Leukocytes.

Leukocytes, or white blood cells, are colorless cells containing a nucleus and protoplasm. Their size is 8-20 microns. In the blood of healthy people at rest, the number of leukocytes fluctuates within 4,0—9,0- 10 9 /l(4000-9000 in 1 mm 3). An increase in the number of white blood cells in the blood is called leukocytosis, decrease - leukopenia.

Leukocytes are divided into two groups: granular leukocytes, or granulocytes, and non-grained, or agranulocytes.

Granular leukocytes differ from non-granular ones in that their protoplasm has inclusions in the form of grains that can be stained with various dyes. The granulocytes are neutrophils, eosinophils and basophils . Neutrophils according to the degree of maturity, they are divided into myelocytes, metamyelocytes (young neutrophils), rod-nuclear and segmented. The bulk of the circulating blood is made up of segmented neutrophils. Myelocytes and metamyelocytes are not found in the blood of healthy people.

Agranulocytes do not have inclusions in their protoplasm. These include lymphocytes and monocytes .

Percentage between certain types leukocytes are called leukocyte formula

In a number of diseases, the nature of the leukocyte formula changes. At acute inflammatory processes (acute bronchitis, pneumonia) increases the number of neutrophilic leukocytes (neutrophilia). In allergic conditions (bronchial asthma, hay fever), the content of eosinophils mainly increases ( eosinophilia). Eosinophilia observed also with helminthic invasions. For sluggish chronic diseases (rheumatism, tuberculosis) is characterized by an increase in the number of lymphocytes (lymphocytosis). Thus, the analysis of the leukocyte formula has a diagnostic value.

properties of leukocytes. Amoeba mobility- the ability of leukocytes to actively move due to the formation of protoplasmic outgrowths - pseudopods (pseudopodia). Under diapedesis should understand the property of leukocytes to penetrate through the wall of the capillary. In addition, leukocytes can absorb and digest foreign bodies and microorganisms - phagocytosis.

Leukocytes that absorb and digest microorganisms are called phagocytes. Leukocytes absorb not only bacteria that have entered the body, but also dying cells of the body itself.

Functions of leukocytes. One of the most important functions performed by leukocytes is protective. Leukocytes are able to produce special substances - leukins , which cause the death of microorganisms that have entered the human body. Some white blood cells (basophils, eosinophils) form antitoxins - substances that neutralize the waste products of bacteria, and thus have a detoxifying property. Leukocytes are capable of producing antibodies. Antibodies can long time remain in the body, so re-infection of a person becomes impossible. Finally, leukocytes (basophils, eosinophils) are related to the processes of blood coagulation and fibrinolysis - defensive reactions of the body.

Leukocytes stimulate regenerative(restorative) processes in the body, accelerate wound healing.

Monocytes take an active part in the processes destruction dying cells and tissues of the body due to phagocytosis.

Enzymatic function. Leukocytes contain various enzymes necessary for the process of intracellular digestion.

Immunity- immunity of the body to infectious and non-infectious agents and substances with antigenic properties. And immune system - the totality of all lymphoid organs (thymus gland, spleen, lymph nodes) and the accumulation of lymphoid cells. The main element of the lymphoid system is lymphocyte.

Distinguish humoral and cellular immunity. humoral immunity provided primarily through B-lymphocytes . B-lymphocytes as a result complex interactions With T-lymphocytes and monocytes are converted into plasmocytes- Cells that produce antibodies. As a result of the development of humoral immunity, the body is freed from foreign substances (bacteria, viruses, etc.), which enter it from environment.Cellular immunity (the reaction of transplanted tissue rejection, the destruction of genetically degenerated cells of one's own body) is provided mainly T-lymphocytes . In the reactions of cellular immunity can also take part and macrophages (monocytes).

platelets.

platelets, or platelets, are oval or rounded formations with a diameter of 2–5 µm. The number of platelets in the blood is 180-320 x 10 9 /l(180,000-320,000 in 1 mm 3). An increase in platelets in peripheral blood is called thrombocytosis, decrease - thrombocytopenia.

properties of platelets. Platelets are capable of phagocytosis and movement due to the formation of pseudopodia (pseudopodia). The physiological properties of platelets also include their the ability to adhere to a foreign surface and stick together between yourself under the influence of various reasons. Platelets are very easily destroyed. They are able to secrete and absorb some biologically active substances: serotonin, epinephrine, norepinephrine. All the considered features of platelets determine their participation in stopping bleeding.

