Allergies are becoming a problem for many people of all ages. Its high-quality treatment, the prevention of attacks depends on the time of the established substance, causing an inadequate reaction of the body when interacting with it. In some cases, a person develops delayed-type allergic reactions. Then a quality diagnosis becomes the basis for maintaining health.
Inadequate Answer
Everyone has heard about allergies. But the fact that there are allergic reactions of an immediate and delayed type is known only to those who have encountered such a health problem firsthand. But in any case, this is a serious violation of well-being, which can lead to death in the event of an acute attack of an allergy and untimely provision of medical care.
Although the mechanisms of the inadequate response of the body to certain substances have been studied, they are not yet fully understood. In close connection with allergies, hypersensitivity is defined as an excessive undesirable reaction of the body's immune system to any substance. Initially, it was hypersensitivity that was divided into two types according to the rate of occurrence. Then the allergy got such a division. Slow-type allergic reactions include processes that occur as stimulation of cellular immunity in response to the interaction of antigen with macrophages and type 1 T-helpers.
Type division
Scientific studies of hypersensitivity and allergies have come a long way, as a result of which 4 types of allergic reactions have been identified:
- anaphylactic;
- cytotoxic;
- precitipine;
- delayed hypersensitivity.
The anaphylactic type is an immediate type reaction that develops only 15-20 minutes after the contact of antibody reagins with allergens, as a result of which special biologically active substances are released into the body - mediators, for example, heparin, histamine, serotonin, prostaglandin, leukotrienes and others.
The cytotoxic reaction is associated with hypersensitivity to medications. It is based on the combination of antibodies with altered cells, which leads to the destruction and removal of the latter.
The third type of hypersensitivity is also called immunocomplex. This is due to the repeated ingestion of a large number of soluble proteins, for example, during blood or plasma transfusion, during vaccination. The same reaction is possible with infection of blood plasma with fungi or microbes, against the background of the formation of proteins due to neoplasms, infections, helminth infections, and some other pathological processes.
The fourth type of allergic reaction combines the effects of the interaction of T-lymphocytes and macrophages with carriers of a foreign antigen and is called tuberculin, infectious-allergic, cell-mediated. Another name for this hypersensitivity, which has become the most common, is a delayed type reaction. It is characteristic of contact dermatitis, rheumatoid arthritis, tuberculosis, leprosy, salmonellosis and other diseases, and pathologies. It is by the type of allergen that a classification of delayed-type allergic reactions is carried out.
Does an allergy have a speed?
Hypersensitivity is determined by specialists as the result of a violation of the mechanism of the body's immune response. And it is precisely speed, as well as development mechanisms, that determine the differences between allergic reactions of an immediate and delayed type. Initially, specialists noted that various allergen substances can cause a reaction to the body after a different period of time. So delayed-type allergic reactions develop in 12-48 hours. And hypersensitivity of the immediate type appears 15-20 minutes after contact with the allergen.
Classification of an allergic reaction of a delayed type
In order to better understand the essence of a delayed-type allergy, one should study its classification, because it is in the structuring of an inadequate response of the body's immune system that its main aspects are reflected:
- Contact: a characteristic manifestation is skin dermatitis. It develops a day or two after contact with an allergen, lymphocytes, macrophages participate in its development. The main characteristic of the manifestation is tissue edema.
- Tuberculin manifests itself after 6-48 hours, lymphocytes, macrophages, monocytes are involved.
- Granulomatous - this type of reaction develops after 21-28 hours, macrophages, epithelioid cells are determined in development. The manifestation is fibrosis.
The mechanism for the development of a delayed-type allergic reaction is basically similar to the mechanism of cellular immunity. The difference between them can be determined by the final result: if an allergic reaction did not lead to tissue damage, then we can talk about cellular immunity.
