They protect the human body from all diseases and are due to the innate properties of the body, which contribute to the destruction of a wide variety of microorganisms on the surface of the body and its cavities. Non-specific immunity factors include:
1. Tissue (cellular) factors. Among tissue factors, an important role is played by:
a) Immunological barriers, which include the protective properties of the skin, mucous membranes and lymph nodes. The skin and mucous membranes are a mechanical barrier, the secretion of sweat, sebaceous glands and the secretion of mucous membranes inhibit many types of pathogenic microorganisms. Lymph nodes prevent the spread of microorganisms in the macroorganism, being a powerful natural barrier
b) Species reactivity of cells - the absence of receptors on the surface of cells makes it impossible for the adsorption and penetration of an infectious agent or poison into the cell
c) Phagocytosis is the process of active absorption by the cells of a macroorganism of foreign substances (including microorganisms) that have entered it, followed by their digestion with the help of intracellular enzymes. Stages of phagocytosis: 1) the approach of the phagocyte to the object - positive chemotaxis; 2) adhesion of a microorganism to phagocytes - adhesion; 3) absorption (invagination) of microorganisms by phagocytes and the formation of phagosomes; 4) formation of phagolysosome, digestion and death of the microorganism - killing-inactivation. Distinguish completed phagocytosis - ends with complete destruction and death of the microorganism - and incomplete - microorganisms inside the phagocyte not only do not die, but even multiply. Microphages have phagocytic activity - these are neutrophils, eosinophils, basophils - granular leukocytes, macrophages - blood monocytes, histiocytes, endothelial and reticular cells of internal organs and bone marrow.
d) Normal killer cells (killer cells) are cytotoxic lymphocytes that destroy target cells infected with viruses and oncogenic cells under the influence of lymphotoxins.
2. Humoral factors of nonspecific protection. Numerous, produced by T-lymphocytes and macrophages. These include:
a) Complement is a non-specific blood enzyme system consisting of 9 different protein fractions adsorbed in the process of cascade attachment on the antigen + antibody complex and having a lysing effect on antibody-bound cellular antigens
b) Lysozyme - a protein found in saliva, blood, lacrimal and tissue fluid, is active against gram-positive bacteria, because interferes with the synthesis of murein in the cell wall.
c) β-lysines - released from leukocytes and are more active against gram-negative bacteria
d) leukins - proteolytic enzymes that are released during the destruction of leukocytes and violate the integrity of the surface proteins of microbial cells
e) interferon - α and β, produced respectively by mononuclear phagocytes and fibroblasts and have antiviral activity
f) properdin - a complex of proteins that have antiviral, antibacterial activity in the presence of magnesium salts, causing lysis of microorganisms and enhancing the phagocytic reaction and inflammation
g) erythrin - has an inhibitory effect on corynebacterium diphtheria and is released when erythrocytes are destroyed
h) normal antibodies - found in the blood of newborns in very low titers, have a cytophilic effect, their level increases under the action of a microorganism as a trigger signal. The formation of normal antibodies is genetically programmed; they are expressed on the surface membranes of immature B-lymphocytes in the form of receptors.
3. Factors of self-regulation: are manifested by an increase in body temperature, a change in the pH and rH 2 of the affected tissues, an increase in the excretory functions of the body, the excretion of microorganisms and their toxins with urine, feces, sputum and other excretions.
Acquired postinfectious immunity is due to humoral and tissue factors of high specificity - immunoglobulins and immunocompetent cells. Its formation is induced by antigens.
Antigens- (in literal translation, the term "antigen" means "anti" - against, "genos" - generative) - substances that are genetically alien to the body, to the introduction of which the body responds with the development of specific immunological reactions (the formation of antibodies).
Properties of antigens:
1. Immunogenicity - the ability of antigens to cause the production of antibodies
2. Ability to interact with antibodies
3. Specificity - is determined by the epitope (determinant group) of the antigen - a small section of the antigen, with the help of which it is connected with a strictly defined antibody.
Types of antigens:
1. Immunogens - high-molecular compounds that induce antibody formation and interact with immunoglobulins
2. Defective antigens (haptens) - not capable of causing the production of antibodies, but capable of reacting with ready-made antibodies. Haptens, when combined with proteins of the human body, are able to turn into immunogens. The antigenic structure of microorganisms is very diverse. There are: 1) somatic O-antigens, 2) envelope, capsular K-antigens, 3) flagellar H-antigens, 4) protective (protective) antigens - appear in microorganisms only when they enter the human body, 5) ribosomal, 6) Vi -antigens - antigens of virulence. Conditions under which substances are converted into antigens: foreignness, macromolecularity, colloidal state, solubility. Individual types of microorganisms contain species- and type-specific antigens, but may also contain group antigens, common with related or distant species. The group commonality of the antigenic structure in different types of cells is called antigenic mimicry, in which the human immune system loses the ability to quickly recognize someone else's label and develop immunity (this explains persistence, stable microbe carrier and post-vaccination complication).
