Profilin sensitization detected in the office by skin prick test: a study of prevalence and clinical relevance of profilin as a plant food allergen

Background Profilin, a pan‐allergen present in all eukaryotic cells, is one of the main causes of cross‐sensitization between pollen and plant‐derived foods, but its clinical relevance as a food allergen is still debated. Objective To investigate the prevalence of profilin sensitization in a pollen‐allergic population and its clinical relevance as a food allergen. Methods Two hundred consecutive patients with pollen allergy underwent skin prick tests (SPT) with purified natural date palm profilin (Pho d 2; 50 μg/mL; Alk Abello, Madrid, Spain). Those reporting adverse reactions to foods (confirmed by SPT with either commercial food extracts or fresh foods) underwent SPT with an apple extract containing uniquely Mal d 1 (2 μg/mL; ALK‐Abello), and with a commercial peach extract containing uniquely lipid transfer protein (LTP 30 μg/mL; ALK‐Abello). Results Sixty patients (30%) showed skin reactivity to date palm profilin, Pho d 2. All were sensitized to grass pollen, and most of them reacted to birch, mugwort, ragweed and plantain pollen as well. SPT with pellitory and cypress scored negative in a high proportion of profilin reactors [26/60 (43%) and 33/60 (55%), respectively]. More than one half (34/60 [57%]) of profilin reactors had food allergy; 21 of these were monosensitized to profilin, 11 were sensitized to both profilin and Bet v 1 homologous protein, one to both profilin and LTP, and one to all the three allergens. The large majority of profilin‐allergic patients reported oral allergy syndrome as the only food‐induced symptom and were able to tolerate the offending foods if they were cooked or otherwise processed. Twenty‐eight of 34 reported reactivity to two or more plant‐derived foods. Rosaceae, tree nuts, melon and watermelon, tomato, pineapple, citrus fruits and banana were the more frequently offending foods. Conclusion Profilin should be considered a clinically relevant food allergen. Allergy to melon, watermelon, tomato, banana, pineapple and orange may be considered as a marker of profilin hypersensitivity. This study underlines the clinical importance of being able to diagnose hypersensitivity to single food allergenic proteins by SPT, particularly when the relevant food allergen sources contain several allergens that show different chemical/physical features and, hence, completely different risk profiles.     

Factors affecting the determination of threshold doses for allergenic foods: how much is too much?

BACKGROUND: Ingestion of small amounts of an offending food can elicit adverse reactions in individuals with IgE-mediated food allergies. The threshold dose for provocation of such reactions is often considered to be zero. However, because of various practical limitations in food production and processing, foods may occasionally contain trace residues of the offending food. Are these very low, residual quantities hazardous to allergic consumers? How much of the offending food is too much? Very little quantitative information exists to allow any risk assessments to be conducted by the food industry. OBJECTIVE: We sought to determine whether the quality and quantity of existing clinical data on threshold doses for commonly allergenic foods were sufficient to allow consensus to be reached on establishment of threshold doses for specific foods. METHODS: In September 1999, 12 clinical allergists and other interested parties were invited to participate in a roundtable conference to share existing data on threshold doses and to discuss clinical approaches that would allow the acquisition of that information. RESULTS: Considerable data were identified in clinical files relating to the threshold doses for peanut, cows' milk, and egg; limited data were available for other foods, such as fish and mustard. CONCLUSIONS: Because these data were often obtained by means of different protocols, the estimation of a threshold dose was very difficult. Development of a standardized protocol for clinical experiments to allow determination of the threshold dose is needed.     

Systemic urticaria in an infant after ingestion of processed food that contained a trace quantity of wheat.

