Allergy? What’s all the fuss?

Proven content

In recent years, the word “allergy” has become perhaps one of the most popular medical terms. Sometimes it causes fear and anxiety, sometimes – especially when news of sudden death after an insect sting is circulated in the media – sometimes it causes collective hysteria, but most often it seems to be completely misunderstood. Many people vehemently say that “in their day” there was no allergy at all, children went barefoot, played with animals, and no one had ever seen any rash. Is allergy a product of the modern world and modern medicine, then? What’s all the fuss about?

Storm in a glass of water

The term “allergy” appeared in the medical dictionary at the beginning of the twentieth century and initially referred to adverse reactions occurring in response to a contract with foreign particles. It is now known that not all of these reactions are harmful, and a significant part of them is a defense activity of the organism, which in this way recognizes foreign particles that are dangerous to itself (viruses, bacteria, proteins). However, the problem begins when the body’s defenses are mobilized excessively when exposed to a substance that is completely harmless to the majority of the population. These immune-triggering particles are called allergens. And this inadequately intensified defensive reaction of the body, in which cells of the immune system and the chemicals they release, are involved in the infamous “allergy”.

It is known that the immune response to an allergen is very complex and involves numerous cells and antibodies. There are four main types of allergic reactions. The most common of them are the so-called Type I allergic reactions, in which IgE antibodies play a major role. They are formed in the body when it first comes into contact with an allergen and then anchor to the surface of white blood cells (mast cells and basophils). During the next contact with the allergen, it combines with the antibodies already present in the body, which activates white blood cells, which release various chemical substances accumulated inside them, responsible for the occurrence of allergy symptoms.

Hypersensitivity, allergy, atopy or maybe an allergy?

These words are often treated as synonyms, but in medical nomenclature each of them refers to a slightly different phenomenon related to the reaction to an allergen. Distinguishing these concepts can be left to allergists, but what you should know and keep in mind is that not every allergen reaction is associated with the production of specific IgE antibodies. This means that the diagnosis of hypersensitivity is determined by the repeatability of symptoms, but not always due to the activation of immunological mechanisms. Conversely, the diagnosis of an immune disorder – an excessive amount of IgE antibodies in the blood serum – does not always mean the diagnosis of the disease, because these disorders do not translate directly into the symptoms. This has serious implications for the diagnosis of allergic diseases and requires appropriate interpretation prior to treatment.

All kinds of theories

In the second half of the twentieth century, an increased incidence of various types of allergic diseases began to be noted, including mainly bronchial asthma and allergic rhinitis. Some are even talking about an allergy epidemic. Medicine is looking for the causes of this phenomenon in the hope that if it can be identified, it will be possible to fight and counteract them. Unfortunately, despite the recent enormous progress in this field, the causes of the development of allergic diseases remain unknown. It is known that at the cellular level as early as in the fetal stage, during the formation of the immune system, the cooperation between the cells of the immune system is disturbed. This leads to an inappropriate reaction of the body to certain allergens. In addition to environmental factors (the number and type of allergens, exposure to infections) that modify the maturation process of the immune system, genetic factors also play an undeniable role here. It is known that atopy – i.e. the tendency to overproduce IgE antibodies in response to contact with an allergen – is genetically determined, but its inheritance is associated with many, not fully understood, genes. But where does the increase in the incidence of the disease come from?

At the end of the 80s, the theory of excessive hygiene appeared. She said that improving living conditions, increasing its hygiene (reducing the number of parasitic infections, the frequency of hepatitis A, introducing antibiotics, improving the purity of drinking water, etc.) reduces the exposure of the immune system to contact with various allergens, and thus prevents its proper functioning. functioning and maturation, which in turn leads to the development of allergies. Opponents of this theory, however, point out that the changes in hygiene, however, far outpaced the increase in the incidence of the disease. Moreover, an increased incidence of e.g. bronchial asthma is also observed in developing countries, where the hygienic conditions are much worse than in highly developed countries. And while some data indirectly suggest that childhood exposure may reduce the risk of developing allergic diseases, there is also a growing body of evidence that there is a relationship between RSV infection and the development of bronchial asthma.

Some researchers also emphasize the role of increasing air pollution and the amount of allergens accumulated in closed, poorly ventilated rooms where we spend more and more time. Here, the ubiquitous house dust mite is considered to be the main culprit. There are also studies linking less exercise to a higher incidence of asthma. A study published in 2009 in the journal Thorax found that children who watched TV for more than 3 hours a day at age 2 had a double risk of developing asthma by the age of 11. And although there are many theories, none of them fully explains the observed increase in the incidence of allergic diseases.

From rash to death

The difficulty in recognizing and treating allergic diseases lies in the variety of their symptoms. They depend on how the allergen enters the body. There are inhalation allergens, food allergens, contact allergens, latex allergens and medications. Allergic mechanisms underlie a broad spectrum of diseases, including bronchial asthma, rhinitis (also known as hay fever), conjunctivitis, urticaria, atopic and contact dermatitis. Symptoms of an allergy may vary in severity. For example, in a person allergic to wasp venom, only itchy urticarial skin lesions may appear after a bite, but in extreme cases an anaphylactic reaction may develop with shortness of breath resulting from bronchospasm and laryngeal edema, and a drop in blood pressure, which leads to the so-called anaphylactic shock, which is an immediate life-threatening condition. In addition to allergy to insect venoms, the most common causes of fatal anaphylactic reactions are hypersensitivity to various types of drugs (including most often antibiotics) and contrast agents used during medical diagnostic procedures, allergy to peanuts, cow’s milk proteins and seafood, as well as allergy to latex. In about 1/3 of cases of anaphylactic reactions, their cause cannot be determined.

Skin test, tell me …

It can be extremely difficult to confirm that the observed symptoms are allergic. This is due to the imperfections of diagnostic methods and the fact that the presence of antibodies against specific allergens is not synonymous with the disease, and vice versa – their absence does not exclude hypersensitivity. It should be remembered that atopy (i.e. the excessive production of antibodies in response to contact with an allergen) occurs in up to 20% of the population. Available diagnostic methods – skin tests and determination of the level of allergen-specific IgE antibodies – confirm the existence of an immune response, however, they are not sufficient to diagnose an allergy. A positive test result alone, in the absence of any allergy symptoms, cannot be interpreted as the presence of a disease. Commercial food allergy test kits based on the determination of specific IgG antibodies in blood serum are also available on the market. So far, their effectiveness in diagnosing food hypersensitivity has not been confirmed, and issuing dietary recommendations on their basis, ordering the elimination of certain foods, is unjustified and exposes patients to nutritional deficiencies. Due to the complexity of the problem, the diagnosis and treatment of allergic diseases should therefore be carried out in an experienced specialist center.

Text: lek. Paulina Jurek

Learn more about the effects of an untreated allergy