Hypersensitivity is an immune system response that causes undesirable phenomena, including tissue damage and multiple diseases. These pathological phenomena caused by the activity of the immune system are called hypersensitivity phenomena. As the immune system protects the body from external harmful objects, especially pollutants. And the reason
The most common occurrence of hypersensitivity phenomena is the non-distinction of the immune system sometimes between autoantibodies and foreign bodies (exotic). This distinction is an essential characteristic of the immune system to ensure proper functioning, and so that the immune system does not attack the self-tissue. This failure in self-tolerance, due to which allergic reactions appear against the body itself, appears as a series of clinical symptoms known as Autoimmune diseases.
Hypersensitivity can occur due to an overly immune response against external causes, as is the case with allergies. Excessive allergies include a wide variety of symptoms. The two main factors that determine the pathogenic form of hypersensitivity are: the type of immune response that damages tissues, and the characteristics of the pathogen (antigen) that constitutes the target that the immune system attacks, and its location. According to this, hypersensitivity diseases were classified into four types:
1. Immediate hypersensitivity is the mechanism that causes allergic diseases such as rhinitis, asthma or which causes a widespread allergic reaction in many body systems, which is called anaphylactic reaction.
These reactions are an indication of the presence of IgE antibodies present on the surface of mast cells present in many tissues of the body, especially those cells exposed to the outside world. The confluence of these antibodies with the antigen coming from outside, such as flower seeds, food compounds, medicines, etc., causes activation of mast cells and secretion of multiple chemical media that cause tissue damage, so that they lead to the emergence of various pathological phenomena characteristic of allergies. These phenomena are defined as Type 1 hypersensitivity.
2. Antibodies that are not from the IgE family can damage tissues by recruiting and activating inflammatory cells, by disrupting the normal system of cell function in damaged tissues. For example, antibodies directed against compounds present in the membrane of red blood cells can damage cell performance and can cause degradation (the situation that causes hemolytic anemia) by activating cells or enzymatic systems that are linked to the immune system. These phenomena are classified as type 2 hypersensitivity.
3. Other antibodies can immune complexes (groups of antibodies and antigens) that are soluble and which travel with the bloodstream, and are deposited in different and multiple tissues, especially the vascular wall. This deposition, which provokes an inflammatory reaction, causes damage to the tissues, and it is observed with multiple diseases such as vasculitis, or glomerulonephritis. Diseases caused by immune groups are classified as type 3 hypersensitivity.
4. Tissue damage from cell activation that is not antibody, known as Delayed hypersensitivity, is classified as type 4 of hypersensitivity. In such cases, T-type lymphocytes respond against the specific antigen by secreting multiple chemical media, causing tissue damage. So that the effects of allergies appear after several hours, and even for a few days, after exposure to the antigen other than the situation in type 1 hypersensitivity, as the height of sensitization is after several minutes.
Examples of long-term hypersensitivity are contact dermatitis, which is characterized by an inflammatory reaction after contacting the skin with an external substance such as metal, cosmetic materials, etc., or the reaction observed after injecting the skin with an antigen known to the immune system such as a tuberculosis diagnostic test (Tuberculin / Mantoux).
Diagnosis of hypersensitivity is diagnosed by an allergist and includes accurate examination of the past, skin and blood tests to determine the level of isonvylate and the level of IgE antibodies.