Antibodies- These are serum immunoglobulins that are formed in response to the introduction of an antigen and are able to react with them.
The structure of immunoglobulins:
In appearance, the immunoglobulin resembles the letter Y and consists of 4 polypeptide chains connected to each other by a disulfide bond: two long, heavy H-chains resembling a stick and two short, light L-chains. The structure of the upper sections of the H and L chains varies greatly and is called V-sites or Fab-fragments - representing an antigen-binding center or paratope. The lower end of the H-chains is designated by the C-region or Fc-fragment, with the help of which immunoglobulins are adsorbed on the receptors of immunocompetent cells (complement-fixing fragment).
By the nature of the action of antibodies on microorganisms, antitoxins, lysins, agglutinins, precipitins, hemolysins, cytotoxins, bacteriocins, hemagglutinins are distinguished.
There are 5 main classes of immunoglobulins:
1. Ig G - monomers, highly specific, make up 75% of all human immunoglobulins, are the most active in the development of human immunity, the only immunoglobulins penetrate the placenta, provide passive fetal immunity, and remain long after the disease
2. Ig M - consist of 5 monomers, form large lattices (agglutinins, precipitins, complement-fixing antibodies), are produced at the initial meeting with the antigen, therefore they appear first after infection, are formed first in a child at 5 months of age, are low specific, have no diagnostic value , indicate the primacy and freshness of the processes, after the disease and in the chronic course they are not
3. Ig A - have the ability to penetrate the secrets of the mucous membranes (colostrum, saliva, bronchial contents, etc.), protect the mucous membranes of the respiratory and digestive tract from the action of microorganisms
4. Ig E - monomers with a blocked Fab-end, are allergic, skin-sensitizing substances. The Fc-terminus is attached to shock cells (basophils, mast cells, vascular endothelium, epithelium of the skin and mucous membranes), which release inflammatory mediators, causing spasm of blood vessels, bronchi, and swelling of the mucous membranes. HIT and polynoses (anaphylactic shock, bronchial asthma, edema, migraines) are associated with the presence of these immunoglobulins.
5. Ig D - poorly understood, one Fab-end is blocked in them and they are found in collagenoses (rheumatism, lupus erythematosus)
The formation of antibodies as an immune reaction to antigens occurs in the lymphoid tissue of the peripheral organs of immunity, mainly in the lymph nodes and white pulp of the spleen. Plasma cells are the producers of antibodies. In the dynamics of the formation of antibodies, 2 phases are distinguished:
1) inductive (latent)- the length of time between the introduction of the antigen and the appearance of the first plasma cells or traces of immunoglobulins. In this phase, antigens are phagocytosed by macrophages, accumulated in them, processed and presented (presented) by macrophages for recognition by T-helpers. Under the influence of T-helpers, B-lymphocytes turn into plasma cells, which subsequently carry out the synthesis of antibodies;
2) productive (reproductive)- in this stage there is an intensive synthesis of antibodies.
Immunity reactions are reactions based on the interaction of an antigen with antibodies. These include: agglutination reaction, precipitation, RSK, RIF, ELISA, RTGA, RNGA, etc. Immunity reactions are used to diagnose infectious diseases in two directions:
1. Serodiagnosis - determination of unknown antibodies in the patient's serum using known antigens - diagnosticums, which are a suspension of killed microorganisms and produced by the microbiological industry.
2. Identification of a pure culture of a microorganism isolated from a patient - determination of an unknown antigen of a pure culture of microorganisms isolated from a patient using known antibodies of the immune serum produced by the microbiological industry.
Questions for self-control
1. Define the term "infectious process"
2. What is the name of the clinical manifestation of an infectious process, accompanied by a number of characteristic clinical symptoms?
3. What is meant by the term "infection"?
4. Define the concept of "pathogenicity"
5. What is the degree or measure of pathogenicity of a strain within a pathogenic species called?
6. List the virulence factors
7. What types of toxins produced by microorganisms do you know?
8. What signs are typical for exotoxins?
9. List the properties characteristic of endotoxins
10. What microorganisms are called opportunistic pathogens?
11. What is the name of the infections caused by LPB?
12. Define the concept of "immunity"
13. How is immunity classified by origin?
14. What is the name of the immunity that develops after an infectious disease?
15. What group does the immunity of newborns belong to, which is formed due to the receipt of ready-made antibodies from the mother's body?
16. What type of immunity develops after the introduction of vaccines and toxoids into the body?
17. What type of immunity occurs when ready-made antibodies obtained from another immune organism are introduced into a macroorganism?
