IgE and IgG 4 epitopes revealed on the major fish allergen Lat c 1.

Background: The IgE- and IgG ₄ -binding patterns of the major fish allergen parvalbumins are not clearly understood. IgE antibody-binding to parvalbumin from Asian seabass, Lat c 1.01, is implicated in up to 90 % of allergic reactions, although the region of IgE or IgG4 epitopes are unknown. In the present study, we characterized the specific IgE- and IgG ₄ -binding regions of Lat c 1.01 using serum from pediatric and adult patients with clinically-confirmed fish allergy.
Methods: A comparative investigation of patient IgE- and IgG ₄ -binding to recombinant Lat c 1.01 was performed by immunoblotting and indirect ELISA using serum from 15 children and eight adults with clinically confirmed IgE-mediated reactions to fish. The IgE- and IgG ₄ -binding regions of Lat c 1.01 were determined by inhibition ELISA using seven overlapping peptides spanning the entire 102 amino acid sequence. Elucidated IgE-binding regions were modelled and compared to known antibody-binding regions of parvalbumins from five other fish species.
Results: Ninety five percent (22/23) patients demonstrated IgE-binding to rLat c 1.01, while fewer patients (10/15 children and 7/8 adults) demonstrated robust IgG ₄ binding when determined by immunoblots. IgE-binding for both cohorts was significantly higher compared to IgG ₄ -binding by ELISA. All patients in this study presented individual IgE and IgG ₄ epitope-recognition profiles. In addition to these patient-specific antibody binding sites, general IgE epitopes were also identified at the C- and N-terminal regions of this major fish allergen.
Conclusions and Clinical Relevance: Our findings demonstrate two specific IgE epitopes on parvalbumin from Asian seabass, while IgG ₄ binding is much lower and patient specific. This study highlights the importance of advancement in epitope analysis regardless of the age group for diagnostics and immunotherapies for fish allergy.
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