The human immune system is quite diverse in structure. It includes both some organs (for example, the spleen, thymus, lymph nodes) and cells (leukocytes, lymphocytes). The main role is played mainly by cells that synthesize special substances - immunoglobulins. They are responsible for the development of immune and allergic reactions.
Immunoglobulin E plays a special role in the development of allergies.
What is this substance
Immunoglobulin E is a special molecule that is located in the submucosal layer of many tissues and organs. It has a high affinity for many cells, which is why it is predominantly in a bound state in the body. It is practically not determined in the blood plasma in a free form.
In the human body, this fraction of immunoglobulins is responsible for the development of an allergic reaction (type 1 hypersensitivity reaction).
The time it takes for half of the immunoglobulin present in the blood serum to decompose is 3 days. Much more time it is on the membranes of cells (mainly obese, extensively located on the surface of the bronchial mucosa) - about two weeks.
The level of this substance changes throughout life. Normally, in adults, total IgE is about 20-100 kU / l. In children, the concentration is much lower - in newborns it is not (normal 0-3); as you grow older, the concentration gradually increases.
Reasons for increased levels of allergic immunoglobulin
Like any indicator, the level of this molecule can fluctuate depending on the conditions of the internal environment of the body.
IgE is generally elevated in diseases such as bronchial asthma, atopic dermatitis and allergic rhinitis. These diseases begin to manifest themselves from childhood and often persist in adults. An increase in the level of immunoglobulin indicates that the body is sensitized (has a high sensitivity and risk of developing allergies) to many allergens (substances that can cause an allergic reaction).
In children, total IgE is elevated in many diseases, not just those mentioned above. Such diseases include allergic aspergillosis, helminthiasis, Job syndrome, Wiskott-Aldrich syndrome, etc.
An increase in the concentration of immunoglobulin in newborns indicates a high risk of developing atopic diseases from the first days of life.
Low immune substances
A decrease in the level of all immunoglobulins can be observed in many diseases, accompanied by either damage to the thymus (in childhood) or systemic immunodeficiency, which can have many causes.
Bone marrow and liver damage (inchildren) leads to a decrease not only in total IgE, but also in other fractions of immunoglobulins. This happens due to the fact that the main cells responsible for the synthesis of these substances, B-lymphocytes, are affected.
The main function of B-lymphocytes is the synthesis of active substances that take part in the destruction of foreign agents.
In case of damage (hepatitis, radiation, tumor process, massive injuries of the musculoskeletal system), the B-cell germ is also damaged, which, as a result, contributes to a decrease in the level of all immunoglobulins. It is no exception that the total IgE is reduced.
One of the common causes of a decrease in the level of class E immunoglobulins is a disease such as ataxia-telangiectasia.
The mechanism of development of an allergic reaction
How does an allergic reaction develop due to this class of immunoglobulins? If the total IgE is elevated, then the following picture can be observed (the most striking example of an allergic reaction of the first type is asthma).
In the beginning, the body becomes sensitized, i.e., in response to the ingestion of a specific antigen, these immunoglobulins are produced. They are transported with the blood stream to the vessels of the respiratory system (mainly the bronchi) and settle in the mucous membrane. When the antigen hits again, immunoglobulins that have already “inhabited” the mucosa cause the activation of specific cells (mast and goblet cells). They, in turn, produce inflammatory mediators - histamine, serotonin, heparin,which have a constrictor effect (cause contraction of smooth muscle cells of the mucous membrane). Due to this, the lumen of the bronchus decreases, which leads to a significant difficulty in exhalation. This is how asthma develops.
Immunoglobulin test
When the first symptoms of allergy appear, an immunogram should be done. It is a so-called list of all immunoglobulins contained in the blood, indicating their concentration.
Venous blood is required for analysis. Testing is usually scheduled in the morning, on an empty stomach, since eating can provoke an allergic reaction and get unreliable test results.
The collected blood can be stored up to 8 days under certain conditions.
With the help of a special analyzer, the level of all immunoglobulins is determined, and based on the change in their number, a diagnosis is made.
