Modern concept of immunity. Innate and acquired immunity. Types of acquired immunity. Features of antiviral immunity. All about medicine

When a foreign object appears in the body, immunity comes into play to protect human health. The risk of contracting infectious diseases depends on how developed it is. Thus, immunity is the body’s ability to resist foreign invasions.

It is in close interaction with other systems in the human body. Therefore, for example, his existing nervous or endocrine diseases will significantly reduce immunity, and low immunity, in turn, can endanger the entire body.

The described body defense is divided into two: congenital and acquired. Next we will talk in more detail about their features and methods of action.

Innate defense of the body

Each person is born with his own protective functions, which constitute immunity. Innate immunity is inherited and accompanies a person throughout his life.

At birth, a child from a sterile mother’s womb enters a new world for him, where he is immediately attacked by new and not at all friendly microorganisms that can seriously harm the baby’s health. But he doesn't get sick right away. This is exactly what happens because the newborn’s body is helped by the natural innate immunity in the fight against such microorganisms.

Each organism fights on its own for internal security. System innate immunity quite strong, but it directly depends on the heredity of a particular person.

Formation of body defense

Innate immunity begins to develop when the baby is in the womb. Already from the second month of pregnancy, particles are formed that will be responsible for the safety of the child. They are produced from stem cells and then enter the spleen. These are phagocytes - cells of innate immunity . They work individually and have no clones. Their main function is to search for hostile objects in the body (antigens) and neutralize them.

This process occurs through certain mechanisms of phagocytosis:

The phagocyte moves towards the antigen.
Attached to it.
The phagocyte membrane is activated.
The particle is either drawn into the cell, and the edges of the membrane close over it, or is enclosed in the formed pseudopodia that envelop it.
The vacuole with the foreign particle enclosed in it contains lysosomes containing digestive enzymes.
The antigen is destroyed and digested.
Degradation products are released from the cell.

There are also cytokines in the body - signaling molecules. When dangerous objects are detected, it is they that call phagocytes. Using cytokines, phagocytes can call other phagocytic cells to the antigen and activate dormant lymphocytes.

Protection in action

Immunity plays an important role in the body's resistance to infections. Innate immunity in such cases provides 60% protection for the body. This happens through the following mechanisms:

the presence of natural barriers in the body: mucous membranes, skin, sebaceous glands, etc.;
liver function;
functioning of the so-called consisting of 20 proteins synthesized by the liver;
phagocytosis;
interferon, NK cells, NKT cells;
anti-inflammatory cytokines;
natural antibodies;
antimicrobial peptides.

The inherited ability to destroy foreign substances is usually the first line of defense for human health. The mechanisms of innate immunity have such a feature as the presence of effects that quickly ensure the destruction of the pathogen, without preparatory stages. The mucous membranes secrete mucus, which makes it difficult for possible attachment of microorganisms, and the movement of the cilia clears the respiratory tract of foreign particles.

Innate immunity does not change; it is controlled by genes and inherited. NK cells (the so-called natural killer cells) of innate defense kill pathogens that form in the body - these can be virus carriers or tumor cells. If the number and activity of NK cells decreases, the disease begins to progress.

Acquired immunity

If innate immunity is present in a person from birth, then acquired immunity appears during life. It comes in two types:

Naturally obtained - formed during life as a reaction to antigens and pathogens entering the body.
Artificially acquired - formed as a result of vaccination.

The antigen is administered by the vaccine, and the body responds to its presence. Having recognized the “enemy,” the body produces antibodies to eliminate it. In addition, for some time this antigen remains in the cellular memory, and in the event of a new invasion, it will also be destroyed.

Thus, “immunological memory” exists in the body. Acquired immunity can be “sterile”, that is, it can persist for life, but in most cases it exists as long as the harmful pathogen is in the body.

Principles of protection of innate and acquired immunity

The principles of protection have one direction - the destruction of malicious objects. But at the same time, innate immunity fights dangerous particles with the help of inflammation and phagocytosis, and acquired immunity uses antibodies and immune lymphocytes.

These two protections work interconnectedly. The compliment system is an intermediary between them, with its help the continuity of the immune response is ensured. Thus, NK cells are part of the innate immune system, and they produce cytokines, which, in turn, regulate the function of acquired T lymphocytes.

Increased protective properties

Acquired immunity and innate immunity are all a single interconnected system, which means that an integrated approach is required to strengthen it. It is necessary to take care of the body as a whole, this is facilitated by:

sufficient physical activity;
proper nutrition;
favorable environment;
intake of vitamins into the body;
Frequently ventilate the room and maintain favorable temperature and humidity.

Nutrition also plays an important role in the effectiveness of the immune system. For it to work properly, the diet must contain:

meat;
fish;
vegetables and fruits;
seafood;
dairy products;
green tea;
nuts;
cereals;
legumes

Conclusion

From the above it is clear that for normal human life a well-developed immune system is necessary. Innate and acquired immunity act interconnectedly and help the body get rid of harmful particles that have penetrated into it. And for their quality to work, it is necessary to give up bad habits and adhere to a healthy lifestyle so as not to disrupt the vital activity of “useful” cells.

Everyone knows that the body has its own defense, a kind of “security service” - immunity. This topic is of interest to many today. Indeed, immunity is very important for human body- the more stable and stronger immunity, the better your health. The work of the immune system is clearly coordinated, but with age and under the influence of adverse factors environment she is weakening. This leads to the development of various pathological processes. All mechanisms and properties of the immune system are studied by a special science - immunology.

Immunity is a word from Latin language, which means "liberation". Medicine explains immunity as the body’s ability to protect itself from many foreign agents - viruses, bacteria, helminths, various toxins, atypical (for example, cancer) cells, etc.

The protective function is performed by special antibodies, immunoglobulins. If there are enough antibodies, if they are “strong,” then the disease has no chance of developing.

The immune system is complex protective structure. It is well known that many organs take part in the fight against foreign agents. But there are only two main ones - the red bone marrow, in which lymphocytes are born, and the thymus gland (thymus), located in the upper part of the sternum. Immune cells appear in the lymph nodes and mature completely in the spleen. It also destroys old lymphocytes that have already done their job. The external defense of the body is, first of all, the skin, on which various pathogenic bacteria under the influence of special substances contained in sebum. Another barrier is the mucous membranes, saturated with lymphoid tissue and producing special fluids (tears, saliva), which also destroy infectious agents. Sebaceous and sweat glands, villi of the respiratory tract, eyelashes, etc. Phagocytes (leukocytes) constantly move through the blood and lymph, which absorb pathogenic microflora. If there are a lot of leukocytes in the blood, then this is a signal that the disease is developing. When a person has good blood circulation, good composition blood, this indicates that the immune system is fine. Immunity is divided into innate and acquired.

What is innate immunity

Already from the name it is clear that a person has innate immunity (also called nonspecific) from birth. Innate immunity is immunity to diseases that are characteristic of only one type of organism. For example, a person has innate immunity to canine distemper and will never get sick from it. And a dog will never get measles or cholera because it has an innate immunity to these diseases. Based on this, innate immunity can be called species immunity, since it is characteristic of a specific type of living organism.

Every person has innate immunity; it is transmitted from parents, i.e. fixed genetically. Therefore, it is often called hereditary immunity. Antibodies that form the basis of the initial protective forces When a person is born, they are transmitted from the mother. That's why it's very important proper intrauterine development and natural (breast) feeding of the child play a role - only in this case good innate immunity is formed. The blood flow of a child in the womb is closely connected with her circulatory system due to the placental barrier. Due to this barrier, the child receives oxygen, proteins, fats, carbohydrates, vitamins, hormones and other necessary substances, including immune system factors, from the mother through the blood. They protect the child. Therefore, when a child is born, he already has some immunity. As soon as the baby starts to feed mother's milk(and with the milk of the biological mother), the intake of these substances into the body continues. They are not destroyed in the stomach because gastric juice baby low acidity. Next, these substances of the immune system enter the intestines, from which they are absorbed into the blood, and then distributed by the blood throughout the body. It is this mechanism that provides innate immunity.

