The ultimate goal of the immune system is to destroy a foreign agent, which may be a pathogen, a foreign body, a poisonous substance, or a degenerated cell of the organism itself. This achieves the biological individuality of the organism.
Organs that are part of the human immune system: lymph glands (nodes), tonsils, thymus gland (thymus), bone marrow, spleen and intestinal lymphoid formations (Peyer's patches). The main role is played by the complex circulation system, which consists of lymphatic ducts connecting the lymph nodes.
The lymph node is a formation of soft tissues, it has an oval shape and a size of 0.2 - 1.0 cm, which contains a large number of lymphocytes.
The tonsils are small clusters of lymphoid tissue located on both sides of the pharynx. Spleen - Outwardly very similar to a large lymph node. The functions of the spleen are diverse, including a filter for blood, storage for blood cells, and production of lymphocytes. It is in the spleen that old and defective blood cells are destroyed. The spleen is located in the abdomen under the left hypochondrium near the stomach.
Thymus gland (thymus) - this organ is located behind the sternum. Lymphoid cells in the thymus multiply and “learn”. In children and young people, the thymus is active, the older the person is, the less active the thymus becomes and decreases in size.
Bone marrow is a soft, spongy tissue located within tubular and flat bones. The main task of the bone marrow is the production of blood cells: leukocytes, erythrocytes, platelets.
Peyer's patches - This is a concentration of lymphoid tissue in the intestinal wall. The main role is played by the circulatory system, which consists of lymphatic ducts that connect the lymph nodes and transport the lymphatic fluid.
Lymphatic fluid (lymph) is a colorless fluid that flows through the lymphatic vessels and contains many lymphocytes - white blood cells that are involved in protecting the body from disease.
Lymphocytes are figuratively speaking "soldiers" of the immune system, they are responsible for the destruction of foreign organisms or diseased cells (infected, tumor, etc.). The most important types of lymphocytes (B-lymphocytes and T-lymphocytes), they work together with the rest of the immune cells and do not allow foreign substances (infections, foreign proteins, etc.) to invade the body. At the first stage, the body "teaches" T-lymphocytes to distinguish foreign proteins from normal (own) body proteins. This learning process takes place in the thymus gland (thymus) during childhood, as the thymus is most active at this age. Further, a person reaches adolescence, and the thymus decreases in size and loses its activity.
- 1. Natural congenital: a person from birth has antibodies against many diseases.
- 2. Naturally acquired: the body after an illness remembers antibodies. If the pathogen enters the body a second time, then antibodies against it begin to be produced not after 3-5 days, but immediately, and the person will not get sick.
- 3. Artificial active: a person is vaccinated, injected with a vaccine, i.e. killed or weakened pathogens. The body easily copes with them, but at the same time creates and remembers antibodies.
- 4. Artificial passive: a person is injected with serum during illness, i.e. ready-made antibodies. The body itself does not need to do anything, but its own antibodies are not created.
The so-called tissue immunity is the way in which various tissues of the body carry out their own defense. The intensity of the fight against viruses mainly depends on this method.
Cellular immunity is a type of immune response in which neither antibodies nor the complement system are involved. In the process of cellular immunity, macrophages, natural killer cells, antigen-specific cytotoxic T-lymphocytes are activated, and cytokines are released in response to the antigen.
The immune system is historically divided into two parts - the humoral immunity system and the cellular immunity system. In the case of humoral immunity, the protective functions are performed by molecules in the blood plasma, but not by cellular elements. While in the case of cellular immunity, the protective function is associated precisely with the cells of the immune system. The lymphocytes of the CD4 differentiation cluster or T-helper cells provide protection against various pathogens.
Modern understanding of immunity ...
Introduction. 3
General concept of immunity. 4
Organs of the immune system. 8
Immunocompetent cells. ten
Antigen-antibody system 13
The concept of immunoglobulins. fifteen
Conclusion. 17
Bibliography. eighteen
Introduction
The state of human life, to an important extent, depends on the full functioning of the immune system. The immune system is a complexly organized set to distinguish between foreign substances that have entered the body. And it is she who is responsible for the body's reactions aimed at eliminating foreign elements. There are certain factors that reduce the body's defenses: psychological (stress instability), environmental (poor environmental conditions), alimentary (poor nutrition), physical (overweight).
