Allergenicity and Stability of 6 New Korean Bony Fish Extracts

Cross-reactive monoclonal antibodies against fish parvalbumins as a tool for studying antigenic similarity of different parvalbumins and analysis of fish extracts

Fish parvalbumins are heat-stable calcium-binding proteins that are highly cross-reactive in causing allergy symptoms in fish-sensitized patients. The reactivities of parvalbumin-specific monoclonal or polyclonal antibodies with parvalbumins of different fish species allowed their application for development of various immunoassays for allergen identification in fish samples. In this study, monoclonal antibodies (MAbs) were generated against two parvalbumins - natural Atlantic cod parvalbumin and recombinant common carp β-parvalbumin expressed in E. coli. Large collections of recombinant parvalbumins and natural allergen extracts of different fish species and other animals were used to identify the specificities of these MAbs using ELISA, Western blot, and dot blot. MAbs demonstrated different patterns of cross-reactivities with recombinant parvalbumins. Their binding affinities were affected by the addition and removal of Ca²⁺ ions. Moreover, all MAbs showed a broad reactivity with the target antigens in natural fish, chicken, and pork extracts. The ability of two MAbs (clones 7B2 and 3F6) to identify and isolate native parvalbumins from allergen extracts was confirmed by Western blot. Epitope mapping using recombinant fragments of Atlantic cod parvalbumin (Gad m 1) and common carp parvalbumin (Cyp c 1) revealed that 4 out of 5 MAbs recognize parvalbumin regions that contain calcium binding sites. In conclusion, the generated broadly reactive well-characterized MAbs against fish β-parvalbumins could be applied for investigation of parvalbumins of fish and other animals and their detection in allergen extracts.

Evaluation of Allergic Cross-Reactivity Among Fishes by Microfluidic Chips and MALDI-TOF MS

Fish is one of the most common foods that cause allergic reactions. The study of cross-reactivity among fishes using mass spectrometry (MS) is still limited. We developed a strategy using microfluidic chips coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to evaluate cross-reactivity among fishes. The protocol employed commercial magnetic beads functionalized with anti-human IgE antibodies to carry out the IgEs immunomagnetic separation in blood samples, followed by the capture of allergens from seafood protein extracts in a single-straight microfluidic channel. After elution, the captured allergens were digested and identified by MALDI-TOF MS and high-performance liquid chromatography-tandem mass spectrometry and validated by enzyme-linked immunosorbent assay (ELISA). An investigation of the reproducibility revealed that the protocol can sense well the allergens in a food matrix. Seven fish species were analyzed to evaluate the allergic cross-reactivity among fishes. The commercial ELISA test gave consistent results with the presently developed strategy when the same allergenicity test was performed. Parvalbumins were detected from five of the seven analyzed fishes. The sequence alignment of parvalbumins revealed that the similarity of parvalbumins identified from the analyzed fishes is larger than 64%. Boiling may reduce the allergenicity of fish, as demonstrated by a marginal diminish in the parvalbumin content of crucian carp (Carassius carassius) muscle when boiling with water. The method can potentially be used to predict allergic cross-reactivity among fish species, provide advice and guidance to individuals with a history of seafood allergy, and ensure food safety in the food allergy community.