Human health directly depends on the condition immune system. The body's resistance to various pathogens is determined by immunological factors, the activity of which directly depends on the type of immunity. Acquired immunity is formed throughout life, which allows you to adapt to changing conditions external environment habitat of the individual.

Basic Concepts

Immunity is very complex set systems, organs, cells, mechanisms and reactions to ensure the body's resistance to harmful factors environment and pathogens.

The main activity of the immune system:

• Immunity to harmful components;
• Resistance to diseases and external negative factors;
• System for recognizing a genetically alien object;
• Formation and improvement of mechanisms and reactions for the destruction and removal of genetically foreign objects from the body;
• Activation and direction of actions to restore and normalize the constancy of the internal environment of the body.

Thus, the immune system is aimed at providing a high-quality and timely immunological response due to the influence of specific and nonspecific protective mechanisms.

Non-specific actions include:

• Protective functions of mucous membranes and skin;
• Phagocytic reactions - activity of macrophages, microphages, leukocytes;
• Humoral factors are antimicrobial protein compounds;
• The system for the occurrence of the inflammatory response.

The specific influence of defense mechanisms is manifested in:

• Multiple actions to resist antigens are the compliment system, interferons, specific enzymes, cells capable of phagocytes;
• Activities of type B and T lymphocytes - form active lymphocytes according to the existing immunological memory, influence the process of remembering the antigen and the method of combating it, carry out immune reactions
• Formation and activation of antibodies - globular protein compounds for binding antigen, performing specific species functions to neutralize the infectious agent.

Types of immune defense

In immunology, the body's resistance is presented according to the type of its formation. It can be congenital - inherited. And emerging - adaptive, developed individually throughout life.

Congenital

Immunological immunity, which has genetically fixed resistance to certain types of foreign antigens, is an innate defense. In turn, it is defined as absolute, that is, complete immunity to pathogens of animal diseases, and relative - this is when the risk of infection appears when certain conditions arise.

Emerging

Part of the immune system, the mechanisms and reactions of which undergo stages of formation and improvement throughout human life, is called acquired immunity.

A person with an acquired set of protective mechanisms and reactions cannot transmit this protection by inheritance, although resistance to the pathogen persists from a short period (for influenza) to long-term protection (from typhoid fever), and with some infections, such as measles, lifelong resistance is developed.

The main weapons of such resistance for the development of an immunological response are:

• Cellular structures in the form of a phagocytosis system are a set of special cells circulating throughout the body in search of pathogens. Due to the presence of receptor mechanisms, the harmful object is bound and absorbed;
• The humoral properties of the production and activation of antibodies are specifically reactive products of the onset of an immunological response to the appearance of the antigen of the pathogen;
• Arective cellular protection is the absence of cell susceptibility to viral molecules.

Depending on the method of occurrence of immunological protection, two types are distinguished:

• Naturally acquired resistance;
• Passively acquired protection.

Naturally acquired immunity

Natural acquired resistance to infections is a protective concept of the body that arose after infectious process. Consequently, natural acquired immunity occurs after direct penetration of the pathogen antigen into the body during natural or living conditions infection, with an obvious or hidden symptomatic picture.

It can be typical:

• Active - that is, this type immune defense caused by infection and individual production of antibodies. However, it can be sterile - complete elimination foreign gene and recovery, and non-sterile - the causative agent of the disease remains in the cells and causes chronic course illness, which prevents the recurrence of infection. Active acquired immunity is established within two to eight weeks;
• Passive - the child is endowed with this immunological resistance when specific protective protein compounds are transferred through the placenta or breast milk. Moreover, this type does not have a long-lasting effect and persists until the formation of its own active immunity, that is, until the child reaches one year.

Artificially-derived immunity

Immunological defense of the body that occurs during intervention medical supplies based on antigens of bacteria or viruses or antibodies to them is called artificially acquired immunity.

