Innovation in Food Challenge Tests for Food Allergy

Challenge of Precautionary Allergen Labeling for Ensuring the Safety of Children With Food Allergies

BACKGROUND

Precautionary allergen labeling (PAL) is mandatory and legally regulated in Korea. This study aims to investigate the frequency of PAL use in food products, evaluate its competence, and seek direction for improvement.

METHODS

Cow's milk (CM) and hen's egg white (EW) protein concentrations were measured using an enzyme-linked immunosorbent assay (ELISA). The results validated PAL using the Voluntary Incidental Trace Allergen Labeling® 3.0 program. A survey was conducted on guardians to compare preferences and understanding of the current and the arbitrarily revised PAL.

RESULTS

PAL was used in 91.8% (280/305) of baby food products. ELISA results using randomly selected baby food products showed that only 16.7% (5/30; No PAL with no contamination, n = 4; PAL with real-contamination risk, n = 1) were validated to PAL. A detectable CM was found in two products (2/26, 7.7%), with one product exceeding the reference dose (10.3 ± 0.17 ppm). EW was not detected at all (0/16). A total of 207 surveys from guardians were collected and categorized into three groups: food allergy (FA, n = 103), diseases other than food allergies (Others, n = 52), and no disease (Control, n = 52). The FA group exhibited the highest frequency of checking food allergen labeling ("always": 78.6%, "often": 9.7%), with a similar PAL adherence ("always": 58.3%, "often": 10.4%). None of the groups were satisfied with the current PAL. The 'allergen-free' statement was mostly preferred across all groups. The FA group notably preferred PAL with concentration statements.

CONCLUSION

PAL is excessively prevalent and insufficient in ensuring the safety of children with FAs, necessitating a revision towards a more patient-friendly, evidence-based system for affected individuals and their families.

Milk ladder: Who? When? How? Where? with the lowest risk of reaction

The milk ladder (ML) approach, which is the gradual reintroduction of the milk allergen from the least allergenic forms to the most allergenic forms into the diet of the patients, has been utilized mostly in non-IgE-mediated but in some countries also in IgE-mediated-CMPA due to its possible benefits which include nutrition, quality of life and tolerance induction. Despite increasing interest, so far, there is no guideline on ML; thus, the use of this approach shows discrepancies among healthcare professionals as many factors such as dietary habits, patient history, test results, workload, and facilities of the hospitals, the anxiety of the parents/patients may affect the decision on how, when, where and whom to use ML. Here, we reviewed current data on implementing the ML, suggested a 4-step ML including receipts and amounts, and shared our experience on optimal patient selection, appropriate time and steps for initiating ML, and time intervals between the steps targeting the lowest risk of reaction. We also added the newly developed twice-baked biscotti cake to the ML. We presented the analyses of this product, showing its low allergenicity compared to conventional cake, which provides a safer introduction of milk into the diet.

Fatal food anaphylaxis in adults and children

Anaphylaxis is a life-threatening reaction characterized by the acute onset of symptoms involving different organ systems and requiring immediate medical intervention. The incidence of fatal food anaphylaxis is 0.03 to 0.3 million/people/year. Most fatal food-induced anaphylaxis occurs in the second and third decades of life. The identified risk factors include the delayed use of epinephrine, the presence of asthma, the use of recreational drugs (alcohol, nicotine, cannabis, etc.), and an upright position. In the United Kingdom (UK) and Canada, the reported leading causal foods are peanuts and tree nuts. In Italy, milk seems to be the most common cause of fatal anaphylaxis in children < 18 years. Fatal food anaphylaxis in Italian children and adolescents almost always occurs outside and is characterized by cardiorespiratory arrest; auto-injectable adrenaline intramuscular was available in few cases. Mortality from food anaphylaxis, especially in children, is a very rare event with stable incidence, but its risk deeply impacts the quality of life of patients with food allergy and their families. Prevention of fatal food anaphylaxis must involve patients and their families, as well as the general public, public authorities, and patients' associations.

Management of Food Allergies and Food-Related Anaphylaxis

Importance

An estimated 7.6% of children and 10.8% of adults have IgE-mediated food-protein allergies in the US. IgE-mediated food allergies may cause anaphylaxis and death. A delayed, IgE-mediated allergic response to the food-carbohydrate galactose-α-1,3-galactose (alpha-gal) in mammalian meat affects an estimated 96 000 to 450 000 individuals in the US and is currently a leading cause of food-related anaphylaxis in adults.

