Dissecting the Sensitization Profiles in Parvalbumins From 12 Freshwater Fish Species to Improve Diagnosis of Fish Allergy

Abstract

Background: Many fish-allergic patients only react to certain fish species and may tolerate others, mostly because of IgE-mediated recognition of specific epitopes on the major allergen parvalbumin. However, the considerable number of fish species consumed makes it challenging to identify which species are allergenic and which are tolerated by individual patients. Objective: In order to improve the diagnosis of fish allergy, we investigated IgE-mediated reactivity to parvalbumins from 12 freshwater fish species that are largely underrepresented in diagnostic tests. Methods: Parvalbumins were purified from 12 freshwater fish species belonging to 8 families, and their isoform composition was analyzed using mass spectrometry. IgE specific for each parvalbumin was quantified in serum samples from 66 fish-allergic individuals, and basophil activation tests were performed for 5 patients. Crosswise inhibition assays were carried out for all parvalbumins for 7 patients to investigate cross-reactivity between the parvalbumins from the different species. Results: IgE binding and cross-linking potency of the parvalbumins differed, with the strongest reactivities observed for 4 parvalbumins from the salmonid family (results positive for 89%-95% of patients) and the weakest for parvalbumins from Wels catfish, European eel, and tench (results negative for >= 50% of patients). Ninety percent of the patients with negative results for Wels catfish parvalbumin also had negative results for additional parvalbumins from multiple species. Inhibition assays revealed variable recognition of epitopes by several patients, with the primary sensitizers most frequently being parvalbumins from salmonids and percids. Conclusion: Including freshwater salmonids in the diagnostic work-up for fish allergy may help to identify most fish-allergic patients. IgE to Wels catfish could help distinguish between polysensitized and oligosensitized patients.