It has been noted that children who are fed mother's milk for the first 6 months practically do not get sick in the first year of life. The same children who were forced to stay artificial feeding from the first days of life, they often get sick both in the first year of life and thereafter. If the formation of natural defenses is disrupted, this can lead to an immunodeficiency state.

Factors of innate immunity

The mechanism of action of innate immunity is a combination of certain factors that create a line of defense for the human body from foreign agents. It consists of several protective barriers:

The primary barriers are the skin and mucous membranes; upon penetration of a foreign agent, an inflammatory process develops.
Lymph nodes - this defense fights the infectious agent before it enters the blood. If it is weakened, the infection enters the blood.
Blood – when an infection enters the blood, special blood elements come into play. If they are unable to contain the infection, it enters the internal organs.

In addition, innate immunity also has humoral and cellular factors. Humoral factors are divided into specific and nonspecific. The specific ones include immunoglobulins, and the nonspecific ones include liquids that can destroy bacteria (blood serum, lysozyme, secretions of various glands). Cellular factors include those cells of the body that take part in protection against foreign agents - T- and B-lymphocytes, basophils, neutrophils, eosinophils, monocytes.

So, innate immunity has some characteristic features:

does not change during life, determined genetically;
inherited from generation to generation;
is specific, i.e. both formed and fixed for each individual species in the process of evolution;
strictly defined antigens are recognized;
resistance to certain antigens has a certain character;
innate immunity always turns on at the moment when an antigen is introduced;
the antigen is independently removed from the body;
immune memory is not formed.

Acquired immunity

In addition to innate immunity, humans also have so-called acquired immunity.

It is formed throughout life and, unlike innate immunity, is not inherited. Acquired immunity begins to form during the first encounter with an antigen, triggering immune mechanisms that remember this antigen and produce specific antibodies to this antigen. Thanks to this, the next time the body encounters the same antigen, the immune response occurs much faster and becomes more effective. In this case, the disease does not recur. For example, if a person has had measles, chickenpox or mumps once, then he will not get sick a second time. Unlike innate immunity, acquired immunity:

not inherited;
is formed throughout life, while changing the set of genes;
individual for each person;
recognizes any antigens;
resistance to certain antigens is strictly individual;
when the first contact occurs, immunity is activated, on average, from the 5th day;
to remove the antigen, the help of the innate immune system is required;
forms immune memory.

Acquired immunity can be either active or passive.

Active - is formed when a person has suffered a disease or has been given a specific vaccine with weakened microorganisms or their antigens. As a result, lifelong, long-term or short-term immunity may develop. It depends on the properties of the pathogen. For example, from measles - lifelong, from abdominal type- long-term, and from influenza - short-term immunity. Active acquired immunity cannot be realized in case of immunodeficiency. For active acquired immunity to work, the immune system must be healthy. It is this type of immunity that forms immune memory.

Passive – is formed when ready-made antibodies are introduced into the body (for example, from a person who has been ill) or antibodies are transferred to the newborn with the mother’s colostrum. Acquired passive immunity develops instantly and is formed in conditions of immunodeficiency. However, compared to active immunity, acquired passive immunity has lower efficiency, does not form immune memory and has lower efficiency.

Innate and acquired immunity is a single defense system that must be constantly taken care of and constantly strengthened. Because good immunity is the key good health. It is necessary to take a comprehensive approach to strengthening the immune system. A person vitally needs a strong and healthy immune system, which will rid the body of invading foreign agents and prevent the development of various diseases.

The immune system - critical system necessary for the survival of the organism. It includes cells and tissues that protect our body from various damaging factors and infections. The immune system provides immunity, that is, the body's ability to fight infections and other pathogenic factors without signs of illness. Immunity is divided into two types: innate and acquired. How are innate and acquired immunity similar and different?

What is innate and acquired immunity?

The main goal of both types of immunity is to protect the body from disease. Both types are similar, but have a number of differences.

Innate or natural immunity

This type of immunity is activated within a short time after the invasion of the body by a pathogenic factor. The immune response develops over a period of several minutes to several hours, and is therefore called immediate. Innate immunity is provided by two lines of defense. The first line of defense consists of the skin, mucous membranes, gastric juice and other secretions secreted by the mucous membranes of the hollow organs. For example, the mucous membrane of the nasal cavity traps large particles, preventing them from entering the body. The second line of defense consists of chemicals and cells that circulate in the blood.

Acquired immunity

This type of immunity is responsible for more complex reactions. It is activated after a complete response of the innate immune system. Initially, antigens that enter the body are identified by specific immune cells. After determining the type of antigens, antigen-antibody reactions begin, inactivating the antigens. Acquired immunity also involves the generation of a memory of antigens, which stores their identifiers in memory cells. This ensures a future immune response to repeated exposure to antigens.

What is the difference between innate and acquired immunity?

The end result of innate and acquired immunity is the same. The differences between both types can be presented based on the following criteria:

The main components of innate immunity are found in the skin, mucous membranes, and secretions produced by the mucous membranes of hollow organs. acquired immunity is provided by phagocytes and killer cells.
Innate immune cells are active all the time and are ready to fight as soon as a foreign body enters the body. Innate immunity is active from birth. Acquired immune cells are activated only when a certain type of infection enters the body. Acquired immunity develops over time.
The immune response in innate immunity develops immediately and is therefore often called an immediate type response. Acquired immunity develops over time. It appears after one to two weeks, often called delayed.
The effectiveness of innate immunity is limited, while acquired immunity is high, as it is provided by highly specialized cells.
Innate immunity persists throughout life. Acquired immunity against certain types of antigens can be lifelong or short-lived.
Innate immunity is inherited from parents and passed on to offspring; acquired immunity is not inherited.
Innate immunity recognizes all types of antigens, including bacteria, viruses, fungi, etc. Acquired - very specific to certain types antigens.

Thus, both types of immunity act in the same direction, protecting the body from pathogenic factors. Innate immunity quickly ensures the complete elimination of simple antigens, while acquired immunity gives a delayed reaction to specific antigens. The immune system effectively protects the body from any infectious agents and pathogenic factors entering the body

9.1. Introduction to Immunology9.1.1. Main stages in the development of immunology

Every person on the planet (except for identical twins) has unique genetically determined characteristics of the biopolymers from which his body is built. However, his body lives and develops in direct contact with representatives of living and inanimate nature and various bioorganic molecules of natural or artificial origin that have biological activity. When entering the human body, waste products and tissues of other people, animals, plants, microbes, as well as foreign molecules can interfere and disrupt biological processes, posing a threat to the life of an individual. A distinctive feature of these agents is their genetic foreignness. Often, such products are formed inside the human body as a result of the synthetic activity of the microflora inhabiting us, cellular mutations and various modifications of the macromolecules from which we are built.

To protect against unwanted and destructive intervention, evolution has created a special counteraction system among representatives of living nature, the cumulative effect of which was designated as immunity(from lat. immunitas- liberation from something, inviolability). This term was used already in the Middle Ages to designate, for example, exemption from paying taxes, and later - the inviolability of a diplomatic mission. The meaning of this term exactly corresponds to the biological tasks that evolution has determined in relation to immunity.

The main ones are the recognition of the genetic difference between the interventionist and one’s own structures and the elimination of its influence on the biological processes occurring in the body using a set of special reactions and mechanisms. The ultimate goal of the immune defense system is the preservation of homeostasis, structural and functional integrity and genetic individuality of both an individual organism and the species as a whole, as well as the development of means of preventing such interventions in the future.