Observations

In the US, 9 foods account for more than 90% of IgE-mediated food allergies-crustacean shellfish, dairy, peanut, tree nuts, fin fish, egg, wheat, soy, and sesame. Peanut is the leading food-related cause of fatal and near-fatal anaphylaxis in the US, followed by tree nuts and shellfish. The fatality rate from anaphylaxis due to food in the US is estimated to be 0.04 per million per year. Alpha-gal syndrome, which is associated with tick bites, is a rising cause of IgE-mediated food anaphylaxis. The seroprevalence of sensitization to alpha-gal ranges from 20% to 31% in the southeastern US. Self-injectable epinephrine is the first-line treatment for food-related anaphylaxis. The cornerstone of IgE-food allergy management is avoidance of the culprit food allergen. There are emerging immunotherapies to desensitize to one or more foods, with one current US Food and Drug Administration-approved oral immunotherapy product for treatment of peanut allergy.

Conclusions and Relevance

IgE-mediated food allergies, including delayed IgE-mediated allergic responses to red meat in alpha-gal syndrome, are common in the US, and may cause anaphylaxis and rarely, death. IgE-mediated anaphylaxis to food requires prompt treatment with epinephrine injection. Both food-protein allergy and alpha-gal syndrome management require avoiding allergenic foods, whereas alpha-gal syndrome also requires avoiding tick bites.

Eliciting and stop dose during oral food challenges for peanut and common tree nuts in different age groups

BACKGROUND

Oral food challenges (OFCs) are used to confirm or reject a diagnosis of food allergy. However, younger children may encounter difficulties in consuming all offered doses during an OFC in the absence of symptoms, resulting in inconclusive outcomes. Our aim is to assess the eliciting dose for objective symptoms among various age groups and determine the necessity of consuming the final dose step during an uneventful OFC to avoid false negative outcomes.

METHODS

OFCs for common food allergens performed between 2012 and 2019 were analyzed retrospectively. The primary outcome was the association of age with stop dose for OFCs with inconclusive outcome. Secondary outcome measures were the association of age with eliciting dose and the potential number of false negative outcomes.

RESULTS

A total of 1327 OFCs were performed in 707 patients. Of these, 514 (38.7%) were positive, 589 (44.4%) negative, and 224 (16.9%) inconclusive. In OFCs with inconclusive outcome, age appeared to be a significant predictor of the stop dose only for almond (p = .005). Objective symptoms occurred after the last dose step in 2%-13% of all OFCs with positive outcome. In our cohort, potential false negative outcomes may have been drawn in 27.6% of uneventful OFCs.

CONCLUSIONS

Two third of children under 6 years of age successfully consumed all the provided doses during OFCs with a negative outcome. The eliciting dose for objective symptoms was not associated with age, and in a substantial number of OFCs with positive outcome, symptoms occurred after eating the final dose. These findings suggest that in case of an uneventful OFC, the outcome should be drawn only after a cumulative dose of 4.4 g has been consumed to avoid the risk of a potential false negative outcome.

EAACI guidelines on the diagnosis of IgE-mediated food allergy

This European Academy of Allergy and Clinical Immunology guideline provides recommendations for diagnosing IgE-mediated food allergy and was developed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Food allergy diagnosis starts with an allergy-focused clinical history followed by tests to determine IgE sensitization, such as serum allergen-specific IgE (sIgE) and skin prick test (SPT), and the basophil activation test (BAT), if available. Evidence for IgE sensitization should be sought for any suspected foods. The diagnosis of allergy to some foods, such as peanut and cashew nut, is well supported by SPT and serum sIgE, whereas there are less data and the performance of these tests is poorer for other foods, such as wheat and soya. The measurement of sIgE to allergen components such as Ara h 2 from peanut, Cor a 14 from hazelnut and Ana o 3 from cashew can be useful to further support the diagnosis, especially in pollen-sensitized individuals. BAT to peanut and sesame can be used additionally. The reference standard for food allergy diagnosis is the oral food challenge (OFC). OFC should be performed in equivocal cases. For practical reasons, open challenges are suitable in most cases. Reassessment of food allergic children with allergy tests and/or OFCs periodically over time will enable reintroduction of food into the diet in the case of spontaneous acquisition of oral tolerance.

IgE-mediated cow's milk allergy in Brazilian children: Outcomes of oral food challenge

Background

Oral food challenge (OFC) is useful for diagnosing food allergies and assessing tolerance, but severe reactions may occur during the procedure.

Objective

To characterize the frequency and severity of reactions during cow's milk (CM) OFCs.

Methods

A cross-sectional study was conducted to analyze the outcome of cow's milk oral food challenges (CMOFCs) performed to confirm IgE-mediated CM allergy or to assess food tolerance. CM was given first as baked milk (BM), followed by whole CM if there was no prior reaction to BM. An OFC was considered positive if IgE-mediated symptoms developed up to 2 h after ingestion. Symptoms were described and variables including age at OFC, prior anaphylaxis, other atopic diseases, and skin test results were compared according to the OFC outcomes.