Artificial acquired immunity is the reaction of the immune system to:

• The introduction of pathogenic antigens in a weakened or neutralized form, that is, occurs active work protective mechanisms for controlled penetration of the pathogen. Acquired active immunity is developed directly during planned vaccination activities and is characterized by: for a long time actions;
• Introduction of serological serum preparations in the form of ready-made immunoglobulins and antitoxins - this is a passive type of acquired immunological resistance. The immune response occurs within a short time, no more than twenty-four hours, while the duration of exposure to the body is not long - depending on the type of serum material, it ranges from twenty days to five weeks. Passive administration of immunoglobulin substances is justified when urgent treatment fatal dangerous diseases, penetration of poisons, as well as when the risk of infection increases as immunoprophylaxis.

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Immunity– a way to protect the body from living bodies and substances that carry signs of genetically foreign information.

The human and animal body very accurately differentiates between “self” and “foreign”, thus providing protection against the introduction of not only pathogenic microbes, but also foreign substances. The entry into the body of substances with signs of foreign information threatens to disrupt the structural and chemical composition of this organism. The quantitative and qualitative constancy of the internal environment of the body is called homeostasis. Homeostasis ensures self-regulation processes in all living systems. Immunity is one of the manifestations of homeostasis. In this regard, it can be argued that immunity is a property of all living things - humans, animals, plants, bacteria.

The system of organs and cells that responds against foreign substances is called the immune system. Immune system cells constantly circulate throughout the body through the bloodstream. The immune system has the ability to produce highly specific antibody molecules, different in their specificity in relation to each antigen.

Classification of immunity by origin.

There are innate and acquired immunity.

Innate immunity(natural, species, hereditary, genetic) is immunity to infectious agents that is inherited. This type of immunity is characteristic of animals of a certain species to a certain pathogen and is passed on from generation to generation. For example, horses do not get foot and mouth disease, large cattle- glanders, dogs - swine fever. Innate immunity is distinguished between individual and species:

Individual innate immunity is observed in individual individuals of a species, although, as a rule, other individuals of this species are sensitive to this disease.

Species immunity is observed in all individuals of a given species. There are specific immunity, absolute and relative. This type of immunity is called absolute when a disease in a certain species of animal cannot be caused under any circumstances. Species immunity is considered relative if it can be impaired under certain conditions (hypothermia, overheating, age-related changes).

For example, Mechnikov managed to induce tetanus in a frog (very resistant to tetanus toxin) by overheating it in a thermostat. Congenital resistance is mainly found in adult animals; in newborn animals, species-specific resistance is often absent. It is important to note that natural resistance is not only a species characteristic. Among those susceptible to certain types of microorganisms, there are breeds, populations and lines of animals that are highly resistant to this pathogen. Yes, when high sensitivity sheep to the pathogen anthrax, Algerian sheep are highly resistant to it.

Acquired immunity(specific) is the body’s resistance to a specific pathogen, developed during the life of the organism and not inherited.

Naturally acquired immunity is divided into active and passive:

Active(post-infectious) immunity manifests itself after the animal has naturally recovered from the disease. Active immunity can last up to 1...2 years, and in some cases for life (canine distemper, sheep pox). But in some cases, the formation of an immune response is possible even in the absence of clinical signs diseases. This occurs when the pathogen enters the animal’s body in small doses, insufficient to cause the disease. When such doses of a pathogen are systematically ingested, latent immunization of the macroorganism occurs, which in animals that have reached a certain age creates active immunity to a specific pathogen. This phenomenon is called immunizing subinfection. That. immunizing subinfection is the process of formation of active immunity due to immunization of the body with small doses of a pathogen that are not capable of causing disease over a long period of time.

Naturally acquired passive immunity- this is the immunity of newborns acquired by them due to the receipt of maternal antibodies through the placenta (transplacental) or after birth through the intestines with colostrum (colostral). In birds, transovarial (through the lecithin fraction of the yolk). Passive immunity provides a state of immunity from several weeks to several months.

Artificially acquired immunity, in turn, is also divided into active and passive. Active (post-vaccination) immunity occurs as a result of immunization of animals with vaccines. Vaccine immunity in the body develops 7...14 days after vaccination and lasts from several months to 1 year or more. Passive immunity is created when an immune serum containing specific antibodies against a specific pathogen is introduced into the body. Passive immunity can also be created by administering blood sera from convalescent animals. Passive immunity, as a rule, lasts no more than 15 days.

