Allergic reactions: symptoms, causes, treatment of children and adults
Almost everyone at least once in life faced with an allergic reaction. What is it?
Allergy is an acute reaction of the body's defense system to substances to the body are harmless.
Simtomatika this reaction is the most different – from slight redness and lesions on the skin to rapidly developing edema and death. The term Allergy is hiding a variety of immune diseases. Skin and mucous membranes are the most often suffering from the symptoms of allergies places.
How is an allergic reaction
The mechanism of the reaction of the body to the allergen occurs in three stages:
- immunological;
- pathochemical;
- pathophysiological.
In the first stage, an antigen – a substance, an allergen first enters the body. At this point, is the development of antibodies to this antigen sensitization. The duration of this process from several hours to a dozen. Sometimes the antigen have hatched from the body, and antibodies are only developed. Of course, in this case an allergic reaction occurs. It happens with repeated contact with antigen. The developed antibodies have to destroy it and form with it a complex antigen-antibody.
Glossary of terms:
Antibodies are protein molecules formed during the reaction of antigen with b-cells.
Antigens – any molecule capable of specific contact with the antibodies.
In a next step, these complexes damage the fat cells in different tissues. The composition of these cells are set to inactive as mediators of inflammation – histamine, serotonin, bradykinin, and the like. Due to the introduction of the complex they move to the active state and enter into the General circulation.
The last stage is characterized by outward signs of an allergic reaction – muscle spasms, increased secretion and mucus formation, expansion of capillaries, skin rashes. This is due to the impact of released in blood mediators of inflammation.
Types of hypersensitivity, depending on the speed of the reaction
Depending on how quickly the body that was hit by an allergen, go to the pathophysiological stage share the following types of allergic reactions and hypersensitivity:
- immediate type;
- otsrocennosti;
- delayed.
In case of immediate type allergic reaction develops within minutes. In the tissues of developing acute immune inflammation.
At delayed type allergic reaction is from 1 hour to 6. Slow – 24-48 hours in the tissue develops a chronic immune inflammation.
Types of allergic reactions depending on the mechanism of development
Just allocate fivetypes of hypersensitivity:
- Anaphylactic;
- Cytotecuse;
- Immunocomplex reactions;
- Kletochnaia;
- Reactions in which there is a stimulation of cell function after interaction with antigen.
In the reactions of the first type is tissue damage through reactions involving immunoglobulin E, sometimes G reaginovykh mechanism on the cell surface. Thus liberated mediators of inflammation enter the bloodstream and lead to spasm of smooth muscle or increased secretion.
For this type are allergic rhinitis, atopic bronchial asthma, urticaria. Serious hypersensitivity reaction of the first type is anaphylactic shock, growing from a few seconds to 5 hours. The resulting edema of the larynx, bronchospasm and laryngospasm cause suffocation, and a sharp drop in pressure may lead to collapse.
Important! At the first sign of anaphylactic chic urgently needed injection of adrenaline and prednisolone. The first will prevent the development of edema, the second will suppress the allergic reaction.
In case of allergic reactions of cytotoxic type antibodies bind to the cells and damage them and sometimes causing their lysis (dissolution). For this sometimes they are called cellular toxins. This type of hypersensitivity reaction is the basis of drug Allergy, hemolytic disease of the newborn in RH conflict, hemolytic anemia.
Interestingly, not always the cytotoxins cause cell damage. At sufficiently small amount of cell poisons cause stimulation. This phenomenon is used for the development of cytological serum with therapeutic effect for different types of allergic reactions.
Immune complex reactions caused by formation of complexes antigen-antibody with a slight antigen excess. In this case, the complexes are deposited on vessel walls, activating complement system and causing inflammation. In severe cases the inflammation may lead to tissue necrosis, and ulcers in the blood vessels can occur a complete or partial thrombosis and some types of allergic reactions.
This type of reaction is characteristic for exogenous conjunctivitis, allergic dermatitis, rheumatoid arthritis and systemic lupus erythematosus, and it may be after contact with the antibodies in the body is sensitized people. Reactions are triggered by interaction of T-lymphocytes and specific antigens. Re-exposure to antigen leads to the development of T-cleocinonline inflammatory reactions as a result of allergic reactions
Inflammation can be localized and generalized. Characteristically, this type of allergicreactions maximal damage skin, gastrointestinal tract and respiratory system. Clinical examples kletochnaia reactions – infectious diseases-asthma, bracelet, tuberculosis.
Reactions of the fifth type of similar mechanism for cytotoxic when the cell poison causing stimulation of the cells. Therefore, the number of researchers does not emit data of allergic hypersensitivity reactions in a separate type, limited to the description of the phenomenon of stimulation. An example of stimulating allergic reactions are hyperthyroidism, which is overproduction of thyroxine under the influence of antibodies.
Types of allergens
Depending on the nature it is possible to allocate three types of allergens:
- Ecollagen (external antigens).
- The autoantigens.
- Grafts.
To external allergens include drugs, food allergens, various microorganisms and bacteria – anything that gets in the body from the external environment. They cause diseases from the group of exogenous allergies.
Autoantigens is its own antigens, which for a number of reasons cause an allergic reaction. Diseases caused by them, are combined in a group of autoimmune diseases.
Often allergic reactions associated with the high activity of the immune system, which perceives its own cells as foreign and begins to actively damaging. May be affected as different systems and all organism as a whole, and the question, what are the symptoms for allergies are already expanding beyond just the skin.
Share two reasons for the development of autoimmune disease, including external factors of causative agents of certain infectious diseases, radiation, ultraviolet radiation) and internal (mutations genetic character, inherited).
Grafts implanted into the recipient's body may also cause an allergic reaction. Such reaction is called "graft versus host". They are caused by the fact that the immune factors of transplant exhibit hypersensitivity towards the tissues and organs of the recipient.
Most often, allergic reactions occur when a bone marrow transplant. Note that the close relationship of the donor and recipient, the risk of reaction is up to 40% with unrelated transplantation is increased two. The probability of death resulting from allergic reactions of this type is very high.
Risk factors of Allergy development
There are groups of people for whom the risk of allergies is very high. Factors that increase the probability of the following:
- Heredity. The presence of the human genotype of specific genes ensures the development of allergic reactions.
- Allergic reactions due to frequentinteraction with domestic and occupational antigens. Often causes contact dermatitis, but can also lead to more serious allergic reactions.
- Smoking. Cigarette smoke getting into your lungs, it damages mucous membranes. Damaged mucous membrane are open gates to the body for microbes, which are quite often carry on their surface and allergens and allergic reactions.
- Frequent diseases of the upper respiratory tract. Also cause the body's immune system weakens and may fail in the form of allergic reactions, for example, it may be allergic to ragweed.
- Frequent eating products, having in its composition the allergens. A hypersensitivity reaction can trigger various additives – preservatives, coloring agents included in the composition of food products.
- Incorrectly vaccinated. The concentration of the vaccine, its scope and the timing of administration can be determined only by a physician. Not worth it to risk your health.