Functions of platelets. Platelets take active participation in blood coagulation and fibrinolysis(dissolution of the blood clot).

Biologically active compounds were found in the plates, due to which they participate in stop bleeding (hemostasis).

In addition, platelets perform protective function due to gluing (agglutination) of bacteria and phagocytosis, they are able to produce some enzymes(amylolytic, proteolytic, etc.), necessary not only for the normal life of the plates, but also for the process of stopping bleeding. Platelets affect the state of histohematic barriers, changing the permeability of the capillary wall(release of serotonin and a special protein - protein S) into the bloodstream.

Leukocytes, or white blood cells, are colorless cells containing nuclei of various shapes. 1 mm3 of a healthy person's blood contains about 6000-8000 leukocytes.

When examining a stained blood smear under a microscope, one can notice that leukocytes have a variety of color shapes. tab. II). There are two groups of leukocytes: granular and non-granular. The former have small grains (granules) in the cytoplasm, stained with different dyes in blue, red or purple. Non-granular forms of leukocytes do not have such grains.

Among non-granular leukocytes, lymphocytes are distinguished - round cells with very dark rounded nuclei - and monocytes - larger cells with irregularly shaped nuclei.

Granular leukocytes react differently to different dyes. If the grains of the cytoplasm are better stained with basic (alkaline) dyes, then such forms are called basophils, if acidic - eosinophils (eosin is an acidic dye), and if the cytoplasm is stained with neutral dyes - neutrophils.

There is a certain ratio between the individual forms of leukocytes. Ratio various forms leukocytes, expressed as a percentage, is called the leukocyte formula (Table 3).

Table 3. Leukocyte blood formula of a healthy person

In some diseases, characteristic changes in the ratio of individual forms of leukocytes are observed. In the presence of worms, the number of eosinophils increases, with inflammation, the number of neutrophils increases. In tuberculosis, an increase in the number of lymphocytes is usually noted.

Often the leukocyte formula changes during the course of the disease. In the acute period of an infectious disease, with a severe course of the disease, eosinophils may not be detected in the blood, and with the onset of recovery, even before visible signs of an improvement in the patient's condition, they are clearly visible under a microscope.

Some drugs also affect the leukocyte formula. With prolonged treatment with penicillin, streptomycin and other antibiotics, the number of eosinophils in the blood may increase, which should alert the doctor regarding the further use of these drugs.

Leukocytes are counted in the same way as erythrocytes (see experiment 6).

Experience 9

When counting leukocytes, dilute blood 10 or 20 times. At a 20-fold dilution, draw blood into the WBC mixer to the 0.5 mark, and then pump the dilution solution to the 11 mark.

Dilute the blood with 3% acetic acid stained with methylene blue. Acetic acid is necessary in order to destroy red blood cells, the presence of which would interfere with the count of leukocytes, and methylene blue tints the nuclei of leukocytes, which serve as the main reference point in the count.

Count white blood cells at low magnification of the microscope. For greater accuracy, count white blood cells in 25 large squares, which corresponds to 400 small squares. The formula for counting the number of leukocytes:

where L is the number of leukocytes in 1 mm3 of blood;

n is the number of leukocytes in 400 small (25 large) squares;

20 - dilution of blood.

In blood different people contains a different number of leukocytes. The body of an adult contains an average of 60 billion leukocytes. The number of white blood cells in the blood can change. After eating, heavy muscle work, the content of these cells in the blood increases. Especially a lot of leukocytes appear in the blood during inflammatory processes.

