Are allergies a sign of inflammation?

Immunological classification

Medicine distinguishes between four types of allergies - depending on which immunological reactions the allergen allergen
These are substances that are classified as "foreign" by the body's immune system and are therefore attacked, which leads to an excessive defense reaction (= allergy with over-sensitivity of the body to the respective allergen).
A distinction is made between animal, vegetable and chemical allergens, with almost any environmental substance triggering an allergy. A potential allergen is a substance that, due to its biochemical nature, can cause an allergic reaction more frequently than other substances.
evokes. Immune reactions usually take place in several, complicated steps, which are carried out via so-called mediators
The term comes from the Latin (mediator = mediator). Mediators are biomolecules that are released in response to certain stimuli and then initiate a certain biochemical reaction by acting on surrounding cells. They could also be called mediators of a cell reaction.
being controlled. The first three allergy types become antibodies via the body fluids and the antibodies they contain
Antibodies are also called immunoglobulins (Ig) and are proteins (glycoproteins) that the human body forms after contact with a foreign substance (antigen). These antibodies can then specifically bind to the antigens (in the so-called antigen-antibody reaction). The resulting immune complexes are then rendered harmless. Increased Ig levels generally indicate an increased immune defense, as often occurs in acute or chronic infectious diseases (allergic and parasitic diseases). The immunoglobulins are divided into four different classes (Ig A, Ig E, Ig G and Ig M). Depending on which type is more prevalent, this allows conclusions to be drawn about the disease in question.
e.g. factors (humoral) mediated, the fourth allergy type, however, is cell-mediated (via T cells T cells
T lymphocytes or T cells are mainly found in the lymph fluid and mature in the thymus (hence the T). Like B-lymphocytes, they take care of the immune system and are so-called "immunocompetent cells" because they have the ability to individually recognize and specifically combat those foreign substances (or their antigens) with which they come into contact .
) from. However, mixed images also occur.

  • Type I: The allergy of the immediate type
  • Type II: The cytotoxic reaction
  • Type III: The immune complex formation
  • Type IV: The cellular immune response

Type I: The allergy of the immediate type

Symptoms of allergic rhinoconjunctivitis (hay fever) with swollen nasal mucosa, increased formation of nasal secretions and tear fluid, sneezing and itching in the nose and eyes as well as swelling of the eyelids are very typical for this type of allergy.

Type I includes, for example, allergic rhinitis (allergic rhinitis), hives (urticaria) or asthma symptoms, but also pollen allergies, insect venom allergies, some drug or food allergies. Allergic reactions of the immediate type often show a severe course. If the reaction to an allergen is particularly strong, a massive release of histamine can also trigger an anaphylactic shock.

In the case of allergy type I, the body forms suitable antibodies of group Ig E (immunoglobulin EImmoglobulin E
These are class E antibodies that can dock specifically (in the so-called antigen-antibody reaction) to certain antigens and then lead to the release of histamine through a bridge bond to so-called mast cells (see also immediate type allergy, allergy type I). This causes an inflammatory response. Increased Ig E levels in the blood occur mainly in allergic and parasitic diseases.
) - the immune system
The body's defense system consists of three functional circles:
(1) Bone marrow as a place where immune cells form.
(2) Various central immune organs such as thymus (imprinting T lymphocytes) and lymphatic organs near the gut (for imprinting B lymphocytes).
(3) Secondary lymphatic organs such as the spleen, lymph nodes and tonsils (tonsils).
A distinction is made between the so-called humoral defense (via the body fluids containing antibodies and factors from the so-called complement system) and the cell-mediated defense (with B and T cells, macrophages, antigen-presenting cells, granulocytes, etc.).
is now against these antigens antigens
Antigens are certain surface structure features (chemical molecules) that are characteristic of every pathogen and every substance, are recognized by the body's own defense system (immune system) as foreign ("not self") and trigger a defense reaction (immune reaction).
sensitized. The next time it comes into contact with an allergen, the IgE antibodies combine with what are known as mast cells
Mast cells are basophilic granulocytes that occur in tissue and contain the allergy-triggering messenger substance histamine in a storage form (granules) that they release when they come into contact with an allergen. Antibodies (immunoglobulins of class E) are bound on their surface.
found in skin and mucous membranes. They then bind the antigens to themselves. This bridge bond (between mast cell, antibody and antigen) causes the mast cells to release the inflammation mediator histamine (mast cell degranulation). The histamine and other released substances cause the allergy-typical, unpleasant symptoms: In the immediate vicinity, the released histamine causes the vessels to expand so that they become more permeable. Blood flows more and more in order to be able to transport away foreign and waste materials. This leads to reddening and swelling of the skin or mucous membrane. The inflammatory reaction also results in itching and increased mucus formation in the mucous membranes.

