1. 62 Patients with positive sIgE f13 or n n= 38 (f13), n=24 (f17)
Component-resolved diagnosis in peanut and hazelnut allergy. Romy Gadisseur1, Jean-Paul Chapelle1, Anna Blanco-Catafal2, Etienne Cavalier1 1 : University Hospital of Liège, Department of Clinical Chemistry, Liège, Belgium; 2 : University of Barcelona, Faculty of Pharmacy, Barcelona, Spain.
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1. Background:
Allergies to peanut or to hazelnut are very common and are associated with potentially fatal outcome in addition to Oral Allergy Syndrome (OAS).
Actually, the specific IgE (sIgE) for peanut and hazelnut extracts (respectively f13 and f17) are used for the in-vitro diagnosis of allergy. Nevertheless; these measurements don’t allow us to predict the clinical outcome of the patient.
The aim of our study was to evaluate the use of individual allergens for component-resolved diagnosis (CRD) of peanut and/or hazelnut allergies. Our objective was also to see, retrospectively, if CRD could have improved management of sensitized patients.
2. Method:
2.1. Patients.
We selected 62 clinically well designed patients on the basis of positive (>0.10kUA/L) sIgE for f13 (n=38) or f17 (n=24) measured on the ImmunoCAP© 250 (Phadia, Uppsala, Sweden).
2.2. ImmunoCAP ©, Components.
On each sample, we measured the sIgE against :
2 individual allergens of hazelnut (rCor a 1and rCor a 8),
5 components of peanut (rAra h ) ,
the Cross-reactive Carbohydrate Determinants (CCD), MUXF3.
In all, 276 sIgE for recombinant had been performed.
According to the results, we evaluated the clinical outcomes of the 62 patients.
3. Results:
Amongst the 62 patients, 36 (58%) were sensitized to a PR-10 protein (Bet v 1-like: Cor a 1: n=14 or Ara h 8: n=22).
As sensitization to PR-10 proteins is usually associated with minor symptoms like OAS, no avoidance had to be initiated in these patients.
Nine of the 62 patients (14.5%) presented positive sIgE for Lipid-Transfer-Proteins (LTP) (Cor a 8: n=4 or Ara h 9: n=5).
We found out 12 (19.3%) sensitizations to Storage Proteins (Ara h 1: n=5, Ara h 2: n=3, Ara h 3: n=4) which are the major allergens of peanut.
As LTP and storage proteins may cause severe reactions, a strict avoidance had to be recommended to these patients.
Five patients had positive sIgE to CCD, which are associated with in-vitro false positive results but no clinical relevance.
We observed that the sensitization to CCDs is frequently associated with asymptomatic patient or minor symptoms: OAS (n=2), gastrointestinal trouble (n=1), atopic dermatitis (n=1), urticaria (n=1), asymptomatic (n=5).
We observed that the sensitization to PR-10 proteins is mainly associated with respiratory symptoms or minor symptoms: rhinitis (n=18), OAS (n=11), atopic dermatitis (n=14), asthma (n=10), Asymptomatic (n=4), Angioedema (n=2), urticaria (n=3).
We observed that urticaria, angiodema and anaphylaxis occurred more frequently with the patients which were sensitized to nsLTP or Storage Proteins.
Indeed, those proteins are associated with severe reactions.
Asy: Asymptomatic GIT: Gastrointestinal trouble OAS: Oral Allergy Syndorme Rh: rhinitis AD: Atopic Dermatitis As: asthma An: anaphylaxis AO: Angioedema U: Urticaria
62 Patients with positive sIgE f13 or n n= 38 (f13), n=24 (f17)
Patients with positive sIgE for PR-10 proteins : n = 36
Patients with positive sIgE for CCD/MUXF3 : n =5
Patients with positive sIgE for nsLTP : n = 9
Patients with positive sIgE for Storage proteins : n = 12
OAS: n= Rh: n= AD: n= As: n=10 Asy: n=4 AO: n= U: n=3
OAS: n=2 GIT: n= AD: n= U: n= Asy: n=5
OAS: n=2 Rh: n= AD: n= As: n=3 An: n= AO: n= U: n=5
OAS: n=1 Rh: n= AD: n= U: n= As: n=3
rAra h 3 n=4
CCD/MUXF3 n=5
Cor a 1 n=14
rAra h 8 n=22
rAra h 9 n=5
rCor a 8 n=4
rAra h 1 n=5
rAra h 2 n=3
4. Conclusions:
Our results showed that, in patients presenting positive sIgE for f13 or f17, determination of the different recombinant allergens allowed us to evaluate the clinical outcome of these patients.
As the severity of the symptoms is correlated with the sensitization profile, this could help the clinicians to take the right decision when a strict avoidance has to be initiated or not.