Egg Allergy Important food allergy in children Starts early in life Often resolved by school age Symptoms: atopic dermatitis, urticaria, asthma, anaphylaxis Sensitization may predict atopic disease later in life Prevalence: 1-2% Boiled/heated egg may be tolerated

Doctor's challenges Is there a risk for severe reactions? Could the patient tolerate cooked egg? Is the allergy likely to be persistent? How should the patient best be managed? Who needs strict avoidance? Who needs emergency medication?

Common clinical practice Patient Previous At 7 months Anamnesis At 2 years SPT to egg Diagnosis Advice At 5 years sIgE to egg Food challenge Elin, 5 years Eczema Urticaria, asthma +5 Egg allergy Avoid egg 25 kUA/l No symptoms Tolerant to egg Nour, 5 years Eczema Urticaria, asthma +4 Egg allergy Avoid egg 20 kUA/l Urticaria, cough, rhinitis

Egg white components

Egg white components

Main egg allergen components Gal d 2 Ovomucoid – Gal d 1 Ovalbumin – Gal d 2 Ovotransferrin – Gal d 3 Lysozyme – Gal d 4 Gal d 3 Gal d 1 Gal d 4 Latin name: Gal d – Gallus domesticus

Ovomucoid - Gal d 1 The dominant egg white component 11 % of egg white content Highly allergenic Stable to heat and enzymatic digestion Gal d 1

Ovomucoid and tolerance Boiled egg may be tolerated if Ovomucoid-IgE levels are low Persistent egg allergy is seen in patients with high Ovomucoid-IgE levels The stability of Ovomucoid reflects the clinical picture

Characteristics of main egg white components

Using components in clinical practice Patient Previous At 7 months Anamnesis At 2 years SPT to egg sIgE to egg sIgE to Ovomucoid Diagnosis Advice Elin, 5 years Eczema Urticaria, asthma +5 25 kUA/l 0.4 kUA/l Tolerance likely Low risk for reactions Try cooked egg Nour, 5 years Eczema Urticaria, asthma +4 20 kUA/l 12 kUA/l Egg allergy Avoid egg Improved diagnoses and altered advice

What does Molecular Allergology add? Sensitization to Ovomucoid indicates: Risk for reaction to all forms of egg Persistent egg allergy Risk for systemic reactions to egg Absence of sensitization to Ovomucoid indicates: Tolerance to cooked egg

Extra slides

Ovomucoid – clinical utility “-Quantification of ovomucoid antibodies could be useful in guiding the physician in the decision whether to perform a challenge or not”

Ovomucoid – clinical utility “-For prediction of reaction to heated egg white, ovomucoid was superior” (to egg white) 14

Ovalbumin – Gal d 2 The most abundant allergen in egg white (54%) Heat labile Highly allergenic

Conalbumin = Ovotransferrin Conalbumin – Gal d 3 12% of egg white protein Heat labile Present also in egg yolk Conalbumin = Ovotransferrin

Lysozyme – Gal d 4 Minor allergen 3.5% of egg white protein Used as preservative/additive Occupational allergen (food and pharmaceutical industries)