BACKGROUND: Wheat is a food allergen that occasionally causes a systemic allergic reaction; however, little is known about the quantities of wheat allergen required to evoke allergic symptoms. OBJECTIVE: To report the case of a wheat allergic boy who experienced systemic urticaria and angioedema within 40 minutes after the ingestion of 9 g of packed rice crackers. METHODS: A skin prick test and IgE immunoblotting with wheat proteins were performed. Contamination of wheat protein in the offending rice cracker and other processed rice crackers from local food retail outlets, with labels that did not mention wheat, was examined with enzyme-linked immunosorbent assaying. RESULTS: A skin reaction to wheat was positive. IgE-bound bands were observed with water- and salt-soluble wheat protein and ethanol-soluble wheat gliadin in immunoblotting. A trace quantity of wheat protein, 1.50 microg/g, was determined in the offending rice cracker. In addition, 3 of 8 other kinds of processed rice crackers were contaminated by wheat protein, with levels ranging from 0.26 to 1.13 microg/g. CONCLUSIONS: Approximately 13.5 microg of wheat protein can elicit a systemic adverse reaction in highly sensitive, wheat allergic individuals. The present study confirms the need for control of contamination of food by nondeclared proteins.     

Adverse reactions to food additives.

OBJECTIVES: To summarize the literature related to the classification of food additives and their reported adverse reactions and to provide a practical approach for evaluation of patients suspected of having such reactions. DATA SOURCES: Information was derived from selected reviews and original articles published in peer-reviewed journals and from authoritative textbook chapters, supplemented by the clinical experience of the authors. STUDY SELECTION: Priority was given to studies that used blinded, placebo-controlled oral challenges to confirm adverse reactions to food additives. In addition, selected, appropriately evaluated case reports are included. RESULTS: A large number of food additives are widely used in the food industry. Adverse reactions to additives seem to be rare but are likely underdiagnosed in part due to a low index of suspicion. Numerous symptoms have been attributed to food additive exposure, but the cause-and-effect relationship has not been well demonstrated in all. CONCLUSIONS: Reactions to food additives should be suspected in patients who report symptoms to multiple unrelated foods or to a certain food when commercially prepared but not when homemade and the allergy evaluation rules out a role for food protein. It is also prudent to investigate food additives in patients considered to have idiopathic reactions. There is a minor role for skin testing or in vitro testing. Oral challenge testing with common additives, preferably preceded by a trial of an additive-free diet, is the definitive procedure for detecting the offending agent. Once the specific additive is identified, management is basically avoidance of all its forms.     

The national survey of immediate type of food allergy]

BACKGROUND: The actual conditions regarding immediate type food allergy have not been fully understood. Appropriate countermeasures have not been taken so far. The objective of our research is to identify the actual conditions of immediate type food allergy in Japan for the purpose of contributing to future practices. SUBJECT: We conducted a survey on the patients in collaboration with 2689 domestic hospitals which have pediatrics and more than 100 beds. We focused on these cases who presented with symptoms of allergy within 60 minutes of the intake of any offending food. RESULT: 60.4% of collaborators returned the questionnaire. We investigated 1420 cases in 498 hospitals. Average age of cases was 6.7+/-13.1 (Mean+/-SD). Ages not more than 8 years-old comprised 80.1% of the whole population. The most common offending foods were eggs, milk products, wheat, buckwheat, fish and fruits. In addition, offending foods varied depending on age. The clinical symptoms appeared at 24.2 minutes+/-19.4 minutes (Mean+/-SD) after the intake of offending foods. The most common clinical symptom was observed on the skin and respiratory organs. CONCLUSION: Based on the results of this study, the Ministry of Health, Labor and Welfare amended the ministerial ordinance concerning the allergy food labeling system. Five major offending foods (eggs, milk, wheat, buckwheat, and peanuts) were designated as ingredients to be specified on the label.     

Unusual presentations of food allergy.

