Peanut Allergy 10% of children are sensitized but only 1-2% have symptoms Usually life-long Symptoms range from local reactions to anaphylaxis Very small quantities can give symptoms
Genuine or due to cross reactivity? Doctor's challenges Is it a genuine peanut allergy or are the symptoms caused by cross reactivity? Is there a risk for systemic reactions? Is strict avoidance necessary? Is emergency medication needed? Genuine or due to cross reactivity?
Common clinical practice Patient At 6 years Anamnesis SPT to birch At 16 years SPT to peanut sIgE to peanut Diagnosis Advice Caroline, 16 years Rhinitis and conjunctivitis +4 Local reactions to peanuts 26 kUA/l Peanut allergy Avoid peanuts Emma, 16 years Rhinitis and conjunctivitis +4 Local reactions to peanuts 28 kUA/l Peanut allergy Avoid peanuts
Using components in clinical practice Patient Anamnesis Component testing Ara h 1 Ara h 2 Ara h 3 Ara h 8 Ara h 9 Diagnosis Advice Caroline, 16 years Local reaction to peanuts Pollen and peanut allergies kUA/l < 0.1 33 Pollen-associated peanut allergy Suitable for re-introduction Emergency medication unnecessary Emma, 16 years Local reaction to peanuts Pollen and peanut allergies kUA/l 2.1 12.3 3.3 10.3 < 0.1 Genuine peanut allergy Strict peanut avoidance Emergency medication necessary Improved diagnoses and altered advice
Peanut components
Peanut components
Latin name: Ara h = Arachis hypogaea Peanut components Ara h 2 Ara h 1 Ara h 8 Ara h 9 Ara h 3 Latin name: Ara h = Arachis hypogaea
Peanut components
Peanut components
Latin name: Ara h = Arachis hypogaea Peanut components Ara h 2 Ara h 1 Ara h 8 Ara h 3 Ara h 9 Ara h 5 CCD Latin name: Ara h = Arachis hypogaea
Risk assessment of peanut components
Risk assessment of peanut components 12
Ara h 1, Ara h 2, Ara h 3 Peanut-specific markers Storage proteins – proteins expressed in legumes, seeds and nuts Present in high amounts Stable and heat resistant proteins that may cause systemic reactions
Ara h 9 A cross-reactivity marker, associated with allergy to peach and peach-related fruits A Lipid Transfer Protein (LTP). LTPs are present in plant foods (e.g. nuts and fruits), weed and tree pollen Present in low amounts Stable and heat resistant protein that may cause systemic reactions
Cross reactivity - peach and peanut Sensitization to Peanut Ara h 9 likely induced via sensitization to peach 15
Ara h 8 Associated with allergy to birch and birch-related tree pollen A PR-10 protein, homologous to the birch component Bet v 1 Labile protein - mainly causing local symptoms Present in low amounts
Cross reactivity - birch and peanut Sensitization to peanut Ara h 8 is likely induced via sensitization to birch
Ara h 5 A profilin protein Profilins are highly cross-reactive expressed in tree-, grass- and weed pollen, in plant-derived foods and latex labile proteins, seldom associated with clinical symptoms present in very low amounts 18
Sensitization frequencies and clinical reactions show geographical differences
Sensitization frequencies and clinical reactions show geographical differences
In conclusion
In conclusion 22
What does Molecular Allergology add? Assess the risk for systemic reactions Differentiate between genuine peanut allergy and pollen-related peanut allergy Ensure relevant dietary advice and avoid unnecessary elimination
Extra slides
From the literature
Peanut allergens in Arachis hypogaea MW (kD) Comment Ara h 1 64 Storage Protein (Vicilin) Ara h 2 17 Storage Protein (Conglutin) Ara h 3 60 Storage Protein (Glycinin) homology with Ara h 4 Ara h 4 37 Storage Protein (Glycinin) homology with Ara h 3 Ara h 5 15 Profilin, highly cross-reacting, low risk Ara h 6 Storage Protein (Conglutin) Similar to Ara h 2 Ara h 7 Conglutin. Homology with Ara h 2 Ara h 8 PR-10, Cross-reactive with birch Bet v1. Regional differences Ara h 9 9,8 Lipid Transfer Protein (LTP), high risk. Regional difference Ara h 10 16 16 kD Oleosin Ara h 11 14 14 kD Oleosin Arachis hypogaea = peanut