Leukocytes live 2-4 days. They are formed in the red bone marrow, spleen and lymph nodes.

Unlike erythrocytes, leukocytes are able to move independently in the body.

The value of leukocytes

The main function of leukocytes is to protect the body from microorganisms, foreign proteins, foreign bodies penetrating into the blood and tissues.

Leukocytes have the ability to move independently, releasing pseudopods (pseudopodia). They can leave the blood vessels, penetrating through the vascular wall, and move between the cells of various body tissues.

Rice. 9. Phagocytosis of a bacterium by a leukocyte (three successive stages)

In blood vessels, leukocytes move along the walls, sometimes even against the flow of blood. The speed of movement of different leukocytes is not the same. The most rapidly moving neutrophils - about 30 microns in 1 min; lymphocytes and basophils move more slowly. In diseases, the rate of movement of leukocytes, as a rule, increases. This is due to the fact that pathogenic microbes that have entered the body as a result of their vital activity emit substances that are toxic to humans - toxins. They cause the accelerated movement of leukocytes.

Approaching the microorganism, leukocytes wrap it with pseudopods and draw it into the cytoplasm (Fig. 9.). One neutrophil can absorb 20-30 microbes. After 1 hour, all of them are digested inside the neutrophil. This happens with the participation of special enzymes that destroy microorganisms.

If a foreign body is larger than a leukocyte, then groups of neutrophils accumulate around it, forming a barrier. Digesting or destroying this foreign body together with surrounding tissues, leukocytes die. As a result, an abscess forms around the foreign body, which after a while breaks and its contents are thrown out of the body.

Absorption and digestion by leukocytes of various microbes, protozoa and any foreign substances that enter the body is called phagocytosis, and the leukocytes themselves are called phagocytes.

The phenomenon of phagocytosis was studied by I. I. Mechnikov.

Leukocytes play an important role in the release of the body from dead cells. In the human body, the process of aging and death of cells and the birth of new cells is constantly going on. If dead cells were not destroyed, then the body would be poisoned by decay products and life would become impossible. Leukocytes gather around dead cells, draw them inward and, with the help of enzymes, break them down into simpler compounds that are used by the body.

Phagocytosis - defensive reaction organism, contributing to the preservation of the constancy of its internal environment.

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Leukocytes

The content of leukocytes in the peripheral blood of an adult is 4 - 9 x 10 in 1 liter. However, their number is subject to fluctuations: even when eating, their number changes. Leukocytes are mobile cells: they can freely pass through the vascular wall (they are able to pass between vascular endothelial cells and epithelial cells, through basement membranes) into the connective tissue of organs, where they perform the main protective functions. The movement of cells is carried out as a result of a change in viscosity like an amoeba and by the formation of an inducing membrane at the anterior end of the cell due to the surface layers of the cytoplasm. At a temperature of 37 leukocytes move at a speed of 4-50 microns per minute. The rate of movement of leukocytes depends on temperature, chemical composition, Рh, consistency of the medium, etc. The direction of movement of leukocytes is determined by chemotaxis under the influence of chemical stimuli - products of tissue decay.

In leukocytes, the cytoskeleton is well developed, represented by actin filaments and microtubules, which provide the formation of pseudopodia and the movement of leukocytes.

Leukocytes are a heterogeneous group of cells. Among them, granular (granulocytes) and non-granular (agranulocytes) are distinguished. In granular leukocytes, blood staining according to Romanovsky-Giemsa with a mixture of acidic and basic dyes reveals specific granularity (neutrophilic, eosinophilic and basophilic) and segmented nuclei. In accordance with the nature of the granularity, granulocytes are divided into neutrophilic, eosinophilic and basophilic leukocytes. In non-granular leukocytes, there is no specific granularity and contains non-segmented nuclei. Nongranular leukocytes include lymphocytes and monocytes.

The percentage of all leukocytes in human blood is called the leukocyte formula. Content various kinds leukocytes changes with various diseases, with physical and emotional stress. For example, in acute bacterial infections, the content of neutrophils in the blood increases. With viral and chronic infections, the content of lymphocytes increases, and with helminthic invasions, eosinophilia is observed.