Type II: The cytotoxic reaction

Type II reactions are rare. Their episodes appear within minutes or a few hours. An example of a reaction of this type of allergy is the destruction of red blood cells after a blood transfusion with an unsuitable blood type. Other triggers for a type II reaction can be pain relievers, antibiotics, or anticonvulsant medication. The rejection of organ transplants and some autoimmune diseases (e.g. glomerulonephritis) are also based on type II reactions.

The type II reaction also belongs to the immune system-mediated allergic reactions, whereby the antibody groups Ig G and Ig M are involved. These are also formed during non-allergic defense reactions of the organism against pathogens. In the allergic type II reaction, however, the body makes these antibodies against antigens that are found on certain cells or tissues of the body. By binding the antibodies to these cells, larger units (complexes) are formed, which attract certain defense cells (phagocytes). Phagocytes have the task of ingesting intruders, digesting them and thus eliminating them. But because of the considerable size of the resulting complexes, the phagocytes cannot do their job. Fatally, they then send enzymes as well
These are (for the metabolism of all living beings) indispensable protein bodies which, as biocatalysts, enable biochemical processes, accelerate them and allow them to proceed in a desired direction without being changed themselves in the process. There are a large number of different enzymes, each one responsible for a specific process. Enzymes work according to the lock and key principle, which means that every enzyme has a special protein structure that enables it to specifically recognize the substance whose reaction it is supposed to control (substrate specificity). A variety of different metabolic processes are possible in the organism at the same time.
from which the supposed strangers are supposed to dissolve. Since the enzymes are now effective against the body's own cells, this leads to extensive damage, which also affects surrounding healthy tissue.

Type III: The immune complex formation

Type III includes, for example, the farmer's lung, which is recognized as an agricultural occupational disease, and the pigeon fancier's lung.

Type III allergic reactions can occur hours or days, but sometimes months after exposure to the allergen. As with type II, allergens and antibodies "stick together" under certain conditions. In the case of type III, however, the antigens are freely soluble and are not, as in type II, on the surface of the body's own cells. The larger units formed when the antibodies bind to the antigens are called immune complexes. Lured immune cells try to dissolve the complexes with enzymes. If this does not succeed, these complexes can be deposited in organs or on joints and cause inflammation there. In addition to immune cells, blood platelets (thrombocyte platelets
These are certain blood cells that play an essential role in blood clotting.
) and through the increased blood supply through the enlarged vessels increasingly reach the inflammation area. If the blood platelets attach to the immune complexes, tiny blood clots (microthrombi) form, which can clog the small blood vessels - which can lead to the death of the tissue that has been cut off from the supply, functional disorders and, in the worst case, the loss of the organ concerned.

Chronic infections (for example with streptococci, certain parasites or viruses), autoimmune processes (for example systemic lupus erythematosus: SLE) and exposure to certain environmental allergens (molds, pigeon antigens) are possible causes. The symptoms are varied and depend on where the immune complexes are deposited, with more or less painful functional restrictions developing in the affected organs or tissue types - in the pigeon fancier's or farmer's lung, for example, this happens in the lungs.

Type IV: The cellular immune response

Type IV, which is also called the late type, predominantly causes allergy symptoms on the skin, such as nickel allergy. Contact allergies are generally responsible for the majority of cases of occupational disability.

Allergies of this type can develop unnoticed for years, but then suddenly trigger very violent immune reactions. This is where T-lymphocyte lymphocytes attack
These cells are responsible for the immune defense and are so-called "immune competent cells" because they have the ability to individually recognize and specifically fight the antigens with which they come into contact. A distinction is made between B and T lymphocytes
foreign bodies that have penetrated together with helper cells. It is a cell-mediated reaction. Antibodies like IgE do not play a role.

Instead, the T-lymphocytes use so-called lymphokines as mediators in their defensive battle, which have an inflammatory effect. In addition, the attracted phagocytes release cell-damaging enzymes. All of this ultimately leads to the elimination of the exogenous substance (the allergen), but - as a side effect, so to speak - also to an intensified and severe allergic reaction.