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J Allergy Clin Immunol. 2002 Mar;109(3):563-70.

Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results.

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  • 1Allergy Center, 3rd Division of General Medicine, Ospedale Maggiore IRCCS, Milan, Italy.

Abstract

BACKGROUND:

The hazelnut major allergens identified to date are an 18-kd protein homologous to Bet v 1 and a 14-kd allergen homologous to Bet v 2. No studies have reported hazelnut allergens recognized in patients with positive double-blind, placebo-controlled food challenge (DBPCFC) results or in patients allergic to hazelnut but not to birch.

OBJECTIVE:

We characterized the hazelnut allergens by studying the IgE reactivity of 65 patients with positive DBPCFC results and 7 patients with severe anaphylaxis to hazelnut.

METHODS:

Hazelnut allergens were identified by means of SDS-PAGE and IgE immunoblotting. Further characterization was done with amino acid sequencing, evaluation of the IgE-binding properties of raw and roasted hazelnut with enzyme allergosorbent test inhibition, assessment of cross-reactivity with different allergens by means of immunoblotting inhibition, and purification by means of HPLC.

RESULTS:

All the sera from the patients with positive DBPCFC results recognized an 18- and a 47-kd allergen; other major allergens were at molecular weights of 32 and 35 kd. Binding to the 18-kd band was inhibited by birch extract, indicating its homology with the birch major allergen, and abolished in roasted hazelnut. The 47-kd allergen is a sucrose-binding protein, the 35-kd allergen is a legumin, and the 32-kd allergen is a 2S albumin. Patients with severe anaphylactic reactions to hazelnut showed specific IgE reactivity to a 9-kd allergen, totally inhibited by purified peach lipid-transfer protein (LTP), which was heat stable and, when purified, corresponded to an LTP.

CONCLUSIONS:

The major allergen of hazelnut is an 18-kd protein homologous to Bet v 1, and the 9-kd allergen is presumably an LTP. Other major allergens have molecular weights of 47, 32, and 35 kd.

PMID:
11898007
[PubMed - indexed for MEDLINE]
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