Results

A total of 266 CMOFCs were performed, including 159 patients with a median age of 6.3 years old. One hundred thirty-six tests were positive and 62 resulted in anaphylaxis. Thirty-nine anaphylactic reactions were observed up to 30 min after the first dose. Severe anaphylaxis (cardiovascular and/or neurological involvement) was reported in 5 tests. A second dose of epinephrine was required in 3 tests, and 1 presented a biphasic response. Younger patients had a higher risk of anaphylaxis during baked milk oral food challenge (BMOFC) (p = 0.009). The frequency of anaphylaxis was higher in patients submitted to BM (p = 0.009).

Conclusions

Anaphylaxis is a known complication of CMOFCs even when there is no prior anaphylaxis or when conducted with baked products. This study reinforces the importance of conducting OFC in appropriate settings with a well-trained team.

Food Allergies and Quality of Life among School-Aged Children and Adolescents: A Systematic Review

Recently, besides the focus on the medical diagnosis and therapeutic interventions for food allergy (FA), the psychosocial aspects of this frequent condition have also been investigated. The current systematic review aimed to explore and synthesize the scientific evidence published from January 2015 to April 2022 on Health-Related Quality of Life (HRQoL) among children and adolescents with FAs. Twenty-eight research studies were included in the review, which was conducted on three databases (PubMed, Scopus and Cochrane Library). In most studies, the scores indicate an average level of HRQoL for children and adolescents with FAs, with girls and older children being more negatively affected than boys and younger ones, respectively. Few studies compared HRQoL between children with FA and healthy children, with 3 of them showing worse HRQoL for children with FAs. Immunotherapy has been found to improve the QoL of children with FAs. Anaphylaxis history, number of FAs, additional allergies, number and severity of symptoms were identified as the main factors with a negative impact on QoL. More comparative studies on the HRQoL of children and adolescents with FAs and healthy populations or children with other chronic diseases are required in order to improve QoL of children with FAs.

Oral immunotherapy for food allergy: Translation from studies to clinical practice?

Oral immunotherapy (OIT) is now recognized as an alternative active treatment to strict food avoidance in certain patients with IgE-mediated food allergy. Studies have confirmed the efficacy of OIT to desensitize children with allergy to cow's milk, eggs, and peanuts. The benefits, risks, and constraints of OIT are becoming increasingly well understood. However, there is no consensual criteria to select patients to whom OIT could be proposed, and many issues remain to address including the definitions of desensitization and long-term efficacy, the assessment of patient's experience in real life, the optimization of buildup and maintenance protocols, and the utility of multiple food OIT. The recent authorization by medical agency concerning the first medicine for peanut OIT is a step forward towards higher standardization in the practice of OIT. This article summarizes in comprehensive narrative format data on efficacy, tolerance, impact on quality of life and adverse effects of OIT and discuss elements to consider in clinical practice before starting OIT.

Prick-by-Prick Test with Pasteurised Cow’s Milk: A Valuable Tool in Paediatric Practice

Background

This study assessed the utility of a prick-by-prick test with pasteurised cow's milk in predicting a pasteurised cow's milk allergy (CMA) diagnosis.

Methods

This was a retrospective study of 86 paediatric patients who had undergone open pasteurised cow's milk oral food challenges (OFCs). We evaluated the diagnostic performance of a prick-by-prick test with pasteurised cow's milk in predicting a positive OFC result. We calculated the threshold values representing high test specificity and predictive probability in children aged ≤24 and >24 months.

Results

A prick-by-prick test with pasteurised cow's milk was a good classifier of a positive cow's milk OFC outcome. The mean prick − by − prick test wheal diameter ≥ 3 mm yielded 100% sensitivity in both groups of children. Thresholds representing high test specificity and 95% predicted probability were 7 and 11 mm in children ≤ 24 months and 11 and 17 mm in children > 24 months of age, respectively.

Conclusion

A prick-by-prick test with pasteurised cow's milk is valuable in paediatric practice when diagnostic thresholds are implemented.

The dilemma of open or double-blind food challenges in diagnosing food allergy in children: Design of the ALDORADO trial

BACKGROUND

It is of major importance to diagnose food allergy accurately. Current guidelines support the use of oral food challenges to do so. The double-blind placebo-controlled food challenge (DBPCFC) has been regarded as the 'gold standard' for decades. However, DBPCFCs are costly, and time- and resource-intensive procedures. Structural implementation of less demanding open food challenges will only find support if research demonstrates that their outcome is comparable to DBPCFC, yet this has been proven difficult to investigate.

