Epitope-Based IgE Assays and Their Role in Providing Diagnosis and Prognosis of Food Allergy

Diagnosis and management of shrimp allergy

Shrimp allergy, the most common food allergy in the United States, affects up to 2% of the population. Its etiology is multi-factorial with the combination of genetic predisposition and environmental exposures. This review summarizes the latest diagnosis and management strategies for shrimp allergy. Currently, the double-blind, placebo-controlled food challenge is the gold standard for diagnosis. Moreover, mainstream and experimental management strategies include food allergen avoidance, the FDA-approved omalizumab, and oral immunotherapy. Herein, we emphasize the urgent need to develop more effective diagnostic tools and therapies for shrimp allergy.

Serologic measurements for peanut allergy: Predicting clinical severity is complex

Allergist-immunologists use serologic peanut allergy testing to maximize test sensitivity and specificity while minimizing cost and inconvenience. Recent advances toward this goal include a better understanding of specific IgE (sIgE) and component testing, epitope-sIgE assays, and basophil activation testing. Predicting reaction severity with serologic testing is challenged by a range of co-factors that influence reaction severity, such as the amount and form of any allergen consumed and comorbid disease. In 2020, the Allergy Immunology Joint Task Force on Practice Parameters recommended Ara h 2-sIgE as the most cost-effective diagnostic test for peanut allergy because of its superior performance, when compared with skin prick testing and serum IgE. Basophil activation testing, a functional test of allergic response not evaluated in the Joint Task Force on Practice Parameters guideline, is a promising option for both allergy diagnosis and prognosis. Similarly, epitope-sIgE testing may improve prediction of reaction thresholds, but further validation is needed. Despite advances in food allergy testing, many of these tools remain limited by cost, accessibility, and feasibility. In addition, there is a need for further research on how atopic dermatitis may be modifying serologic food allergy severity assessments. Given these limitations, allergy test selection requires a shared decision-making approach so that a patient's values and preferences regarding financial impact, inconvenience, and psychological effects are considered in the context of clinician expertise on the timing and use of optimized testing.

History of food allergy and where we are today

The food allergy (FA) entity went through a long difficult road which led to much delay in its recognition. After long periods of denial and misdiagnosis, it attained its current designation as food hypersensitivity or allergy. This review will briefly address the evolution of the FA entity from the early BC era until our 21st century and highlight the milestones in the main aspects of diagnosis, treatment, prevention, and research. A great recognition of the allergy specialty was gained by the discovery of its main mediator -immunoglobulin E in 1967 - which also helped in classifying FA into IgE-mediated (immediate-type) and non-IgE-mediated. The cause of the increasing prevalence during the past few decades may be attributed to an increased food consumption and the consequences of modern lifestyle (the hygiene hypothesis). In addition to a skillful medical history-taking, helpful tests have been developed involving the skin or blood. The scratch test was modified to the prick test and in certain instances prick-by-prick. The use of intradermal test has been markedly reduced. Blood testing began by measuring specific-IgE antibodies (sIgE) in the serum using the radioallergosorbent test which went through multiple modifications to avoid radioisotope material and increase the test's sensitivity. The test was advanced to measure sIgE to individual allergen components. Recently, cellular tests were developed in the form of basophil activation or mast cell activation. In most cases, FA needs verification by appropriately-designed challenge testing. Regarding treatment, strict avoidance remains the basic approach. Certain food-labeling regulations led to some improvement in the problem of hidden food allergens but more is desired. Recently some protocols for oral immunotherapy (OIT) showed reasonable safety and efficacy in preventing reactions to accidental exposures. The protocol for peanut has been approved in the United States and other foods are expected to follow. Epicutaneous immunotherapy showed higher safety and promising efficacy. Sublingual immunotherapy might follow as well. Studies on the use of certain biologicals, alone or in combination of OIT, showed promising findings. Very recently, omalizumab was approved in the United States for patients with multiple FA. A major change in the strategy of prevention is the benefit of introducing allergenic foods at an early age (4-6 months). Research on FA markedly flourished in recent decades with increasing numbers of investigators, funding, publications, and education. Despite the major strides, still more awaits exploration with expected better understanding and practice of FA.