Cross-reactivity to fish and chicken meat - a new clinical syndrome.

Background: Fish is one of the most allergenic foods. While clinical cross-reactivity among different fishes is a widely accepted feature of fish allergy, associations with other food allergies are not well understood. This study aims at analyzing the relevance of clinical cross-reactivity between fish and chicken meat in patients with allergy to chicken meat without sensitization to hen's eggs.

Methods: Patients with food allergy to fish and chicken meat (n = 29) or chicken meat only (n = 7) were recruited. IgE-reactive chicken proteins were identified (Edman, MS analysis) and quantified (ELISA). Allergens were used in IgE ELISA and skin testing.

Results: Chicken parvalbumin and two new allergens, aldolase and enolase, were identified at 12, 40, and 50 kDa, respectively. They were recognized by sIgE of 61%, 75%, and 83% of all patient sera which were in the majority of the cases positive for the fish homologues as well. Fish and chicken meat allergens were highly cross-reactive while high inhibition rates with fish or chicken allergens correlated with the patients' primary sensitization to fish or chicken. In cooked or roasted foods, enolase and aldolase were detectable in chicken breast while parvalbumin was detectable in chicken legs and wings.

Conclusions: Fish and chicken meat are cross-reactive foods; both fish-allergic and chicken meat-allergic patients might be at risk of developing a food allergy to chicken meat or to fish, respectively. This clinical phenomenon is proposed to be termed 'fish-chicken syndrome' with cross-reactive allergens involved being parvalbumins, enolases, and aldolases.