METHODS

We performed a literature review to investigate the diagnostic accuracy of oral food challenges and interviewed 19 parents of children with proven or suspected food allergy about the design of a trial to study this.

RESULTS

An overview of the dilemma of diagnosing food allergy using oral food challenges, and the methodological issues and parents' opinions to study this. No comparative studies have been performed using the latest guidelines on oral food challenges.

CONCLUSIONS

There is an urgent need to investigate the diagnostic accuracy of different oral food challenge protocols. We present the rationale and design of the ALDORADO trial (ALlergy Diagnosed by Open oR DOuble-blind food challenge) that has been set up to investigate whether the outcome of the open food challenge is comparable to DBPCFC.

Food Allergies: An Example of Translational Research

Food allergies have been rising in prevalence since the 1990s, imposing substantial physical, psychosocial, and economic burdens on affected patients and their families. Until recently, the only therapy for food allergy was strict avoidance of the allergenic food. Recent advances in translational studies, however, have led to insights into allergic sensitization and tolerance. This article provides an overview of cutting-edge research into food allergy and immune tolerance mechanisms utilizing mouse models, human studies, and systems biology approaches. This research is being translated and implemented in the clinical setting to improve diagnosis and reduce food allergy's public health burden.

Investigation of Basophil Activation Test for Diagnosing Milk and Egg Allergy in Younger Children

In children with concomitant food allergy and atopic dermatitis (AD), uncovering the causative food allergen is more arduous. We evaluated the basophil activation test (BAT) for its diagnostic value in children, including those with AD, for milk or egg allergy. We simultaneously measured serum-specific immunoglobulin E (sIgE) levels and performed BATs for cow’s milk and egg white. We compared their overall diagnostic performance using the area under the receiver operating characteristic curve (AUC) with the Delong method and compared them in children with AD. Analyses were completed for 75 children for milk allergy and for 85 children for egg allergy. The sIgE and percentage of basophils with the expression of CD63 were correlated for both milk (r = 0.384, p < 0.001) and egg (r = 0.557, p < 0.001). The AUC of sIgE (0.701) for milk allergy was significantly increased when combined with the BAT (0.805; p = 0.029). In children with AD, the AUC of the BAT (0.924) for milk allergy was significantly larger than that of sIgE (0.701; p = 0.017). The BAT is a potentially useful diagnostic tool for milk allergy in children when combined with sIgE. Moreover, it may be a surrogate marker for milk allergy in children with AD.

Advances and novel developments in mechanisms of allergic inflammation

In the past decade, research in the molecular and cellular underpinnings of basic and clinical immunology has significantly advanced our understanding of allergic disorders, allowing scientists and clinicians to diagnose and treat disorders such as asthma, allergic and nonallergic rhinitis, and food allergy. In this review, we discuss several significant recent developments in basic and clinical research as well as important future research directions in allergic inflammation. Certain key regulatory cytokines, genes and molecules have recently been shown to play key roles in allergic disorders. For example, interleukin-33 (IL-33) plays an important role in refractory disorders such as asthma, allergic rhinitis and food allergy, mainly by inducing T helper (Th) 2 immune responses and clinical trials with IL-33 inhibitors are underway in food allergy. We discuss interleukin 4 receptor pathways, which recently have been shown to play a critical role among the allergic inflammatory pathways that drive allergic disorders and pathogenesis. Further, the cytokine thymic stromal lymphopoietin (TSLP) has recently been shown as a factor in maintaining immune homeostasis and regulating type 2 inflammatory responses at mucosal barriers in allergic inflammation and targeting TSLP-mediated signalling is considered an attractive therapeutic strategy. In addition, new findings establish an important T cell-intrinsic role of mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) proteolytic activity in the suppression of autoimmune responses. We have seen how mutations in the filaggrin gene are a significant risk factor for allergic diseases such as atopic dermatitis, asthma, allergic rhinitis, food allergy, contact allergy, and hand eczema. We are only beginning to understand the mechanisms by which the human microbiota may be regulating the immune system, and how sudden changes in the composition of the microbiota may have profound effects, linked with an increased risk of developing chronic inflammatory disorders, including allergies. New research has shown the important but complex role monocytes play in disorders such as food allergies. Finally, we discuss some of the new directions of research in this area, particularly the important use of biologicals in oral immunotherapy, advances in gene therapy, multifood therapy, novel diagnostics in diagnosing allergic disorders and the central role that omics play in creating molecular signatures and biomarkers of allergic disorders such as food allergy. Such exciting new developments and advances have significantly moved forth our ability to understand the mechanisms underlying allergic diseases for improved patient care.