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Postepy Dermatol Alergol. 2019 Feb;36(1):98-103. doi: 10.5114/ada.2019.82829. Epub 2019 Feb 22.

Immunological characterization of onion (Allium cepa) allergy.

Author information

1
Department of Emergency and Organ Transplantation, School and Chair of Allergology and Clinical Immunology, University of Bari-Aldo Moro, Bari, Italy.
2
Department of Medical and Surgical Sciences, School and Chair of Allergology and Clinical Immunology, University of Foggia, Foggia, Italy.

Abstract

Introduction:

Onion (Allium cepa) handling can induce contact dermatitis, rhinoconjunctivitis and asthma. However, only sporadic reports exist on allergic reactions to onion consumption.

Aim:

We describe herein a case of a 35-year-old man who had an episode of anaphylaxis following cooked onion ingestion. We evaluated onion-specific IgE, the possible cross-reactivity between onion and peach and lymphocyte proliferation in response to onion.

Material and methods:

Specific IgE was evaluated using two techniques: skin test and ImmunoCAP technology. Cross-reactivity between onion and peach was evaluated by IgE-ELISA inhibition test. As for lymphocyte proliferation, blood mononuclear cells were stained with CFSE dye and cultured with an in-house onion extract. Proliferation and phenotype was assessed by flow-cytometry.

Results:

The skin test and ImmunoCAP confirmed the IgE-dependent response towards onion. The incubation of the patient serum with increasing concentrations of the peach extract reduced only scarcely (~30%) onion-specific IgE. Interestingly, B cells but not T cells showed proliferation in response to onion extract.

Conclusions:

In conclusion, our report shows that cooked onion can induce severe allergic reactions, suggesting the presence of thermostable components. Moreover, we applied for the first time a B-cell-based approach to the diagnosis of food allergy. This latter approach might also be applied to other allergic conditions.

KEYWORDS:

IgE-ELISA inhibition; food allergy; lipid transfer proteins; lymphocyte proliferation; onion allergy

Conflict of interest statement

The authors declare no conflict of interest.

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