Relative reactivity to egg white and yolk or change upon heating as markers for baked egg tolerance

Abstract

Background Hen's egg food allergy is frequent in childhood and phenotypically heterogeneous. Some children can tolerate extensively heated egg. We investigated whether individual relative responses could differentiate children who tolerate baked egg. Methods Reactivities to raw, pasteurized or hard‐boiled egg (E), egg white (EW), and egg yolk (EY) fractions were tested by skin prick test (SPT) in 54 egg‐allergic children. IgE‐sensitization to EW and EY was determined by ImmunoCAP and IgE‐binding to EW and 8 EW proteins and to EY and 4 EY sub‐fractions by ELISA. Population heterogeneity was assessed by hierarchical ascending classification upon individual variations of reactivity and links between classifications and clinical features by analyzing the contingency tables. Results All children had positive SPT to raw E and raw EW and 72% to raw EY. Heating decreased SPT‐reactivity for some children, pasteurization being less effective than hard‐boiling. Children were classed into three classes from relative SPT‐reactivity to raw fractions, two from variations of SPT‐reactivity with each thermal processing or EW/EY ratio of sensitization, and four from their sensitization pattern. Classifications according to heating were found independent of each other. SPT variations with hard‐boiling, IgE‐sensitization (ratio or pattern) were linked to allowance by the physicians of egg in baked products. Conclusions Egg‐allergic children were often both sensitized to EY and EW, and heterogeneous patterns of relative responses were evidenced. Irrespective of age and level of sensitization, a low EW/EY ratio or SPT getting null with hard‐boiling was found in children allowed to eat baked egg.

Safe egg yolk consumption after a negative result for low‐dose egg oral food challenge

“…Therefore, we can safely recommend that children who passed the low-dose egg OFC consume EY with scEW. Although children with egg allergies are often sensitized to both egg yolk and egg white, and the reactivities to egg yolk and egg white have heterogeneous patterns, most children react to egg white 10. Although the egg yolk OFC is safe and useful,13 our study also confirmed that the amount of contaminating egg white in egg yolk OFC varies occasionally.…”

“…9 This disadvantage is overcomed by performing an OFC with 1/25 of a heated whole egg (low-dose egg) as egg juice, a product with a stable protein dose that varies only by 10%. 10,11 Almost 80% of children with egg allergies can safely consume low-dose egg. 11 In vitro data of enzymelinked immunosorbent assay (ELISA) showed that low-dose egg juice has antigenicity (265.8 mg) similar to that of pumpkin cake, containing EY with scEW (213.2 mg).…”

“…Nevertheless, the challenge foods used in egg yolk OFC have the disadvantage of a variable amount of egg white 5 because egg yolk is separated manually from the whole egg 9 . This disadvantage is overcomed by performing an OFC with 1/25 of a heated whole egg (low‐dose egg) as egg juice, a product with a stable protein dose that varies only by 10% 10,11 . Almost 80% of children with egg allergies can safely consume low‐dose egg 11 .…”

Can food processing produce hypoallergenic egg?

“…There is more focus on allergy to egg white than egg yolk, but egg yolk has also been reported as a source of egg allergens and clinically relevant. A study reported that of the 54 children with egg allergy who participated in a skin prick test, 100% reacted with raw egg white and 72% reacted with raw egg yolk (Brossard et al., 2018). In early life, hyper‐response to boiled egg yolk was found to prolong egg allergy (Horino, Kitazawa, Satou, & Miura, 2019).…”

Tolerance to heated egg in egg allergy: Explanations and implications for prevention and treatment

“…When the elicitation capacity was studied in a clinical setting, several studies showed that the wheal diameter of patient skin‐prick tests (SPT) using baked egg in the presence ( muffin ) or absence ( oven‐baked ) of wheat was generally smaller when compared to raw EW 73,74 (see Table 4). Similarly, using hard‐boiled egg, EW or egg yolk, part of children responsive to raw egg forms were not responsive any more in SPT (43% (egg), 33% (EW) or 72% (egg yolk)) 75 . Pasteurization of egg or EW did not significantly affect SPT size, and only very few raw egg reactive patients became non‐reactive upon pasteurization 75 (see Table 4).…”