Fragment of work for review
According to the direction to a particular antigen, immunity is divided into antibacterial, antiviral, antifungal, anthelmintic, antitoxic, antitumor, transplantation. Organs of the immune system. Anatomically, the immune system is subdivided into central and peripheral organs. The central organs include the bone marrow and thymus (thymus), while the peripheral organs include lymph nodes, accumulations of lymphoid tissue (Peyer's patches, appendix, tonsils), as well as the spleen, blood and lymph. The central organs of the immune system are the bone marrow and the thymus gland, or thymus. These are organs of reproduction of cells of the immune system - birth, reproduction, differentiation and "learning" of cells of the immune system. Bone marrow contains pluripotent stem cells, which are the ancestors of all blood cells and, accordingly, cells of the immune system. The total bone marrow mass in an adult is approximately 2.5-3 kg (4.5-4.7% of body weight). Red bone marrow consists of the reticular stroma (myeloid tissue) and lymphoid elements (lymphoid tissue) at different stages of development. In the bone marrow, the B-lymphocyte population differentiates and multiplies, which are then carried throughout the body by the bloodstream. Here, precursors of lymphocytes are formed, which subsequently migrate to the thymus and form a population of T-lymphocytes. The thymus (thymus gland) is a two-lobed organ located in the chest cavity. In the thymus, from stem cells coming here from the bone marrow with the blood stream, T-lymphocytes are formed, which leave the thymus with the blood stream and populate the thymus-dependent zones of the peripheral organs of the immune system. The thymus also secretes substances that affect the function of T-lymphocytes. In the peripheral organs, cells of the immune system are localized, which directly exercise immune surveillance. They provide local immunity of the intestinal mucosa and its lumen, nasopharynx, oral cavity, upper respiratory tract and genitourinary system. Here, the stimulation of cells of the immune system, the development of the immune response and the neutralization of a foreign agent take place. Lymph nodes are located on the pathways of lymph flow from organs and tissues to the lymphatic ducts and lymphatic trunks that flow into large veins in the lower parts of the neck. Lymph nodes are biological filters for tissue fluid and the particles of cells contained in it, which have died as a result of cellular renewal, and other foreign substances of endogenous and exogenous origin. The spleen is a filtering device that provides detoxification, removal of old erythrocytes and other cells, differentiation of old and damaged erythrocytes, lymphocytes occurs in it: antibodies are formed. The spleen takes part in the formation of an immune response when antigens, bacteria enter the body, and intoxication occurs. The palatine tonsils are located in the oral cavity and protect the upper respiratory tract from infection, supply the lymphatic system with immunocompetent cells, and take part in the formation of the microbial flora of the oral cavity. The palatine tonsils function in close connection with the thymus gland, thymectomy leads to hypertrophy of the tonsils, tonsillectomy - to atrophy of the thymus. Peyer's patches are located in the intestine, they are involved in the maturation of T- and B-lymphocytes and the formation of the immune response. When the antigen enters the intestine, it enters the Peyer's patches through specialized epithelial cells and stimulates antigen-reactive T and B lymphocytes. B cells make up 50-70%, T cells - 10-30% of all Peyer's patch cells. Peyer's patches support the immunogenesis of B-lymphocytes and their differentiation into plasma cells that produce antibodies - secretory immunoglobulins, mainly of classes A and E. IgA accounts for about 70% of all daily immunoglobulins produced in the body. Immunocompetent cells. The main cells of the immune system - lymphocytes, macrophages and dendritic cells. According to their functional activity, cells of the immune system are divided into regulatory and effector cells. Regulatory cells control the function of the immune system by producing immune mediators - immunocytokines. The effector cells are the executors of the immune response and act on the object directly or by biosynthesis of biologically active substances (AT). Lymphocytes are motile cells, which, depending on the place of formation in the body, are subdivided into T- and B-lymphocytes. Lymphocytes make up 20-45% of the total number of blood leukocytes. Blood is the medium in which lymphocytes circulate between the organs of the lymphatic system and other tissues. Lymphocytes can leave the vessels into the connective tissue, as well as penetrate the basement membrane and enter the epithelium (for example, in the intestinal mucosa). The lifespan of lymphocytes is from several