OBJECTIVE: This presentation is designed to critically review information on presentations of food hypersensitivity reactions that may be considered unusual regarding the source or nature of allergen, route of exposure, or clinical manifestation. DATA SOURCES: Information has been gathered primarily through a thorough search of the English literature relevant to human subjects. Some clinical cases were also included from the author's own clinical experience. STUDY SELECTION: Information summarized here was critically selected on the basis of proven or acceptable scientific validity. RESULTS: The findings indicate that food allergy presentation can be unusual in three main aspects. First, the offending allergen may not be the obvious food that was ingested or be a food protein incorporated in a nonfood product. Second, systemic reactions can be provoked by very minute quantities of food allergens that may even get access through noningestant routes, eg, inhalation, odor, skin contact, or mucous membrane contact. Third, the clinical manifestations are not limited to the few gastrointestinal, cutaneous, and respiratory symptoms with which we are generally familiar. CONCLUSIONS: The extent of food allergy presentation is more than has been generally realized. Our awareness of such unusual presentations adds new knowledge and should prompt our interest in carefully evaluating patients with obscure allergic reactions for possible food allergy.     

Usefulness of Measurement of Antibodies in Serum in Diagnosis of Sensitivity to Cow Milk and Soy Proteins in Early Childhood

A noteworthy feature of this study is that comparisons were made between specific, sensitive, quantitative measurements of serum antibodies to food proteins and objective appraisal of clinical manifestations buy double-blind food challenges. Over 50 children, 4–30 months of age, with suspicious histories of adverse reactions to cow milk or soy products were investigated. Levels of serum antibodies to cow-milk proteins were clearly higher in children with adverse reactions to milk, confirmed by blind challenge; there was no overlap with the lower levels of serum antibodies in children without confirmed reactions. Findings with serial determinations of serum antibodies to cow milk in selected cases are also presented.
The levels of serum antibodies evoked by cow milk and soy formulae fed from birth until 4 months of age were similar. The levels of serum antibodies to soy protein in children with and without adverse reactions to soy products were not definitive.
The bearing of these data on the comparative "antigenicity" of cow milk and soy products and the distinction between asymptomatic and clinically significant, symptomatic, sensitivity are discussed.     

Comparing immediate‐type food allergy in humans and companion animals—revealing unmet needs

Adverse food reactions occur in human as well as veterinary patients. Systematic comparison may lead to improved recommendations for prevention and treatment in both. In this position paper, we summarize the current knowledge on immediate‐type food allergy vs other food adverse reactions in companion animals, and compare this to the human situation. While the prevalence of food allergy in humans has been well studied for some allergens, this remains to be investigated for animal patients, where owner‐reported as well as veterinarian‐diagnosed food adverse reactions are on the increase. The characteristics of the disease in humans vs dogs, cats, and horses are most often caused by similar, but sometimes species‐dependent different pathophysiological mechanisms, prompting the specific clinical symptoms, diagnoses, and treatments. Furthermore, little is known about the allergen molecules causative for type I food allergy in animals, which, like in human patients, could represent predictive biomarkers for risk evaluation. The definite diagnosis of food allergy relies—as in humans—on elimination diet and provocation tests. Besides allergen avoidance in daily practice, novel treatment options and tolerization strategies are underway. Taken together, numerous knowledge gaps were identified in veterinary food allergy, which need to be filled by systematic comparative studies.     

Animal models of allergen‐specific immunotherapy in food allergy: Overview and opportunities

Food allergy is an adverse reaction to otherwise harmless proteins in food. The disease is a major health problem of growing concern, affecting approximately 5%‐8% of young children and 2%‐4% of adults. No accepted strategy exists for prevention and treatment of food allergy, and strict avoidance of the offending food is presently the only viable management option. Living with food avoidance may have a huge impact on the quality of life of food allergic patients, with daily fear of serious or even fatal reactions. The urgent need for safe and efficient food allergy treatment options has led to massive research efforts to develop and improve strategies for food allergy immunotherapeutic approaches. A first step in developing new and improved strategies of immunotherapy often involves the use of animal models. In present review, we provide an overview of animal studies of allergen‐specific immunotherapy highlighting opportunities and challenges for each approach. The presented models, almost exclusively performed in mice, assess therapeutic efficacy and immunological outcomes following oral, intraperitoneal, subcutaneous, epicutaneous, and sublingual administration of native allergens, or preparations of hydrolyzed allergen, T‐cell‐directed peptides, or allergen with immunomodulatory adjuvants. Recently, approaches using immune cell therapy have demonstrated efficacy. Current models mainly assess anaphylaxis as the primary clinical outcome. With the increased appreciation that food allergy is a heterogeneous disease presenting different phenotypes, there is a continued need to develop new disease‐relevant therapeutic models of food allergy.     