Allergens
Most often, it is believed that allergens are certain substances that can cause an inadequate reaction of the body's immune system in contact with them. But allergens also include those substances that are capable of potentiating allergens. An inadequate response of the immune system, called an allergy, occurs when interacting with the following substances:
- dust;
- dust mites;
- foreign proteins (donor plasma and vaccines);
- pollen;
- mold;
- medicines: penicillins, salicylates; sulfonamides, local anesthetics;
- food products: legumes, sesame seeds, honey, milk, seafood, nuts, citrus fruits, eggs;
- insect bites, arthropods;
- animal products: particles of skin (epithelium flakes) of animals, wool, cockroaches, tick;
- chemicals - latex, cleaning products, nickel compounds.
This is not a complete list, even groups of allergens are difficult to list, not to mention the line of each group. It is constantly updated, expanded and refined. Therefore, most likely, delayed-type allergic reactions include not only already identified health problems, but also some others that have not yet been differentiated as hypersensitivity.
How does a delayed reaction to an allergen develop?
Any process, including human allergies, goes through several stages in its development. An allergic reaction of a delayed type proceeds as follows: sensitization; then the appearance in the regional lymph nodes of a large number of pyroninophilic cells, from which in turn sensitized immune lymphocytes are formed. These cells serve as the so-called transfer factor and, circulating in the blood, spread through the tissues. The next contact with the allergen activates them with the formation of the allergen-antibody immune complex, which causes tissue damage.
Science has so far failed to elucidate the nature of antibodies in HRT. Studying this type of animal allergy, scientists noted that the passive transfer of delayed allergies from animal to animal is possible only with the help of cell suspensions. But with blood serum, such a transfer is almost impossible, the presence of at least a small number of cellular elements is necessary.
The development of a delayed type of allergy is impossible, apparently, without cells of the lymphoid series. Blood lymphocytes can serve as carriers of hypersensitivity to such biological substances as tuberculin, picryl chloride, and other allergens. Sensitivity on contact is passively transmitted by the cells of the thoracic lymphatic duct, spleen. A remarkable connection has been established between the lack of the ability to develop a delayed-type allergy and the deficiency of the lymphoid system.
For example, patients with lymphogranulomatosis do not suffer from delayed allergies. Science supposedly concluded that exactly how lymphocytes are the main carriers and carriers of antibodies in delayed allergies. The presence of such antibodies on lymphocytes is also evidenced by the fact that they, with a delayed allergy, are able to fix an allergen on themselves. However, many processes in the human body, for various reasons, have not been studied enough.
Reaction mediators
The occurrence of any type of allergy is a complex mechanism in which many substances are involved. So, a delayed-type allergy develops with the help of so-called mediators. Here are the main ones:
- Blastogenic factor that accelerates the transformation of lymphocytes into blasts.
- Lymphotoxin is a protein with a molecular weight of 70,000-90000. This compound inhibits the growth or destruction of lymphocytes, as well as proliferation (proliferation) of lymphocytes. This delayed-type allergy mediator inhibits the synthesis of human and animal DNA.
- The inhibition factor of macrophage migration is also a protein with a mass of 4000-6000. This biological active substance affects the speed of movement of macrophages in tissue culture, slowing it down.
In addition to these structures, scientists have identified several more mediators of delayed-type allergies in animals. In humans, they have not yet been discovered.
Discovery story
At the end of the 19th century, the microbiologist R. Koch noticed the relationship between the delayed occurrence of hyperergy and contact with certain substances. The same observation was made by the Vienna pediatrician Clemens von Pirke, noting in children the relationship between exposure to certain substances and poor health. The study of the inadequate reaction of the human body to contact with some components of nature, life, production continues.
In the early 60s of the last century, British immunologists Jell and Coombs identified 4 main types of hypersensitivity reactions. For a long time, it was believed that the inadequate response of the immune system is caused by impaired functional of immunoglobulins E. But then it was found that such a reaction is based on a complex of mechanisms of interaction between the human body and various components. Therefore, the term "allergy" was retained for the first of the above types of hypersensitivity.
Symptomatic pathology
Allergic reactions of a delayed type are manifestations of fairly familiar symptoms:
- Infectious allergies resulting from exposure to microorganisms that can cause brucellosis, gonorrhea, syphilis, tuberculosis, and anthrax.
- Tuberculin hypersensitivity is familiar to everyone, like the Mantoux test, which allows you to detect infection with Koch's bacillus.
