Egg Allergy

1
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

2
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?

3
Common clinical practice
Patient Previous At 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
4
Egg white components
5
Egg white components
6
Main egg allergen components
Gal d 2
Gal d 3

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

Gal d 1
Gal d 4
Latin name Gal d Gallus domesticus
7
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
8
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

9
Characteristics of main egg white components
10
Using components in clinical practice
Patient Previous At 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

• Improved diagnoses and altered advice

11
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

12
Extra slides
13
Ovomucoid clinical utility

• -Quantification of ovomucoid antibodies could be
  useful in guiding the physician in the decision
  whether to perform a challenge or not

14
Ovomucoid clinical utility

• -For prediction of reaction to heated egg white,
  ovomucoid was superior (to egg white)

15
Ovalbumin Gal d 2

• The most abundant allergen in egg white (54)
• Heat labile
• Highly allergenic

16
Conalbumin Gal d 3

• 12 of egg white protein
• Heat labile
• Present also in egg yolk

• Conalbumin Ovotransferrin

17
Lysozyme Gal d 4

• Minor allergen
• 3.5 of egg white protein
• Used as preservative/additive
• Occupational allergen (food and pharmaceutical
  industries)