Immunity is also usually classified according to the direction of action protective forces on microorganisms and their waste products:

Antibacterial immunity. Defense mechanisms are directed against a pathogenic microbe, as a result, the reproduction and spread of the microorganism in the animal’s body is prevented.

Antiviral immunity. It is caused by the body’s production of antiviral antibodies and cellular defense mechanisms.

Antitoxic immunity. The bacteria are not destroyed, but the body of a sick animal produces antibodies that can effectively neutralize toxins.

If after past illness The body is released from the pathogen, acquiring a state of immunity, then such immunity is called sterile. If the body is not freed from the pathogen, then such immunity is called non-sterile. As a rule, the state of immunity persists as long as the causative agent of the disease is in the body. When the pathogen is removed, the

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There are many criteria by which immunity can be classified.
Depending on the nature and method of occurrence, development mechanisms, prevalence, activity, object of the immune reaction, maintenance period immune memory, reacting systems, type of infectious agent are distinguished:

A. Innate and acquired immunity

1. Innate immunity (specific, nonspecific, constitutional) is a system of protective factors that exist from birth, determined by the anatomical and physiological characteristics inherent in a given species and fixed hereditarily. It exists initially from birth even before the first entry into the body of a certain antigen. For example, people are immune to canine distemper, and a dog will never get cholera or measles. Innate immunity also includes barriers to entry harmful substances. These are the barriers that first meet aggression (cough, mucus, stomach acid, skin). It does not have strict specificity for antigens, and does not have a memory of initial contact with a foreign agent.
2. Acquired immunity is formed during the life of an individual and is not inherited. Formed after the first encounter with an antigen. At the same time they are launched immune mechanisms which remember this antigen and form specific antibodies. Therefore, when the same antigen is encountered again, the immune response becomes faster and more effective. This is how acquired immunity is formed. This applies to measles, plague, chickenpox, mumps, etc., with which a person does not get sick twice.

If there is a predisposition in the family to certain immune-related diseases (tumors, allergies), then defects in innate immunity are inherited.

There are anti-infectious and non-infectious immunity.

1. Anti-infective- immune response to antigens of microorganisms and their toxins.
   • Antibacterial
   • Antiviral
   • Antifungal
   • Anthelmintic
   • Antiprotozoal
2. Non-infectious immunity- aimed at non-infectious biological antigens. Depending on the nature of these antigens, they are distinguished:
   • Autoimmunity is the reaction of the immune system to its own antigens (proteins, lipoproteins, glycoproteins). It is based on a violation of the recognition of “own” tissues; they are perceived as “foreign” and are destroyed.
   • Antitumor immunity is the response of the immune system to tumor cell antigens.
   • Transplantation immunity occurs during blood transfusion and transplantation of donor organs and tissues.
   • Antitoxic immunity.
   • Reproductive immunity "mother-fetus". It is expressed in the reaction of the mother's immune system to fetal antigens, since there are differences in the genes received from the father.

F. Sterile and non-sterile anti-infective immunity

1. Sterile– the pathogen is removed from the body, and immunity is preserved, i.e. specific lymphocytes and corresponding antibodies are retained (for example, viral infections). Supported immunological memory.
2. Non-sterile— to maintain immunity, the presence of a corresponding antigen—pathogen—in the body is necessary (for example, with helminthiases). Immunological memory not supported.

G. Humoral, cellular immune response, immunological tolerance

Based on the type of immune response, there are:

1. Humoral immune response– antibodies produced by B lymphocytes and non-cellular structure factors contained in biological fluids human body(tissue fluid, blood serum, saliva, tears, urine, etc.).
2. Cellular immune response– macrophages are involved, T- lymphocytes, which destroy target cells carrying the corresponding antigens.
3. Immunological tolerance is a kind of immunological tolerance to an antigen. It is recognized, but effective mechanisms capable of removing it are not formed.

H. Transient, short-term, long-term, lifelong immunity

According to the period of maintenance of immune memory, they are distinguished:

1. Transitory– quickly lost after antigen removal.
2. Short-term– maintained from 3-4 weeks to several months.
3. Long term- Maintained from several years to several decades.
4. Life- maintained throughout life (measles, chickenpox, rubella, mumps).

