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Defensin Proteins

This is a simplified description of defensin proteins – there are more resources available at the bottom of the page for further reading for those who are interested in knowing more.

What are defensin proteins?

Defensins are found in both animals and plants. In plants they have the potential to act as food and airway allergens. The proteins are small but highly stable, their primary function in the plants is to assist the plant immune system in protecting against fungal pathogens.

Defensin proteins are considered to be minor panallergens. They are less commonly associated with allergy than Lipid Transfer Proteins and seed storage proteins, but have become more studied in recent years due to the possibility of cross reactivity between different species of fish and occasionally other meat sources.

These proteins vary from species to species in how the allergenicity is changed due to heat, but most studies show many are heat resistant and will still elicit an allergic reaction after cooking or processing.

Which foods contain defensin proteins?

The World Health Organization (WHO) recognises 2 defensin allergens which have been identified as causing allergic reactions after consumption of food.

Celery and peanuts both contain defensin proteins. They are also listed as a contact allergen in chestnuts.

More recent studies have suggested that mango and sunflower seeds also contain these proteins.

Which pollens contain defensin proteins?

The World Health Organization (WHO) recognises 15 defensin allergens which have been identified as causing airway allergic reactions.

These pollens include various species of wormwood, ragweed, sagebrush, mugwort, feverfew and soya bean pollen.

If you are interested in which foods contain which allergenic proteins you can visit the Food Allergy Tool Page.

What symptoms do they cause?

Allergy to foods containing defensin proteins have a wide range of symptoms and severity including urticaria (hives or welts), angioedema (swelling under the skin), nausea, abdominal pain, vomiting or breathlessness and anaphylactic shock.

What is the importance of knowing whether a reaction is to defensin proteins or other allergens?

Multiple allergies are becoming more common and this often leads people to impose a strict restrictive diet on themselves. This can lead to a poor diet lacking in essential nutrients and frustration over a lack of eating options. Knowing which foods are the most likely to be causing your reactions can bring more options back into your diet.

This is why food diaries continue to be an important tool in diagnosis of your allergies – noting the times reactions took place and what medications were taken are a necessary starting point for a proper diagnosis.

There is more information on food diaries HERE.


DermNet NZ - Antomicrobial Peptides

Articles and Journals

The Role of Defensins as Pollen and Food Allergens, 2023

Immunomodulatory and Allergenic Properties of Antimicrobial Peptides, 2022

Identification of a defensin as novel allergen in celery root: Api g 7 as a missing link in the diagnosis of celery allergy? 2022

Pathogenesis related proteins: A defensin for plants but an allergen for humans, 2020

Plant defensin antibacterial mode of action against Pseudomonas species, 2020

Plant defensins: types, mechanism of action and prospects of genetic engineering for enhanced disease resistance in plants, 2019

Antibacterial Activity of Plant Defensins, 2019

Peanut defensins: Novel allergens isolated from lipophilic peanut extract, 2015

Antifungal defensins and their role in plant defense, 2014

Plant defensins, 2009

Plant defensins—Prospects for the biological functions and biotechnological properties, 2009

Art v 1, the major allergen of mugwort pollen, is a modular glycoprotein with a defensin-like and a hydroxyproline-rich domain, 2002

Let me know if you found any of these interesting or useful. If you spot an article or research that you think is interesting you can message me or tag me on Facebook or Twitter - links at the bottom of the page.

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