Prolonged type of food allergy]

OBJECT: Prevalence of food allergy is the most frequent during infancy, and it is gradually decreasing with age. We can not distinguish patients developing tolerance from those with persistent food allergy, therefore we are unable to advice patients accelerating the development of tolerance. To clarify the factors developing tolerance or intolerance, we conducted the following study. METHOD: Patients who were diagnosed as food allergy to hen's egg, or cow's milk or wheat in infancy by the definitive history of positive food allergic reactions or food provocation tests were recruited to this study. Patients were divided into two groups; one (prolonged group, n=27) is those who needed to eliminate some of the main offending foods even at the age of 6 years old and the other (tolerized group, n=37) is those who had released all main offending foods by the age of 6 years old. RESULT: The factors which distinguished the prolonged group from the tolerized group were the positive clinical history of the atopic dermatitis and its prolonged clinical course, past history of anaphylactic shock, and maximum number of offending foods in the past clinical history. The specific IgE against main antigens such as egg white, cow's milk and wheat in the tolerized group was lower compared to that in the prolonged group, whereas no significant difference was found in non specific IgE value, peripheral eosinophil counts, and specific IgE against other antigens. CONCLUSION: We could find the clinical factors discriminating food allergy patients against three major food allergen among children developing tolerance by the age of 6 years old form those without tolerance.     

Randomized, double-blind, crossover challenge study in 53 subjects reporting adverse reactions to melon (Cucumis melo)

BACKGROUND: Few studies have evaluated IgE-mediated hypersensitivity to melon with details of clinical reactions confirmed by double-blind, placebo-controlled, food challenges (DBPCFCs). OBJECTIVE: We sought to investigate clinical features (type and severity of reactions, age at onset, results of skin prick and in vitro tests, and incidence of other allergic diseases and associated food allergies) of acute allergic reactions to melon confirmed by DBPCFCs. METHODS: Fifty-three consecutive adult patients complaining of adverse reactions to melon were included in the study. Skin prick tests and detection of specific IgE were performed in all patients with melon, avocado, kiwi, banana, chestnut, latex, pollen, and other offending foods. Patients first underwent an open food challenge, unless they had a convincing history of severe anaphylaxis. Positive open food challenge reactions were subsequently evaluated by DBPCFCs. RESULTS: Actual clinical reactivity was confirmed in 19 (36%) of 53 patients. The most frequent symptom was oral allergy syndrome (n = 14), but two patients experienced life-threatening reactions, including respiratory symptoms and hypotension. The positive predictive value for a skin prick test was 42%, and that for specific IgE measurement was 44%. Forty-five reactions to 15 other foods were confirmed in 18 patients. The most common foods associated with melon allergy were avocado (n = 7), banana (n = 7), kiwi (n = 6), watermelon (n = 6), and peach (n = 5). Onset of melon-induced allergic symptoms occurred from 6 to 45 years (median, 20 years), preceded by seasonal rhinitis, asthma, or both in 88% (15/17). CONCLUSION: About one third of reported reactions to melon are confirmed by means of DBPCFC, which has been proven to be the most reliable procedure in the diagnosis of clinical fruit allergy. Isolated melon allergy is rare, with most patients either having allergic rhinitis, asthma, or both and associated food allergies.     

