soy allergy important protein source sensitization frequency varies largely prevalence of soy...
Post on 21-Dec-2015
215 views
TRANSCRIPT
Soy Allergy
• Important protein source
• Sensitization frequency varies largely
• Prevalence of soy allergy 0.1-0.4%
• Symptoms– cuteaneous or gastrointestinal– respiratory and systemic reactions
may occur
• Commonly used as additive in foods
Different types of soy allergy
• Genuine soy food allergy– Mostly in small children
– Often resolves in childhood
• Soy allergy due to cross-reactivity– Mainly in adults
– In birch-related tree pollen allergic patients
– In legume allergic patients
• Occupational allergy
Doctor's challenges
• What kind of soy allergy is it?– Is it a genuine soy allergy or
are the symptoms caused by cross-reactivity?
• Is there a risk for systemic reactions?
• Is strict avoidance necessary?• What dietary advice should be
given?
Genuine or cross-reactive soy allergy?
Common clinical practice
Patient
At 4 years
Anamnesis
SPT to soy SPT to birch
Diagnosis
Advice
Anna
Eczema, Wheeze
+2 +2
Soy and birch allergy
Avoid soy
Oliver
Eczema, Wheeze
+2 +2
Soy and birch allergy
Avoid soy
Using components in clinical practice
Improved diagnoses and altered advice
Patient
At 4 years
Anamnesis
SPT to soySPT to birch
At 8 years
sIgE to soy
Gly m 4
Gly m 5
Gly m 6
sIgE to birch
Diagnosis
Advice
Anna
Eczema, Wheeze
Milk allergy outgrow
+2 +2
0.8 kUA/l
15
< 0.1
< 0.1
58
Pollen-associated soy allergy Birch pollen allergy
No need for total avoidance Avoid large amounts of unprocessed soy
Oliver
Eczema, Wheeze
Milk allergy outgrow
+2+2
24 kUA/l
2.5
16.2
6.7
20
Genuine soy allergyBirch pollen allergy
Strict soy avoidance
Gly m 4
• A cross-reactivity marker, associated with allergy to birch and birch-related tree pollens
• A PR-10 protein, homologous
to birch component Bet v 1
• Labile protein - mainly causing local symptoms, e.g. OAS, but systemic reactions may occur
Cross reactivity - birch and soy
Sensitization to soy Gly m 4 likely induced via sensitization to birch
Gly m 5 and Gly m 6
• Are specific marker allergens for soy allergy
• Are storage proteins- proteins expressed in legumes, seeds and nuts
• Stable and heat resistant proteins that may cause systemic reactions
Peanut associated soy allergy
Peanut (f13) 72.1
Ara h 1 22.4
Ara h 2 23.1
Ara h 3 13.4
Ara h 8 3.7
Ara h 9 <0.1
Boy 15 years old with confirmed peanut and birch allergies. Upon having a Japanese lunch he gets mouth itch.
Soybean (f14) 1.5
Gly m 4 1.9
Gly m 5 1.4
Gly m 6 2.2
What does Molecular Allergology add?
• Differentiation between genuine soy allergy and soy allergy due to cross-reactivity
• Enables assessment of the risk for systemic reactions
• Enables more precise dietary advice