Consequently, immunity is a way of protecting the body from genetically foreign substances of exogenous and endogenous origin, aimed at maintaining and preserving homeostasis, the structural and functional integrity of the body and the genetic individuality of each organism and species as a whole.

Immunity as a general biological and general medical phenomenon, its anatomical structures, and mechanisms of functioning in the body are studied by a special science - immunology. This science originated more than 100 years ago. As human knowledge progressed, views on immunity, its role in the body, and the mechanisms of immune reactions changed, the scope of practical use of the achievements of immunology expanded, and in accordance with this, the very definition of immunology as a science changed. Immunology is often interpreted as a science that studies specific immunity to pathogens of infectious diseases and develops methods of protection against them. This is a one-sided view that does not provide a comprehensive, comprehensive understanding of science, based on the essence and mechanisms of immunity and its role in the life of the body. On modern stage development of the doctrine of immunity, immunology can be defined as a general biological and general medical science that studies the methods and mechanisms of protecting the body from genetically foreign substances exogenous and endogenous origin in order to maintain homeostasis, the structural and functional integrity of the body and the genetic individuality of the individual and the species as a whole. This definition emphasizes that immunology as a science is unified regardless of the object of study: humans, animals or plants. Of course, the anatomical and physiological basis, a set of mechanisms and reactions, as well as methods of protection against antigens in animal representatives

and the plant world will vary, but the fundamental essence of immunity will not change. In immunology, there are three areas: medical immunology (homoimmunology), zooimmunology and phytoimmunology, which study immunity in humans, animals and plants, respectively, and in each of them - general and specific. One of its most important sections is medical immunology. Today, medical immunology solves such important problems as the diagnosis, prevention and treatment of infectious diseases (immunoprophylaxis or vaccinology), allergic conditions (allergology), malignant tumors (immuno-oncology), diseases in the mechanism of which immunopathological processes play a role (immunopathology), maternal immune relationships and the fetus at all stages of reproduction (reproductive immunology), studies immune mechanisms and makes a practical contribution to solving the problem of organ and tissue transplantation (transplant immunology); One can also distinguish immunohematology, which studies the relationship between donor and recipient during blood transfusion, immunopharmacology, which studies the effect on immune processes medicinal substances. IN last years clinical and environmental immunology were distinguished. Clinical immunology studies and develops the problems of diagnosis and treatment of diseases arising as a result of congenital (primary) and acquired (secondary) immunodeficiencies, and environmental immunology is the influence on the immune system of all kinds environmental factors(climate-geographical, social, professional, etc.).

Chronologically, immunology as a science has already passed two long period(Ulyankina T.I., 1994): the period of protoimmunology (from the ancient period to the 80s of the 19th century), associated with spontaneous, empirical knowledge of the body’s defense reactions, and the period of the emergence of experimental and theoretical immunology (from the 80s of the 19th century until the second decade of the 20th century). During the second period, the formation of classical immunology, which was mainly in the nature of infectious immunology, was completed. Since the middle of the 20th century, immunology has entered the third, molecular genetic, period, which continues to this day. This period is characterized by rapid development of molecular and cellular immunology and immunogenetics.

Protection against smallpox by inoculating a person with cowpox was proposed more than 200 years ago by the English physician E. Jenner, but this observation was purely empirical. Therefore, the French chemist L. Pasteur, who discovered the principle of vaccination, and the Russian zoologist I.I. are rightfully considered the founders of scientific immunology. Mechnikov is the author of the doctrine of phagocytosis and the German biochemist P. Ehrlich, who formulated the hypothesis of antibodies. In 1888, for the outstanding services of L. Pasteur to humanity, the Institute of Immunology (now the Pasteur Institute) was established with public donations, which was a school around which immunologists from many countries were grouped. Russian scientists actively participated in the formation and development of immunology. For more than 25 years I.I. Mechnikov was deputy director for science at the Pasteur Institute, i.e. was his closest assistant and like-minded person. Many outstanding Russian scientists worked at the Pasteur Institute: M. Bezredka, N.F. Gamaleya, L.A. Tarasovich, G.N. Gabrichevsky, I.G. Savchenko, S.V. Korshun, D.K. Zabolotny, V.A. Barykin, N.Ya. and F.Ya. Chistovichi and many others. These scientists continued to develop the traditions of Pasteur and Mechnikov in immunology and essentially created the Russian school of immunologists.

Russian scientists have made many outstanding discoveries in the field of immunology: I.I. Mechnikov laid the foundations of the doctrine of phagocytosis, V.K. Vysokovych was one of the first to formulate the role of the reticuloendothelial system in immunity, G.N. Gabrichevsky described the phenomenon of leukocyte chemotaxis, F.Ya. Chistovich stood at the origins of the discovery of tissue antigens, M. Raisky established the phenomenon of revaccination, i.e. immunological memory, M. Sakharov - one of the founders of the doctrine of anaphylaxis, academician. L.A. Zilber stood at the origins of the doctrine of tumor antigens, academician. P.F. Zdrodovsky substantiated the physiological direction in immunology, academician. R.V. Petrov made a significant contribution to the development of non-infectious immunology.

Russian scientists are rightfully leaders in the development of fundamental and applied problems of vaccinology and immunoprophylaxis in general. The names of the creators of vaccines against tularemia (B.Ya. Elbert and N.A. Gaisky), anthrax (N.N. Ginzburg), polio are well known in our country and abroad.

litha (M.P. Chumakov, A.A. Smorodintsev), measles, mumps, influenza (A.A. Smorodintsev), Q fever and typhus(P.F. Zdrodovsky), polyanatoxins against wound infections and botulism (A.A. Vorobyov, G.V. Vygodchikov, P.N. Burgasov), etc. Russian scientists took an active part in the development of vaccines and other immunobiological preparations, strategies and tactics of immunoprophylaxis, global elimination and reduction of infectious diseases. In particular, on their initiative and with their help, smallpox was eradicated from the globe (V.M. Zhdanov, O.G. Andzhaparidze), polio was successfully eradicated (M.P. Chumakov, S.G. Drozdov).

Over a relatively short historical period, immunology has achieved significant results in reducing and eliminating human diseases, preserving and maintaining the health of the people of our planet.

9.1.2. Types of immunity

Ability to recognize foreign structures and protect own body from the interventionists was formed quite early. Lower organisms, in particular invertebrates (sponges, coelenterates, worms), already have elementary systems of protection against any foreign substances. The human body, like all warm-blooded animals, already has a complex system of counteracting genetically foreign agents. However, the anatomical structure, physiological functions and reactions that provide such protection in certain animal species, in humans and lower organisms in accordance with the level of evolutionary development differ significantly.

Thus, phagocytosis and allogeneic inhibition, as one of the early phylogenetic defense reactions, is inherent in all multicellular organisms; differentiated leukocyte-like cells that perform the functions of cellular immunity already appear in coelenterates and mollusks; in cyclostomes (lamreys) thymus rudiments, T-lymphocytes, immunoglobulins appear, and immune memory is noted; fish already have lymphoid organs typical of higher animals - the thymus and spleen, plasma cells and class M antibodies; birds have a central organ of immunity in the form of the bursa of Fabricius, they have the ability to react in the form of immediate hypersensitivity

new type. Finally, in mammals the immune system reaches its most high level development: T-, B- and A-systems of immune cells are formed, their cooperative interaction occurs, the ability to synthesize immunoglobulins of different classes and forms of immune response appears.

Depending on the level of evolutionary development, the characteristics and complexity of the formed immune system, and the ability of the latter to respond with certain reactions to antigens, in immunology it is customary to distinguish separate types of immunity.