18. How is immunity classified according to the direction of action?
19. How is immunity classified according to the mechanism of action?
20. What immunity factors are classified as non-specific protection factors?
21. List the tissue (cellular) factors of nonspecific protection
22. What provides the protective properties of the skin, mucous membranes and lymph nodes?
23. Define the concept of "phagocytosis"
24. List the stages of phagocytosis
25. What types of phagocytosis do you know?
26. List the cells of the human body that have phagocytic activity
27. What are called cytotoxic lymphocytes that destroy target cells infected with viruses and oncogenic cells under the influence of lymphotoxins?
28. List the humoral factors of nonspecific protection
29. What reactions of the human body are referred to as self-regulation factors?
30. Define the concept of "antigens"
31. What properties of antigens do you know?
32. What is the difference between complete antigens (immunogens) and defective antigens (haptens)?
33. What antigens can be found in microorganisms?
34. Define the concept of "antibodies"
35. What is the structure of immunoglobulins?
36. What classes of immunoglobulins do you know?
37. What phases are distinguished in the dynamics of antibody formation?
38. What are the reactions called, which are based on the interaction of an antigen with antibodies?
39. What reactions are classified as immune reactions?
40. What is the practical application of the immune response?
Test - yes-, -no - on the topic
"Infection and Immunity".
1. Infection is an evolutionarily established form of relationship between pathogenic microbes and the environment.
2. Various forms of manifestation of infection are determined by biological and social environmental factors.
3. A group of microbes that cause infectious diseases is called infectious.
4. Pathogenicity as a species trait is subject to variability.
5. Virulence - an indicator of pathogenic activity.
6. Invasiveness is the ability of microorganisms to invade and reproduce.
7. Aggressiveness is the ability to survive, reproduce and strike.
8. Resistance is the resistance of the organism, which is determined by non-specific factors of anti-infective protection.
9. Susceptibility is the body's ability to respond to the introduction of pathogenic microbes.
10. Susceptibility is of two types: general and individual.
11. Infectious diseases differ from somatic ones: infectivity, the ability to multiply by the transmission of a specific mechanism, the specific localization of the pathogen in certain organs and tissues, and immunity.
12. Infectious diseases proceed cyclically.
13. The incubation period begins from the moment of the disease.
14. According to the mechanism of transmission, all infectious diseases are divided into intestinal, respiratory, blood, infections of the skin and mucous membranes.
15. Translated from Greek, the word "immunity" means immunity.
16. Modern immunology is a biological science that studies the physiology and pathology of a diseased organism.
17. There are four types of immunocompetent cells.
18. Immunity is a phenomenon of a homeostatic order.
19. There are three types of immunity: natural, antiviral, acquired.
20. Species unresponsiveness of cells to pathogenic microbes and toxins is determined by the genotype.
1. The skin and mucous membranes have a protective function. For most microorganisms, including pathogens, normal intact skin and mucous membranes of various organs are a barrier that prevents penetration into the body. Rejection of the upper layers of the epidermis, the secrets of the sebaceous and sweat glands contribute to the removal of microbes from the surface of the skin and mucous membranes. However, the skin is not only a mechanical barrier. Since it has bactericidal properties associated with the action of lactic and fatty acids, various enzymes secreted by the sweat and sebaceous glands, microorganisms are not its permanent inhabitants, they cannot remain on the skin for a long time and quickly disappear.
The conjunctiva of the eye, mucous membranes of the nasopharynx, respiratory, gastrointestinal and urogenital tracts have more pronounced protective functions. The fluids secreted by the mucous, lacrimal and digestive glands not only wash away microbes from the surface of the mucous membrane, but also have a bactericidal effect due to the enzyme lysocine contained in them. It damages the cell wall of bacteria, as a result of which they die. This enzyme has the ability to cause lysis (dissolve) of many non-pathogenic bacteria, but has a less pronounced lytic effect on pathogenic bacteria such as staphylococci, streptococci, does not affect viruses. Lysocin is a thermostable crystalline protein. It is found in the tissues of animals and plants, in humans - in tears, saliva, plasma and blood serum, in leukocytes, in mother's milk and other fluids. The protective effect of lysocine in relation to infectious agents is especially pronounced in the conjunctiva and cornea, the mucous membrane of the oral cavity, pharynx and nose. The rapid healing of wounds in these organs, which are in contact with a large number of different microbes, including pathogens, is to a certain extent due to the presence of lysocine.
2. The lymphoid tissue also performs a protective function - the lymph nodes of the subcutaneous tissue, mucous membranes, liver, spleen. After penetration through the skin and mucous membranes, the bacteria linger in nearby lymph nodes. In the case of a small amount and low pathogenicity, the bacteria are destroyed and digested by leukocytes.
3. The normal microflora of various organs also plays a protective role: skin, mucous membranes, especially the intestines, where bifidumbacteria, lactobacilli, E. coli are located, which have a detrimental effect on pathogenic bacteria that enter the digestive tract.
