The immune system- this is a set of organs, tissues and cells, the work of which is aimed directly at protecting the body from various diseases and at exterminating those that have already entered the body foreign substances.

It is this system that is an obstacle to infectious agents (bacterial, viral, fungal). When the immune system fails, the likelihood of developing infections increases, this also leads to the occurrence of autoimmune diseases, including multiple sclerosis.

Organs included in the human immune system: lymph glands (nodes), tonsils, thymus (thymus), Bone marrow, spleen and lymphoid formations of the intestine (Peyer's patches). They are united by a complex circulation system, which consists of ducts connecting the lymph nodes.

Lymph node- This is a formation from soft tissues, which has an oval shape, a size of 0.2 - 1.0 cm and contains a large number of lymphocytes.

The tonsils are small collections of lymphoid tissue located on either side of the throat.

The spleen is an organ that looks very much like a large lymph node. The functions of the spleen are diverse: it is both a filter for blood, and a storage for its cells, and a place for the production of lymphocytes. It is in the spleen that old and defective blood cells are destroyed. This organ of the immune system is located in the abdomen under the left hypochondrium near the stomach.

Thymus gland (thymus) located behind the chest. Lymphoid cells in the thymus proliferate and "learn". In children and young people, the thymus is active, the older the person, the more passive and smaller this organ becomes.

Bone marrow is a soft spongy tissue located inside tubular and flat bones. The main task of the bone marrow is the production of blood cells: leukocytes, erythrocytes, platelets.

Peyer's patches these are concentrations of lymphoid tissue in the walls of the intestine, more specifically, in the appendix (vermiform appendix). However, the main role is played by the circulatory system, consisting of ducts that connect the lymph nodes and transport lymph.

Lymph fluid (lymph) is a colorless liquid that flows through lymphatic vessels, it contains a lot of lymphocytes - white blood cells involved in protecting the body from diseases.

Lymphocytes are, figuratively speaking, the "soldiers" of the immune system, they are responsible for the destruction of foreign organisms or their own diseased cells (infected, tumor, etc.). The most important types of lymphocytes are B-lymphocytes and T-lymphocytes. They work together with other immune cells and do not allow foreign substances (infectious agents, foreign proteins, etc.) to invade the body. At the first stage of development of the human immune system, the body "teaches" T-lymphocytes to distinguish foreign proteins from normal (own) proteins of the body. This learning process takes place in the thymus gland in early childhood, as the thymus is most active at this age. When a child reaches puberty, his thymus decreases in size and loses its activity.

Interesting fact: in many autoimmune diseases, for example, in multiple sclerosis, the patient's immune system "does not recognize" the healthy tissues of his own body, treats them as foreign cells, begins to attack and destroy them.

The role of the human immune system

The immune system appeared with multicellular organisms and developed as an assistant to their survival. It unites organs and tissues that guarantee the protection of the body from genetically alien cells and substances coming from environment. In terms of organization and mechanisms of functioning, immunity is similar to the nervous system.

Both of these systems are represented by central and peripheral organs capable of responding to different signals, have a large number of receptor structures and specific memory.

The central organs of the immune system include the red bone marrow, thymus, and the peripheral organs include the lymph nodes, spleen, tonsils, and appendix.

The leading place among the cells of the immune system is occupied by leukocytes. With their help, the body is able to provide various forms of immune response upon contact with foreign bodies, for example, the formation of specific antibodies.

History of Immunity Research

The very concept of "immunity" in modern science introduced by the Russian scientist I.I. Mechnikov and the German doctor P. Ehrlich, who studied the body's defense reactions in the fight against various diseases primarily infectious. Their joint work in this area was even awarded the Nobel Prize in 1908. A great contribution to the science of immunology was also made by the work of the French scientist Louis Pasteur, who developed a method of vaccination against a number of dangerous infections.

The word "immunity" comes from the Latin "immunis", which means "pure from something." Initially, it was believed that the immune system protects us only from infectious diseases. However, the studies of the English scientist P. Medawar in the middle of the twentieth century proved that immunity provides protection in general from any alien and harmful interference in the human body.

At present, immunity is understood, firstly, as resistance to infections, and secondly, as the body's responses aimed at destroying and removing from it everything that is alien to it and poses a threat. It is clear that if people did not have immunity, they simply could not exist, and it is precisely its presence that makes it possible to successfully fight diseases and live to old age.

The immune system has developed long years human evolution and acts like a well-oiled mechanism. It helps us fight disease and harmful environmental influences. The tasks of immunity include recognizing, destroying and bringing out both foreign agents penetrating from the outside and decay products formed in the body itself (during infectious and inflammatory processes), as well as exterminating pathologically changed cells.

The immune system is able to recognize many "aliens". Among them are viruses, bacteria, poisonous substances of plant or animal origin, protozoa, fungi, allergens. Among the enemies, she also includes those that have turned into cancer cells, and therefore their own cells that have become dangerous. The main goal of immunity is to provide protection against intrusions and preserve the integrity of the internal environment of the body, its biological individuality.

How is the recognition of "outsiders"? This process takes place at the genetic level. The fact is that each cell carries its own genetic information inherent only to this particular organism (you can call it a label). It is her immune system that analyzes when it detects penetration into the body or changes in it. If the information matches (the label is present), then it’s your own, if it doesn’t match (the label is missing), then it’s someone else’s.

