IgE cross-reactivity between fish roe (Salmon, Herring and Pollock) and chicken egg in patients anaphylactic to salmon roe

Background: Salmon roe (SR) anaphylaxis has often been reported and SR-containing foods are designated as 'recommended for allergic labeling'; however, there have been no reports about its allergenicity, including its cross-reactivity. Because its cross-reactivity is controversial, clinicians are often confused concerning education regarding its dietary elimination. The purpose of this study was to examine the cross-reactivity between SR and other kinds of fish roe, salmon, or chicken egg (CE). Methods: We measured the specific-IgE to SR, herring roe (HR), pollock roe (PR), salmon and CE using RAST in 27 patients with a fish allergy and 26 control subjects. Then, using the sera of 2 patients with SR anaphylaxis, an ELISA inhibition study was performed to examine the cross-reactivity between SR and HR, PR, salmon or CE. We then compared the IgE binding patterns to SR between the anaphylaxis patients and fish allergy patients with immunoblotting. Results: There were positive correlations between SR and HR or PR, but none between SR and salmon or CE. In the ELISA study using sera from two patients with SR anaphylaxis, IgE-binding to SR was inhibited more than 50% only when the sera were pre-incubated with HR, inhibited almost 50% by PR in a dose-dependent manner, but not inhibited by CE or anisakis. Salmon inhibited the IgE binding to SR more than 50% in a SR-anaphylaxis patient. The IgE binding patterns to SR from anaphylaxis patients were almost identical and unlike those of patients with fish allergy. Conclusions: There was a cross-reactivity between SR and HR, but no relationship between SR and CE.