4. Complement plays a special role in natural immunity - a complex system of whey proteins with enzymatic properties. Complement consists of 11 different components found in the blood serum of humans and animals. By itself, complement has a weak bactericidal effect, but it enhances other protective factors of the body and is involved in specific immune responses.
Complement is a thermolabile substance of a protein nature (it is destroyed at 56 ° C for 30 minutes). Its main property is the ability to cause lysis (dissolution) of cells.
5. Natural protective factors include normal (natural) antibodies. These antibodies arise without visible manifestation of diseases and react with various antigens (microbe, toxin), contributing to their neutralization, cause lysis (dissolution) of bacteria in the presence of complement, neutralize toxins, viruses.
And for the road, an interesting question: is it possible that pressure increases are also the protective properties of the body, provided by nature in certain circumstances.
Distinguish between species and acquired immunity.
Species immunity is inherited but is characteristic of a given species. For example, humans are immune to rinderpest, chicken cholera, dogs are immune to tuberculosis. Species immunity is nonspecific, that is, the same defense mechanisms act against different types of microbes. This is the strongest type of immunity.
Non-specific factors of natural resistance protect the body from microbes at the first meeting with them. These same factors are also involved in the formation of acquired immunity.
Areactivity of cells is the most persistent factor of natural protection. In the absence of cells sensitive to this microbe, toxin, virus, the body is completely protected from them. For example, rats are insensitive to diphtheria toxin.
The skin and mucous membranes are a mechanical barrier for most pathogenic microbes. In addition, secretions from sweat and sebaceous glands containing lactic and fatty acids have a detrimental effect on microbes. Clean skin has stronger bactericidal properties. Desquamation of the epithelium contributes to the removal of microbes from the skin.
The secrets of the mucous membranes contain lysozyme (lysozyme) - an enzyme that lyses the cell wall of bacteria, mainly gram-positive. Lysozyme is found in saliva, conjunctival secretion, blood, macrophages, and intestinal mucus. Opened for the first time by P.N. Lashchenkov in 1909 in the protein of a chicken egg.
The epithelium of the mucous membranes of the respiratory tract is an obstacle to the penetration of pathogenic microbes into the body. Dust particles and liquid droplets are thrown out with mucus secreted from the nose. From the bronchi and trachea, the particles that have got here are removed by the movement of the cilia of the epithelium, directed outward. This function of the ciliated epithelium is usually impaired in heavy smokers. A few dust particles and microbes that have reached the lung alveoli are captured by phagocytes and rendered harmless.
The secret of the digestive glands. Gastric juice has a detrimental effect on microbes that come with water and food, due to the presence of hydrochloric acid and enzymes. Reduced acidity of gastric juice helps to weaken resistance to intestinal infections such as cholera, typhoid fever, dysentery. Bile and enzymes of intestinal contents also have a bactericidal effect.
The lymph nodes. Microbes that have penetrated the skin and mucous membranes are retained in the regional lymph nodes. Here they undergo phagocytosis. The lymph nodes also contain the so-called normal (natural) killer-lymphocytes (English, killer - killer), carrying the function of antitumor surveillance - the destruction of the body's own cells, altered due to mutations, as well as cells containing viruses. Unlike immune lymphocytes, which are formed as a result of an immune response, natural killer cells recognize foreign agents without prior contact with them.
Inflammation(vascular-cellular reaction) is one of the phylogenetically ancient protective reactions. In response to the penetration of microbes, a local inflammatory focus is formed as a result of complex changes in the microcirculation, blood system and connective tissue cells. The inflammatory response promotes the removal of microbes or delays their development and therefore plays a protective role. But in some cases, when the agent that caused the inflammation is re-entered, it can take on the character of a damaging reaction.
Phagocytosis- the process of active absorption by the cells of the body of microbes and other foreign particles (Greek phagos - devouring + kytos - cell), including the body's own dead cells. I.I. Mechnikov, the author of the phagocytic theory of immunity, showed that the phenomenon of phagocytosis is a manifestation of intracellular digestion, which in lower animals, for example, in amoebas, is a way of feeding, and in higher organisms, phagocytosis is a defense mechanism. Phagocytes free the body from microbes, and also destroy the old cells of their own body.
According to Mechnikov, all phagocytic cells are divided into macrophages and microphages. Microphages include polymorphonuclear blood granulocytes: neutrophils, basophils, eosinophils. Macrophages are blood monocytes (free macrophages) and macrophages of various body tissues (fixed) - liver, lungs, connective tissue.
Microphages and macrophages originate from a single precursor, the bone marrow stem cell. Blood granulocytes are mature short-lived cells. Peripheral blood monocytes are immature cells and, leaving the bloodstream, enter the liver, spleen, lungs and other organs, where they mature into tissue macrophages.
