Reaction thresholds to milk, egg higher for children who tolerate baked proteins
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Children with milk and egg allergies who tolerated baked proteins had higher reactivity thresholds than the general population of children with these allergies, according to a study published in Allergy.
Risk stratification should account for these differences among individuals and the overall population of children with food allergies, Rocco Luigi Valluzzi, MD, research fellow in the department of pediatric medicine at Bambino Gesù Children’s Research Hospital in Rome, and colleagues wrote.
The study involved 288 children (mean age, 69.5 months; standard deviation, 46.5 months; 67.1% boys) who had a history of an acute IgE-mediated allergic reaction. Of these, 146 children completed a seven-step oral food challenge for milk and 142 for egg at the Bambino Gesù Allergy Department between January 2018 and December 2020, with 87 children (30.2%) showing positive OFC results.
The researchers classified reactive symptoms into five groups ranging from subjective symptoms such as nausea, abdominal pain, pruritis and oral allergy syndrome to systemic reactions.
Of the 38 children with a positive milk OFC, 28 (73.6%) developed urticarial eruptions classified as group 2 reactions, three developed group 3 reactions and seven developed a group 4 systemic reaction.
Of the 49 children with a positive egg OFC, symptoms led the researchers to classify 26 of these children (53.1%) as group 2 with generalized urticaria, nine as group 3 and 11 as group 4 with systemic reactions.
There were no group 5 reactions in either group, which the researchers attributed to their trained staff providing prompt interventions at the first signs of objective symptoms.
Each group had one child who reacted to the first dose, including a child who reacted to 3.43 mg of milk proteins and another who reacted to 12.36 mg of egg proteins. Both children had group 4 reactions of emesis with dyspnea.
Both groups also included at least one positive OFC for each single step-dose, with 10.5% of the reactions in the milk group and 24.5% of the reactions in the egg group happening after the seventh dose.
The Voluntary Incidental Trace Allergen Labelling (VITAL) scheme from the Australian and New Zealand food industries has determined eliciting doses (EDs) that are predicted to elicit allergic reactions in 1% (ED01) and 5% (ED05) of the population. These guidelines — calculated based on populations of patients who were allergic to both raw and baked foods — include an ED01 of 0.2 mg total protein and an ED05 of 0.5 mg to 2.4 mg total protein for milk and egg.
However, the researchers used their data to extrapolate their own ED01 and ED05 levels as well as EDs for 10% (ED10), 25% (ED25) and 50% (ED50) of patients with milk and egg allergies who also were tolerant to beef and baked proteins.
The EDs in the milk group ranged from 0.3 mg to 1.4 mg of protein for ED01, to 185.6 mg to 268.6 mg for ED50.
The EDs in the egg group ranged from 14.4 mg to 29.7 mg of protein for ED01, to 1,195.5 mg to 1,595.5 mg for ED50.
The researchers called their threshold values higher but still similar to those VITAL uses for ED01 and ED05 for milk, but considerably higher for ED01 and ED05 for egg.
Specifically, the researchers’ thresholds were 1.5 times higher for milk ED01 and 1.75 times higher for milk ED05 compared with the VITAL guidelines. They also were 72 times higher for egg ED01 and 38.35 times higher for egg ED05.
These findings suggest that children who are tolerant to baked egg may have less of a risk for severe reactions compared with children who are tolerant to baked milk. Further, the researchers found that these children possibly could tolerate egg traces and consume prepackaged foods with precautionary allergen labelling for egg.
Considering these differences, the researchers found that clinical attitudes toward milk and egg allergies could be differentiated. Also, the researchers plan to evaluate these differences in thresholds are present in children with baked egg and milk allergies.