| Summary: | Background: Fish roe allergy is a common health problem in countries where sea food is a major part of the diet, such as Japan. β′-component (β′-c) in fish roe has been identified as a major antigen for patients who show hypersensitivity to various fish roes. However, little is known about causative antigens for patients reactive to fish roe of specific species. Methods: Serum and basophils were obtained from patients who had reactivity to roes of Gadus chalcogrammus (GC) and/or other fish species. GC roe specific antigens were analyzed by immunoblotting, histamine release assay (HRA) and mass spectrometry. Recombinant-fragments of vitellogenin (Vg) were obtained by the Escherichia coli expression system. Results: Serum IgE of a patient with specific reactions to GC roe bound to 15, 28, 40 and 70 kDa-proteins in GC roe extract. Mass spectrometry analysis revealed that proteins in these bands contained fragments corresponding to Vg. Immunoblotting of Vg immunoprecipitated by rabbit anti-Vg antiserum from the extract revealed 15, 28 and 54 kDa fragments bound by the patient's IgE. These bindings were inhibited by the pretreatment of recombinant phosvitin (rPv) and β′-c (rβ′-c). Fractions obtained by native gel electrophoresis containing 15, 28 and 54 kDa proteins, but not the other fractions, induced significant histamine release from the patient's basophils. Sera of the other patients with GC roe specific-IgE showed IgE binding to rPv and/or rβ′-c. Conclusions: The 15, 28 and 54 kDa-fragments of Vg which include structures of Pv and β′-c, could be antigens for GC roe specific type-I-hypersensitivity. Keywords: Antigen, Fish roe allergy, Phosvitin, Vitellogenin, β′-component
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