The human immune system is quite diverse in its structure. It includes both some organs (for example, 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.
In the development of allergies, a special role is played by immunoglobulin E.
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 the body is mainly in a bound state. In a blood plasma in a free form it is practically not defined.
In the human body, this fraction of immunoglobulins is responsible for the development of an allergic reaction (type 1 hypersensitivity reaction).
The time during which half of the immunoglobulin present in the blood serum breaks up is 3 days. Much more time it is on the membranes of cells (mainly fat, extensively located on the surface of the mucous membrane of the bronchi) - about two weeks.
The level of this substance changes throughout life. Normally, in adults, total IgE is about 20-100ke / l. In children, the concentration is much lower - in newborns it is not (norm 0-3); as you grow older, the concentration gradually increases.
Causes of an increase in allergic immunoglobulin levels
Like any indicator, the level of a given molecule can fluctuate depending on the conditions of the internal environment of the body.
General IgE is usually elevated in diseases such as bronchial asthma, atopic dermatitis and allergic rhinitis. These diseases begin to manifest from childhood and often persist in adults. An increase in the level of immunoglobulin suggests 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 increased in many diseases, and not only in the above. Such diseases include allergic aspergillosis, helminthiasis, Job syndrome, Wiskott-Aldrich, 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 levels
A decrease in the level of all immunoglobulins can be observed in many diseases, accompanied either by damage to the thymus (in childhood), or systemic immunodeficiency, which can have many causes.
Damage to the bone marrow and liver (in children) leads to the fact that not only the total IgE, but also other fractions of immunoglobulins is reduced. This is 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 involved in the destruction of foreign agents.
In case of damage (hepatitis, radiation, tumor process, massive injuries of the musculoskeletal system), damage to the B-cell sprout also occurs, which as a result helps to reduce the level of all immunoglobulins. It is no exception that total IgE is reduced.
One of the common causes of a decrease in class E immunoglobulins is a disease such as ataxia-telangiectasia.
The mechanism of development of an allergic reaction
How is the development of an allergic reaction caused by this class of immunoglobulins? If total IgE is increased, then the following picture can be observed (the most striking example of an allergic reaction of the first type is asthma).
At first, the organism sensitizes, i.e., in response to the ingestion of a specific antigen, the production of these immunoglobulins occurs. They are transported with blood flow to the vessels of the respiratory system (mainly the bronchi) and settle in the mucous membrane. When the antigen re-enters, the immunoglobulins that have already “populated” the mucosa cause activation of specific cells (mast and goblet). They, in turn, produce inflammatory mediators - histamine, serotonin, heparin, which have a constrictive effect (cause a reduction in smooth muscle cells of the mucous membrane). Due to this, the lumen of the bronchus is reduced, which leads to a significant difficulty in exhaling. Thus, asthma develops.
Immunoglobulin test
When the first symptoms of the development of allergies appear, an immunogram should be made. It is a so-called list of all immunoglobulins contained in the blood with an indication of their concentration.
For analysis, venous blood is required. Testing is usually prescribed in the morning, on an empty stomach, as as a result of eating, you can provoke an allergic reaction and get unreliable research results.
Collected blood can be stored for up to 8 days under certain conditions.
Using a special analyzer, the level of all immunoglobulins is determined, and already, based on a change in their number, a diagnosis is made.
If an elevated level of immunoglobulins is detected (the total 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 level may indicate a weakened immunity.
Features of immunoglobulins in children
In the fetal body, immunoglobulins E begin to be produced at a period of 11 weeks. Moreover, 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 rapid. At the age of 15 years, the amount of the E-fraction of immunoglobulins is about 200 kE / L, and up to 18 years, its concentration decreases to 100, which is a normal indicator in an adult.
If high amounts of immunoglobulins appear in cord blood , the possibility of developing atopic dermatitis or asthma should be suspected.
Based on the foregoing, it is clear that the period from 10 to 15 years is the most dangerous age for the development of allergies in children. Total 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 a normal level of these molecules are known.
- Bronchial 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 the case of the development of helminthiases. In parallel, an increase in the level of eosinophils is observed.
- One of the most serious diseases is hyper-IgE syndrome. With it, an increase in the level of this molecule is possible more than 2000 (up to 50 000ke / l). The disease is accompanied by severe allergic manifestations, urticaria, allergies to most substances. This condition requires a mandatory study, and the delivery of tests should be carried out as soon as possible.
Danger of high concentration of immunoglobulin E
As was said, high concentrations of this molecule already suggest the development of allergies. The most dangerous is the sensitivity to most allergens, since in this case an allergy can develop on almost any substance.
An excessively high number 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 refers to life-threatening), a blood test should be performed. 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, skin tests should be performed. They allow you to determine the sensitivity to specific allergens and prevent the development of allergies in the future.
The main indication for these samples is immunological analysis - the total IgE in it will be increased. In addition, the history should have at least one allergic attack (although a diagnostic study is possible on the risk of developing an allergy, even if no clinical manifestations were noticed).
The test is carried out using weak solutions of allergens (diagnostic kits - suspensions of allergens - quite a lot, which makes it possible to find out the exact allergen that can provoke the development of an immune response). Be sure to take a blood test for general IgE before conducting a study, as well as conduct a general blood test. It is imperative to prepare a set of emergency drugs before analysis in case an unforeseen complication of the procedure develops.
Research need
Why is this immunoglobulin so important to determine in time?
Usually it is the main indicator that the immune system began to give an allergic reaction (in the event that its concentration increased), so the necessary measures should be taken to protect the body from all kinds of complications.
If the norm (IgE total) is recorded in the blood, then one should not immediately rejoice. As was said, normal values can also be observed in some diseases, therefore it is imperative to conduct skin tests to exclude allergic diagnoses (if there is an appropriate clinic).
With reduced immunoglobulin, the danger lies in the fact that the immune system may not respond to the received antigen, because of which a more serious disease can be missed, which will lead to irreversible consequences.
It is because of all the above that the importance of this molecule should be taken into account and its definition not to be neglected.