Leukocytes perform a protective function, since almost all white blood cells are capable of phagocytosis. Lymphocyte cells are actively involved in the implementation of humoral and cellular immunity. Finally, leukocytes determine the group affiliation of blood by leukocytes. There are currently 92 known leukocyte blood groups. The last blood type was found in Shanghai (СSh3), it is found mainly in eastern peoples. Blood groups by leukocytes must be taken into account when determining consanguinity, as well as during bone marrow and various organ transplantation.

Granular leukocytes

Neutrophils are the most numerous group of leukocytes in peripheral blood: their number is 40-75%. Their diameter in a live drop is 8-10 microns, and in a smear 10-12 microns. Life expectancy is 8-10 days. The nucleus of a mature neutrophil consists of several segments connected by thin bridges, therefore such neutrophils are called segmented. During the life of the cell, the number of segments in the nucleus increases. Women are characterized by the presence in most neutrophils of sex chromatin (X-chromosome) in the form of a drumstick - Barr's body. In the peripheral blood of an adult, young neutrophils are also found, in which the nucleus is round or slightly bean-shaped. The content of such neutrophils should not exceed 0.5% of the total number of leukocytes. In addition, stab neutrophils are found in the blood, which contain a nucleus in the form of a stick or the letter S. The content of such cells in the peripheral blood ranges from 2-5%. Young and stab neutrophils are poorly differentiated neutrophils. The number of young neutrophils increases with blood loss or inflammation, when hematopoiesis in the bone marrow increases and immature neutrophils are released into the blood.

Organoids are located in the inner part of the cytoplasm: the Golgi apparatus, granular endoplasmic reticulum, single mitochondria. Neutrophil contains a large number of inclusions of glycogen. The energy obtained by glycolysis allows the cell to exist in oxygen-poor damaged tissues. The number of mitochondria and organelles required for protein synthesis is minimal, so neutrophils cannot exist for long.

There are two types of granularity in neutrophils: specific and azurophilic. The number of grains in each neutrophil can reach 200. The specific granularity is very fine (dusty), distributed evenly throughout the cytoplasm and stained with a mixture of acidic and basic dyes in lilac color. Specific granularity contains proteins with bacteriostatic and bactericidal properties: lactoferrin (it binds iron ions, which promotes adhesion of bacteria), lysozyme, which has a bactericidal effect.

Azurophilic granularity is represented by larger granules containing proteins with an antibacterial effect: myeloperoxidase (it produces molecular hydrogen with a bactericidal effect from hydrogen peroxide), cationic proteins and lysozyme, as well as acid phosphatase. Azurophilic granules are primary lysosomes. In the process of differentiation in the bone marrow, azurophilic granules appear earlier, therefore they are called primary granularity, in contrast to secondary-specific.

Neutrophils are capable of active migration and active phagocytosis. The main activity of neutrophils takes place outside the vascular bed. They enter the connective tissue and accumulate in the foci of inflammation, where they actively phagocytize microbes. The destruction and digestion of the absorbed particles occurs with the help of lysosomes, which gradually disappear. After the disappearance of all lysosomes, the neutrophil dies. The phagocytic activity of neutrophils gradually decreases with age. The most pronounced phagocytic activity in neutrophils at the age of 18-20 years.

Thus, neutrophils perform a protective function due to active phagocytosis: they phagocytize tissue decay products, microorganisms, therefore they are called the main cellular elements of the body's nonspecific defense. In addition, neutrophils secrete biologically active compounds - cytokines (neutrophilokines), which stimulate the proliferation of lymphocytes and the production of immunoglobulins.

Eosinophils are a less common white blood cell population than neutrophils. The blood of an adult contains 2-5% of eosinophils. Their number varies during the day and maximum in the morning. In the peripheral blood, they circulate for only 5-8 hours, and then, as a rule, they go into tissues that are in contact with the external environment (mucous membranes of the respiratory, genitourinary tract and intestines). In a live drop, the size of eosinophils is 8-10 microns, and in a smear - 12-14 microns. Life expectancy is 8-14 days.