months to several years. Lymphocytes are immunocompetent cells that are of great importance for the body's immune defenses. Lymphocytes directly recognize genetically foreign substances and are involved in the regulation of the immune response, the formation of humoral and cellular immunity. B-lymphocytes are formed in the red bone marrow and make up approximately 10% of blood lymphocytes. Part of B-lymphocytes in tissues differentiates into clones of plasma cells. Each clone forms and secretes antibodies against a single antigen. In other words, plasma cells and the antibodies they synthesize provide humoral immunity. The T-lymphocyte precursor cell enters the thymus from the bone marrow. The formation of T-lymphocytes occurs in the thymus. Mature T-lymphocytes leave the thymus, they are found in the peripheral blood (80% or more of all lymphocytes) and organs of the lymphatic system. The main functions of T-lymphocytes are participation in cellular and humoral immunity (for example, T-lymphocytes destroy foreign agents of the body, participate in allergic reactions and in the rejection of a foreign transplant). T-helpers (helpers) recognize foreign antigens. They regulate the immune response by stimulating B lymphocytes and other T cells specialized for this antigen. The activated T-helper produces a wide range of immunocytokites, with the help of which it controls the biological activity of many cells involved in the immune response. T-killers spontaneously, without participation, antibodies recognize incompatible antigens of histocompatibility, infected with viruses and tumor cells. The killer T-cell attaches to the surface of the antigen, a polar redistribution of the killer's intracellular organelles occurs. Killer T cells are activated immediately upon direct contact with foreign cells. In the process of contact with foreign cells, immunological memory develops. Suppressor T lymphocytes are inducer cells that inhibit the body's immune response. T-suppressors interfere with the production of antibodies (of various classes) due to delayed differentiation of B-lymphocytes. With a normal immune response to the ingress of a foreign molecule into the body, the maximum activation of T-suppressors is noted after 34 weeks. T-suppressors have a suppressive effect mainly in inflammatory processes, viral infections and oncological diseases. Macrophage is a large (about 20 μm), active cell of the mononuclear phagocyte system. The life span of macrophages is months. Macrophages capture denatured proteins from the blood, aged red blood cells (fixed macrophages of the liver, spleen, bone marrow). Macrophages produce factors that activate the production of immunoglobulins by B-lymphocytes, differentiation of T- and B-lymphocytes; cytolytic antitumor factors, as well as growth factors influencing the differentiation of cells of their own population, stimulate the function of fibroblasts. NK cells are lymphocytes devoid of surface cell determinants characteristic of T and B cells. These cells make up about 5-10% of all circulating lymphocytes, contain cytolytic granules with perforin, destroy transformed (tumor) and infected with viruses, as well as foreign cells. Antigen-presenting cells (APC) capture, process (digest) and present molecules of the foreign agent T- helpers for recognizing "friend or foe". The main APCs are dendritic cells, B-lymphocytes and macrophages. Dendritic cells are cells of bone marrow origin that function as APC. They circulate in the blood and lymph. Immature dendrite cells migrate to the sites of antigen introduction or tissue damage, come into contact with the antigen, after which they begin to mature. Mature dendritic cells are transported to the T-cell zones of the lymph nodes or spleen. Three types of cells are involved in the body's immune defense: macrophages, T- and B-lymphocytes. The activity of these cells is aimed at recognizing and destroying genetically foreign substances and objects, regulating the functioning of the components of the immune system and maintaining homeostasis. Such work is carried out in the constant interaction of all types of immunocompetent cells. The point of application of the immune system is foreign agents, or antigens, - polymers of bioorganic nature, genetically alien to the macroorganism, causing immune reactions in it aimed at eliminating them. Antigen-antibody system Antigen - any molecule (compounds of different chemical nature: peptides, carbohydrates, polyphosphates, steroids), which can potentially be recognized by the body's immune system as foreign ("not native"). The ability to induce such responses is not inherent in the entire antigen molecule, but only in a special part of it, which is called the antigenic determinant, or epitope. There are exogenous (entering the body from the outside) and endogenous antigens (autoantigens - products of the body's own cells), as well as antigens that cause allergic reactions - allergens.
