylaxis to peanut, fish, cow's milk, hen's egg, wheat and shrimps. A total of eight allergens account for 83% of IgE-mediated food allergies in Swiss infants and children, with differences in the distribution and order of the most frequently involved food allergens between paediatric age groups.

Epidemiology of food allergy in European infants

The prevalence and causes of food allergy in Europe is still unclear. Individual studies show very different data. Within the EU-funded collaborative translational research project EuroPrevall, a meta-analysis was performed to assess the prevalence of food allergy. The foods assessed were cow’s milk, hen’s egg, peanut, fish, shellfish, and an overall estimate of food allergy. The prevalence of self-reported food allergy was ranging from 3% to 35% for any food and was very high compared with objective measures. Interestingly, there was marked heterogeneity between studies regardless of type of assessment or food item considered. Whether this reflects real differences or is a problem of different study designs could not be answered. In order to obtain comparable prevalence data for food allergy in Europe a multi-centre birth cohort study was started within EuroPrevall in 2005. A total of over 12,000 newborns from nine countries of four climatic regions across Europe were recruited. Standardised telephone interviews were scheduled at birth, 12, 24 and 30 months. In addition, parents were asked to immediately report to the study centres in case of the development of an atopic disease such as atopic dermatitis or about possible allergic reactions to food at any time. All children with atopic dermatitis that required treatment or symptoms possibly caused by food allergy were invited for standardised clinical evaluations including the diagnostic gold standard, double-blind placebo-controlled food challenge tests. Looking at the patterns of food allergy in these infants and young children we found that hen’s egg, cow’s milk, peanut and wheat were the most frequent food allergens in Europe. Interestingly, we saw a marked heterogeneity for some allergens between different countries despite the usage of the same study protocols and close monitoring. This finding might be important for future risk assessment in food allergy.

Provoking allergens and treatment of anaphylaxis in children and adolescents – data from the anaphylaxis registry of German‐speaking countries

Anaphylaxis is the most severe reaction of an IgE-mediated hypersensitivity. Data about affected patients may help to improve our knowledge of anaphylaxis and its medical care. We analysed data from the anaphylaxis registry of German speaking countries with regard to the provoking allergens and treatment modalities of anaphylaxis in children and adolescents. Inclusion criteria were severe systemic allergic reactions with concomitant pulmonary and/or cardiovascular symptoms. The data are collected by a password-controlled online-questionnaire. For this analysis, data of 197 reported anaphylactic reactions from children and adolescents registered between 2006 and 2009 were included. The data show that within the registered cases the most frequently affected organ systems for children and adolescents were the skin (89%) and the respiratory tract (87%) followed by symptoms of the cardiovascular system (47%) and the gastrointestinal tract (43%). The most frequent elicitors were food allergens accounting for 58% of cases, followed by insect venom (24%) and drugs (8%). The most frequent food allergens were peanuts followed by tree nuts and animal related food products. In 18% aggravating factors such as physical exercise were noted by the clinicians. 26% of the analysed patients had experienced more than one reaction. The data regarding the emergency treatment show that antihistamines (87%) and corticosteroids (85%) were often used but that adrenaline was rarely used (22% of the registered cases). Taken together these data show that the analysis of anaphylaxis by registration of affected individuals can provide data about provoking allergens and treatment measures but also suggest the impact of aggravating factors on anaphylactic reactions. The under-represented usage of adrenaline indicates the need of educational measures for patients and their physicians.

Nahrungsmittelallergien im Kindesalter

There is a discrepancy between self-reported and pysician-diagnosed food hypersensitivity in children, and parents tend to self-initiated dietary interventions. Evidence based guidelines for prevention of atopic diseases recommend breast feeding for at least four months. Conventional cow mild formula should be used if breast feeding is not possible. Only in high risk children, hypoallergenic formula are recommended. In children with atopic dermatitis, the possible influence of food allergies has to be investigated by history, skin and in vitro tests as well as by elimination and/or provocation diet. Children allergic to cow milk should be fed with extensively hydrolysed hypoallergenic formula. As most children lose their food allergy, the necessity of interventional diets has to be reevaluated every 12 - 24 month. Pollen-associated food allergies in children do not differ from those in adults and lead to oral allergy syndrome, especially in those with sensitizations to birch or mugwort. Pseudoallergens may trigger symptoms in children with chronic idiopathic urticaria, while in acute urticaria and in anaphylaxis, peanuts, tree nuts and cow milk are the main eliciting factors. Therapeutically, food avoidance is essential, which is facilitated by the duty of declaration regarding the 14 most frequent food allergens. In severe cases of food allergy, emergency kits have to be provided.