In immunology, foreign agents are called antigens. When the immune system detects them, defense mechanisms immediately turn on, and a fight begins against the “stranger”. Moreover, for the destruction of each specific antigen, the body produces specific cells, they are called antibodies. They fit antigens like a key to a lock. Antibodies bind to the antigen and eliminate it, so the body fights the disease.

One of the main human immune reactions is the state of increased body response to allergens. Allergens are substances that contribute to the occurrence of the corresponding reaction. Allocate internal and external factors provocateurs of allergies.

External allergens include certain foods (eggs, chocolate, citrus fruits), various chemicals (perfumes, deodorants), and drugs.

Internal allergens - own cells, usually with altered properties. For example, during burns, the body perceives dead tissues as foreign, and creates antibodies for them. The same reactions can occur with the stings of bees, bumblebees and other insects.

Allergies develop rapidly or sequentially. When an allergen acts on the body for the first time, the immune system produces and accumulates antibodies with increased sensitivity to it. When the same allergen enters the body again, allergic reaction, for example, skin rashes, swelling, redness and itching appear.

Is there a "superimmunity"?

There are people who convince that there is super-immunity, and this phenomenon is not so rare. But they cannot give an answer to the question that arises: why hasn’t nature still naturally created a super-powerful system that would not be affected by any pathogenic microorganism? In fact, the answer is obvious: extra strong immunity will become a threat to the human body. Any distortion of this complex multi-component living system threatens to disrupt the functioning of vital organs. Here are just a few examples:

What of the above is meant by those who are promoting "immunity boost"? The above examples prove that raising the level of sensitivity of the immune system, or increasing the amount of substances produced by it in special cases, as well as increasing the number of cells - all this causes great harm to the body.

It is necessary to pay attention to the fact that when the immune system comes into contact with an external attack and reacts with an increase in its cellular balance, then, as the “victory” comes, the body is diligently cleansed of the excess “ballast” of protective cells - they collapse in the process of programmed destruction - apoptosis.

Therefore, scientists do not have arguments for the existence of a hyperstrong immune system. If we consider immunity, it becomes clear that “norm” and “pathology” are exactly those concepts that you cannot argue with. And the meaning of the expressions: “strengthen immunity”, “strengthen it”, “improve the state of the immune system” - have no basis and are the result of high-quality advertising.

Factors that weaken our immune system

At birth, nature “gives” a person an almost ideal and most effective protective system. It is so perfect that it takes a lot of effort to “weaken” it. So what causes a real deterioration in the work of this protective mechanism, or a decrease in immunity?

Prolonged severe stress (for example, the sudden loss of a loved one, the threat of an incurable disease, war), hunger and food shortages, Stable lack of important microelements and vitamins by the body. If these conditions are observed for months or even years, then they really affect the decrease in the protective segments of the immune system.

The undermining of the protective function is influenced by some chronic diseases. These include diabetes.

Congenital and acquired immunodeficiencies (), as well as procedures that knowingly depress the immune system: chemotherapy, immunosuppressive therapy.

Advanced age. Elderly people experience a drop in the work of all systems, including the immune system. For example, the number of T-lymphocytes produced in response to infection in the body decreases markedly over the years. As a result, disease resistance decreases.

It should be noted that "traditional" infections - influenza, colds and others - are not afraid of the immune system. The kind of painful conditions that people experience when they get sick from time to time are just part of the immune system's response. This is not her downfall.

Useless methods to increase immunity

For an ordinary person who overcomes severe diseases that destroy the immune system, any immunostimulants are useless. It is already known from the above that the immunity of a patient whose condition is statistically average does not need additional stimulation.

In fact, pharmaceutical companies They produce proven drugs, the action of which is aimed at strengthening the immune defense (immunostimulants) or weakening it (immunosuppressors). But doctors still prescribe drugs to patients in the complex therapy of especially serious diseases. Taking such powerful drugs by an ordinary person during a common cold is not only superfluous, but even dangerous.

Another point, called "immunostimulants" in pharmacies, drugs with unconfirmed effectiveness are very often offered. And their harmlessness, the absence of side effects, which advertising so vividly talks about, confirms that, in fact, these are placebos, and not real drugs.

Immunologist Elena Milovidova:

People are already accustomed to attribute various ailments to “decreased immunity” and tend to buy its stimulants, using them at their own discretion. They do not want to hear the opinion of experts that problems with the body's immune response occur in unique cases: after taking aggressive antibiotics, after surgery, implantation, and others.

Today, all kinds of medicines based on interferons, components that affect immune metabolism. But almost all immunologists believe that immunostimulants are either absolutely useless, or more serious drugs should be used. This refers to the need to introduce them into the course of treatment for patients with a specific diagnosis, for example, with secondary immunodeficiency. The rest of the stimulation is harmful - it leads to exhaustion. If you constantly stimulate the production of leukocytes with drugs, the immune system will begin to lose its immediate functions. If you stuff the body with various stimulants on an ongoing basis, then it will become a "beggar", constantly begging. That's when it starts serious problems with immunity.

If you intend to improve your tone, cheer up, then you should pay attention to natural adaptogens: Chinese magnolia vine, ginseng, eleutherococcus, radiola rosea. They act as enhancers of RNA and protein synthesis (the basis of human cells), activate metabolic enzymes and the work of the endocrine and vegetative systems without affecting the immune system at all.