In the first 2 cases, the pathogen usually does not pose a serious danger.
The following 2 types of immunity are formed when dangerous pathogens which may cause severe violations in the body.

I. Primary and secondary immune response

1. Primary- immune processes that occur upon first encounter with an antigen. It is maximum by the 7-8th day, persists for about 2 weeks, and then decreases.
2. Secondary- immune processes that occur upon repeated encounter with an antigen. It develops much faster and more intensely.

The basis of the mechanisms of manifestation of acquired immunity is determined by immune reactivity, which combines the action of the following factors: antibodies, immediate hypersensitivity, delayed hypersensitivity, immunological memory, immunological tolerance, idiotypes-antiidiotypes, phagocytosis, complement.

Acquired immunity - specific immunity to foreign substances (antigens), acquired by the body as a result of a previous disease or other interaction with an antigen, with the help of immune drugs.

Thus, unlike nonspecific resistance and species immunity, acquired immunity is created during a person’s life and is the result of interaction with pathogenic microorganisms. Acquired immunity is always highly specific, that is, it is formed strictly on certain type or strain of microorganisms. Its development is based on specific reactivity (immunoreactivity).

Depending on the origin, acquired immunity is divided into natural and artificial, and according to the mechanisms of acquisition - into active and passive.

Natural active - a type of acquired immunity formed as a result of human infection with virulent strains.

Artificial active - is created as a result of human immunization with bacterial or viral antigenic preparations (vaccines).

Natural passive - vertical, transplacental route of transmission immune antibodies from mother to fetus.

Artificial passive - introduction into the body immune sera, immunoglobulins.

Thus, active acquired immunity is determined by the specific reaction of the immune system to the introduced antigen, and passive immunity is determined by the introduction of immune reaction products into the body.

Immune system- the totality of all lymphoid organs and accumulations of lymphoid cells in organs and tissues.

There are two types of immune response. One of them is shared by antibodies (humoral), and the other by cells (cellular). The main immunocompetent cells responsible for both cellular and humoral immunity are lymphocytes.

Initial stage development of immunity is associated with migration, proliferation and differentiation of stem (original) cells concentrated in the human bone marrow. From here, stem cells, subject to humoral regulation, enter the primary lymphoid organs, where they receive “instructions” that determine their further differentiation and function in response to an encounter with an antigen. From the primary lymphoid organ, cells settle into different departments peripheral lymphoid tissue.

The primary lymphoid organ that controls the cell-mediated immune response is thymus(thymus). Stem cells receiving “instruction” in the thymus are called T -lymphocytes.

Another primary lymphoid organ is the bursa (bursa) of Fabricius (in birds). In mammals, including humans, the bursa of Fabricius is absent. It is assumed that this function is performed bone marrow, tonsils, appendix, group lymphatic follicles (Peyer's patches), interepithelial lymphocytes, etc. Cells specializing in this primary lymphoid organ, are called B lymphocytes. They control the antibody response, that is, they perform the function of humoral immunity.

In terms of immunological function, T cells are heterogeneous. Some of them produce substances called mediators, or lymphokines, which give the effect of delayed-type hypersensitivity. There are T-lymphocytes-helpers (helpers), stimulating B lymphocytes, T-lymphocytes-effectors, capable of destroying foreign antigens, T-killers (killers), destroying target cells, T-suppressors, suppressive functions of B lymphocytes, T-lymphocytes with immunological memory.

Content

Defensive reaction or immunity is the body's response to external danger and irritants. Many factors in the human body contribute to its defense against various pathogens. What is innate immunity, how does the body’s defense occur and what is its mechanism?

Innate and acquired immunity

The very concept of immunity is associated with the evolutionarily acquired ability of the body to prevent foreign agents from entering it. The mechanism for combating them is different, since the types and forms of immunity differ in their diversity and characteristics. According to its origin and formation, the protective mechanism can be:

• congenital (nonspecific, natural, hereditary) - protective factors in the human body that were formed evolutionarily and help fight foreign agents from the very beginning of life; Also this type protection causes species-specific immunity of humans to diseases that are characteristic of animals and plants;
• acquired - protective factors that are formed during life, can be natural and artificial. Natural protection is formed after exposure, as a result of which the body is able to acquire antibodies to this dangerous agent. Artificial protection involves the introduction of ready-made antibodies (passive) or a weakened form of the virus (active) into the body.

