Help the development of the site, sharing the article with friends!

Allergen is a substance that causes a hypersensitivity reaction (allergic, allergic) to occur in the patient's body. The allergen can be grass pollen, celery or even… water. It is not clear what is really responsible for the fact that patients' organisms are hypersensitive to various antigens, but there are various diseases that are associated with allergens, such as asthma and angioedema.

Allergens , or more precisely, the reactions that occur as a result of the presence of allergens in the human body, are responsible for the growing prevalence of various allergic reactions and diseases. But what areallergens ?

Well, in fact, an allergen can be any molecule from the external environment to which elements of the patient's immune system will overreact.

In this case, an antigen is treated as an allergen, which leads to the occurrence of an allergic reaction in the patient, mainly related to the production of IgE antibodies by the cells of the immune system.


  1. Allergens - types
  2. Allergens and an allergic reaction
  3. Allergens: cross allergies
  4. Allergens: Diseases caused by allergens
  5. Allergens: how can the body stop being hypersensitive to them?

Allergens: types

Allergens, as well as their divisions, can be distinguished relatively many. Just as some of us love some foods and other people hate the same foods, so is the case with different antigens.

Some antigen may be completely neutral for one patient's organism, in the case of another person the same antigen may already be an allergen for him and after contact with him, an allergic reaction may appear. the way in which the allergen can be contacted. In this case, the following can be distinguished:

  • inhaled allergens (e.g. house dust mites, pollen of various plants - e.g. trees or grasses, fungal spores),
  • food allergens (patients can be sensitized by a lot of different foods, the most common food allergens, however, are peanuts, seafood, celery and egg white, as well as milk proteins, soy and wheat, anddifferent fish),
  • contact allergens (leading to allergic reactions after direct contact of the allergen with the surface of the body, including latex, various ingredients of cosmetic preparations, as well as metals, such as nickel),
  • drugs (allergic reactions can appear after many different drugs, some of them are extremely dangerous - this is why doctors ask patients in such detail whether they are allergic to any pharmaceuticals; preparations that extremely often lead to allergic reactions, mainly beta-lactam antibiotics, non-steroidal anti-inflammatory drugs and salicylates).

However, it can really … everything. There are sometimes observed hypersensitivity reactions to male semen, there is even a problem in which the patient sensitizing substance is … water.

However, other allergies are more common, such as hypersensitivity to iodine contrast agents (which are used in imaging tests, such as computed tomography) or allergy to hymenoptera venom (e.g. wasp venom) and hypersensitivity to the fur animals (the most common is hypersensitivity to cat hair).

The breakdown of allergens also takes into account the time during which patients may come into contact with allergenic antigens. In this approach, all-year allergens (such as house dust mites) and seasonal allergens (which include mainly plant pollen) are distinguished.

Allergens and an allergic reaction

People develop allergic reactions when they come into contact with an allergen to which their body is hypersensitive.

In such a situation, the cells of the immune system are over-stimulated, resulting in a cascade of various allergic symptoms.

They appear after IgE antibodies are combined with the allergen and with specific types of white blood cells (mainly mast cells).

The final effect of the process is the release of substances contained in these cells, such as for example histamine.

It is mediators released from mast cells that cause a specific inflammation to develop after contact with an allergen, which may result in both urticaria and even the development of an anaphylactic shock that is life-threatening.

Anaphylaxis is the most severe type of allergy. May be life threatening


Worth knowing

Patients may sometimes wonder that they had eaten a given food before and that they did not experience any symptoms, and during their life - aftercontact with exactly the same food - they may already have allergic reactions.

This possibility is mainly due to the fact that the hypersensitivity of the immune system may not appear until some time in the patient's life.

In addition, the first contact with an allergen does not have to lead to allergic symptoms - after the first contact with a sensitizing particle, the cells of the immune system can produce antibodies that - at the next exposure to the allergen - will bind to it and then lead to the occurrence of allergic reaction.

Allergens: cross allergies

There is an interesting term associated with allergens: it is about cross-allergens. It happens that a patient who is hypersensitive to one allergen - e.g. birch pollen - also experiences allergic reactions after eating celery or parsley.

This phenomenon is referred to as cross-allergy and it results from the fact that the exact structure of different antigens is actually different, although it may be largely similar.

One antigen has many different epitopes, i.e. fragments that bind directly to antibodies.

Different antigens, however, may have similar epitopes to some extent, so that antibodies initially directed against e.g. birch pollen allergens may also bind to allergens, e.g. celery, and thus lead to allergic reactions in patients.

Allergens: Diseases caused by allergens

The contact of the patients' organisms with allergens may result in both mild allergic reactions (in the form of e.g. mild rashes), as well as various disease entities.

The best known diseases associated with allergens include:

  • asthma
  • allergic rhinitis
  • allergic conjunctivitis
  • contact eczema
  • hives
  • angioedema

After contact with an allergen, the patient may also experience the above-mentioned, often very dangerous, anaphylactic shock.

Basically, it is the most severe form of an allergic reaction, and in its course there are, among others, problems such as severe breathlessness, severe angioedema, severe hives, and low blood pressure and tachycardia.

Allergens: how can the body stop being hypersensitive to them?

The symptoms of allergic reactions experienced by patients can definitely be extremely bothersome, but there are ways to alleviate them.

Sometimes you get fed upit is easy to avoid contact with an allergen - this is the case with many food allergies, where you can prevent allergic reactions by eliminating a given allergen from the diet.

However, the situation is different for patients who are sensitive to different types of allergens, such as, for example, pollen. Rather, it is difficult to avoid them completely (even shutting yourself up completely at home might not be enough), and therefore patients may receive treatment to reduce allergy symptoms.

The main application in this case are antihistamines (histamine, as mentioned above, is, after all, one of the main mediators of allergic reactions). These preparations include, for example, loratidine or cetirizine.

In order to make the patient's body stop being hypersensitive to a given allergen (especially when it is impossible to completely avoid exposure to the allergenic antigen), specific immunotherapy (commonly known as desensitization) may be used.

It is based on the controlled, regular administration of an allergen to which the patient is hypersensitive. Gradually, the doses of the allergen administered to the subject are increased - the ultimate goal is to ensure that contact with the allergen does not lead to the development of an allergic reaction in a patient undergoing specific immunotherapy.

Allergologist Piotr Dąbrowiecki: Not every type of allergy can be desensitized

Source:ń Dobry TVN

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

Read more articles by this author

Help the development of the site, sharing the article with friends!