Vitamins are a group of components that are artificially attached to the glory of substances that have a positive effect on the immune system. The exception is vitamin D. It really has a direct bearing on this process - it activates inactive immune cells T-lymphocytes and promotes their transformation into T-killers. They take part in the destruction of negative pathogenic microorganisms.

All other groups of vitamins are not directly involved in the functioning of the immune system. They, of course, make people healthier and this is excellent, but they do not play any role in improving immunity. Note that the much-lauded anti-cold effect of vitamin C, during clinical research, has not been confirmed.

Bath

The assertion of a positive effect of a sauna or bath on the immune system also has no basis. As for the cardiovascular - it definitely affects, moreover, very often - negatively. Therefore, before visiting the bath, get an assessment of your health, and do not focus on a cold or flu.

The immune system provides specific protection of the body from genetically alien molecules and cells.

Cells have a unique ability to recognize foreign antigens.

The immune system emphasizes the unity of cells with a common origin, functional action and regulation mechanisms.

Central or primary organs of the immune system- red bone marrow and thymus.

red bone marrow- the birthplace of all cells of the immune system and the maturation of B-lymphocytes. In it, erythrocytes, granulocytes, monocytes, dendritic cells, B-lymphocytes, precursors of T-lymphocytes and NK cells are formed from pluripotent stem cells.

Red bone marrow in children under 4 years of age is located in the cavities of all flat and tubular bones.

And At the age of 18, it remains only in flat bones and epiphyses of tubular bones.

With age, the number of red bone marrow cells decreases and it is replaced by yellow bone marrow.

thymus- is responsible for the development of T-lymphocytes, which come there from the red bone marrow from pre-T-lymphocytes.

In the thymus, T-lymphocytes with clusters (receptors that determine the functional abilities) of CD4+ CD8+ differentiation are selected and those variants that are highly sensitive to the antigens of their own cells, i.e. it prevents an autoimmune reaction.

Thymus hormones accompany the functional maturation of T-lymphocytes and increase their secretion of cytokines.

The thymus is surrounded by a thin connective tissue capsule, consists of 2 asymmetric lobes, divided into lobules. Under the capsule is a basal membrane, on which epithelioreticulocytes are located in one layer. The periphery of the lobules is the cortical substance, the central part is the medulla, all the lobules are populated by lymphocytes. With age, Timu undergoes involution.

T-lymphocytes differentiate into mature immune cells in the thymus, responsible for cellular lymphocytes, B-lymphocytes - Bursa Fabricius

The secondary organs of the immune system are peripheral organs.

Group 1 - structured organs of the immune system - the spleen and lymph nodes.

Group 2 - unstructured.

lymph nodes- filter the lymph, extract antigens and foreign substances from it. In the lymph nodes, antigen-dependent proliferation and differentiation of T and B lymphocytes occurs. Mature non-immune lymphocytes formed in the bone marrow, with the lymph / blood flow, enter the lymph nodes, meet the antigen in the bloodstream, receive antigenic and cytokine stimulus and turn into mature immune lymphocytes capable of recognizing and destroying the antigen.

The lymph node is covered with a connective tissue capsule, trabeculae depart from it, have a cortical zone, a paracortical zone, cerebral cords and a cerebral sinus.

The cortex contains lymphoid follicles, which contain dendritic cells and B-lymphocytes. A primordial follicle is a small follicle with non-immune B lymphocytes.

After interacting with the antigen, dendritic cells and t-lymphocytes, the B-lymphocyte is activated and forms a clone of proliferating B-lymphocytes, as a result, a germinal center is formed that contains proliferating B-lymphocytes, and after the completion of immunogenesis, the primary follicle becomes secondary.

In the paracortical zone there are T-lymphocytes and postcapillary venules with high epithelium, through their walls lymphocytes migrate from the blood to the lymph nodes and back. It also contains interdigitating cells that migrated to the lymph node through the lymphatic vessels from the integumentary tissues from the skin and from the mucous membranes together with the already processed (antigen processing) antigen. The cords lie beneath the paracortex and contain macrophages activated by B lymphocytes, which differentiate into antibody-producing plasma cells. The cerebral sinus accumulates lymph with antibodies and lymphocytes and it is diverted into the lymphatic channel and it is diverted along the efferent lymphatic vessel.

Spleen

It has a connective tissue capsule, trabeculae depart from it, making up the frame of the organ. It has a pulp that forms the basis of the organ. The pulp contains lymphoid reticular tissue, vessels and blood cells. In the white pulp, there is an accumulation of lymphoid cells in the form of periarterial lymphoid muffs. They are located around the arterioles. The white pulp also contains germinal centers and B cell follicles.

The red pulp contains capillary loops, erythrocytes, macrophages.

Functions of the spleen - in the white pulp, the cells of the immune system come into contact with the antigen that has penetrated into the blood, the processing and presentation of this antigen. And also the implementation various types immune response, predominantly humoral.

Platelets are deposited in the red pulp, up to 1/3 of all platelets are found in the spleen, erythrocytes and granulocytes, and this is the destruction of damaged erythrocytes and platelets.

Lymphoid tissue associated with the skin.

