Baked Egg and Milk Exposure as Immunotherapy in Food Allergy

Basophil activation test in the food allergy clinic: its current use and future applications

INTRODUCTION

The basophil activation test (BAT) has shown evidence of high sensitivity and high specificity to support the diagnosis of IgE-mediated allergy. It is a functional test that uses live cells analyzed by flow cytometry and thus needs to be performed within 24h of blood collection. BAT has shown to be reproducible and reliable when tested in a clinical diagnostic laboratory with standardized protocols and flow cytometry settings.

AREAS COVERED

In this review, we summarize the evidence to support clinical use of BAT and the next steps required for clinical implementation for an improve clinical care for patients with suspected IgE-mediated food allergy.

EXPERT OPINION

BAT has recently been included in Clinical Guidelines of Food Allergy Diagnosis and its implementation in clinical practice depends largely on availability. Proposed clinical applications of the BAT include: distinction between food allergy and asymptomatic IgE sensitization; determination of food allergic status to peanut, tree nuts and seeds in polysensitized children; evaluation of tolerance to baked egg and baked milk in egg and milk allergic children; identification of patients at high-risk of severe allergic reactions; monitoring for spontaneous resolution of food allergy; confirmation of eligibility for specific treatments of food allergy; prediction and monitoring of response to immunomodulatory treatments.

Baked milk and egg diets revisited

Most children with milk and egg allergy are nonreactive to modified forms of milk and egg in bakery products such as muffins because of conformational changes in proteins. These baked milk (BM) and baked egg (BE) diets have become commonplace in the management of milk and egg allergy, respectively. Current laboratory- and skin test-based diagnostic approaches remain limited in their ability to predict BM/BE tolerance, resulting in various approaches to introduce these foods. One approach to introduce BM/BE is to offer a medically supervised oral food challenge and then advise dietary introduction of baked products for children who have tolerance. Another approach is adapted from a home-based protocol of graded ingestion of BM or BE originally intended for non-IgE mediated allergy, often referred to as a "ladder." The ladder advises home ingestion of increasing amounts of BM or BE. For children who have allergy to BM or BE, the ladder is essentially oral immunotherapy, although not always labeled or recognized as such. Risk assessment and education of patients suitable for home introduction are essential. A home approach that may be called a ladder can also be used to escalate diets after demonstrated tolerance of baked forms by introducing lesser cooked forms of milk or egg after tolerating BM or BE. A randomized controlled trial provided clear evidence that baked diets can hasten the resolution of IgE-mediated milk allergy. Moreover, BM/BE foods have an emerging role in the treatment of non-IgE-mediated allergy. There is tangential evidence for BM and BE diets in the prevention of IgE-mediated allergy.

Baked Milk and Baked Egg Survey: A Work Group Report of the AAAAI Adverse Reactions to Foods Committee

Most milk- and egg-allergic children can tolerate milk and egg in baked forms. Some allergists have extended the use of baked milk (BM) and baked egg (BE) to advocating for the stepwise introduction of small amounts of BM and BE to children who are reactive to larger amounts of BM and BE. Little is known about the practice of introducing BM and BE and existing barriers to this approach. The purpose of this study was to gather a current assessment of the implementation of BM and BE oral food challenges and diets for milk- and egg-allergic children. We conducted an electronic survey of North American Academy of Allergy, Asthma & Immunology members offering BM and BE introduction in 2021. The response rate was 10.1% of distributed surveys (72 of 711). Surveyed allergists had a similar approach to both BM and BE introduction. Demographic features of time in practice and region of practice were significantly associated with the odds of introducing BM and BE. A wide variety of tests and clinical features guided decisions. Some allergists determined BM and BE to be appropriate for home introduction and offered this for BM and BE more often than other foods. The use of BM and BE as a food for oral immunotherapy was endorsed by almost half of respondents. Less time in practice was the most significant factor associated with offering this approach. Published recipes were used and written information was widely provided to patients by most allergists. The wide practice variabilities reveal a need for more structured guidance about oral food challenges, in-office versus home procedures, and patient education.