Properties of innate immunity

Vital property innate immunity is the constant presence in the body of natural antibodies that provide primary reaction to invade pathogenic organisms. Important property The natural response is the compliment system, which is a complex of proteins in the blood that provide recognition and primary defense against foreign agents. This system performs the following functions:

• opsonization is the process of attaching elements of the complex to a damaged cell;
• chemotaxis - a set of signals through chemical reaction, which attracts other immune agents;
• membranotropic damage complex - complement proteins that destroy the protective membrane of opsonized agents.

The key property of the natural response is primary defense, due to which the body can receive information about foreign cells that are new to it, as a result of which an already acquired response is created, which, in the event of further encounters with similar pathogens, will be ready for a full fight, without the involvement of other protective factors (inflammation , phagocytosis, etc.).

Formation of innate immunity

Every person has nonspecific protection; it is genetically fixed and can be inherited from parents. A specific feature of humans is that they are not susceptible to a number of diseases characteristic of other species. For the formation of innate immunity important role plays a role in intrauterine development and breast-feeding after birth. The mother passes on important antibodies to her child, which lay the foundation for his first defenses. Violation of the formation of natural defenses can lead to an immunodeficiency state due to:

• exposure to radiation;
• chemical agents;
• pathogens during fetal development.

Factors of innate immunity

What is innate immunity and what is its mechanism of action? Totality common factors innate immunity is designed to create a certain line of defense for the body against foreign agents. This line consists of several protective barriers that the body builds on the path of pathogenic microorganisms:

1. The skin epithelium and mucous membranes are the primary barriers that have colonization resistance. Due to the penetration of the pathogen, an inflammatory reaction develops.
2. Lymph nodes are important protective system, which fights the pathogen before it enters the circulatory system.
3. Blood – when an infection enters the blood, a systemic inflammatory response develops, which involves the use of special shaped elements blood. If the microbes do not die in the blood, the infection spreads to the internal organs.

Innate immune cells

Depending on the defense mechanisms, there is a humoral and cellular response. The totality of humoral and cellular factors create a unified protection system. Humoral defense is the body’s response in the liquid environment, the extracellular space. Humoral factors of innate immunity are divided into:

• specific - immunoglobulins that are produced by B-lymphocytes;
• nonspecific - gland secretions, blood serum, lysozyme, i.e. liquids with antibacterial properties. Humoral factors include the compliment system.

Phagocytosis is the process of uptake of foreign agents and occurs through cellular activity. The cells that participate in the body's response are divided into:

• T lymphocytes are long-lived cells that are divided into lymphocytes with different functions ( natural killers, regulators, etc.);
• B lymphocytes – produce antibodies;
• neutrophils - contain antibiotic proteins, have chemotaxis receptors, and therefore migrate to the site of inflammation;
• eosinophils – participate in phagocytosis and are responsible for neutralizing helminths;
• basophils - responsible for allergic reaction in response to stimuli;
• monocytes are special cells that turn into different types macrophages ( bone tissue, lungs, liver, etc.), have many functions, incl. phagocytosis, activation of compliment, regulation of the inflammation process.

Stimulators of innate immune cells

Recent WHO research shows that in almost half of the world's population, important immune cells - natural killer cells - are in short supply. Because of this, people are more often susceptible to infectious, oncological diseases. However, there are special substances that stimulate the activity of killer cells, these include:

• immunomodulators;
• adaptogens (general strengthening substances);
• transfer factor proteins (TP).

TB is most effective; stimulators of innate immune cells of this type were found in colostrum and egg yolk. These stimulants are widely used in medicine; they have been isolated from natural sources, so transfer factor proteins are now freely available in the form of medications. Their mechanism of action is aimed at restoring damage in the DNA system, establishing immune processes of the human species.

Video: innate immunity

Attention! The information presented in the article is for informational purposes only. The materials of the article do not call for self-treatment. Only a qualified doctor can make a diagnosis and make recommendations for treatment based on individual characteristics specific patient.