These are white outgrowth interdigitating Langengars cells. They fix the antigen coming from the skin, process it and migrate to regional lymph nodes ("these are the border guards who catch the saboteur and take him to the commandant's office")

Lymphoid cells of the epidermis, mainly T-lymphocytes and keratinocytes, as a mechanical barrier.

Lymphoid tissue associated with mucous membranes (the area of ​​which is 400 m 2)

It is presented structured - solitary follicles, appendix and tonsils, single lymphoid cells. The antigen penetrates into the lymphoid tissue from the surface of the mucous membranes through special epithelial M-cells. Macrophages and dendritic cells located under the pithelium process the antigen and deliver its specific part to T and B lymphocytes.

It is characteristic that each tissue has populations of limophycetes capable of recognizing their place of residence. They have homing "Home" receptors on their membranes. CLA - skin lymphocytic antigen.

Peyror's plaques - Lymphoid formations located in their own mucosal membrane have three main components - the epithelial dome consists of an epithelium devoid of intestinal villi and containing many M - cells. A lymphoid follicle with a germinal center filled with B-lymphocytes.

Interfollicular zone - N lymphocytes and interdigitating cells.

The main function of the specific immune response is the specific recognition of an antigen.

Forms of the immune response.

1. Cellular immunity is the accumulation of antigen specific active T-lymphocytes that perform effector functions, either directly by the lymphocytes themselves, or through the cellular mediators of lymphokines secreted by them.
2. Humoral immunity is based on the production of specific antibodies - immunoglobulins that perform the main effector functions.
3. Immunological memory is the body's ability to respond more intensely to a second encounter with an antigen than to the first. This ability is acquired as a result of immunization with the same antigen.
4. Immunological tolerance is a state of specific immunological a-reactivity of the organism to certain antigens. It is characterized -

A) lack of response to an antigen

B) the absence of antigen elimination upon its repeated administration

C) Absence of antibodies to a given antigen. Antigens that cause immunological tolerance are called tolerogenic

Forms of immunological tolerance

Natural- formed on antigens in the prenatal period

Artificial- when introducing very high or very low doses of the antigen into the body.

Immunoglobulins- contained in the blood and tissue fluid. The molecule is composed of a protein and an oligosaccharide. According to electrophoretic properties, gamma globulins are mainly, but alpha and beta are found.

Immunoglobulin monomers consist of 2 pairs of chains - 2 short or L chains and 2 long or heavy H chains. The chains have constant C and variable - V regions.

light chains There are 2 types - lambda or kappa, they are the same for all immunoglobulins, contain 200 amino acid residues.

heavy chains divided into 5 isotypes - gamma, mu, alpha, delta and upsilon.

They have 450 to 600 amino acid residues. According to the type of heavy chain, there are 5 classes of immunoglobulins - IgI, IgM, IgA, IgD, IgE.

The papain enzyme cleaves the immunoglobulin molecule into 2 identical antigen-binding Fab fragments and one Fc fragment.

Immunoglobulins classes A, M, G- major immunoglobulins, D, E-minor. G, D, E, as well as serum fractions A are monomers, i.e. have 1 pair of heavy and 1 pair of light chains and 2 antigen binding sites.

Immunoglobulin M- is a pentamer.

The secretory fraction of immunoglobulin A is a dimer connected to each other by a j - chain (join - connect). The antigen binding site is called the active site of the antibody and is formed by the hypervariable regions of the H and L chains.

These sites - there are specific molecules that are complementary to certain antigenic epitopes.

The FC fragment is capable of binding compliment and is involved in the transfer of some immunoglobulins across the placenta.

Immunoglobulins have compact structures held together by a disulfide bond. They are called domains. Available variable domains and constant domains. Light L chains have 1 variable and one constant domain, and heavy H chains have 1 variable and 3 constant domains. The CH2 domain contains a complement-binding site. Between the CH1 and CH2 domains there is a hinged area ("antibody waist"), it contains a lot of proline, makes the molecule more flexible and, as a result, F ab and F ac can rotate in space.

Characterization of classes of immunoglobulins.

IgG(80%) - concentration in the blood 12 g per liter. Mol. Weight 160 daltons, formed during the primary and secondary administration of antigens. It is a monomer. There are 2 epitope-binding sites. It has a high activity in binding to bacterial antigens. Participates in the activation of the compliment along the classical pathway and in lysis reactions. Penetrates through the placenta of the mother into the body of the fetus. The Fc fragment can bind to macrophages, neutrophils and NK cells. The half-life is from 7 to 23 days.

IgM- 13% of all immunoglobulins. Its serum concentration is 1 g per liter. It is a pentamer. This is the first immunoglobulin produced in the body of the fetus. Formed during the primary immune response. Normal antibodies, as well as isohemagglutinin, belong to this class. It does not pass through the placenta, it has the most high speed binding to antigens. When interacting with an antigen in vitro causes reactions of agglutination, pretepetation, compliment binding. Its Fc fragments are also involved. Immunoglobulin monomers in the form of membranes are present on the surface of B lymphocytes.

IgA - 2 subclasses - serum and secretory. 2.5 g per liter It is synthesized by plasma cells of the spleen and lymph nodes, does not give the phenomenon of agglutination and pretepetation, does not lyse the antigen. The half-life is 5 days. The secretory subclass has a secretory component that binds 2 or rarely 3 IgA monomers. The secretory component has a j chain (beta globulin with a molecular weight of 71 kilodaltons, is synthesized by the cells of the epithelium of the mucous membranes and can join the serum immunoglobulin when it passes through the cells of the mucous membrane - transcytosis). SIgA Involved in local immunity, dimer, 4 epiope binding sites. Interferes with adhesion of microbes on cells of mucous and absorption of viruses. IgA controls compliment through an alternative pathway.