Phagocytes perform a variety of functions. They absorb and destroy foreign agents: microbes, viruses, dying cells of the body itself, products of tissue decay. Macrophages take part in the formation of the immune response, firstly, by presenting (presenting) antigenic determinants (epitopes on their membranes) and, secondly, by producing biologically active substances - interleukins, which are necessary to regulate the immune response.
In the process of phagocytosis, several stages are distinguished (Fig. 12):
- 1) the approach and attachment of a phagocyte to a microbe is carried out due to chemotaxis - the movement of a phagocyte in the direction of a foreign object. Movement is observed due to a decrease in the surface tension of the phagocyte cell membrane and the formation of pseudopodia. Attachment of phagocytes to the microbe occurs due to the presence of receptors on their surface,
- 2) absorption of the microbe (endocytosis). The cell membrane flexes, an invagination is formed, as a result, a phagosome is formed - a phagocytic vacuole. This process is linked with the participation of complement and specific antibodies. For phagocytosis of microbes with antiphagocytic activity, the participation of these factors is necessary;
- 3) intracellular inactivation of the microbe. The phagosome merges with the lysosome of the cell, a phagolysosome is formed, in which bactericidal substances and enzymes accumulate, as a result of which the death of the microbe will occur;
- 4) digestion of the microbe and other phagocytosed particles occurs in phagolysosomes.
Phagocytosis, which leads to the inactivation of the microbe, that is, it includes all four stages, is called complete. Incomplete phagocytosis does not lead to the death and digestion of microbes. Microbes captured by phagocytes survive and even multiply inside the cell (for example, gonococci).
In the presence of acquired immunity to a given microbe, opsonin antibodies specifically enhance phagocytosis. Such phagocytosis is called immune. In relation to pathogenic bacteria with antiphagocytic activity, for example, staphylococci, phagocytosis is possible only after opsonization.
Macrophage function not limited to phagocytosis. Macrophages produce lysozyme, complement protein fractions, participate in the formation of the immune response: interact with T- and B-lymphocytes, produce interleukins that regulate the immune response. In the process of phagocytosis, particles and substances of the organism itself, such as dying cells and tissue decay products, are completely digested by macrophages, that is, to amino acids, monosaccharides and other compounds. /Foreign agents such as microbes and viruses cannot be completely destroyed by macrophage enzymes. The foreign part of the microbe (determinant group - epitope) remains undigested, is transferred to T- and B-lymphocytes, and thus the formation of an immune response begins. Macrophages produce interleukins that regulate the immune response.
Humoral protective factors. In the blood, lymph and other body fluids (Latin humor - liquid) there are substances that have antimicrobial activity. The humoral factors of nonspecific protection include: complement, lysozyme, beta-lysins, leukins, antiviral inhibitors, normal antibodies, interferons.
Complement - the most important humoral protective blood factor, is a complex of proteins, which are designated as C1, C2, C3, C4, C5, ... C9. Produced by liver cells, macrophages and neutrophils. In the body, complement is in an inactive state. When activated, proteins acquire the properties of enzymes.
There are two ways of complement activation: classical and alternative.
The classical way is carried out with the participation of antibodies. The C1 fraction joins the antigen-antibody complex, then C4, C2, C3 in succession, then C5, C6, C7, C8, C9 are activated. Each previous faction causes the activation of the next one. As a result of such a "cascade" activation process, the last fractions acquire the ability to lyse microbes, erythrocytes, etc.
The alternative pathway takes place without the participation of antibodies, under the influence of the antigen, and begins with the activation of C3.
The complement system carries out: 1) cell lysis; 2) activation of phagocytosis; 3) participation in the reaction of anaphylaxis and in the process of inflammation; 4) participation in the immune response.
Complement is thermolabile, destroyed at 56°C for 30 minutes. Serum treated in this way is called inactivated. The commercial complement preparation used in the laboratory is guinea pig serum. Produced in ampoules in lyophilized form.
Lysozyme It is produced by blood monocytes and tissue macrophages, has a lysing effect on bacteria, and is thermostable.
Beta Lysine secreted by platelets, has bactericidal properties, thermostable.
Normal antibodies contained in the blood, their occurrence is not associated with the disease, they have an antimicrobial effect, promote phagocytosis.
Interferon - a protein produced by cells in the body and also by cell cultures. Interferon inhibits the development of the virus in the cell. The phenomenon of interference is that in a cell infected with one virus, a protein is produced that inhibits the development of other viruses. Hence the name - interference (lat. inter - between + ferens - transferring). Interferon was discovered by A. Isaac and J. Lindenman in 1957.
The protective effect of interferon turned out to be non-specific in relation to the virus, since the same interferon protects cells from different viruses. But it has species specificity. Therefore, the interferon that is formed by human cells acts in the human body.
Later it was found that the synthesis of interferon in cells can be induced not only by live viruses, but also by killed viruses and bacteria. Interferon inducers can be some drugs.
