Dysregulated specific IgE production to bystander foods in children with peanut allergy but not egg allergy.

Background: Food specific immunoglobulin E (sIgE) levels are associated with the development of allergic responses and are used in the clinical evaluation of food allergy. Food sIgG4 levels have been associated with tolerance or clinical nonresponsiveness, particularly in interventional studies.

Objective: We aimed to characterize food-specific antibody responses and compare responses with different foods in food allergy.

Methods: Serum sIgA, sIgG4, and sIgE to whole peanut, egg white, and wheat, along with total IgE were measured in 57 children. Children with food allergy, children with natural tolerance, and controls were studied. The Mann-Whitney test or Kruskall Wallis test with the Dunn correction were used for statistical analysis.

Results: As expected, total IgE levels were highest in the subjects with food allergy compared with the subjects who were nonallergic (p < 0.001) or the subjects who were naturally tolerant (p < 0.001). Peanut sIgE levels were higher in subjects with peanut allergy compared with the subjects who were naturally tolerant (p < 0.0001) and the control subjects (p < 0.03). Interestingly, peanut sIgG4 levels were also highest in children with peanut allergy compared with subjects who were naturally tolerant and control subjects (p = 0.28 and p < 0.001, respectively). Subjects with peanut allergy alone had comparable egg white sIgE levels to children with egg white allergy. In addition, the subjects with peanut allergy alone also had higher levels of egg white and wheat sIgE compared with the control subjects (p < 0.02 and p = 0.001, respectively). In contrast, the subjects with egg white allergy did not demonstrate elevated peanut or wheat sIgE levels.

Conclusion: These novel findings suggested that IgE production is dysregulated in patients with peanut allergy, who are much less likely to outgrow their allergy, and suggest that the mechanisms that drive more persistent forms of food allergy may be distinct from more transient forms of food allergy.