IgE-mediated food allergies in Swiss infants and children

Summary OBJECTIVE: To determine the most frequent food allergens causing immediate hypersensitivity reactions in Swiss children of different age groups and to investigate the clinical manifestation of IgE-mediated food allergies in young patients. PATIENTS AND METHODS: The study was a prospective analysis of children referred for assessment of immediate type I food hypersensitivity reactions. The diagnostic strategy included a careful history, skin prick tests with commercial extracts and native foods, in vitro determination of specific IgE to food proteins and food challenges when appropriate. A total of 278 food allergies were identified in 151 children with a median age of 1.9 years at diagnosis. RESULTS: Overall, the most frequent food allergens were hen’s egg (23.7%), cow’s milk (20.1%), peanut (14.0%), hazelnut (10.4%), wheat (6.1%), fish (4.3%), kiwi and soy (2.2% each). In infancy, cow’s milk, hen’s egg and wheat were the most common allergens. In the second and third year of life however, the top three food allergens were hen’s egg, cow’s milk and peanut, whereas above the age of 3 years, peanut was number one, followed by hen’s egg and fish. Overall, urticaria (59.0%) and angioedema (30.2%) were the most frequent clinical manifestations. Gastrointestinal symptoms were found in 25.9% and respiratory involvement in 25.2%. There were 13 cases (4.7%) of anaphylaxis to peanut, fish, cow’s milk, hen’s egg, wheat and shrimps. CONCLUSIONS: A total of eight allergens account for 83% of IgE-mediated food allergies in Swiss infants and children, with differences in the distribution and order of the most frequently involved food allergens between paediatric age groups.

Aktuelles zur Nahrungsmittelallergie bei atopischer Dermatitis

Food allergy is a common problem in patients with atopic dermatitis, particularly in children. Cow's milk, hen's egg, soy and wheat have been identified as frequent food allergens in this age group. 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. We have investigated the importance of food for the induction of late eczematous reactions in children with atopic dermatitis aged 1 - 10 years. This article shows the results of our study and discusses the previous literature. 46% of our challenges were related to a clinical reaction. 43% of these reactions were associated with an isolated immediate reaction. An exacerbation of atopic dermatitis (late eczematous reaction) commonly occured 24 hours after the ingestion of food. Isolated late eczematous reactions were seen in 12% of all positive challenges. 45% of the positive challenges were associated with late eczematous responses, which followed immediate-type reactions. We correlated the clinical outcome to the results of specific IgE determinations and atopy patch tests, which resulted in poor predictive values for both in-vitro and skin tests particularly for the late eczematous reactions. Therefore, food challenges have still to be regarded as the gold standard for the appropriate diagnosis of food responsive eczema in children with atopic dermatitis.

Specificity of the Human IgE Response to the Different Purified Caseins in Allergy to Cow’s Milk Proteins

Background: Cow’s milk is one of the most frequent food allergens. Whole casein appears to be highly allergenic. It corresponds to an association of four different proteins, α_s1-, α_s2-, β- and *-caseins in approximate proportions of 40, 10, 40, and 10%, respectively. Methods: These different components were thus purified and used as immobilized antigens in an original enzyme immunoassay to measure specific serum IgE response in a population of 58 children (median age 11 months) allergic to cow’s milk who were sensitive to whole casein. Results: A great variability was observed in the affinity and specificity of specific IgE responses in milk-allergic patients’ sera. 85% of the patients presented IgE against each of the four caseins. Statistically higher amounts of specific IgE were found to be directed against the most abundant fractions (α_s1- and β-casein). Co- and/or cross-sensitization to the different caseins were seen in most of the patients sensitive to whole casein. Conclusion: These results suggest that both distinct and common epitopes may occur on these different caseins. The major site of phosphorylation which is the most conserved domain in three caseins could be involved in the IgE response to casein and in immunocross-reactivity between these proteins.