In a clinical trial, the immunomodulatory effects of partial egg intake altered the diagnostic performance of allergy tests.
Egg allergy is one of the most common food allergies in children, with the majority of egg-allergic children being tolerable to partial egg intake in their diet. The pre-oral food challenge (pre-OFC) consumption of eggs can modify the diagnostic performance of allergic tests such as allergen-specific immunoglobulin E (sIgE), the basophil activation test (BAT), and the skin prick test (SPT).
In the Basophil Activation Test to Diagnose Food Allergy (BAT2) clinical trial, published in the Journal of Allergy and Clinical Immunology: In Practice, the authors stratified the diagnostic performance of allergy tests based on the status of egg intake of study participants.
Study Participants
The study enrolled 139 participants; 53 were baked egg-allergic, 81 were baked egg-tolerant, and the oral food challenge was inconclusive in 5 participants. Approximately 45% of the participants reported partial egg intake and were labeled ‘consumers’, and the remaining cohort was labeled ‘avoiders’.
Partial Egg Consumption and Egg-Specific Immune Response
Avoiders were found to have higher basophil activation after allergic stimulation (p < 0.001), higher levels of IgE in response to eggs (p = 0.002), and higher SPT response to egg extracts (p < 0.001). Compared to avoiders, consumers had increased levels of sIgG4 in response to eggs.
Diagnostic Performance of Allergy Tests and Egg Consumption
The best overall diagnostic performance was observed in BAT and sIgE tests in response to egg whites. BAT was the best test for identifying participants who reacted to baked eggs in the consumer group. In the avoider group, the best tests were BAT and sIgE to identify participants who reacted to egg white.
Diagnostic Accuracy of Allergy Tests for Patient Outcomes
Compared to other diagnostic tests, BAT was associated with the lowest requirement for OFC, particularly in the consumer group. Approximately 22% of patients required OFC when sIgE to ovalbumin and BAT were performed in consumers, with 64% of OFC being positive. On the contrary, 27% of consumers required OFC when sIgE to egg white and BAT were performed, with 38% of OFC being positive.
The most reliable test for egg allergy diagnosis for participants with partial egg consumption was BAT. The immunomodulatory effects of egg intake can alter the diagnostic performance of allergy tests.
Source:
Marques‐Mejias, A., Radulovič, S., Foong, R., Bartha, I., Krawiec, M., Kwok, M., Jama, Z., Harrison, F., Ricci, C., Lack, G., Du Toit, G., & Santos, A. F. (2023). Partial egg consumption modifies the diagnostic performance of allergy tests to predict outcome of double-blind placebo-controlled food challenges to egg. The Journal of Allergy and Clinical Immunology: In Practice, 12(3), 660–669.e5. https://doi.org/10.1016/j.jaip.2023.12.036