40% - serum, 60% - secretory

IgD- 0.03 g per liter. The monomer, 2 epitope-binding sites, does not pass through the placenta, does not bind the compliment. It is located on the surface of B lymphocytes and activates their activation or suppression.

properties of antibodies.

1. Specificity - each antigen has its own antibody
2. Affinity - the strength of binding to an antigen
3. Avidity - the rate of binding to an antigen and the amount of bound antigen
4. Valence - the number of working active centers or antideterminant groups. There are 2 valent and 1 valent antibodies (1 active center is blocked)

Antigenic property of antibodies

Allotypes are intraspecific antigenic differences. There are 20 types in humans.

Idiotypes are antigenic differences in antibodies. Characterize the active differences in the active centers of antibodies.

Isotypes - classes and subclasses of immunoglobulins, isotypes are defined by cezdamides and heavy chains.

Functions of immunoglobulins.

The main one is antigen binding. This ensures the neutralization of toxins and the prevention of the penetration of pathogens into the cell.

Effector function - binding to cells or tissues with the participation of specific receptors, binding to cells of the immune system, phagocytes, to complement components and binding to staphylococcal and staphylococcal antigens.

Types of antibodies

According to their properties, they are distinguished - complete bivalent (agglutinin, lysins, pretepicins), incomplete monovalent blocking

By location - circulating and supracellular

In relation to temperature - thermal, cold and 2-phase

Dynamics of antibody formation

1. Lag phase - antibodies are not formed in the blood
2. Log phase - logarithmic increase in antibody concentration
3. Plateau phase - stable high concentration of antibodies
4. Attenuation, recession - termination of the action of antibodies.

With a secondary immune response

The lag phase accelerates, antibody titers are higher, with the primary immune response, immunoglobulin M is formed, and then G, with the secondary, IgG is immediately formed, and IgA is formed even later

The characteristic of incomplete antibodies is monovalent, blocking, one active center. They are formed during infection, allergies, Rh conflict, are thermostable, appear the earliest and disappear late, pass through the placenta. Their detection is carried out by the Coombs method, enzyme methods.

The level of antibodies in the blood or other fluids is estimated by titer, i.e. the maximum dilution of the biological fluid, at which a visible reaction phenomenon is observed when the antigen interacts with the antibody. Analytical methods are used and the concentration is determined in grams per litre.

Components of the immune system

The structure of the organs of the immune system is quite complex and is only slightly inferior to how the nervous system is built. Its central organs are:

1. Red and yellow bone marrow. Its purpose is to be responsible for the hematopoietic process. Spongy substances of short bones contain red brain. It is also found in the spongy components of flat bones. Tubular bones in their cavities contain a yellow brain. In children's bones, there is only red. This type contains stem cells.
2. Thymus (thymus). Located behind the chest. Represents 2 shares: with right side and from the left. Both lobes are divided into smaller lobules, containing the cortex at the edges and the medulla in the center. The basis of the thymus gland are epithelioreticulocytes. They are responsible for the formation of a network of T-lymphocytes, the production of thymosin and thymopoietin (bioactive components). Lymphocytes are produced by the cortical substance, then they enter the brain, and from there into the blood.

The immune system also contains peripheral organs. Their total weight (both those and others) is about 1 kilogram.

Back to index

What organs are peripheral?

The immune system has 6 tonsils:

1. Palatine steam room. Located on both sides of the pharynx. It is an organ covered with several layers of squamous epithelium.
2. Tubal tonsil (also steam room). Its basis is lymphoid tissue. Located in the area auditory tube. Surrounds the opening of the pharynx.
3. Pharyngeal tonsil (unpaired organ). Its location is the wall of the pharynx from above.
4. Lingual tonsil (also unpaired). The place of its localization is the region of the linguistic root.

The following organs also belong to the peripheral part of the immune system:

1. lymph nodes. They are located in the following systems: digestion, respiration, urination. They form a ball shape, consisting of a large number of lymphocytes. Protect the body from the ingress of foreign harmful substances into it. If an antigenic danger arises, then the process of formation of lymphocytes starts, since the centers of their reproduction are located in the nodules.
2. Lymphoid plaques. Their location is the small intestine. Consist of several nodules of the same name. These plaques do not allow foreign substances to enter the bloodstream or lymph. It is in the small intestine that there are especially many strangers, since the process of digestion of food takes place here.
3. Appendix (is a vermiform appendix). It contains a lot of lymphoid nodules. They lie close to each other. The process itself is located in the border zone between small intestine and thick. It is one of the main functions of the immune system.
4. The lymph nodes. They are located in places where lymph flows. In the lymph nodes, foreign substances and dead cells of the body are retained. There they are destroyed. Lymph nodes in the body are not located one at a time. Usually there are two or more.
5. Spleen. Its location - abdomen. The task of this important organ is to control blood and its composition. The spleen consists of a capsule with trabeculae extending from it. It also contains pulp, white and red pulp. The basis of the white is the lymphatic tissue, the red is the reticular stroma. 78% of the entire organ is given by nature to the red pulp, which contains many lymphocytes and leukocytes, as well as other cells.