Currently, several interferons are known. They not only prevent the reproduction of the virus in the cell, but also retard the growth of tumors and have an immunomodulatory effect, that is, they normalize immunity.
Interferons are divided into three classes: alpha interferon (leukocyte), beta interferon (fibroblast), gamma interferon (immune).
Leukocyte a-interferon is produced in the body mainly by macrophages and B-lymphocytes. Donor alpha-interferon preparation is obtained in cultures of donor leukocytes exposed to an interferon inducer. It is used as an antiviral agent.
Fibroblast beta-interferon in the body is produced by fibroblasts and epithelial cells. The preparation of beta-interferon is obtained in cultures of human diploid cells. It has antiviral and antitumor activity.
Immune gamma-interferon in the body is produced mainly by T-lymphocytes stimulated by mitogens. The preparation of gamma-interferon is obtained in a culture of lymphoblasts. It has an immunostimulating effect: it enhances phagocytosis and the activity of natural killers (NK cells).
The production of interferon in the body plays a role in the process of recovery of a patient with an infectious disease. With influenza, for example, the production of interferon increases in the first days of the disease, while the titer of specific antibodies reaches a maximum only by the 3rd week.
The ability of people to produce interferon is expressed to varying degrees. "Interferon status" (IFN-status) characterizes the state of the interferon system:
- 1) the content of interferons in the blood is determined by their action on certain types of viruses;
- 2) the ability of leukocytes obtained from the patient to produce interferon in response to the action of inductors.
In medical practice, alpha, beta, gamma interferons of natural origin are used. Recombinant (genetically engineered) interferons have also been obtained: reaferon and others.
Effective in the treatment of many diseases is the use of inductors that promote the production of endogenous interferon in the body.
One of the main mechanisms of inflammation is phagocytosis - the process of absorption of bacteria. Various cells of the body (blood leukocytes, endothelial cells of blood vessels) have phagocytic activity.
The process of phagocytosis has several stages: 1) approximation phagocyte to the object due to the chemical influence of the latter (chemotaxis).
2) adhesion microorganisms to phagocytes;
3) absorption of microorganisms by the cell;
4) death and digestion of the pathogen.
The blood contains soluble specific substances that have a detrimental effect on microorganisms. These include complement, properdin, β-lysines, x-lysines, erythrin, leukins, plakins, lysozyme, etc.
Complement is a complex system of protein fractions of the blood, which has the ability to lyse microorganisms and other foreign cells, such as red blood cells.
properdin- a group of components of normal blood serum that activates complement.
β - lysines- thermostable substances of human blood serum with antimicrobial action. Mainly in relation to gram-positive bacteria.
Lysozyme - an enzyme that destroys the membrane of microbial cells. It is found in tears, saliva, blood fluids. Rapid healing of wounds of the conjunctiva of the eye, mucous membranes of the oral cavity, nose due to the presence of lysozyme.
Normal serum contains small amounts interferon(a protein that is synthesized by cells of the immune system and connective tissue).
Anatomically, the immune system is divided into central and peripheral organs. TO central authorities relate bone marrow and thymus ), and to peripheral - lymph nodes, accumulations of lymphoid tissue (Peyer's patches, tonsils), spleen, blood and lymph.
The main cells of the immune system are lymphocytes and phagocytes, as well as granulocytes and blood monocytes.
B-lymphocytes- immunocompetent cells responsible for the synthesis of immunoglobulins are involved in the formation of humoral immunity.
T-lymphocytes- provide cellular forms of the immune response (transplacental antitumor immunity).
T-helpers(helpers) - a subpopulation of T-lymphocytes-regulators that perform a regulatory function. They act on clones of T- and B-lymphocytes.
T-killers– subpopulation of T-lymphocytes-effectors. Recognize cells with a modified structure, its target is mutated, as well as virus-affected cells and transplants.
specific immune system responds to the introduction of foreign cells, particles or molecules (antigens) by the formation of specific protective substances localized inside the cells or on their surface (specific cellular immunity) or antibodies dissolved in plasma (specific humoral immunity). In specific cellular immunity, the most important role belongs to T-lymphocytes, and in specific humoral immunity - to B-lymphocytes.
IMMUNITY
Plan
The concept of immunity.
Types of immunity.
Nonspecific protective factors of the body.
Cellular factors of nonspecific protection.
Humoral factors of nonspecific protection
Organs of immunity and immunocompetent cells.
1 The concept of immunity
concept immunity denotes the body's immunity to any genetically alien agents, including pathogenic microorganisms and their poisons (from Lat. immunitas - liberation from something).
When genetically alien structures (antigens) enter the body, a number of mechanisms and factors come into action that recognize and neutralize these substances alien to the body.
The system of organs and tissues that carries out protective reactions of the body against violation of the constancy of its internal environment (homeostasis) is called immune system.
