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