Shellfish allergens: tropomyosin and beyond

IgE‐mediated shellfish allergy constitutes an important cause of food‐related adverse reactions. Shellfish are classified into mollusks and crustaceans, the latter belonging to the class of arthropoda. Among crustaceans, shrimps are the most predominant cause of allergic reactions and thus more extensively studied. Several major and minor allergens have been identified and cloned. Among them, invertebrate tropomyosin, arginine kinase, myosin light chain, sarcoplasmic calcium‐binding protein, and hemocyanin are the most relevant. This review summarizes our current knowledge about these allergens.     

A cross‐sectional study on the prevalence of food allergy to eggplant (Solanum melongena L.) reveals female predominance

Background Only a few case reports of allergy to eggplant (Solanum melongena) have been reported. A relatively large number of individuals appear to experience food‐related symptoms to eggplant in India. Objective The major aims of this study are to assess the prevalence of food allergy to eggplant and analyse the age and gender distribution. Methods Seven hundred and forty‐one subjects (age range: 5–60 years) randomly selected from rural and urban areas of Mysore city were analysed for the prevalence of eggplant allergy based on case history, skin prick test (SPT) with eggplant extracts and allergen‐specific IgE. The age and gender distribution for the prevalence of eggplant allergy and its association with other atopic conditions were assessed. Results Sixty‐eight (9.2%) subjects reported adverse reactions to ingestion of eggplant, of which 32 (4.3%) subjects had positive history/positive SPT and 36 (4.9%) had positive history/negative SPT. Sixteen (2.2%) subjects had negative history/positive SPT. Ten subjects (1.4%) experienced allergic symptoms in <2 h. Sensitization to eggplant by SPT was more in atopic (16.7%) compared with non‐atopic subjects (3.8%). All the SPT‐positive subjects (n=48) underwent evaluation for eggplant allergen‐specific IgE, which was detected in 6 subjects (0.8%). Majority of the subjects sensitized to eggplant were in the age groups 16–45 years, and females were twice as likely to be sensitized as males. Female predominance (4 : 1) is more in the 16–30 year group. Conclusions Many subjects experience adverse reactions to the ingestion of eggplant, possibly due to the pharmacologic action of histamine and other non‐protein components, rather than to specific protein allergen(s). The prevalence of IgE‐mediated eggplant allergy is estimated at ～0.8%, with higher rates of sensitization in females.     

Food legislation and the protection of allergic and hypersensitive persons: an overview.

So far there are worldwide no legal instruments in protecting people against adverse allergic reactions to the consumption of foods. Instruments, which generally were developed for health protection in food legislation, are not suitable to regulate the protection of allergic persons because they automatically would exclude all protein-containing foods from commercial market. The only approach to an effective protection is to indicate the presence of adverse effect causing agents or ingredients on the label. This preventive instrument was developed by the Codex Alimentarius and led to an open "hit list" of ten Major Serious Allergens, which have to be labeled. The hit list principle was adopted by the EU-Commission as a draft for an EC-Directive. Unsolved problems are exeptions from the labeling requirement for refined oils and a minimum limit of adverse effect causing agents which do not require labeling.     

The appearance of macrophage migration-inhibition factor in drug reactions

Drug-induced adverse reactions were suspected in 2030 patients with known exposure to 243 different drugs. A modified direct macrophage migration-inhibition factor (MIF) test for the different drugs was carried out on blood samples from these patients. There was a positive MIF response toward one or more of the suspected drugs in 53.4% of the patients as compared to 4.9% of the control group; 155 of the 243 drugs elicited a positive MIF response. The percentage of positive responses for each particular drug was not related to the number of patients tested, reflecting the variability in specific immunogenicity of the different drugs. The high percentage of positive MIF reactions in relation to the clinical diagnosis suggests that this test can be a useful aid in the detection of the offending drug in cases of suspected drug-induced reactions.     

Impact of ingredient labeling practices on food allergic consumers.