The science of immunity immunology studies the body's reactions to foreign substances, including microorganisms; body reactions to foreign tissues (compatibility) and to malignant tumors: determines immunological blood groups, etc.
Types of immunity
Types of immunity
hereditary acquired
(specific)
Natural Artificial
Active Passive Active Passive
Hereditary (innate, species) immunity- this is the most durable and perfect form of immunity, transmitting by inheritance.
This type of immunity is passed down from generation to generation and is determined by the genetic and biological characteristics of the species.
acquired immunity a person is formed during life, it is not inherited.
natural immunity.active immunity formed after the disease (post-infectious). In most cases, it lasts for a long time.
Passive Immunity- this is the immunity of newborns (placental), acquired by them through the placenta during fetal development. Newborns can get immunity from their mother's milk. This type of immunity is short-lived and disappears by 6-8 months. The significance of this immunity is great - it ensures the immunity of infants to infectious diseases.
artificial immunity.active immunity a person acquires as a result of immunization (vaccinations).
At the same time, an active restructuring takes place in the body, aimed at the formation of substances that have a detrimental effect on the pathogen and its toxins. (antibodies). The development of active immunity occurs gradually over 3-4 weeks and it persists for a relatively long time - from 1 to 3-5 years.
Passive Immunity creates the introduction of ready-made antibodies into the body. This immunity occurs immediately after the introduction of antibodies (sera and immunoglobulins), but lasts only 15-20 days, after which the antibodies are destroyed and excreted from the body.
There are forms of immunity directed to different antigens.
Antimicrobial Immunity develops in diseases caused by various microorganisms or with the introduction of corpuscular vaccines (from live, weakened or killed microorganisms).
Antitoxic Immunity produced in relation to bacterial poisons - toxins.
Antiviral Immunity formed after viral diseases. This type of immunity is long and persistent (measles, chicken pox, etc.). Antiviral immunity also develops when immunized with viral vaccines.
Sterile immunity - immunity that persists after the release of the body from the pathogen.
Non-sterile immunity (infectious) - due to the presence of a living infectious agent in the body and is lost when the body is released from the pathogen.
Nonspecific immunity includes mechanisms effective against any pathogens.
specific immunity consists in the development of specific antibodies effective against a specific pathogen.
There are mechanical, chemical and biological factors that protect the body from the harmful effects of various microorganisms.
Leather. Intact skin is a barrier to the penetration of microorganisms. In this case, mechanical factors are important: the rejection of the epithelium and the secretion of sebaceous and sweat glands, which contribute to the removal of microorganisms from the skin.
The role of chemical protection factors is also performed by the secretions of the glands of the skin (sebaceous and sweat). They contain fatty and lactic acids, which have a bactericidal (killing bacteria) effect.
Biological protection factors are due to the detrimental effect of the normal microflora of the skin on pathogenic microorganisms.
mucous membranes different organs are one of the barriers to the penetration of microorganisms. In the respiratory tract, mechanical protection is carried out with the help of ciliated epithelium. The movement of the cilia of the epithelium of the upper respiratory tract constantly moves the mucus film along with various microorganisms towards the natural openings: the oral cavity and nasal passages. The hairs of the nasal passages have the same effect on bacteria. Coughing and sneezing help remove microorganisms and prevent their aspiration (inhalation).
Tears, saliva, breast milk and other body fluids contain lysozyme. It has a destructive (chemical) effect on microorganisms. The acidic environment of gastric contents also affects microorganisms.
The normal microflora of the mucous membranes, as a factor of biological protection, is an antagonist of pathogenic microorganisms.
Control questions
1. What are non-specific protective factors?
2. What factors prevent the penetration of pathogenic microorganisms through the skin and mucous membranes?
Inflammation- the reaction of a macroorganism to foreign particles penetrating into its internal environment. One of the causes of inflammation is the introduction of infectious agents into the body. The development of inflammation leads to the destruction of microorganisms or release from them.
Inflammation is characterized by a violation of the circulation of blood and lymph in the lesion. It is accompanied by fever, swelling, redness and pain.
Cellular non-specific defense factors
Phagocytosis
One of the main mechanisms of inflammation is phagocytosis - the process of absorption of bacteria.
The phenomenon of phagocytosis was first described by I. I. Mechnikov. He began studying phagocytosis from a single-celled amoeba, for which phagocytosis is a way of digesting food. Having traced this process at different stages of the development of the animal world, I. I. Mechnikov completed it with the discovery of specialized human cells, with the help of which the destruction of bacteria, the resorption of dead cells, foci of hemorrhages, etc. is of great importance.
Various cells of the body (blood leukocytes, endothelial cells of blood vessels) have phagocytic activity. This activity is most pronounced in mobile polymorphonuclear leukocytes, blood monocytes and tissue macrophages, and to a lesser extent in bone marrow cells. All mononuclear phagocytic cells (and their bone marrow precursors) are combined into a system of mononuclear phagocytes (MPS).