Bibliography
1. Medical microbiology, virology and immunology: textbook. In 2 volumes. Volume 1. / Ed. V.V. Zvereva, M.N. Boychenko. 2014 .-- 448 p.
2. Immunology: textbook / A. A. Yarilin. - M.: GEOTAR-Media, 2010 .-- 752 p.
3. Khaitov R.M. Immunology: textbook / R.M. Khaitov. - 2nd ed., Rev. and add. - M .: GEOTAR-Media, 2013 .-- 528 p.
4. Dokuchaeva G.V. Immune System Health - ed. Litres, 2013 .-- 1279 p.
5. Clinical laboratory diagnostics: a textbook for nurses / А.А. Kishkun - M.: GEOTAR-Media, 2009 .-- 720 p.
6. Syrtsov V.K., Voloshin N.A., Alieva E.G. Peripheral organs of the immune system. // Journal "Actual problems of pharmaceutical and medical science". Issue No. 1, volume 24. 2011., p. 8-11.
7. Voronina E.V. Andronova T.M. An ode to innate immunity. // Journal "Allergology and Immunology". Volume 15, No. 2, 2014, p. 109-113.
Please carefully study the content and fragments of the work. Money for the purchased finished work due to the non-compliance of this work with your requirements or its uniqueness will not be returned.
* The category of work is of an evaluative nature in accordance with the qualitative and quantitative parameters of the material provided. This material, either in its entirety or any of its parts, is not a ready-made scientific work, final qualifying work, scientific report or other work provided for by the state system of scientific certification or necessary for passing the interim or final certification. This material is a subjective result of processing, structuring and formatting the information collected by its author and is intended, first of all, to be used as a source for self-preparation of work on this topic.
Immune reaction disorders.
One of the founders of the science of the mechanisms of the body's immune (defense) reactions is the French scientist Louis Pasteur, who developed and introduced vaccination into practice as a method of combating infectious diseases. The Russian scientist II Mechnikov developed the cellular theory of immunity, having established the mechanism of cellular immunity, according to which the immunity of the organism is determined by the phagocytic activity of leukocytes. The German scientist Paul Ehrlich created the humoral theory of immunity, which explained the immunity of the body by the production of protective humoral substances in the blood - antibodies. According to modern concepts, immunity is the ability of an organism to respond with defensive reactions to everything that is genetically alien to it, i.e. on microbes, viruses, foreign cells and tissues, on their own, but genetically modified cells, as well as on some poisons and toxins. These damaging agents have been collectively referred to as antigens. As a result of the development of immunity, the body acquires resistance to repeated exposure to the same antigens, which are quickly neutralized.
Protection against antigens is carried out through non-specific and specific mechanisms, which in turn are subdivided into humoral and cellular ones.
Nonspecific mechanisms are used to neutralize even those antigens that the body has never encountered before. Nonspecific humoral immunity is created by protective proteins lysozyme, interferon, etc., which are constantly present in the blood plasma. Nonspecific cellular immunity is due to the phagocytic activity of eosinophils, basophils, neutrophils and monocytes, which was discovered by II Mechnikov. Nonspecific humoral and nonspecific cellular immunity determine hereditary immunity.
In the presence of hereditary immunity, the body is not susceptible to infection from birth. Distinguish between species hereditary immunity and individual hereditary immunity. For example, mankind is characterized by a specific hereditary immunity to foot and mouth disease; for 1.5 million diseases of foot and mouth disease in agricultural animals, there is only one human case. Sharks almost do not suffer from infectious diseases, their wounds are not susceptible to suppuration.
In contrast to the nonspecific mechanisms underlying hereditary immunity, specific mechanisms provide acquired immunity. Specific mechanisms are based on "memorizing" the antigen at the first contact with the body, "recognizing" it upon repeated contact and rapid destruction with the help of a special variety of T-lymphocytes (T-killers) and specially synthesized antibodies, mainly immunoglobulins.