- Protein allergy - hypersensitivity to food products - eggs, milk, fish, nuts, legumes, cereals.
- Autoimmune allergy - the inability of the immune system to distinguish between its own substances and foreign substances, reacting to them as allergens.
Features of HRT
The studied mechanisms of delayed-type allergic reactions are based on two main forms of the T-cell immune response. Sensitization occurs first.
From the place where the allergen enters the lymph node, regional with respect to this place, the migration of white process epidermocytes (Langerhans cells) or dendritic cells of the mucous membranes moving the peptide fragment of the antigen as part of the MHC class II membrane molecules begins.
Then a reaction of a certain group of lymphocytes and their response in the form of proliferation of differentiation into Th1 cells occurs. When the antigen re-enters the body, already sensitized lymphocytes react, activating first the resident and then the migrating macrophages. This process causes inflammation, in which cell infiltration dominates vascular changes.
Here, a special role is given to the humoral products of effector cells - cytokines. As a result of immune protection against cell damage upon contact with an allergen, delayed-type hypersensitivity becomes a factor that damages the body. For example, a granulomatous reaction in tuberculosis: macrophages and T-lymphocytes surround cells with a pathogen, forming a protective granuloma. Inside this formation, the cells die, which leads to tissue disintegration according to the caseous type. So the protective reaction of the body turns into a damaging one.
Typical diseases
Delayed allergic reactions occur no earlier than 6-24 hours after contact with the allergen. In this case, the diagnosis is posed by a specific problem, based on the available symptoms:
- Hansen's disease;
- gonorrhea;
- phototoxic dermatitis;
- allergic conjunctivitis;
- mycoses;
- syphilis.
Also, the concept of delayed-type allergic reactions can include graft rejection and the reaction of antitumor immunity. Only the specialist can establish the exact causes of a health problem that has arisen after a thorough and high-quality diagnosis.
Diagnostics
Slow-type allergic reactions develop according to mechanisms similar to cellular immunity. For their proper treatment, reliable diagnosis is necessary, because it will help to identify the substance that causes an inadequate reaction. Such a determination is carried out using allergic tests - biological reactions used in the diagnosis and based on an increased sensitivity of the body to a specific allergen.
Such a study is carried out according to two methods - in vivo and in vitro. The first in vivo is carried out directly with the patient. The second is outside the body, such a test or study is also called a "test tube" reaction. In both cases allergens act as diagnostic tests. The well-known Mantoux reaction refers specifically to an in vivo study when mycobacterium tuberculosis is administered subcutaneously. If the body is sensitized with a Koch wand, the answer will be inadequate: the skin at the injection site turns red, swells. According to the size of the infiltrate, the specialist records the result of the sample.
How and what to treat?
Allergic reactions of a delayed type are a delayed inadequate response to the interaction of the human body and its irritating substances. Treatment of this type of problem is carried out only on the recommendation of a specialist - an allergist and immunologist. To cure such a problem, therapy is used with drugs that stop systemic diseases of the connective tissue, as well as immunosuppressants.
The first group of drugs used in the treatment of HRT include:
- glucocorticoids, for example, "Dexamethasone", "Prednisolone", "Triamcinolone";
- non-steroidal anti-inflammatory drugs, such as Diclofenac, Indomethacin, Naproxen, Piroxicam.
Immunosuppressant drugs used in delayed-type allergic reactions are divided into the following groups:
- cytostatics - "Azathioprine", "Mercaptopurin", "Cyclophosphamide";
- anti-lymphocyte serum, anti-lymphocyte globulin and human anti-allergic immunoglobulin;
- slow-acting antirheumatic drugs ("Hingamin", "Penicillamine");
- antibiotics - "Cyclosporin A".
Any drug should be recommended only by your doctor!
Allergic reactions of an immediate and delayed type are a serious health problem that requires high-quality diagnosis and proper comprehensive treatment. Slowed down hypersensitivity reactions occur at the cellular level, changing the structure of tissues and causing their destruction, which can cause disability and death without proper therapy. Only an attentive attitude to your health and timely diagnosis of the disease with subsequent high-quality treatment will give a positive result.