This is a simplified description of beta expansin 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 beta expansin proteins?
Expansin proteins are a large group of plant proteins involved in maintaining the functionality of the plant cell walls. There are 4 subsets of expansins, but in terms of allergy the most interesting proteins are the beta expansins (β-expansin), sometimes also referred to as 'EXPB' .
They are mostly found in grass and food crop pollens. They are very cross-reactive.
Beta expansin proteins have high sensitisation rates compared to other allergenic proteins and are therefore considered to be major pollen panallergens. Other pollen panallergens include Bet v 1
allergens, profilin proteins
and Lipid Transfer Proteins
Which pollens contain beta expansin proteins?
There are 15 pollen allergens associated with beta expansin proteins according to the World Health Organization (WHO) Allergen Index. These include various grasses
You can look at the cross reactivity of these plants on the Cross Reactivity Tool or you can read more about them on the dedictaed Pollen Page
Are there any foods which contain beta expansin proteins?
The World Health Organization (WHO) does not recognise any beta expansin allergen identified as causing allergic reactions after consumption of food.
What symptoms do they cause?
Beta expansin proteins are most commonly associated with seasonal allergic rhinitis (hayfever) and allergic asthma.
What is the importance of knowing whether a reaction is to beta expansin or other allergens?
Pollen allergies are difficult to manage, especially in comparison to foods, it is much easier to avoid certain foods than it is to avoid certain pollens.
Recognising what groups of pollens may be aggravating your seasonal allergies or asthma may help in management of your symptoms. You can remove offending plants from your garden or have a better understanding of what times of the year you may suffer the most so you can be prepared with antihistamines.
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