Acquired immunity is divided into actively acquired, which is formed after vaccination or transfer of this disease, and passively acquired, which is formed as a result of the administration of blood serum of the body that has undergone this disease. For the formation of active immunity in order to protect against infectious diseases, vaccinations are performed, i.e. injecting vaccines into the body. Vaccines consist of killed, or live, but weakened germs or viruses. Active immunity lasts for months, years and even decades. Distinguish between actively acquired naturally occurring immunity (after suffering a disease) and actively acquired artificially immunity (after vaccination). With both types of active immunity in the body, antibodies are formed in the blood after the administration of the vaccine or the transfer of the disease. With passive immunity, ready-made antibodies are contained in the blood serum introduced into the body.
Lymphocytes play the main role in the development of the body's defense reactions. Lymphocytes are formed from stem cells in the bone marrow. Leaving the bone marrow, one part of the stem cells goes to the thymus gland or thymus, where they multiply and turn into thymus-dependent lymphocytes, or T-lymphocytes. The rest of the stem cells do not pass through the thymus gland, but are converted into lymphocytes in other organs. In birds, such an organ is the bursa (Bursa), so this type of lymphocyte is called B-lymphocytes. In mammals and humans, B-lymphocytes mature in the lymph nodes. B-lymphocytes live for several days and then begin to multiply, producing identical daughter cells.
T-lymphocytes provide cellular immunity. Different types of T-lymphocytes have different functions. So, T-lymphocytes - killers (killer cells) connect with foreign cells and kill them. Receptor proteins are built into the killer membrane, which are antibodies, possibly fixed immunoglobulins. It is these receptors that make contact of lymphocytes with foreign antigens and neutralize them. This process requires the participation of the so-called helper T cells (helper lymphocytes). Helper T cells also help B lymphocytes to synthesize antibodies. The third group of T-lymphocytes is the so-called T-cells of immunological memory. These cells, living for more than 10 years, circulate in the blood and after the first contact with the antigen "remember" it for many years. Upon repeated contact with the same antigen, the cells of the immunological memory "recognize" it and ensure its rapid neutralization. The fourth type of T-lymphocytes - T-suppressors, can suppress the production of antibodies by B-lymphocytes and the activity of other T-lymphocytes.
B-lymphocytes provide humoral immunity. When the antigen enters the body, B-lymphocytes are first converted into plasmablasts, which, as a result of a series of successive divisions, produce plasma cells. The cytoplasm of plasma cells is rich in ribosomes that actively produce antibodies, or immunoglobulins. T-helpers are involved in the production of antibodies, but the exact mechanism of their participation is not yet known. Plasma cells are strictly specific for certain antigens - each cell synthesizes only one type of antibodies.
Antibodies, or immunoglobulins, are complex proteins called glycoproteins. They specifically bind to foreign substances - antigens. According to the structure of the molecule, immunoglobulins are monomeric and polymeric. Each molecule has constant (COOH-terminal) and variable (changing) (NH2-terminal) parts in its chains. The variable parts form an active center (a cavity of a special configuration, corresponding in size and structure to the antigen), which determines the ability of the antibody to specifically bind to the antigen. As a result of this binding, a strong antigen-antibody complex is formed.
The disease AIDS (acquired immunodeficiency syndrome), which has appeared in recent years, is caused by the HIV retravirus, which selectively affects helper T-lymphocytes in the body, as a result of which the specific mechanisms of the immune system cease to function. The patient becomes practically defenseless against any most harmless infection. In addition to T-helpers, HIV infects monocytes, microphages and cells of the central nervous system, which have a T4 receptor on their surface, through which the virus enters the cell.
Immunity is also suppressed by ionizing radiation.
Starting in the middle XIX for centuries, in medicine, immunity was understood as the formation of immunity to infectious diseases, which developed as a result of vaccination or a past illness. What are now called secondary immune response reactions.
From the middle XX century, a different view of immunity is being formed. The system of immunity began to be understood as the system of lymphoid cells, which ensured the recognition of "ours" and "aliens" in the body.
In recent years, the immune system has begun to include almost all white blood cells, as well as a number of other cells. The main function of immunity is seen in shield the body from various manifestations of biological aggression, both exogenous and endogenous.
