Soluble IgE‐binding factors in the serum of food‐allergic patients: Possible pathophysiological role of soluble FcεRI as protective factor

Abstract

Background: IgE-mediated food allergy is the result of an aberrant immune response involving the interaction of a food allergen with its specific IgE bound to FceRI, the high affinity IgE receptor, on mast cells. Allergen-specific IgE also binds to soluble binding factors, but, their expression and role in food allergy is not well characterized. Here, we assess the prevalence and relevance of soluble IgE binding factors in food allergy and tolerance.

Methods: We measured serum levels of four IgE binding factors, that is, galectin-3, galectin-9, soluble Fc epsilon RI (sFc epsilon RI) and soluble CD23 (sCD23) in 67 adults sensitized to peanut or hazelnut and sFc epsilon RI in 29 children sensitized to hen's egg. Adults without food allergen sensitization (n = 17) served as healthy controls. We compared serum levels of patients and controls and assessed them, in the former, for links to clinical features including allergy and tolerance.

Results: Serum levels of sFc epsilon RI and sCD23, but not galectin-3 and galectin-9, significantly differ in food-sensitized patients as compared to healthy controls. A subgroup (28%) of peanut and hazelnut allergic patients had elevated sFc epsilon RI levels, that were associated with higher total and specific IgE levels. Furthermore, sFc epsilon RI levels were significantly higher in tolerant subjects compared to allergics. Among hazelnut allergic patients, those with high sFc epsilon RI levels tolerated the highest protein amounts in the oral food challenge.

Conclusion: sFc epsilon RI but not sCD23, galectin-3 and galectin-9 might play a role in the pathophysiology of food allergy. Its functional role or use as biomarker should be assessed in further studies.