Prospective evaluation of tolerance to unheated milk-boiled egg after baked milk-egg tolerance under 2 years

BACKGROUND

The time to acquisition of tolerance to unheated milk and regular egg after achievement of tolerance to baked goods is not known.

OBJECTIVE

To determine the time to acquisition of unheated-milk-regular-egg tolerance, after the tolerance of the baked forms, in children younger than 2 years.

METHODS

An initial oral food challenge with baked milk (BM) and baked egg (BE) was performed on patients who were reactive to unheated milk-regular egg, respectively. Patients who were BM-BE tolerant were offered unheated-milk-regular-egg challenges, and patients who were BM-BE reactive were offered BM-BE challenges at an average of 3-month intervals. Food-induced atopic dermatitis was included.

RESULTS

Thirty-six children with unheated-milk allergy (median age, 7.3 months [interquartile range (IQR), 6.0-13.5]) and 65 with regular-egg allergy (median age, 7 months [IQR, 5.8-11.0]) were included. Seven of 13 children who were BM tolerant acquired unheated-milk tolerance after a median 4.0 months (IQR, 2.0-7.0). Twelve of 23 children who were BM reactive acquired unheated-milk tolerance after a median 5.0 months (IQR, 3.0-8.0) after BM tolerance. Twenty-one of 29 children who were BE tolerant acquired regular-egg tolerance after a median 3.0 months (IQR, 1.0-6.0). Sixteen of 36 children who were BE reactive acquired regular-egg tolerance after a median 4.0 months (IQR, 2.0-6.8) after BE tolerance.

CONCLUSION

Different tolerance rates were determined for baked products at different time points in the first 2 years of life. Unheated-milk-regular-egg allergy resolved in up to 65.5% and 75.5% of cases, respectively, in an average 4 to 5 months after acquisition of BM-BE tolerance. Baked-milk-baked-egg tolerance may be regarded as a precursor of tolerance.

Oral immunotherapy in pediatrics

IgE-mediated food allergy (FA) has been emerging as a public health priority, mainly in children. It represents a heavy burden for the entire society and not only for the patients and their families. There is evidence that in children with persistent FA, at least to cow's milk, hen's egg, and peanut, oral immunotherapy (OIT) may increase the reaction threshold to food allergen(s), while receiving active therapy (the so-called "desensitization"). Furthermore, OIT protects patients from the occurrence of severe reactions in the event of accidental ingestion of the culprit food during treatment. However, many gaps are still unsolved, including safety issues, identification of predictive biomarkers, and post-desensitization efficacy. This article briefly summarizes the current evidence and the main needs in OIT to stimulate the development of longitudinal, prospective, well-designed studies able to fill the current gaps soon.

Recent developments and highlights in food allergy

The achievement of long-lasting, safe treatments for food allergy is dependent on the understanding of the immunological basis of food allergy. Accurate diagnosis is essential for management. In recent years, data from oral food challenges have revealed that routine allergy testing is poor at predicting clinical allergy for tree nuts, almonds in particular. More advanced antigen-based tests including component-resolved diagnostics and epitope reactivity may lead to more accurate diagnosis and selection of therapeutic intervention. Additional diagnostic accuracy may come from cellular tests such as the basophil activation test or mast cell approaches. In the context of clinical trials, cellular tests have revealed specific T-cell and B-cell populations that are more abundant in food-allergic individuals with distinct mechanistic features. Awareness of clinical markers, such as the ability to eat baked forms of milk and egg, continues to inform the understanding of natural tolerance development. Mouse models have allowed for investigation into multiple mechanisms of food allergy including modification of epithelial metabolism, and the induction of regulatory cell subsets and the microbiome. Increasing numbers of children who underwent food immunotherapy enlarged the body of evidence on mechanisms and predictors of treatment success. Experimental immunological markers in conjunction with clinical determinants such as lower age and lower initial specific IgE appear to be of benefit. More research on the optimal dose, preparation, and route of application integrating a high-level safety and efficacy is demanded. Alternatively, biologics blocking TSLP, IL-33, IL-4 and IL-13, or IgE may help to achieve that.