BACKGROUND: Food allergic consumers depend on ingredient labels for allergen avoidance, and the modality of labeling is changing. OBJECTIVE: To investigate current responses to food labels so that the impact of future label changes can be anticipated. METHODS: Adults who attended Food Allergy & Anaphylaxis Network conferences completed a survey regarding their experiences with food labels for their family's most severely affected food allergic individual (FAI). RESULTS: There were 489 completed surveys (84% participation). Most FAIs were young (41% <4 years of age and 56% 4-18 years of age) and highly atopic (51% had asthma and 69% had atopic dermatitis). Food allergies included the following: peanut, 81%; tree nuts, 53%; milk, 51%; egg, 51%; and soy, 17%. All chocolate products were avoided by 37% of FAIs who were avoiding peanut and 40% who were avoiding tree nuts; 91% of tree nut allergic FAIs avoided all tree nuts. Of FAIs who avoided soy, 41% avoided soybean oil and 38% avoided soy lecithin. Of those who avoided milk, 82% avoided lactose. Allergic reactions were attributed to misunderstanding label terms (16%) and to nonspecific terms (spice, flavor) (22%). Ingredient labels were "always" or "frequently" read before purchase by 99%. Product brand choice was "very much influenced" by the manner of labeling for 86%, and manufacturers were contacted for more information by 86%. CONCLUSIONS: Our results suggest that improved product allergen labeling will reduce allergic reactions and simplify allergy management. However, the new labeling may not indicate the form or source of the allergen, and individuals who do not currently avoid foods with minimal or irrelevant protein content, such as soy oil or soy lecithin, may face additional ambiguity and unnecessary dietary restrictions.     

Treatments for food allergy: how close are we?

Food allergy continues to be a challenging health problem, with prevalence continuing to increase and anaphylaxis still an unpredictable possibility. While improvements in diagnosis are more accurately identifying affected individuals, treatment options remain limited. The cornerstone of treatment relies on strict avoidance of the offending allergens and education regarding management of allergic reactions. Despite vigilance in avoidance, accidental ingestions and reactions continue to occur. With recent advances in the understanding of humoral and cellular immune responses in food allergy and mechanisms of tolerance, several therapeutic strategies for food allergies are currently being investigated with the hopes of providing a cure or long-term remission from food allergy.     

Allergen immunotherapy for IgE‐mediated food allergy: a systematic review and meta‐analysis

Background

The European Academy of Allergy and Clinical Immunology (EAACI) is developing Guidelines for Allergen Immunotherapy (AIT) for IgE‐mediated Food Allergy. To inform the development of clinical recommendations, we sought to critically assess evidence on the effectiveness, safety and cost‐effectiveness of AIT in the management of food allergy.

Methods

We undertook a systematic review and meta‐analysis that involved searching nine international electronic databases for randomized controlled trials (RCTs) and nonrandomized studies (NRS). Eligible studies were independently assessed by two reviewers against predefined eligibility criteria. The quality of studies was assessed using the Cochrane Risk of Bias tool for RCTs and the Cochrane ACROBAT‐NRS tool for quasi‐RCTs. Random‐effects meta‐analyses were undertaken, with planned subgroup and sensitivity analyses.

Results

We identified 1814 potentially relevant papers from which we selected 31 eligible studies, comprising of 25 RCTs and six NRS, studying a total of 1259 patients. Twenty‐five trials evaluated oral immunotherapy (OIT), five studies investigated sublingual immunotherapy, and one study evaluated epicutaneous immunotherapy. The majority of these studies were in children. Twenty‐seven studies assessed desensitization, and eight studies investigated sustained unresponsiveness postdiscontinuation of AIT. Meta‐analyses demonstrated a substantial benefit in terms of desensitization (risk ratio (RR) = 0.16, 95% CI 0.10, 0.26) and suggested, but did not confirm sustained unresponsiveness (RR = 0.29, 95% CI 0.08, 1.13). Only one study reported on disease‐specific quality of life (QoL), which reported no comparative results between OIT and control group. Meta‐analyses revealed that the risk of experiencing a systemic adverse reaction was higher in those receiving AIT, with a more marked increase in the risk of local adverse reactions. Sensitivity analysis excluding those studies judged to be at high risk of bias demonstrated the robustness of summary estimates of effectiveness and safety of AIT for food allergy. None of the studies reported data on health economic analyses.