In the second half of the 19th century, when various approaches to vaccination were intensively developed in European countries, the term "immunity" is firmly included in medical practice. This term was borrowed from the Latin language, where the word "Immunitas" was used as a political term meaning the inviolability of someone, non-proliferation of generally accepted rules. (By the way, this term is still used in the field of diplomacy.)
Initially, immunity was understood as a state of increased resistance (immunity) of a person (or animal) to infection. The elegance of this term lay in the fact that an organism with immunity really was, as it were, "inviolable" for this infection, and the generally accepted rules of mandatory infection of all representatives of the species did not apply to this organism.
Usually, this immune state was achieved by prior vaccination or due to a previous illness. That is, in those days, immunity was practically understood as a reaction of a secondary immune response.
Further attempts to explain this intriguing infection resistance phenomenon lead to detailed
the study of various reactions that occur when the body is infected. There are two ingenious theories of immunity - the phagocytic Mechnikov and the humoral Ehrlich, who initially stood on antagonistic positions. It was the struggle of these theories and their all-round development that made it possible by the middle of the 20th century to raise the curtain over many unknown defense mechanisms.
Since the 60s of the twentieth century, a new understanding of the functions and purpose of immunity has arisen. At this time, the unique ability of lymphocytes to recognize genetically foreign material was discovered. Prominent Australian scientist Burnet created his own theory of immunity. Immunity was considered by him as the main mechanism aimed at differentiating “ours” and “others”. And the main role here belonged to lymphocytes, which Burnet proposed to call "immunocytes".
Proceeding from the need to distinguish “one's own” and “not one's own,” immunity began to be understood as the mechanisms of maintaining the genetic constancy of the internal environment of the organism. That is, specific control over the presence in the body of precisely "own" cells and the destruction of all "foreign" (bacteria, tumor cells, cells of a foreign transplant, etc.).
Later, many authors, describing the manifestations of immunity, associated it only with specific reactions of lymphoid cells. Other cells, actively participating in the body's defense reactions (macrophages, neutrophils, eosinophils, dendritic cells, etc.), appeared to be outside the sphere of immunology. At best, they were considered as cells that help the development of "true" immunity. This led to a misunderstanding of many processes occurring in infectious pathology. For some reason, this "lymphocentric" bias was especially pronounced in the domestic literature.
In the early stages, these were primitive reactions of phagocytic amoebocytes and proteins similar to the proteins of the complement system and proteins of the "acute phase". And already at more advanced stages of evolution, lymphoid cells appear, carrying out specific reactions to a specific antigen, and circulating, specifically directed molecules - antibodies.
A remarkable property of the evolution of the immune system is that in the process of its development, the emerging more perfect defense mechanisms did not exclude more ancient, preceding mechanisms. They developed and improved in parallel, thus forming an interconnected, "layered" system of defense against the aggression of pathogenic microorganisms.
Some authors, among the reasons for the evolution of immunity, highlight the need to contain and control the processes of mutagenesis, which should increase under conditions of increasing body weight and the number of somatic cells. However, this approach is not entirely convincing, since the “goal” of evolution is hardly a simple increase in the number of somatic cells in the body. Apparently, we are talking here, rather, we can talk about an increase in the number of differentiated groups of cells, which is clearly supported by the evolutionary process.
Thus, in recent years, an understanding of immunity (the immune system) has been formed as a system of factors that provide the internal defense of the body against exogenous (bacteria, viruses, etc.) and endogenous (altered or tumor cells) biological aggression. This system has several lines (echelons) of defense.
It is based on ancient, evolutionarily entrenched defense reactions carried out by leukocytes and blood plasma proteins. They are often referred to as non-specific immunity factors. They are the first to fight infection and provide primitive (lectin-like) recognition of the main bacterial antigens, as well as damaged own cells (by unshielded carbohydrate residues, denatured proteins, or the absence of “own” histocompatibility proteins).
They also implement the processes of neutralization and elimination (removal) of foreign material, which occur in the reactions of phagocytosis, extracellular cytolysis, cytotoxic reactions of natural killer cells (NK cells) or cytolytic effects of complement.
In parallel, a second, specific line of defense is activated. In this case, the biological material formed as a result of the activity of cells of a nonspecific line
struggle, serves as a factor triggering the reactions of the second, specific line. They are processed (processed) antigens and various cytokines.
