Variability of allergens in commercial fish extracts for skin prick testing.
BACKGROUND
Commercial allergen extracts for allergy skin prick testing (SPT) are widely used for diagnosing fish allergy. However, there is currently no regulatory requirement for standardization of protein and allergen content, potentially impacting the diagnostic reliability of SPTs. We therefore sought to analyse commercial fish extracts for the presence and concentration of fish proteins and in vitro IgE reactivity using serum from fish-allergic patients.


METHODS
Twenty-six commercial fish extracts from five different manufacturers were examined. The protein concentrations were determined, protein compositions analysed by mass spectrometry, followed by SDS-PAGE and subsequent immunoblotting with antibodies detecting 4 fish allergens (parvalbumin, tropomyosin, aldolase and collagen). IgE-reactive proteins were identified using serum from 16 children with confirmed IgE-mediated fish allergy, with focus on cod, tuna and salmon extracts.


RESULTS
The total protein, allergen concentration and IgE reactivity of the commercial extracts varied over 10-fold between different manufacturers and fish species. The major fish allergen parvalbumin was not detected by immunoblotting in 6/26 extracts. In 7/12 extracts, five known fish allergens were detected by mass spectrometry. For cod and tuna, almost 70% of patients demonstrated the strongest IgE reactivity to collagen, tropomyosin, aldolase A or β-enolase but not parvalbumin.


CONCLUSIONS
Commercial fish extracts often contain insufficient amounts of important allergens including parvalbumin and collagen, resulting in low IgE reactivity. A comprehensive proteomic approach for the evaluation of SPT extracts for their utility in allergy diagnostics is presented. There is an urgent need for standardized allergen extracts, which will improve the diagnosis and management of fish allergy.
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D000293:Adolescent D000485:Allergens D000818:Animals D000906:Antibodies D000940:Antigenic Variation D002648:Child D002675:Child, Preschool D005260:Female D005396:Fish Products D005399:Fishes D005512:Food Hypersensitivity D006801:Humans D007073:Immunoglobulin E D007223:Infant D008297:Male D013058:Mass Spectrometry D012882:Skin Tests
skin prick test fish allergy IgE reactivity parvalbumin allergy diagnostics