When an elevated level of immunoglobulins is detected (general IgE in a child is especially indicative), an allergy to any antigen should be suspected, for which skin tests should be performed. A decrease in the level may indicate a weakened immune system.
Features of immunoglobulins in children
In the body of the fetus, immunoglobulins E begin to be produced for a period of 11 weeks. However, they are so large that they do not pass through the placenta and remain in the body of the child. Total IgE in a child gradually begins to grow over a period of up to 15 years,and the growth is quite fast. At the age of 15, the amount of the E-fraction of immunoglobulins is about 200kU / l, and before the age of 18, its concentration decreases to 100, which is a normal indicator in an adult.
At the appearance of a high amount of immunoglobulins in the umbilical cord blood, the possibility of developing atopic dermatitis or asthma should be suspected.
Based on the above, it is clear that the most dangerous age for the development of allergies in children is the period from 10 to 15 years. General IgE in a child is quite sensitive to various antigens, and during the period of “adolescence”, against the background of changes in hormonal levels, sensitivity increases significantly.
Changes in the level of immunoglobulins in various diseases
The concentration of immunoglobulins may vary depending on the nature of the disease.
- Many atopic diseases usually occur with a significant increase in the amount of immunoglobulin E, although cases of the development of diseases with normal levels of these molecules are known.
- Asthma can occur without an increase in the level of molecules if there is sensitivity to only one allergen.
- Total IgE in a child may increase in case of development of helminthiases. In parallel, there is an increase in the level of eosinophils.
- One of the most severe diseases is hyper-IgE syndrome. With it, it is possible to increase the level of this molecule by more than 2000 (up to 50,000 kU/l). The disease is accompanied by severe allergicmanifestations, urticaria, allergies to most substances. This condition requires mandatory research, and testing should be carried out as early as possible.
Danger of high concentration of immunoglobulin E
As mentioned, high concentrations of this molecule already suggest the development of an allergy. The most dangerous is the presence of sensitivity to most allergens, since in this case an allergy can develop to almost any substance.
Excessively high amounts of these molecules in the mucous membrane suggests the development of such a dangerous condition as angioedema (Quincke's edema). For its timely diagnosis (since the condition is life-threatening), it is imperative to conduct a blood test. IgE (general) cannot be detected in it, but its development can be suspected in the case of a high concentration of lymphocytes.
In severe allergies, mucosal necrosis may develop. The condition is dangerous in that it is possible to develop intoxication of the body, as well as the formation of fistulas between the bronchi and lung tissue, the development of pneumothorax and pneumoperitoneum.
Skin tests
When determining the high concentration of these molecules in the blood serum, it is necessary to conduct skin tests. They allow you to determine the sensitivity to specific allergens and prevent the development of allergies in the future.
The main indication for these tests is an immunological analysis - IgE total in it will be increased. Besides, ina history of at least one allergic attack (although a diagnostic test for the risk of developing an allergy is possible, even if clinical manifestations were not noticed).
The test is carried out using weak solutions of allergens (there are quite a lot of diagnosticums - suspensions of allergens, which allows you to find out the exact allergen that can provoke the development of an immune response). Be sure to take a blood test for IgE general before conducting a study, as well as conduct a general blood test. Be sure to prepare a set of emergency drugs before the analysis in case an unforeseen complication of the procedure develops.
Need for research
Why is it so important to determine this immunoglobulin in time?
Usually it is the main indicator that the immune system has begun to give an allergic reaction (if its concentration has increased), so the necessary measures should be taken to protect the body from all sorts of complications.
If the (IgE general) norm is registered in the blood, then you should not immediately rejoice. As mentioned, normal values can be observed in some diseases, so skin tests are required to exclude allergic diagnoses (if there is an appropriate clinic).
With reduced immunoglobulin, the danger is that the immune system may not respond to the incoming antigen, because of which you can miss a more severe disease, which will lead to irreversibleconsequences.
It is because of all that has been said that the importance of this molecule should be taken into account and its definition should not be neglected.
