Collagen - an important fish allergen for better diagnosis
Published online: May 7, 2020
Fish allergy prevalence is increasing worldwide, and this allergy is associated with a higher rate of anaphylaxis than other food allergies. Diagnostic tools for fish allergy are not comprehensive enough due to the limited knowledge about the repertoire of allergens present in the fish. Fish collagen is a major structural protein abundant in the skin, bones and muscle of fish. In addition to fish consumption, people are exposed to this protein via various cosmetics, pharmaceutical and food products which contain fish collagen. Although previous studies reported severe allergic reactions following exposure to fish collagen, it has not received broad attention and its allergenic properties have not been well understood. Fish collagen was not included in diagnostic tests for fish allergy nor registered as an official allergen by the Allergen Nomenclature Sub-Committee of the World Health Organization and the International Union of Immunological Societies (WHO/IUIS).
The study by Kalic et al, published in The Journal of Allergy and Clinical Immunology: In Practice, investigated the clinical significance of fish collagen as an allergen in a large cohort of patients with fish allergy. This study was performed by researchers from Austria and Australia and included a cohort of over 100 fish-allergic individuals.
A possible reason for the lack of understanding the allergenicity of fish collagen is the insolubility in aqueous solutions, leading to the absence of this allergen from solutions routinely used in research and diagnosis. The researchers isolated collagen from skin and muscle tissues of three frequently consumed fish species (tuna, salmon and Asian seabass), using a specific purification approach with highly acidic solutions. The serum samples of fish-allergic patients were tested for the presence of IgE antibodies for isolated collagen. In addition, the ability of collagen to induce allergic reactions was analysed in cell-based assays using mast cells and basophils. These cell types are rapidly activated in patients upon exposure to allergens and their activation leads to the release of preformed mediators responsible for allergic symptoms.
This study demonstrated that collagen is an important allergen for approximately 20% of fish-allergic individuals, some of which tested negative to other known fish allergens. Based on these findings, fish collagen has now been registered as an official allergen with the Allergen Nomenclature Sub-Committee of the WHO/IUIS. This study emphasized the importance of inclusion of fish collagen in routine diagnosis for fish allergy, which is required for improved management and safety of the patients.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.