The largest concentrations of dust mites are in our beds and bedsheets, but they can also be found in dust, carpets, or curtains. A mite allergy is commonly referred to as a dust allergy. Why? Because studies have shown a correlation of exacerbation of its symptoms after contact with dust in which dust mites were found [1]. However, it is important to remember that other allergens may also be present in dust. These include pet allergens, tree pollen, and grasses.
In Poland, the most common and abundant dust mites in homes, as well as the best-known, include the species:
- Dermatophagoides pteronyssinus,
- Dermatophagoides farinae
- Euroglyphus maynei.
The mite – small but annoying
House dust mites are one of the most common causes of allergy and asthma [2]. They can cause allergic rhinitis (ANN), skin lesions, atopic dermatitis (AD), or bronchial asthma. They feed on the keratinised epidermis we shed every day and, in principle, if it were not for their allergenic proteins, they would not be a problem for us.
Mites are present in our homes all year round. However, they produce their most severe symptoms in autumn and winter. This is when we increasingly close our windows against the cold and stay indoors [1]. The symptoms of this allergy are further aggravated by switching on the central heating. It causes dust mite faeces to drift into the air we breathe. These proteins, acting as an irritant on the mucous membranes in the respiratory tract, cause a series of changes leading to local inflammation.
What is allergenic in mites?
More than 30 different mite proteins are known to be potentially allergenic.
– Der p 1 and Der p 2 – the main allergens of mites
The most common allergenic mite proteins are Der p 1 and Der p 2. More than 80% of people who are allergic to mites are allergic to them. Importantly, they are excellent candidates for desensitization. As studies show, it is in such patients that the efficacy of immunotherapy is the highest [3].
– Der p 23 – small protein, big problem
People with symptoms of mite allergy may also be allergic to Der p 23. This can present some diagnostic and later therapeutic problems. The point is that both in the preparation used for skin testing and in blood tests, this tiny protein may not be present in sufficient quantity. It can also happen that it is not present at all in the preparations. As a result, a person allergic to the Der p 23 protein may test negative despite symptoms of mite allergy. This happens in about 8-10% of people with mite allergy who are only sensitized to Der p 23 protein [4]. Allergy in this particular case can be detected by determining E (IgE) antibodies to individual mite allergen proteins. Such a method is called molecular diagnostics of allergy. In the 10 years, it has led to an increase in the precision of diagnosis for many allergies. This includes allergies to mites, but also allergies to dog, bee, wasp, soy, peanut, or hazelnut.
The absence of Der p 23 protein or insufficient amounts of Der p 23 protein in desensitization preparations can also be a reason for the failure of immunotherapy. This causal treatment for mite allergy, lasts 3 to 5 years and is very effective. In contrast, in individuals sensitized only to Der p 23, it may not be successful [5]. Therefore, it is advisable to deepen the diagnosis before starting immunotherapy. Of course, the test results should be consulted with an allergologist, who will decide on the best form of treatment.
– Der p 10 – food allergen…? After all, we don’t eat mites!!!
Another mite allergen that can cause diagnostic problems is the Der p 10 protein. Unlike the proteins discussed above, which are found in mite faeces, Der p 10 is found in the muscles of these arachnids. Many of the preparations used to diagnose mite allergies only contain mite faecal proteins. Therefore, people who are only allergic to Der p 10 may also not be diagnosed. Similarly, to Der p 23 protein, immunotherapy may be ineffective in people sensitized to Der p 10 only. Therefore, it is advisable to rule out sensitization to only the Der p 10 molecule in mites before starting it.
While the proteins Der p 1, Der p 2 and Der p 23 are inhalant allergens, Der p 10 is a food allergen. Contact with this protein can result in dangerous systemic symptoms. And even including anaphylactic shock, which is an immediate life-threatening condition.
It can occur as a result of a so-called cross-reaction. It affects people with a Der p 10 allergy after eating foods that contain a protein similar in structure to the Der p 10 mite. This is because the immune system can recognize this ‘similar’ protein as Der p 10 and start producing E antibodies. This can result in severe anaphylactic reactions.
– To eliminate or not to eliminate?
Foods that have such a ‘similar’ protein in their composition are shrimps, clams, snails, and crabs. Such proteins are also contained in the nematode Anisakis simplex. These are parasites of saltwater fish such as cod, herring, sardines, mackerel, tuna, sole, and anchovies. It is worth noting that these proteins are thermostable. This means that they retain their ability to cause symptoms even after shrimps and other seafood, as well as nematode-infected fish, have been cooked, fried, or baked.
According to scientific studies, about 10-15% of people with a mite allergy are specifically allergic to the Der p 10 protein. Therefore, patients with a mite allergy should be tested for this protein. In this way, dangerous allergic reactions can be prevented after eating foods containing similar allergens to Der p 10 [6]. However, it should be emphasised that based on current scientific evidence, patients allergic to house dust mite should not be advised not to eat or to stop eating shrimp or other seafood only because ofpositive skin tests or positive serum E antibody determinations [7]. In each such case, the allergologist, having the test results and analyzing them based on the patient’s accompanying symptoms, will consider the appropriateness of eliminating these foods from the diet.
In people with symptoms of house dust mite allergy, positive results for the proteins 𝗗𝗲𝗿 𝗽 𝟭 𝗶/𝗹𝘂𝗯 𝗗𝗲𝗿 𝗽 𝟮 are good markers predicting a good chance of allergen vaccine desensitization being effective! However, immunotherapy in people with sensitization to Der p 10 or Der p 23 proteins may not be successful. This is because the amount of Der p 10 and Der p 23 protein in the desensitization vaccines may not be sufficient for the body to develop mite tolerance.
Patients with allergy to Der p 1, Der p 2 and Der p 23 usually present respiratory and skin symptoms. Symptoms can be year-round and increase in autumn and winter. In contrast, those allergic to Der p 10 may develop gastrointestinal symptoms and even anaphylactic shock as a result of cross-reactions.
Not easy diagnosis
We can therefore say that for people with mite allergy, it is good to extend the diagnosis with molecular tests. By doing so, we can increase its effectiveness, and predict possible symptoms and the effectiveness of desensitization. So, if you often have a blocked nose, persistent sneezing or headaches during the autumn-winter season, these could be symptoms of a mite allergy. In such a situation, it is best to see an allergologist, who will take a detailed medical history and order the appropriate diagnostics. Your allergologist may also order a more in-depth diagnosis of individual mite proteins. This is usually done when, despite obvious symptoms of mite allergy, skin or blood tests come back negative. He or she may also use this type of diagnosis while considering the appropriateness of immunotherapy in a particular case.
Molecular diagnostics in house dust mite allergy allows us to determine precisely which PROTEIN is responsible for our symptoms and to predict whether desensitization will be effective
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translation: Julia Majsiak