All of them are located so that they surround the place where the mouth and nose cavities enter the pharynx. If foreign substances (from food or from inhaled air) try to enter the body, then it is in this place that lymphocytes await them.

The interaction of all organs presents a complex picture. Their coordinated work, as well as the structure and functions of the immune system, provide reliable protection organism.

Long before the baby is born, even in the womb, the formation of the child's immune system begins. In order for it to develop in the future, the child needs mother's milk. For the same purpose, an antigenic load is needed - the contact of the child's body with various microorganisms.

Back to index

What is the immune system responsible for?

The functions of the human immune system can be represented as the following algorithm:

• recognize a foreign element;
• destroy the alien;
• provide maximum protection to your body.

In the body, nothing passes without a trace, including the immune response. The immune system at the first encounter with any foreign substance (infection, microbe, etc.) will definitely remember its properties. The next meeting with him affects him more effectively.

Bacteria appear in the life of the baby almost immediately after his birth. Many parents believe that the child should be as sterile as possible. But this opinion is wrong. Basic hygiene rules are necessary, but you should not go to extremes. Excessive sterility can prevent the infant's immune system from developing its properties. If the mother's milk contains a certain amount of bacteria, then you can not refuse it. The child's body must learn to deal with harmful substances. The function of the immune system is to fight various viruses and bacteria.

In most cases, she copes with them before they have time to show their negative impact on the human body, that is, the person does not even notice that not everything is in order in the body.

But if there are too many pathogenic substances, then not every immune system will be able to cope. There are also pathogens that, even in small quantities, are not subject to the best immunity. For example, cholera or chicken pox. A decrease in the functions of the immune system is manifested by frequent colds, chronic infections, and a constant temperature of 37-38 ° C. There are diseases, the peculiarities of which are that a person suffers from them only once in a lifetime. For example, measles. This is due to the immune system, which forms a stable immunity to the transferred disease.

The immune system, consisting of special proteins, tissues and organs, daily protects humans from pathogens, and also prevents the influence of some special factors (for example, allergens).

In most cases, she does a huge amount of work aimed at maintaining health and preventing the development of infection.

Photo 1. The immune system is a trap for harmful microbes. Source: Flickr (Heather Butler).

What is the immune system

The immune system is a special, protective system of the body that prevents the effects of foreign agents (antigens). Through a series of steps called the immune response, it “attacks” all microorganisms and substances that invade organ and tissue systems and are capable of causing disease.

Organs of the immune system

The immune system is amazingly complex. It is able to recognize and remember millions of different antigens, producing the necessary components in a timely manner to destroy the “enemy”.

She is includes central and peripheral organs, as well as special cells, which are produced in them and are directly involved in the protection of man.

Central authorities

The central organs of the immune system are responsible for the maturation, growth and development of immunocompetent cells - lymphopoiesis.

Central authorities include:

• Bone marrow- spongy tissue of a predominantly yellowish hue, located inside the bone cavity. Bone marrow contains immature, or stem cells, which are capable of transforming into any, including immunocompetent, cell of the body.
• Thymus(thymus). It is a small organ located in the upper part of the chest behind the sternum. In shape, this organ somewhat resembles thyme, or thyme, Latin name which gave the organ its name. T-cells of the immune system mainly mature in the thymus, but the thymus is also able to provoke or support the production of antibodies against antigens.
• During the intrauterine period of development, the liver also belongs to the central organs of the immune system..

It is interesting! The largest size of the thymus gland is observed in newborns; with age, the organ shrinks and is replaced by adipose tissue.

Peripheral Organs

Peripheral organs are distinguished by the fact that they already contain mature cells of the immune system that interact with each other and with other cells and substances.

Peripheral organs are represented by:

• Spleen. The largest lymphatic organ in the body, located under the ribs on the left side of the abdomen, above the stomach. The spleen contains predominantly white blood cells and also helps to get rid of old and damaged blood cells.
• The lymph nodes(LU) are small, bean-shaped structures that store cells of the immune system. The LN also produces lymph, a special clear liquid that transports immune cells to various parts of the body. As the body fights infection, the nodules can grow in size and become painful.
• Accumulations of lymphoid tissue containing immune cells and located under the mucous membranes of the digestive and genitourinary tract, as well as in the respiratory system.

Cells of the immune system

The main cells of the immune system are leukocytes, which circulate in the body through the lymphatic and blood vessels.

The main types of leukocytes capable of an immune response are the following cells:

• Lymphocytes, which allow you to recognize, remember and destroy all antigens that invade the body.
• phagocytes absorbing foreign particles.

Phagocytes can be various cells; the most common type are neutrophils, fighting mainly bacterial infection.

Lymphocytes are located in the bone marrow and are represented by B-cells; if lymphocytes are found in the thymus, they mature into T-lymphocytes. B and T cells have different functions from each other:

• B-lymphocytes try to detect foreign particles and send a signal to other cells when an infection is detected.
• T-lymphocytes destroy pathogenic components identified by B-cells.

How the immune system works

When antigens (that is, foreign particles that invade the body) are detected, B-lymphocytes producing antibodies(AT) - specialized proteins that block specific antigens.