Thus, the concept of innate and acquired immunity was introduced (Fig. 9.1). Innate, or species, immunity, also known as hereditary, genetic, constitutional, is the genetically fixed, inherited immunity of individuals of a given species to any foreign agent developed in the process of phylogenesis. An example is human immunity to certain pathogens, including those that are especially dangerous for farm animals (plague cattle, Newcastle disease, which affects birds, horse pox, etc.), human insensitivity to bacteriophages that infect bacterial cells. Species immunity can be explained from different positions: the inability of a foreign agent to adhere to cells and target molecules that determine the initiation of the pathological process and activation of the immune system, its rapid destruction by enzymes of the macroorganism, and the absence of conditions for colonization of the macroorganism.

Species immunity may be absolute And relative. For example, frogs that are insensitive to tetanus toxin respond to its administration when their body temperature rises. Laboratory animals that are insensitive to any foreign agent react to it against the background of the introduction of immunosuppressants or the removal of the central organ of immunity - the thymus.

Acquired immunity is immunity to a foreign agent in a human or animal body that is sensitive to it, acquired in the process of individual development, i.e. development of each individual individually. Its basis is the potential for immune protection, which is realized only when necessary and under certain conditions. Acquired immunity, or rather its final result, is not inherited in itself (unlike, of course, potency); it is an individual lifetime experience.

Rice. 9.1. Classification of types of immunity

Distinguish natural And artificial acquired immunity. An example of natural acquired immunity in humans is immunity to infection that occurs after an infectious disease (so-called post-infectious immunity), for example after scarlet fever. Artificial acquired immunity is created deliberately to create immunity in the body

to a specific agent by introducing special immunobiological preparations, for example vaccines, immune sera, immunocompetent cells (see Chapter 14).

Acquired immunity can be active And passive. Active immunity due to the direct involvement of the immune system in the process of its formation (for example, post-vaccination, post-infectious immunity). Passive immunity is formed by introducing ready-made immunoreagents into the body that can provide the necessary protection. These drugs include antibodies (immunoglobulin preparations and immune serums) and lymphocytes. Passive immunity is formed in the fetus in the embryonic period due to the penetration of maternal antibodies through the placenta, and during breastfeeding - when the child absorbs antibodies contained in milk.

Since cells of the immune system and humoral factors take part in the formation of immunity, it is customary to differentiate active immunity depending on which component of the immune reactions plays the leading role in the formation of protection against the antigen. In this regard, there is a distinction humoral, cellular immunity. An example of cellular immunity is transplantation immunity, when the leading role in immunity is played by cytotoxic killer T-lymphocytes. Immunity during toxinemic infections (diphtheria) and intoxications (tetanus, botulism) is mainly due to antibodies (antitoxins).

Depending on the direction of immunity, i.e. nature of the foreign agent, emit antitoxic, antiviral, antifungal, antibacterial, antiprotozoal, transplantation, antitumor and other types of immunity.

Immunity can be maintained or maintained either in the absence or only in the presence of a foreign agent in the body. In the first case, such an agent plays the role of a triggering factor, and immunity is called sterile, in the second - non-sterile. An example of sterile immunity is post-vaccination immunity with the introduction of killed vaccines, and non-sterile immunity is immunity in tuberculosis, which is maintained by the constant presence of Mycobacterium tuberculosis in the body.

Immunity may be systemic those. generalized, spreading throughout the entire body, and local, at which

More pronounced resistance of individual organs and tissues is observed. As a rule, taking into account the features anatomical structure and organization of functioning, the concept “ local immunity" is used to denote resistance of the mucous membranes (hence why it is sometimes called mucosal) and skin. This division is also conditional, since in the process of developing immunity these types of immunity can transform into each other.

9.2. Innate immunity

Congenital(species, genetic, constitutional, natural, nonspecific) immunity- this is resistance to infectious agents (or antigens) developed in the process of phylogenesis, inherited, and inherent in all individuals of the same species.

The main feature of the biological factors and mechanisms that ensure such resistance is the presence in the body of ready-made (preformed) effectors that are capable of ensuring the destruction of the pathogen quickly, without lengthy preparatory reactions. They constitute the body's first line of defense against external microbial or antigenic aggression.

9.2.1. Factors of innate immunity

If we consider the trajectory of a pathogenic microbe in the dynamics of the infectious process, it is easy to notice that the body builds various lines of defense along this path (Table 9.1). First of all, it is the integumentary epithelium of the skin and mucous membranes, which has colonization resistance. If the pathogen is armed with appropriate invasive factors, then it penetrates the subepithelial tissue, where an acute inflammatory reaction develops, limiting the pathogen at the entrance gate. The next station on the path of the pathogen is the regional lymph nodes, where it is transported by lymph through the lymphatic vessels draining connective tissue. Lymphatic vessels and nodes respond to penetration by developing lymphangitis and lymphadenitis. After overcoming this barrier, microbes penetrate into the blood through the efferent lymphatic vessels - in response, a systemic inflammatory response can develop.

vet. If the microbe does not die in the blood, then it spreads hematogenously to the internal organs - generalized forms of infection develop.

Table 9.1. Factors and mechanisms of anti-infectious immunity (the principle of echeloning of antimicrobial defense according to Mayansky A.N., 2003)

Factors of innate immunity include:

Skin and mucous membranes;

Cellular factors: neutrophils, macrophages, dendritic cells, eosinophils, basophils, natural killer cells;

Humoral factors: complement system, soluble receptors for the surface structures of microorganisms (pattern structures), antimicrobial peptides, interferons.

Skin and mucous membranes. The thin layer of epithelial cells lining the surface of the skin and mucous membranes is a barrier that is practically impenetrable to microorganisms. It separates the body's sterile tissues from the microbial outside world.

Leather covered with multilayered squamous epithelium, in which two layers are distinguished: horny and basal.

Keratinocytes of the stratum corneum are dead cells that are resistant to aggressive chemical compounds. There are no receptors on their surface for adhesive molecules of microorganisms, therefore they have significant resistance to colonization and are the most reliable barrier to most bacteria, fungi, viruses, and protozoa. The exception is S. aureus, Pr. acnae, I. pestis, and they most likely penetrate either through microcracks, or with the help of blood-sucking insects, or through the mouths of the sweat and sebaceous glands. The mouth of the sebaceous and sweat glands, hair follicles in the skin are the most vulnerable, since here the layer of keratinized epithelium becomes thinner. In protecting these areas, products of the sweat and sebaceous glands, containing lactic and fatty acids, enzymes, and antibacterial peptides that have an antimicrobial effect, play an important role. It is in the mouths of the skin appendages that deep resident microflora is located, forming microcolonies and producing protective factors (see Chapter 4).

In addition to keratinocytes, the epidermis contains two more types of cells - Langerhans cells and Greenstein cells (processed epidermocytes, constituting 1-3% of the karyocytes of the basal layer). Langerhans and Greenstein cells are of myeloid origin and belong to dendritic cells. It is assumed that these cells are opposite in function. Langerhans cells are involved in antigen presentation and induce an immune response, and Greenstein cells produce cytokines that suppress the immune response.

mune reactions in the skin. Typical keratinocytes and dendritic cells of the epidermis, together with the lymphoid structures of the dermis, take an active part in the reactions of acquired immunity (see below).

Healthy skin has a high ability to self-cleanse. This is easy to prove if you apply bacteria atypical for skin to its surface - after a while such microbes disappear. Methods for assessing the bactericidal function of the skin are based on this principle.

Mucous membranes. Most infections begin not from the skin, but from the mucous membranes. This is due, firstly, to their larger surface area (mucous membranes about 400 m2, skin about 2 m2), and secondly, to less protection.

