Chicken serum albumin (Gal d 5 *) is a partially heat-labile inhalant and food allergen implicated in the bird-egg syndrome

Background: Chicken serum albumin (α-livetin) has been implicated as the causative allergen of the bird-egg syndrome. However, the clinical relevance of sensitization to this allergen has not been confirmed by specific challenge tests and environmental sampling. We investigated whether chicken albumin can be detected in air samples collected in a home with birds, and whether sensitization to this protein may cause respiratory and food allergy symptoms. The heat resistance of chicken albumin and the possible cross-reactivity with conalbumin were also investigated. Methods: We studied eight patients with food allergy to egg yolk who also suffered from respiratory symptoms (rhinitis and/or asthma) caused by exposure to birds. Sensitization to egg yolk and bird antigens was investigated by skin and serologic tests. Hypersensitivity to chicken albumin was confirmed by specific bronchial, conjunctival, and oral provocation tests. Results: All patients had positive skin tests and serum IgE against egg yolk, chicken serum, chicken meat, bird feathers, and chicken albumin. The presence of airborne chicken albumin in the domestic environment was confirmed. Specific bronchial challenge to chicken albumin elicited early asthmatic responses in six patients with asthma. An oral challenge with chicken albumin provoked digestive and systemic allergic symptoms in the two patients challenged. IgE reactivity to chicken albumin was reduced by 88% after heating at 90°C for 30 min. ELISA inhibition demonstrated only partial cross-reactivity between chicken albumin and conalbumin. Conclusions: Chicken albumin (Gal d 5) is a partially heat-labile allergen that may cause both respiratory and food-allergy symptoms in patients with the bird-egg syndrome.