Antibodies are able to recognize the antigen, but they cannot destroy it on their own - this function belongs to T-cells that perform several functions. T cells can not only destroy foreign particles (for this there are special T-killers, or “killers”), but also participate in the transmission of an immune signal to other cells (for example, phagocytes).

Antibodies, in addition to identifying antigens, neutralize toxins produced by pathogenic organisms; also activate complement, a part of the immune system that helps destroy bacteria, viruses, and other and foreign substances.

Recognition process

After the formation of antibodies, they remain in the human body. If the immune system encounters the same antigen in the future, the infection may not develop.: for example, after the transferred chicken pox the person is no longer sick.

This process of recognition of a foreign substance is called antigen presentation. The formation of antibodies during re-infection is no longer required: the destruction of the antigen by the immune system is carried out almost instantly.

allergic reactions

Allergies follow a similar mechanism; a simplified state development scheme is as follows:

1. Primary entry of the allergen into the body; is not clinically expressed.
2. Formation of antibodies and their fixation on mast cells.
3. Sensitization is an increase in sensitivity to an allergen.
4. Re-entry of the allergen into the body.
5. Release of special substances (mediators) from mast cells with the development of a chain reaction. Subsequent produced substances affect organs and tissues, which is determined by the appearance of symptoms of an allergic process.

Photo 2. Allergy occurs when the body's immune system takes a substance as harmful.

Immunity is the body's ability to get rid of foreign bodies and compounds and thereby maintain the chemical and biological constancy of the internal environment and its own tissues.

The combat task that nature has set for our internal protection is a guarantee of the complete safety of the body, i.e. providing immunity.

When the immune system recognizes the "invaders", it sets into motion a sequence of reactions involving dozens of special proteins. Each of these proteins activates the next, strengthening the counterattack. At any time, the immune system strives to cut through everything foreign and activates a number of means that destroy all this foreign.

The role of immunity comes down to maintaining the constancy of the internal environment of the body (homeostasis), monitoring the genetic uniformity of body cells, jealously protecting our "I" and destroying everything genetically alien - and penetrated into the body from the outside: (infectious pathogens, foreign substances and transplanted tissues), and emerging developed inside (abnormal, degenerated cells).

We depend on the amount of resources involved in the work of our internal defense mechanisms, which works continuously, like clockwork, to protect us from a hostile world. Without a healthy physiological defense function capable of destroying all our enemies, we are condemned to a quick death, like a child living under a glass jar. In light of the above, it is not difficult to understand that if you want to have excellent health, one of your most important goals should be to strengthen the physiological defenses.

STRUCTURE OF IMMUNITY

The immune system is an amazing complex of structures and mechanisms designed to protect us from all kinds of damaging agents, including bacteria and viruses. These mechanisms can be divided into two complementary systems.

The first, in a matter of hours, arranges an attack on the invading microbes. And the second reacts after a few days, but it strikes pathogens right on target. This second system has a good memory, so even if a particular "invader" returns in years, it will be quickly destroyed.

The whole system works so efficiently that we often do not notice how the infection entered our body and was successfully eliminated. It is amazing how the immune system distinguishes hundreds of types of cells in our body from everything foreign.

Microbes penetrate with inhaled air, food, as well as through the genitourinary tract and damage to the skin. When the immune system recognizes the "invaders", it sets into motion a sequence of reactions involving dozens of special proteins. Each of these proteins activates the next, strengthening the counterattack.

The first barrier skin and mucous membranes are in the way of the attackers. They are not only a physical barrier, sweat and sebaceous glands skin is harmful to many microbes. Tears, saliva, hydrochloric acid and a number of other substances secreted by mucous membranes are also harmful to microbes. Along with this, there is also “environmental protection”: on the skin and mucous membranes there are microorganisms that destroy microbes harmful to humans.

second barrier on the way of pathogenic microbes are elements of the internal environment of the body: blood, tissue fluid and lymph.

Thus, immunity is a multi-level defense of the body. It is known that such a physiological function can be reduced due to the impact of a number of adverse factors. With burns, hypothermia, blood loss, starvation, injuries (skin and mental). In this case, the body becomes more sensitive to infections, the mechanisms of regeneration (healing) and recovery are delayed.

The total weight of all organs and cells of the immune system of an adult is less than 1 kilogram, but, as you know, it is not the quantity that matters, but the quality.

Long-term suppression of the body's natural defense mechanisms dramatically increases the chance of developing cancer, since cancer cells are mutant in relation to the body, and in healthy body they are quickly recognized by T-lymphocytes and destroyed by them.The lack of internal resources to protect the body tenfold increases the risk that lymphocytes will miss cancer cell and that will set the progressive and inevitable growth of daughter cancer cells.

TYPES OF IMMUNE

Immunity is divided into: congenital and acquired.

Congenital, is hereditary. As a rule, it does not have strict specificity for antigens, and does not have a memory of the initial contact with a foreign agent. For example:

• All humans are immune to canine distemper.
• Some people are immune to tuberculosis.
• Some people have been shown to be immune to HIV.

Acquired immunity is divided into: active and passive.

Acquired Active immunity occurs after a disease or after a vaccine is administered.

Acquired Passive immunity develops when ready-made antibodies are introduced into the body in the form of serum or transferred to a newborn with mother's colostrum or in utero. And also passive, in the transfer of antibodies to the child from the mother.

Immunity is also divided into: natural and artificial.

