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

PreviousAt 7 months Anamnesis

At 2 yearsAnamnesis

SPT to eggDiagnosisAdvice

At 5 yearssIgE to eggFood challenge

Diagnosis

Elin, 5 years

Eczema

Urticaria, asthma

+5Egg allergyAvoid egg

25 kUA/l

No symptoms

Tolerant to egg

Nour, 5 years

Eczema

Urticaria, asthma

+4Egg allergyAvoid egg

20 kUA/l

Urticaria, cough, rhinitis

Egg allergy

Egg white components

Egg white components

Main egg allergen components

• Ovomucoid – Gal d 1 • Ovalbumin – Gal d 2• Ovotransferrin – Gal d 3 • Lysozyme – Gal d 4

Latin name: Gal d – Gallus domesticus

Gal d 1

Gal d 2

Gal d 3

Gal d 4

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

Patient

PreviousAt 7 months Anamnesis

At 2 yearsAnamnesis

SPT to eggsIgE to eggsIgE to Ovomucoid

Diagnosis

Advice

Elin, 5 years

Eczema

Urticaria, asthma

+525 kUA/l

0.4 kUA/l

Tolerance likelyLow risk for reactions

Try cooked egg

Nour, 5 years

Eczema

Urticaria, asthma

+420 kUA/l

12 kUA/l

Egg allergy

Avoid egg

Using components in clinical practice

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)

Ovalbumin – Gal d 2

• The most abundant allergen in egg white (54%)

• Heat labile• Highly allergenic

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)