Reactivity thresholds in children allergic to cow's milk and egg, but tolerant of baked milk and baked egg.

Background. The use of eliciting doses (EDs) for food allergens is necessary to inform individual dietary advice and food allergen risk-management. The Eliciting Dose 01 (ED01) for milk and egg, calculated from populations of allergic subjects undergoing diagnostic Oral Food Challenges (OFCs), are 0.2 mg total protein. The respective Eliciting Dose 05 (ED05) are 2.4 mg for milk and 2.3 mg for egg. As about 70% children allergic to such foods may tolerate them when baked, we sought to verify the EDs of that subpopulation of milk and egg-allergic children. Methods. We retrospectively assessed consecutive diagnostic OFC for fresh milk and egg between January 2018 and December 2020 in a population of baked food-tolerant children. Results. Among 288 children (median age 56 - IQR 36-92.5 months, 67.1% male) included, 87 (30.2%) returned positive OFC results, 38 with milk and 49 with egg. The most conservative ED01 were 0.3 mg total protein (IQR 0.03-2.9) for milk and 14.4 mg total protein (IQR 3.6-56.9) for egg. The respective ED05 were 4.2 (IQR 0.9-19.6) mg for milk and 87.7 (IQR 43-179) mg for egg. Such thresholds are respectively 1.5 (milk ED01), 1.75 (milk ED05), 72 (egg ED01), and 38.35 (egg ED05) times higher than the currently used thresholds. Conclusions The subpopulation of children allergic to milk and egg, but tolerant to baked proteins, displays higher reactivity thresholds than the general population of children allergic to milk and egg. Their risk stratification, in both individual and population terms, should consider this difference. In baked milk-tolerant children, milk causes reactions at lower doses than egg in our group of egg-tolerant children. This could be associated with the relative harmlessness of egg compared to milk in the determinism of fatal anaphylactic reactions in children

A Simple and Rapid Light-Initiated Chemiluminescence Assay for Quantitation of Artemisia-Specific Immunoglobulin E

<b><i>Background:</i></b> Light-initiated chemiluminescence assay (LICA) is a homogeneous assay that has been successfully used for the quantitation of food allergen-specific immunoglobulin E (sIgE), but not inhaled allergen-sIgE. Simultaneously, current assays used to detect allergen-sIgE are serum consuming and/or time consuming. Hence, we established a method for the quantitation of <i>Artemisia</i>-sIgE based on LICA and verified its performance according to the clinical guideline documents, laying a foundation for the quantitation of inhaled and food allergen-sIgE in parallel on LICA. <b><i>Methods:</i></b> The assay was established after optimizing the first incubation time and the dilutions of <i>Artemisia</i>-coated chemibeads, biotinylated goat anti-human IgE, and serum. In order to quantitate <i>Artemisia</i>-sIgE, the calibration curve was established with a high positive serum of known concentration. The assay performance was confirmed per the clinical guideline documents. In addition, the correlation between the results of LICA and capture enzyme-linked immunosorbent assay was evaluated. <b><i>Results:</i></b> The developed LICA’s coefficients of variation of repeatability and intermediate precision were 3.20%, 2.14%, and 3.85% and 4.30%, 4.00%, and 4.40%, respectively. The limit of detection was 0.10 kU_A/L, and the limit of quantitation was 0.11 kU_A/L. The range of linearity was from 0.27 kU_A/L to 97.53 kU_A/L (<i>r</i> = 0.9968). The correlation coefficient (<i>r</i>) for the correlation analysis between results of LICA and capture ELISA was 0.9087. This assay was successfully applied in 64 human serum samples, showing good sensitivity (82.20%) and specificity (100%). <b><i>Conclusion:</i></b> An <i>Artemisia</i>-sIgE quantitation assay based on LICA was successfully established. Its performance satisfied the clinical requirements and could be widely used in clinical laboratories.

Intrinsic Atopic Dermatitis: Titration of Precipitins in the Screening of Food Allergens for Prescription of Elimination Diets and Desensitization Strategies

Background: The diagnosis of non-IgE mediated food allergies may be a complex puzzle when there is no start point to establish an elimination diet to allow a clear clinical field to initiate diagnostic Oral Food Challenges tests. Objective: To evaluate the opportunity of the tube titration of precipitins to select food allergens to proceed with elimination diets to assist the diagnosis and management of adult patients with Food Allergy manifested as Intrinsic Atopic Dermatitis (IAD). Methods: The tube titration of specific precipitins against anamnesis-chosen food allergens were performed in 64 IAD patients and their titers were associated with an Improvement Verbal Scale Rate (IVSR) of the patient’s perception of the benefits of the Precipitins-based Elimination Diet (PED) performed with these specific food allergens, as well correlated with their positive or negative perception of the impairment of symptoms after the reintroduction of the Symptom-Related Food Allergen (SRFA). Results: In most cases, the PED contributed to a significant clinical improvement that allowed the patients to evaluate the individual effect of the reintroduction of each food allergen on their diets. There was a significant positive correlation coefficient between the titers of the food-specific titration of precipitins and the percentage of positive SRFA (Pearson r = 0.91; p-value = 0.0004). Conclusion: The semiquantitative titration of specific precipitins against food allergens is a promising triage test to select food allergens to proceed with elimination diets to support the diagnosis and management of non-IgE mediated Food Allergy in patients with Intrinsic Atopic Dermatitis.