egg allergy important food allergy in children starts early in life often resolved by school age...

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 years

Anamnesis

SPT to egg

Diagnosis

Advice

At 5 years

sIgE to egg

Food challenge

Diagnosis

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 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 years

Anamnesis

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

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)