The mucous membranes do not have stratified squamous epithelium. On their surface there is only one layer of epithelial cells. In the intestine, these are single-layer columnar epithelium, goblet secretory cells and M-cells (membrane epithelial cells), located in the layer of epithelial cells, covering lymphoid accumulations. M cells are the most vulnerable to the penetration of many pathogenic microorganisms due to a number of features: the presence of specific receptors for some microorganisms (Salmonella, Shigella, pathogenic Escherichia, etc.), which are not found on neighboring enterocytes; thinned mucous layer; ability for endocytosis and pipocytosis, which ensures facilitated transport of antigens and microorganisms from the intestinal tube into the mucous-associated lymphoid tissue(see chapter 12); the absence of a powerful lysosomal apparatus, characteristic of macrophages and neutrophils, due to which bacteria and viruses move into the subepithelial space without destruction.

M cells belong to an evolutionarily formed system of facilitated transport of antigens to immunocompetent cells, and bacteria and viruses use this pathway for their translocation across the epithelial barrier.

Epithelial cells, similar to intestinal M-cells, associated with lymphoid tissue, are present in the mucous membranes of the bronchoalveolar tree, nasopharynx, and reproductive system.

Colonization resistance of the integumentary epithelium. Any infectious process begins with the adhesion of the pathogen to the

the surface of sensitive epithelial cells (with the exception of microorganisms transmitted through insect bites or vertically, i.e. from mother to fetus). Only after gaining a foothold do microbes acquire the ability to multiply at the entrance gate and form a colony. Toxins and pathogenicity enzymes accumulate in the colony in quantities necessary to overcome the epithelial barrier. This process is called colonization. Colonization resistance is understood as the resistance of the epithelium of the skin and mucous membranes to colonization by foreign microorganisms. Colonization resistance of mucous membranes is provided by mucin, secreted by goblet cells and forming a complex biofilm on the surface. All protective tools are built into this biolayer: resident microflora, bactericidal substances (lysozyme, lactoferrin, toxic metabolites of oxygen, nitrogen, etc.), secretory immunoglobulins, phagocytes.

The role of normal microflora(see chapter 4.3). The most important mechanism for the participation of resident microflora in colonization resistance is their ability to produce bacteriocins (antibiotic-like substances), short-chain fatty acids, lactic acid, hydrogen sulfide, and hydrogen peroxide. Lacto-, bifidobacteria, and bacteroides have these properties.

Thanks to the enzymatic activity of anaerobic bacteria in the intestine, bile acids are deconjugated to form deoxycholic acid, which is toxic to pathogenic and opportunistic bacteria.

Mucin along with polysaccharides produced by resident bacteria (in particular, lactobacilli), it forms a pronounced glyconalix (biofilm) on the surface of the mucous membranes, which effectively screens adhesion sites and makes them inaccessible to random bacteria. Goblet cells form a mixture of sialo- and sulfomycins, the ratio of which varies in different biotones. The unique composition of microflora in various ecological niches is largely determined by the quantity and quality of mucin.

Phagocytic cells and their degranulation products. Macrophages and neutrophils migrate into the mucous biolayer on the surface of the epithelium. Along with phagocytosis, these cells secrete biocide

outward products contained in their lysosomes (lysozyme, peroxidase, lactoferrin, defansins, toxic oxygen and nitrogen metabolites), which increase the antimicrobial properties of the secretions.

Chemical and mechanical factors. In the resistance of the integumentary epithelium of the mucous membranes, an important role is played by secretions that have pronounced biocidal and anti-adhesive properties: tears, saliva, gastric juice, enzymes and bile acids of the small intestine, cervical and vaginal secretions of the female reproductive system.

Thanks to targeted movements - peristalsis of smooth muscles in the intestines, cilia of the ciliated epithelium in the respiratory tract, urine in urinary system- the resulting secretions, together with the microorganisms contained in them, move in the direction of the exit and are brought out.

Colonization resistance of mucous membranes is enhanced by secretory immunoglobulins A, synthesized by mucous-associated lymphoid tissue.

The integumentary epithelium of the mucosal tract constantly regenerates due to stem cells located in the thickness of the mucous membranes. In the intestine, this function is performed by crypt cells, in which, along with stem cells, Paneth cells are located - special cells that synthesize antibacterial proteins (lysozyme, cationic peptides). These proteins protect not only stem cells, but also integumentary epithelial cells. With inflammation in the wall of the mucous membrane, the production of these proteins increases.

Colonization resistance of the integumentary epithelium is ensured by the entire set of protective mechanisms of innate and acquired (secretory immunoglobulins) immunity and is the basis of the body’s resistance to most microorganisms that live in external environment. The absence of specific receptors for certain microorganisms on epithelial cells appears to be the basic mechanism of genetic resistance of animals of one species to microbes that are pathogenic for animals of another species.

9.2.2. Cellular factors

Neutrophils and macrophages. The ability for endocytosis (the absorption of particles with the formation of an intracellular vacuole) is

produced by all eukaryotic cells. This is how many substances penetrate into cells pathogenic microorganisms. However, in most infected cells there are no mechanisms (or they are weak) that ensure the destruction of the pathogen. In the process of evolution, specialized cells with powerful intracellular killing systems were formed in the body of multicellular organisms, the main “profession” of which is phagocytosis (from the Greek. phagos- I devour, cytos- cell) - absorption of particles with a diameter of at least 0.1 microns (as opposed to pinocytosis - absorption of particles of smaller diameter and macromolecules) and destruction of captured microbes. Polymorphonuclear leukocytes (mainly neutrophils) and mononuclear phagocytes (these cells are sometimes called professional phagocytes) have these properties.

The idea of the protective role of motile cells (micro- and macrophages) was first formulated in 1883 by I.I. Mechnikov, who was awarded the Nobel Prize in 1909 for the creation of the cellular-humoral theory of immunity (in collaboration with P. Ehrlich).

Neutrophils and mononuclear phagocytes have a common myeloid origin from the hematopoietic stem cell. However, these cells differ in a number of properties.

Neutrophils are the most numerous and mobile population of phagocytes, the maturation of which begins and ends in the bone marrow. About 70% of all neutrophils are stored as a reserve in the bone marrow depots, from where they are influenced by appropriate stimuli ( pro-inflammatory cytokines, products of microbial origin, the C5a component of complement, colony-stimulating factors, corticosteroids, catecholamines) can urgently move through the blood to the site of tissue destruction and participate in the development of an acute inflammatory response. Neutrophils are the “rapid response team” in the antimicrobial defense system.

Neutrophils are short-lived cells, their lifespan is about 15 days. From bone marrow they enter the bloodstream as mature cells that have lost the ability to differentiate and proliferate. From the blood, neutrophils move to tissues, where they either die or come to the surface of the mucous membranes, where they complete their life cycle.

Mononuclear phagocytes are represented by bone marrow promonocytes, blood monocytes and tissue macrophages. Monocytes, unlike neutrophils, are immature cells that, entering the bloodstream and further into tissues, mature into tissue macrophages (pleural and peritoneal, Kupffer cells of the liver, alveolar, interdigital cells lymph nodes, bone marrow, osteoclasts, microgliocytes, mesangial cells of the kidneys, Sertoli cells of the testicles, Langerhans and Greenstein cells of the skin). The lifespan of mononuclear phagocytes is from 40 to 60 days. Macrophages are not very fast cells, but they are scattered throughout all tissues, and, unlike neutrophils, they do not need such urgent mobilization. If we continue the analogy with neutrophils, then macrophages in the innate immune system are “troops” special purpose».

An important feature of neutrophils and macrophages is the presence in their cytoplasm of a large number of lysosomes - granules 200-500 nm in size containing various enzymes, bactericidal and biologically active products (lysozyme, myeloperoxidase, defensins, bactericidal protein, lactoferrin, proteinases, cathepsins, collagenase, etc.). d.). Thanks to such diverse “weapons,” phagocytes have powerful destructive and regulatory potential.