Natural immunity includes innate immunity and acquired active (after a disease).

Artificial immunity includes acquired active after vaccination (administration of the vaccine) and acquired passive (administration of serum)

ORGANS OF THE IMMUNE SYSTEM

Allocate central and peripheral organs of the immune system.

to the central organs include: red bone marrow and thymus;

to peripheral- spleen, lymph nodes and lymphoid tissue: broncho-lymphoid tissue (BLT), skin-lymphoid tissue (CLT), intestinal-lymphoid tissue (KiLT, Peyer's patches).

IMMUNOCOMPETENT CELLS

Immunocompetent cells are cells that are part of the immune system and are responsible for immunity. This is a large army of phagocytes and lymphocytes, which guard human health around the clock. The following cells are known:

phagocytes(leukocytes) - means "cells - eaters." These are peculiar border guards who are the first to attack dangerous microorganisms and foreign substances. Having found a foreign body, they seize it with pseudopods, absorb it and destroy it.

Only one phagocyte is capable of destroying up to 20 bacteria, but, alas, if there are more opponents, then he himself dies. The temperature often rises at the site of such battles, and the “heroes” who fall in them, during a cold, are usually removed with a handkerchief.

Lymphocytes is a large group of cells that matures in lymph nodes and the thymus gland. These are fighters of a slightly different sort. They produce antibodies that neutralize poisons and microbes, making them more vulnerable to phagocytes.

Macrophages are larger cells than leukocytes. When microorganisms penetrate the skin or mucous membranes into the internal environment of the body, macrophages move to them and participate in their destruction.

AUTOIMMUNE DISEASES

In case of violation of immunological tolerance or damage to tissue barriers, the development of immune reactions to the body's own cells is possible. For example, the pathological production of antibodies to the receptors of one's own muscle cells.

In some parts of the body of mammals and humans, the appearance of foreign antigens does not cause an immune response. These areas include the brain and eyes, the testes, the embryo, and the placenta. Violation of immune privileges can cause autoimmune diseases.

Protection methods:

1. Protection of the body is carried out not only by protecting against the ingress of foreign substances into it, but also by cleansing all organs and tissues from antigens that have already entered. Cleansing is a very important aspect in the normalization of the body's defenses! Viruses, bacteria and their toxins, decay products of bacteria are excreted from the body with sweat, sputum, urine, feces and other excrement with sufficient stimulation of the body's cleansing mechanisms.

2. Interferon, an antiviral protein produced by an infected cell, is also an additional component of the protective function of the human body. Spreading through the intercellular fluid and settling on the membranes of healthy cells, interferon protects a healthy cell from the penetration of viral particles into it.

3. There are a number of drugs (immunomodulators) containing both synthesized and natural substances (Cordyceps, Spirulina, Ikan, Chitosan, Anti-lipid tea, Biocalcium), which increase the strength of nonspecific immunity.

OUR IMMUNITY LOVES:

1. Fresh air.
2. Light physical activity.
3. Bath, massage.
4. Complete sleep.
5. Positive emotions.
6. Protein. The lack of protein in the diet affects our immune system in the most unfavorable way, because the protein contains a complete set of essential amino acids. The body obtains essential fatty acids from food and through a series of chemical reactions produces "good" and "bad" prostaglandins. The action of "beneficial" prostaglandins is aimed at stimulating immune function, but more important is the balance between "beneficial" and "harmful" prostaglandins.
7. Vitamin C". This vitamin, which is often prescribed to us by doctors for flu, colds and acute respiratory infections, is most directly responsible for immunity.
   
8. B group vitamins. B vitamins help stimulate the immune system during periods of physical stress, such as after surgery or injury. If the levels of these vitamins fall, the body's ability to produce antibodies to fight infections is markedly reduced.
   
9. Microelement Zinc. Of all the trace elements for immunity, ZINC is especially important. When there is a lack of it, new cells are not formed in the body. But in case of danger, the immune system must, as quickly as possible, create additional defender cells!
10. Microelement Selenium. Heavy metals do not allow the immune system to work optimally. To neutralize them, you need a special trace element - SELENIUM, which helps to cleanse the body of mercury and lead.
    
11. Beneficial bacteria. Sometimes the strength of lymphocytes and phagocytes is not enough - and then you can send them reinforcements - bifidobacteria and lactobacilli, which destroy the pathogenic microflora in the large intestine, activate digestion and synthesize substances important for the body. Where to look for them? Of course, in living products - yogurt, fermented baked milk, kefir, yogurt, ayran and matsoni. All fermented foods are also alive: pickled apples, sauerkraut, kvass.
12. Alimentary fiber. Beneficial microorganisms inside a person need to eat something, so dietary fiber (fiber) is vital for them. Dietary fiber is divided into soluble and insoluble. The first ones contribute to normal digestion and act as an adsorbent (remove toxins from the body). Soluble fiber is what feeds beneficial bacteria.Insoluble fibers are also very useful - they absorb excess liquid, ballast substances and undigested food like sponges.
13. Sugar. Foods high in refined sugar weaken the body by impairing the body's ability to produce the necessary antibodies to fight infections, as well as by reducing the ability of some immune defenses to fight foreign factors.
    

OUR IMMUNE DOES NOT LIKE:

1. Stress and depression.
2. Tobacco and alcohol.
3. Hypodynamia and excessive physical activity.
4. Work at night.