With a sufficiently rapid neutralization and removal of foreign material (for example, avirulent or weakly virulent microorganisms), the development of specific immune reactions is not supported and dies out.
However, with a massive dose of foreign material or high virulence of the pathogen, the reaction of nonspecific factors is intense and much longer. This means that the first line is experiencing significant difficulties and needs the help of the second, specific line of defense.
The subsequent inclusion of the second line allows for a more effective, more "targeted" and accurate fight against the pathogen, carrying specific, specific antigens. At the same time, the efficiency of the basic reactions of nonspecific immunity also increases, since specific antibodies, adsorbed on the membranes of killer cells or targets, seem to indicate where exactly the attack should be directed.
The biological meaning of a temporary lag in the development of reactions of a specific system is quite obvious. It consists in the fact that the reserves of this system are not spent "on trifles", on aggression, which does not pose a danger to the life of the host's organism.
When reactions are triggered, leading to the development of a pronounced specific response, the formation and accumulation of long-lived memory cells automatically occurs. A repeated meeting with a complementary antigen leads to their accelerated and intensive reproduction. As a result, the number of protective factors (activated cells and antibodies) is so significant that the invading pathogen is quickly and efficiently neutralized and removed. In this case, the clinical manifestations of the disease are extremely insignificant or not detected at all. In this case, we can talk about immunity to this disease.
Thus, the understanding of immunity as a multifactorial and multi-stage defense system of the body is most productive at the present stage. Currently, it is proposed to distinguish two main types of immunity - congenital and acquired.
In the organism of animals and humans, evolutionarily developed and consolidated the ability to protect against the interference of foreign substances and infectious agents that violate the constancy of its internal environment. This protection is carried out through a series non-specific and specificmechanisms. Among those and others secrete humoral and cellular.
Non-specific mechanisms have a wider range of functions and are used to neutralize even those foreign bodies that the body has not previously encountered at all. This is primarily hereditary immunity.
Specific mechanisms - are based on the experience of previous contact with a foreign principle, when a specific immunity has already been developed to it. For example, when an infectious agent, an antigen, is introduced, antibodies are produced in the body. These are specific substances that protect against this microbe (virus) or neutralize it. Immune reactions arise not only as a result of the introduction of an infectious principle into the body, they also appear when incompatible agents are received, for example, during blood transfusion, organ and tissue transplants, in the process of a non-group pregnancy.
Nonspecific humoral immunity. Here the main role is played by protective substances of blood plasma, such as lysozyme, properdin, interferon. They provide the innate immunity of the body to infections.
Non-specific cellular immunity. This type of immunity is determined by the phagocytic activity of granulocytes, monocytes, platelets and, as recent studies have shown, lymphocytes. Granulocytes and monocytes contain a large number of lysosomal enzymes, their phagocytic activity is most pronounced. In this reaction, several stages are distinguished: the attachment of the phagocyte to the microbe, the absorption of the microbe, its fusion with the lysosome, the intracellular inactivation of the microbe, its enzymatic digestion and the removal of material that remains intact.
Specific cellular immunity... Here the main role is played by immunocompetent T-lymphocytes. Upon contact with antigen, some cells proliferate. One part of the formed daughter T-lymphocytes binds to the antigen and destroys it. Another part of the daughter lymphocytes forms a group of so-called T-cells of immunological memory. These lymphocytes are long-lived and, having "memorized" the antigen from the first meeting, they "recognize" it upon repeated contact.
Specific humoral immunity... Unlike cellular, this type of immunity is created by B-lymphocytes of lymph nodes, tonsils and other lymphoid organs. Here, at the first meeting with the antigen, immunocompetent B-lymphocytes divide. Some of the daughter cells turn into cells of immunological memory and is carried throughout the body. Others remaining in the lymphoid organs are converted into plasma cells... They produce and release humoral antibodies into the blood plasma. And here T-helpers are involved in the production of antibodies. The repeated meeting of plasma cells with the antigen is accompanied by a powerful and rapid humoral response with a sharp increase in the level of immunoglobulins in the blood. An example of such a response is an allergic reaction to plant pollen and drugs.