Neutrophils and macrophages are sensitive to any changes in homeostasis. For this purpose, they are equipped with a rich arsenal of receptors located on their cytoplasmic membrane (Fig. 9.2):

Receptors for foreign recognition - Toll-like receptors (Toll-like receptor- TLR), first discovered by A. Poltorak in 1998 in the fruit fly and subsequently found in neutrophils, macrophages and dendritic cells. The significance of the discovery of Toll-like receptors is comparable to the earlier discovery of antigen recognition receptors in lymphocytes. Toll-like receptors recognize not antigens, the diversity of which in nature is extremely large (about 10 18 variants), but coarser repeating molecular carbohydrate and lipid patterns - pattern structures (from the English. pattern- pattern), which are not on the cells of the host body, but which are present in protozoa, fungi, bacteria, viruses. The repertoire of such patterns is small and amounts to about 20

Rice. 9.2. Functional structures of a macrophage (diagram): AG - antigen; DT - antigenic determinant; FS - phagosome; LS - lysosome; LF - lysosomal enzymes; PL - phagolysosome; PAG - processed antigen; G-II - class II histocompatibility antigen (MHC II); Fc - receptor for the Fc fragment of the immunoglobulin molecule; C1, C3a, C5a - receptors for complement components; γ-IFN - receptor for γ-MFN; C - secretion of complement components; PR - secretion of peroxide radicals; ILD-1 - secretion; TNF - secretion of tumor necrosis factor; SF - secretion of enzymes

riants. Toll-like receptors are a family of membrane glycoproteins; 11 types of such receptors are known, capable of recognizing the entire palette pattern-structures of microorganisms (lipopolysaccharides, glyco-, lipoproteins-

ys, nucleic acids, proteins heat shock etc.). The interaction of Toll-like receptors with appropriate ligands triggers the transcription of genes for pro-inflammatory cytokines and co-stimulatory molecules, which are necessary for migration, cell adhesion, phagocytosis and the presentation of antigens to lymphocytes;

Mannose-fucose receptors that recognize carbohydrate components of the surface structures of microorganisms;

Receptors for garbage (scavenger receptor)- for binding phospholipid membranes and components of own destroyed cells. Participate in phagocytosis of damaged and dying cells;

Receptors for C3b and C4b complement components;

Receptors for Fc fragments of IgG. These receptors, like receptors for complement components, play an important role in the binding of immune complexes and phagocytosis of bacteria labeled with immunoglobulins and complement (opsonization effect);

Receptors for cytokines, chemokines, hormones, leukotrienes, prostaglandins, etc. allow you to interact with lymphocytes and respond to any changes in the internal environment of the body.

The main function of neutrophils and macrophages is phagocytosis. Phagocytosis is the process of absorption of particles or large macromolecular complexes by a cell. It consists of several sequential stages:

Activation and chemotaxis - the targeted movement of a cell towards the object of phagocytosis towards an increasing concentration of chemoattractants, the role of which is played by chemokines, components of complement and microbial cells, products of degradation of body tissues;

Adhesion (attachment) of particles to the surface of the phagocyte. Toll-like receptors play an important role in adhesion, as well as receptors for the Fc fragment of immunoglobulin and the C3b component of complement (this phagocytosis is called immune). Immunoglobulins M, G, C3b-, C4b-complement components enhance adhesion (they are opsonins) and serve as a bridge between the microbial cell and the phagocyte;

Absorption of particles, their immersion in the cytoplasm and formation of a vacuole (phagosome);

Intracellular killing (killing) and digestion. After absorption, the phagosome particles merge with lysosomes - a phagolysosome is formed, in which the bacteria die under the influence of the bactericidal products of the granules (oxygen-independent bactericidal system). At the same time, the consumption of oxygen and glucose in the cell increases - a so-called respiratory (oxidative) explosion develops, which leads to the formation of toxic metabolites of oxygen and nitrogen (H 2 O 2, superoxide anion O 2, hypochlorous acid, pyroxynitrite), which are highly bactericidal (oxygen-dependent bactericidal system ). Not all microorganisms are sensitive to bactericidal systems of phagocytes. Gonococci, streptococci, mycobacteria and others survive after contact with phagocytes; such phagocytosis is called incomplete.

Phagocytes, in addition to phagocytosis (endocytosis), can carry out their cytotoxic reactions by exocytosis - releasing their granules outward (degranulation) - thus phagocytes carry out extracellular killing. Neutrophils, unlike macrophages, are capable of forming extracellular bactericidal traps - during the activation process, the cell throws out DNA strands in which granules with bactericidal enzymes are located. Due to the stickiness of DNA, bacteria stick to the traps and are killed by the enzyme.

Neutrophils and macrophages are the most important component of innate immunity, but their role in protection against various microbes is different. Neutrophils are effective against infections caused by extracellular pathogens (pyogenic cocci, enterobacteria, etc.) that induce the development of an acute inflammatory response. Neutrophil-complement-antibody cooperation is effective in such infections. Macrophages protect against intracellular pathogens (mycobacteria, rickettsia, chlamydia, etc.) that cause the development of chronic granulomatous inflammation, where main role Macrophage-T-lymphocyte cooperation plays a role.

In addition to participating in antimicrobial defense, phagocytes are involved in removing dying, old cells and their decay products, inorganic particles (coal, mineral dust, etc.) from the body. Phagocytes (especially macrophages) are antigen-preparing

constituents, they have a secretory function, synthesize and secrete out wide range biologically active compounds: cytokines (interleukins-1, 6, 8, 12, tumor necrosis factor), prostaglandins, leukotrienes, interferons α and γ. Thanks to these mediators, phagocytes actively participate in maintaining homeostasis, in the processes of inflammation, in the adaptive immune response, and regeneration.

Eosinophils belong to polymorphonuclear leukocytes. They differ from neutrophils in that they have weak phagocytic activity. Eosinophils ingest some bacteria, but their intracellular killing is less efficient than that of neutrophils.

Natural killers. Natural killer cells are large lymphocyte-like cells that arise from lymphoid precursors. They are found in the blood and tissues, especially in the liver, the mucous membrane of the female reproductive system, and the spleen. Natural killer cells, like phagocytes, contain lysosomes, but do not have phagocytic activity.

Natural killer cells recognize and eliminate target cells that have altered or absent markers characteristic of healthy cells. This is known to happen primarily to cells that have been mutated or infected by a virus. That is why natural killer cells play an important role in antitumor surveillance, the destruction of cells infected with viruses. Natural killer cells exert their cytotoxic effect with the help of a special protein, perforin, which, like the membrane-attack complement complex, forms pores in the membranes of target cells.

9.2.3. Humoral factors

Complement system. The complement system is a multicomponent multienzyme self-assembling system of serum proteins that are normally in an inactive state. When appearing in internal environment microbial products trigger a process called complement activation. Activation occurs as a cascade reaction, when each previous component of the system activates the next one. During the process of self-assembly of the system, active protein breakdown products are formed, which perform three important functions: cause membrane perforation and cell lysis, provide opsonization of microorganisms for their further phagocytosis, and initiate development vascular reactions inflammation.

The complement called “alexin” was described in 1899 by the French microbiologist J. Bordet, and then called complement by the German microbiologist P. Ehrlich (complement- addition) as a factor additional to antibodies that cause cell lysis.

The complement system includes 9 main proteins (designated as C1, C2-C9), as well as subcomponents - the breakdown products of these proteins (Clg, C3b, C3a, etc.), inhibitors.

The key event for the complement system is its activation. It can occur in three ways: classical, lectin and alternative (Fig. 9.3).