Conclusions

AIT may be effective in raising the threshold of reactivity to a range of foods in children with IgE‐mediated food allergy whilst receiving (i.e. desensitization) and post‐discontinuation of AIT. It is, however, associated with a modest increased risk in serious systemic adverse reactions and a substantial increase in minor local adverse reactions. More data are needed in relation to adults, long term effects, the impact on QoL and the cost‐effectiveness of AIT.     

The range of minimum provoking doses in hazelnut-allergic patients as determined by double-blind, placebo-controlled food challenges

BACKGROUND: The risk for allergic reactions depends on the sensitivity of individuals and the quantities of offending food ingested. The sensitivity varies among allergic individuals, as does the threshold dose of a food allergen capable of inducing an allergic reaction. OBJECTIVE: This study aimed at determining the distribution of minimum provoking doses of hazelnut in a hazelnut-allergic population. METHODS: Thirty-one patients with a history of hazelnut-related allergic symptoms, a positive skin prick test to hazelnut and/or an elevated specific IgE level, were included. Double-blind, placebo-controlled food challenges (DBPCFC) were performed with seven increasing doses of dried hazelnut (1 mg to 1 g hazelnut protein) randomly interspersed with seven placebo doses. RESULTS: Twenty-nine patients had a positive challenge. Itching of the oral cavity and/or lips was the first symptom in all cases. Additional gastrointestinal symptoms were reported in five patients and difficulty in swallowing in one patient. Lip swelling was observed in two patients, followed by generalized urticaria in one of these. Threshold doses for eliciting subjective reactions varied from a dose of 1 mg up to 100 mg hazelnut protein (equivalent to 6.4-640 mg hazelnut meal). Extrapolation of the dose-response curve showed that 50% of our hazelnut-allergic population will suffer from an allergic reaction after ingestion of 6 mg (95% CI, 2-11 mg) of hazelnut protein. Objective symptoms were observed in two patients after 1 and 1,000 mg, respectively. CONCLUSION: DBPCFCs demonstrated threshold doses in half of the hazelnut-allergic patients similar to doses previously described to be hidden in consumer products. This stresses the need for careful labelling and strategies to prevent and detect contamination of food products with hazelnut residues.     

Studies of hypersensitivity reactions to foods in infants and children

In order to extend previous investigations of adverse reactions to foods performed at this institution, 68 children, aged 5 mo to 15 yr, were studied. All subjects reported a history of adverse reaction to ingestion of one or more of the 14 foods under study. Sixteen of 43 subjects, 3 yr of age or older, had 22 adverse reactions during 94 food challenges with one or more of the 14 foods. All reactions confirmed were to peanut or other nuts, milk, egg, and soy. Skin testing with 1:20 weight/volume concentrations of food extracts applied by the puncture technique produced a net wheal reaction 3 mm or greater in all subjects 3 yr of age or older in whom double-blind food challenges confirmed the history of adverse reaction. Thirteen of 25 children less than 3 yr of age manifested adverse reactions during 49 food challenges. Skin testing by puncture technique produced a net wheal 3 mm or greater in 9 children less than 3 yr of age in whom food challenge elicited a clinical response within 2 hr. One of 4 subjects less than 3 yr of age in whom the adverse reaction occurred more than 4 hr after food challenge exhibited a wheal to puncture skin test of 3 mm or greater. These studies suggest that at present double-blind food challenge is an indispensible tool for the unequivocal evaluation of adverse reactions to foods.