Phagocytic cells have lysosomes that contain more than 25 different hydrolytic enzymes and proteins with antibacterial properties.
Stages of phagocytosis. Stage 1 - the approach of the phagocyte to the object due to the chemical influence of the latter. This movement is called positive chemotaxis (towards the object).
Stage 2 - adhesion of microorganisms to phagocytes.
Stage 3 - the absorption of microorganisms by the cell, the formation of phagosomes.
Stage 4 - the formation of a phagolysosome, where enzymes and bactericidal proteins enter, the death and digestion of the pathogen.
The process that ends with the death of phagocytosed microbes is called complete phagocytosis.
However, some microorganisms, being inside phagocytes, do not die, and sometimes even multiply in them. These are gonococci, Mycobacterium tuberculosis, Brucella. This phenomenon is called incomplete phagocytosis; while phagocytes die.
Like other physiological functions, phagocytosis depends on the state of the body - the regulatory role of the central nervous system, nutrition, age.
The phagocytic activity of leukocytes changes in many and often non-infectious diseases. By determining a number of indicators of phagocytosis, it is possible to establish the course of the disease - recovery or deterioration of the patient's condition, the effectiveness of the treatment, etc.
To assess the functional state of phagocytes, the absorption activity is most often determined by two tests: 1) phagocytic index - the percentage of phagocytic cells (the number of leukocytes with absorbed microbes out of 100 observed); 2) phagocytic number - the average number of microbes or other objects of phagocytosis absorbed by one leukocyte.
The bactericidal capabilities of phagocytes are determined by the number of lysosomes, the activity of intracellular enzymes, and other methods.
The activity of phagocytosis is associated with the presence of antibodies in the blood serum - opsonins. These antibodies enhance phagocytosis, preparing the cell surface for absorption by the phagocyte.
The activity of phagocytosis largely determines the body's immunity to a particular pathogen. In some diseases, phagocytosis is the main protective factor, in others it is an auxiliary one. However, in all cases, the lack of phagocytic ability of cells dramatically worsens the course and prognosis of the disease.
Cellular reactivity
The development of the infectious process and the formation of immunity are completely dependent on the primary sensitivity of cells to the pathogen. Hereditary species immunity is an example of the lack of sensitivity of cells of one animal species to microorganisms that are pathogenic for others. The mechanism of this phenomenon is not well understood. It is known that cell reactivity changes with age and under the influence of various factors (physical, chemical, biological).
Control questions
1. What is phagocytosis?
2. What stages of phagocytosis do you know?
3. What is complete and incomplete phagocytosis?
Humoral factors of nonspecific protection
In addition to phagocytes, there are soluble non-specific substances in the blood that have a detrimental effect on microorganisms. These include complement, properdin, β-lysines, x-lysines, erythrin, leukins, plakins, lysozyme, etc.
Complement (from Latin complementum - addition) is a complex system of protein fractions of the blood, which has the ability to lyse microorganisms and other foreign cells, such as red blood cells. There are several complement components: C1, C2, C3, etc.
e. Complement is destroyed at a temperature of 55 ° C for 30 minutes. This property is called thermolability. It is also destroyed by shaking, under the influence of UV rays, etc. In addition to blood serum, complement is found in various body fluids and in inflammatory exudate, but is absent in the anterior chamber of the eye and cerebrospinal fluid.
Properdin (from Latin properde - to prepare) is a group of components of normal blood serum that activates complement in the presence of magnesium ions. It is similar to enzymes and plays an important role in the body's resistance to infection. A decrease in the level of properdin in the blood serum indicates an insufficient activity of immune processes. β-lysines are thermostable (temperature-resistant) substances of human blood serum that have an antimicrobial effect, mainly against gram-positive bacteria. Destroyed at 63 ° C and under the action of UV rays.
X-lysine is a thermostable substance isolated from the blood of patients with high fever. It has the ability to complement lyse bacteria, mainly gram-negative ones, without participation. Withstands heating up to 70-100°C.
Erythrin isolated from animal erythrocytes. It has a bacteriostatic effect on diphtheria pathogens and some other microorganisms.
Leukins are bactericidal substances isolated from leukocytes. Thermostable, destroyed at 75-80 ° C. Found in the blood in very small quantities.
Plakins are substances similar to leukins isolated from platelets.
Lysozyme is an enzyme that destroys the membrane of microbial cells. It is found in tears, saliva, blood fluids. The rapid healing of wounds of the conjunctiva of the eye, mucous membranes of the oral cavity, nose is largely due to the presence of lysozyme.
The constituent components of urine, prostatic fluid, extracts of various tissues also have bactericidal properties. Normal serum contains a small amount of interferon.
Control questions
1. What are humoral nonspecific defense factors?
2. What humoral factors of nonspecific defense do you know?