The classic way. In the classical pathway, the activating factor is antigen-antibody complexes. In this case, the Fc fragment and IgG of immune complexes are activated by the Cr subcomponent, Cr is cleaved to form Cls, which hydrolyzes C4, which is cleaved into C4a (anaphylotoxin) and C4b. C4b activates C2, which, in turn, activates the C3 component (a key component of the system). The C3 component is cleaved into anaphylotoxin C3a and opsonin C3b. Activation of the C5 component of complement is also accompanied by the formation of two active protein fragments: C5a - anaphylotoxin, a chemoattractant for neutrophils and C5b - activating the C6 component. As a result, complex C5, b, 7, 8, 9 is formed, which is called membrane attack. The terminal phase of complement activation is the formation of a transmembrane pore in the cell and the release of its contents to the outside. As a result, the cell swells and lyses.

Rice. 9.3. Complement activation pathways: classical (a); alternative (b); lectin (c); C1-C9 - complement components; AG - antigen; AT - antibody; ViD - proteins; P - properdin; MBP - mannose binding protein

Lectin pathway. It is in many ways similar to the classic one. The only difference is that in the lectin pathway, one of the acute phase proteins, mannose-binding lectin, interacts with mannose on the surface of microbial cells (the prototype of the antigen-antibody complex), and this complex activates C4 and C2.

Alternative way. It occurs without the participation of antibodies and bypasses the first 3 components C1-C4-C2. Initiate an alternative path components cell wall gram-negative bacteria (lipopolysaccharides, peptidoglycans), viruses that bind sequentially to proteins P (properdin), B and D. These complexes directly convert the C3 component.

A complex cascade reaction of complement occurs only in the presence of Ca and Mg ions.

Biological effects of complement activation products:

Regardless of the path, complement activation ends with the formation of the membrane attack complex (C5, b, 7, 8, 9) and cell lysis (bacteria, erythrocytes and other cells);

The resulting C3a, C4a and C5a components are anaphylotoxins, they bind to the receptors of blood and tissue basophils, inducing their degranulation - the release of histamine, serotonin and other vasoactive mediators (mediators of the inflammatory response). In addition, C5a is a chemoattractant for phagocytes; it attracts these cells to the site of inflammation;

C3b, C4b are opsonins, increase the adhesion of immune complexes to the membranes of macrophages, neutrophils, erythrocytes and thereby enhance phagocytosis.

Soluble receptors for pathogens. These are blood proteins that directly bind to various conservative, repeating carbohydrate or lipid structures of the microbial cell ( pattern-structures). These proteins have opsonic properties, some of them activate complement.

The main part of the soluble receptors are acute phase proteins. The concentration of these proteins in the blood rapidly increases in response to the development of inflammation due to infection or tissue damage. Acute phase proteins include:

C-reactive protein (it makes up the bulk of acute phase proteins), which received its name due to its ability

bind to phosphorylcholine (C-polysaccharide) of pneumococci. The formation of the CRP-phosphorylcholine complex promotes bacterial phagocytosis as the complex binds to Clg and activates the classical complement pathway. The protein is synthesized in the liver, and its concentration increases rapidly in response to interleukin-b;

Serum amyloid P is similar in structure and function to C-reactive protein;

Mannose-binding lectin activates complement through the lectin pathway and is one of the representatives of whey collectin proteins that recognize carbohydrate residues and act as opsonins. Synthesized in the liver;

Lung surfactant proteins also belong to the collectin family. They have opsonic properties, especially against unicellular fungi Pneumocystis carinii;

Another group of acute phase proteins consists of iron-binding proteins - transferrin, haptoglobin, hemopexin. Such proteins prevent the proliferation of bacteria that require this element.

Antimicrobial peptides. One such peptide is lysozyme. Lysozyme is a muromidase enzyme with molecular weight 14,000-1b,000, causing hydrolysis of murein (peptidoglycan) of the bacterial cell wall and their lysis. Opened in 1909 by P.L. Lashchenkov, isolated in 1922 by A. Fleming.

Lysozyme is found in all biological fluids: blood serum, saliva, tears, milk. It is produced by neutrophils and macrophages (contained in their granules). Lysozyme has a greater effect on gram-positive bacteria, the basis of the cell wall of which is peptidoglycan. The cell walls of Gram-negative bacteria can also be damaged by lysozyme if they have previously been exposed to the membrane attack complex of the complement system.

Defensins and cathelicidins are peptides with antimicrobial activity. They are formed by the cells of many eukaryotes and contain 13-18 amino acid residues. To date, about 500 such peptides are known. In mammals, bactericidal peptides belong to the defensin and cathelicidin families. The granules of human macrophages and neutrophils contain α-defensins. They are also synthesized by epithelial cells of the intestines, lungs, and bladder.

Interferon family. Interferon (IFN) was discovered in 1957 by A. Isaacs and J. Lindeman while studying the interference of viruses (from lat. inter- between, ferens- carrier). Interference is a phenomenon where tissues infected with one virus become resistant to infection by another virus. It was found that such resistance is associated with the production of a special protein by infected cells, which was named interferon.

Currently, interferons are well studied. They are a family of glycoproteins with a molecular weight from 15,000 to 70,000. Depending on the source of production, these proteins are divided into type I and type II interferons.

Type I includes IFN α and β, which are produced by virus-infected cells: IFN-α by leukocytes, IFN-β by fibroblasts. In recent years, three new interferons have been described: IFN-τ/ε (trophoblast-derived IFN), IFN-λ and IFN-K. IFN-α and β are involved in antiviral defense.

The mechanism of action of IFN-α and β is not associated with a direct effect on viruses. It is caused by the activation in the cell of a number of genes that block the reproduction of the virus. The key link is the induction of the synthesis of protein kinase R, which disrupts the translation of viral mRNA and triggers apoptosis of infected cells through Bc1-2 and caspase-dependent reactions. Another mechanism is the activation of latent RNA endonuclease, which causes destruction of the viral nucleic acid.

Type II includes interferon γ. It is produced by T lymphocytes and natural killer cells after antigenic stimulation.

Interferon is constantly synthesized by cells; its concentration in the blood normally changes little. However, the production of IF increases when cells are infected with viruses or the action of its inducers - interferonogens ( viral RNA, DNA, complex polymers).

Currently, interferons (both leukocyte and recombinant) and interferonogens are widely used in clinical practice for the prevention and treatment of acute viral infections (influenza), as well as for therapeutic purposes in chronic viral infections (hepatitis B, C, herpes, multiple sclerosis, etc.). Since interferons have not only antiviral but also antitumor activity, they are also used to treat oncological diseases.

9.2.4. Features of innate and acquired immunity

Currently, factors of innate immunity are not usually called nonspecific. The barrier mechanisms of innate and acquired immunity differ only in the accuracy of tuning to “foreign”. Phagocytes and soluble innate immune receptors recognize “patterns,” and lymphocytes recognize the details of such a picture. Innate immunity is an evolutionarily more ancient method of defense, inherent in almost all living beings from multicellular organisms, plants to mammals due to the speed of reaction to the invasion of a foreign agent; it forms the basis of resistance to infection and protects the body from most pathogenic microbes. Only those pathogens that innate immunity factors cannot cope with include lymphocytic immunity.

The division of antimicrobial defense mechanisms into innate and acquired or pre-immune and immune (according to R.M. Khaitov, 200b) is conditional, since if we consider the immune process in time, then both are links in the same chain: first, phagocytes and soluble receptors for pattern- microbial structures, without such editing, the subsequent development of a lymphocytic response is impossible, after which lymphocytes again attract phagocytes as effector cells for the destruction of pathogens.

At the same time, dividing immunity into innate and acquired is advisable for a better understanding of this complex phenomenon (Table 9.2). The mechanisms of innate resistance provide quick protection, after which the body builds a stronger, layered defense.