Food allergy-From food avoidance to active treatment

The prevalence of food allergy (FA) has increased too rapidly, possibly due to environmental factors. The guidelines recommend strict allergen avoidance, but FA is still the main cause of anaphylaxis in all age groups. Immunotherapy is the only treatment able to change the course of allergic disease, and oral immunotherapy (OIT) is the more effective route in FA. However, it carries the risk of adverse reactions, including anaphylaxis. To improve OIT safety, adjuvant therapy with the immunoglobulin E (IgE) monoclonal antibody omalizumab has been extensively used. Results suggest particular benefit in patients with high risk of fatal anaphylaxis. An alternative approach is to use omalizumab instead of OIT to prevent severe allergic reactions upon accidental exposure. This paper reviews current evidence regarding IgE-mediated FA, focusing on natural tolerance and food sensitization acquisition, and on avoidance measures and their limitations.

The effect of baked milk on accelerating unheated cow's milk tolerance: A control randomized clinical trial

BACKGROUND

Assessing the effect of adding baked milk products to the diet of patients with cow's milk allergy on accelerating the formation of tolerance.

METHOD

A randomized clinical trial was carried out with 84 patients (6 months-3 years old) diagnosed with allergy to cow's milk who tolerated baked milk in form of muffin in oral food challenge (OFC). The subjects were divided randomly into case and control groups matched for age and sex. Patients in the case group were asked to consume baked milk in the form of muffin for 6 months and then to consume baked cheese in the form of pizza for another 6 months. The control group were instructed to strictly avoid any milk products for 1 year. Skin prick test (SPT) and serum-specific immunoglobulin E (sIgE) levels (ImmunoCAP) of milk, casein, and beta-lactoglobulin were measured before and after the study. In addition, those in the case group who had satisfactorily tolerated baked products during the study as well as all the subjects in the control group underwent an OFC to evaluate unheated milk tolerance at the end of the study.

RESULTS

It was shown that by the end of the 1-year study period, 88.1% (37/42) of the patients in the case group and 66.7% (28/42) of those in control group had developed tolerance to unheated milk (P-value: 0.018). The results of milk-specific SPT and sIgE levels showed a significant decrease in the case group. Initial sIgE levels could not predict unheated milk tolerance in case and control groups.

CONCLUSION

Introducing baked milk products into the diet of patients with milk allergy can accelerate the tolerance of unheated milk in these patients. sIgE levels of milk, casein, and beta-lactoglobulin did not predict the tolerance of unheated milk.

New modalities of allergen immunotherapy

Allergen immunotherapy is a rapidly evolving field. Although subcutaneous immunotherapy has been practiced for over a hundred years, improved understanding of the underlying immunological mechanisms has led to the development of new, efficacious and better tolerated allergen-derivatives, adjuvants and encapsulated allergens. Diverse routes of allergen immunotherapy - oral, sublingual, epicutanoeus and intralymphatic - are enabling immunotherapy for anaphylactic food allergies and pollen-food allergy syndrome, while improving the tolerability and effectiveness of aeroallergen immunotherapy. The addition of Anti-IgE therapy decreases adverse effects of subcutaneous and oral immunotherapy.

A general strategy for de novo immunotherapy design: the active treatment of food allergy

INTRODUCTION

IgE-mediated food allergy (FA) has been emerging as a public health priority. It is a potentially life-threatening condition with negative impact on the quality of life of patients and their family and its prevalence is increasing in westernized countries in the recent two decades. The current standard approach to FA consists of the strict avoidance of the triggering food. However, an elimination diet may be difficult and frustrating, above all for those foods (e.g. milk and egg) that are pivotal in the common diet. Oral immunotherapy (OIT) may increase the amount of food that the patient can intake without reaction and reduce the risk of potential life-threatening allergic reactions. It is currently considered the most promising treatment for FA. However, many gaps are still unsolved. Areas covered: The aim of this review is to shed light on the current evidence and the main needs in OIT in order to stimulate the development of longitudinal, prospective, and well-designed studies with the final goal of a 'precision medicine.' Expert commentary: Clinical trials for OIT conducted so far are extremely heterogeneous. The aim in the near future is to identify the most suitable candidates to OIT and algorithms for treatments tailored on well-characterized subpopulations of patients.