Table 9.2. Features of innate and acquired immunity

End of table. 9.2

Tasks for self-preparation (self-control)

Presence of body immunity - necessary protection, which acts as immunity to foreign agents, including infectious pathogens.

The need to have immunity is inherent in nature. The ability to resist begins in hereditary factor. At the same time, one cannot ignore the acquired ability to protect the body, which creates a barrier to penetration and reproduction in the body various kinds bacteria and viruses, and also protects against the effects of the products they produce. But immunity is not necessarily protection against pathogenic active agents. After all, the entry of any foreign microorganism into the body can cause an immunological reaction, as a result of which the agent will be subject to protective effects and subsequently destroyed.

The difference between immunity lies in the diversity of origin, signs of manifestation, mechanism and some other features. Depending on the source, immunity is:

Congenital;
Acquired;

Main distinctive characteristics immunity are considered: genesis, form of appearance, mechanism and other factors. Depending on its occurrence, immunity can be innate or acquired. The first is divided into species and natural type.

Immunology

The term “immunity” is associated with the ability and functions of the body to create a natural obstacle to the entry of negative agents of foreign origin into it, and also provides methods for recognizing foreign in innate immunity. There are mechanisms to counteract such harmful organisms. The variety of methods for combating dangerous pathogens is due to the types and forms of immunity, which are distinguished by their diversity and characterizing characteristics.

Depending on the origin and formation, the protection mechanism may be innate in nature, which is also divided into several directions. There are non-specific, natural, hereditary type the body's natural ability to resist. With this type of immunity, protective factors have formed in the human body. They contribute to the fight against agents of unknown origin from the moment a person is born. This type of immune system characterizes the ability of a human being to be resistant to all kinds of diseases to which the body of an animal or plant may be vulnerable.

Acquired type immunity is characterized by the presence of protective factors formed throughout the entire life period. The unnatural form of body defense is divided into natural and. The production of the first begins after a person has been exposed to an influence as a result of which special cells - antibodies - begin to be produced in him, which counteract the agent of this disease. An artificial type of protection is associated with the body receiving pre-prepared cells in an unnatural way that were introduced inside. Occurs when a form of the virus is active.

Quality properties

A vital function performed by the innate immune system is the body's regular production of antibodies. in a natural way. They are designed to provide a primary response to the appearance of foreign agents in the body. It is important to understand the main differences between innate and acquired immunity. Enough important property the body's natural response in the form of a reaction is the presence of the complement system. This is the so-called complex, which provides for the presence of a protein in the blood that ensures the detection and primary protective reaction to foreign agents. The objectives of such a system are to perform the following functions:

Opsonization is the process of combining complex elements in a damaged cell;
Chemotaxis is the fusion of signals resulting from chemical reaction, which attracts other immune agents;
Membranotropic damaging complex, in which protein combinations in the complement are responsible for the destruction of the protective membrane of opsonization agents;

The predominant property of the body’s natural type of reaction is the manifestation of primary protection, which is influenced by the molecular factors of innate immunity, as a result of which the body receives data about cells of foreign origin unknown to it. Subsequently, this process results in the formation of an acquired reaction, which, in some cases of recognition of unknown organisms, will be ready to counteract without attracting outsiders. protective factors.

Formation process

Speaking about immunity, it is present as primary signs in every organism, and is laid down at the genetic level. It has the distinctive features of innate immunity, and also has the ability to be transmitted hereditarily. Man is special in that he has the internal ability of the body to resist many diseases to which other living beings are vulnerable.

In the process of forming innate protection, the main focus is on the period of intrauterine development and the subsequent stage of feeding the baby after birth. The antibodies transferred to the newborn are of fundamental importance, giving rise to the first protective signs of the body. If the natural process of formation is interfered with or hindered, this will lead to disturbances and cause immunodeficiency state. Such factors that negatively affect children's body, a bunch of:

radiation;
exposure to agents of chemical origin;
pathogenic microbes during development in the womb.

Signs of the body's innate defenses

What is the purpose of innate immunity and how does the process of a protective reaction occur?

The complex of all the signs that characterize innate immunity determines the special function of the body’s resistance to the invasion of foreign agents. The creation of such a protective line occurs in several stages, which adjust the immune system to react to pathogenic microorganisms. Primary barriers include the skin epithelium and mucous membrane, since they have a resistance function. As a result of the entry of a pathogenic organism, an inflammatory process occurs.

An important protective system is the work of the lymph nodes, which fight pathogens before they enter the circulatory system. One cannot ignore the properties of blood, which reacts to infection entering the body through the action of special formed elements. In the case when the death of harmful organisms in the blood does not occur, the infectious disease begins to form and affects internal systems person.

Cell development

The protective reaction, depending on the mechanism of protection, can be expressed by a humoral or cellular response. The combination of which represents a complete protective system. The body's reaction in the environment of fluids and extracellular space is called humoral. This factor of the innate type of immune system can be divided into:

specific – B – lymphocytes form immunoglobulins;
nonspecific - liquids are produced that do not have antibactericidal properties. This includes blood serum, lysozyme;

This includes the compliment system.

The process of absorption of foreign agents by exposure to the cell membrane is called phagocytosis. In other words, the molecules involved in the reaction are differentiated into:

T lymphocytes have a long lifespan and are divided into different functions. These include regulators, natural killers;
group I lymphocytes – responsible for the production of antibodies;
neutrophils - are distinguished by the presence of antibiotic proteins, which have neutrophils, which explains their migration to the site of inflammation;
eosinophils - take part in the process of phagocytosis and are responsible for neutralizing helminths;
basophils - designed to react to the appearance of a stimulus;
monocytes are special purpose cells that turn into various types macrophages and having functions such as the ability to activate the process of phagocytosis and regulate inflammation.

Cell stimulating factors

The latest WHO reports indicate that almost half of the world's population does not have a sufficient number of important immune cells - natural killer cells - in the body. This causes an increase in cases of detection of infectious and oncological diseases in patients. But medicine is developing rapidly, and means have already been developed and are widely used that can stimulate the activity of killer cells.

Among such substances, there is the use of adaptogens, which are distinguished by general strengthening properties, immunomodulators, and transfer fact proteins, which have the greatest degree of effectiveness. A similar type that helps strengthen innate immunity can be found in egg yolk or colostrum.

These stimulants are common and used in medical purposes, are isolated artificially from sources natural origin. Today, transfer factor proteins are available and represented in medical preparations. What is the nature of the impact? It consists of helping the DNA system, starting a protective process based on the characteristics of a person’s immunity.

Having studied the nature of the appearance and formation of immunity to bacteria, the difference in types, it becomes clear that for normal operation you must have an organism. It is necessary to distinguish between congenital and acquired features. Both act in combination, which helps the body fight harmful microelements that have entered it.

In order for the opposition to be strong and the protective functions to be carried out efficiently, it is necessary to remove unhealthy habits from life and try to follow healthy image existence in order to exclude the possibility of destruction of the activity of “strong” and “working” cells.

In this case, the complexity of the approach is important. First of all, changes should affect your lifestyle, nutrition, and the use of traditional methods of increasing immunity. Before viral infection will kill the body, you should prepare for a possible attack. Hardening procedures are needed here, like simple way protection.

Walking without shoes is also practiced, but this is not necessarily walking on the street. They start here, but not on the icy floor. This is also considered the principle of hardening, because the act is aimed at launching protective processes in the body by acting on activation points on the feet, which revitalizes the cells of the immune system.

There are many ways and methods of naturally preparing the body for possible exposure to external factors. The main thing is that the procedures are not contraindicated due to the presence of diseases, which, in combination with hardening methods, can turn out negatively for the body.