In the cytoplasm, a few mitochondria, the Golgi apparatus and the cell center are found. The granular endoplasmic reticulum is poorly developed. The nucleus of eosinophils is lobulated and usually consists of two segments connected by a bridge. Less common are nuclei with three and four segments.

Eosinophils have a positive chemotaxis to histamine secreted by mast cells, as well as to lymphokines secreted by stimulated T-lymphocytes and immune complexes.

Eosinophils suppress the intensity of the allergic inflammatory reaction, as they inactivate histamine (due to histaminase), and suppress mast cell degranulation. In addition, eosinophils absorb histamine granules produced by mast cells, binding it with the help of receptors. That is why with allergic diseases, bronchial asthma, allergic rhinitis, food allergies, allergic dermatitis, the number of eosinophils increases dramatically.

Eosinophils perform a protective function due to the ability to phagocytosis of some tissue decay products, bacteria. In addition, eosinophils are involved in the regulation of the immune response: they are able to phagocytize some foreign compounds, secrete cytokines.

Basophils are a very small population of leukocytes. The blood of an adult contains only 0.5-1% of basophils. At the same time, in a number of animals the content of eosinophils is very high. For example, in birds they contain 3-4%, and in frogs, up to 23%. The content of basophils fluctuates even during the day: there are more of them in the second half of the day. Under stressful conditions, the number of basophils is significantly reduced.

Basophils have sizes in the range of 10-12 microns. The lifespan of these cells has not been precisely established. Basophil nuclei are also segmented and contain several segments, but the number of segments is always less than that of neutrophils.

The cytoplasm of basophils contains a specific granularity: large, unevenly located in the cytoplasm and stained with the main dye in purple due to the high content of sulfated glycosaminoglycans.

In the cytoplasm, mitochondria, a relatively poorly developed secretory apparatus, ribosomes, and the Golgi apparatus are detected.

Secretory granules of basophils contain proteoglycans, glycosaminoglycans (including heparin), vasoactive histamine, neutral proteases and other enzymes. In addition, like neutrophils, basophils produce prostaglandins and leukotrienes.

Basophils are involved in the regulation of the processes of the blood coagulation system due to heparin, and due to histamine they are involved in the regulation of the permeability of the vascular wall. They perform a protective function due to the ability to phagocytosis. Thus, it has been established that basophils are able to phagocytize sensitized erythrocytes, foreign compounds. Basophils are involved in the regulation of the intensity of inflammatory reactions of an allergic nature (immediate type hypersensitivity). When an antigen (allergen) first enters the body, plasma cells secrete IgE, which interact with numerous receptors for the Fc region of IgE on the basophil and mast cell plasmalemma. Re-entry into the body of the allergen causes the development within a few minutes of a secretory reaction - anaphylactic degranulation. As a result, under the influence of secreted substances, vasodilation occurs, the permeability of the vascular wall increases, and tissue damage occurs (for example, the epithelium of the bronchi and intestines). The rapid release of mediators by a large number of mast cells and basophils causes a sharp contraction of smooth muscles (bronchospasm) and the development of an attack of bronchial asthma, as well as allergic rhinitis, allergic dermatitis, food allergies, and in exceptional cases - to the development of anaphylactic shock.

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Leukocytes (white blood cells)

Their number is 3.5–9.010^9 dm^–3, it may depend on sex, age, ecology and other factors.

Leukocytes go through three phases:

1) in the organs of hematopoiesis (red bone marrow and lymphogenous tissue);

2) circulation in the blood (just a few hours);

3) tissue after leaving the bloodstream (several days, then dies).

For some cells, recirculation is possible - a return to the lumen of the vessels.

The number of leukocytes in a blood smear is described by the leukocyte formula. The leukocyte formula is the percentage of the number of leukocytes of one type to total number leukocytes found in a smear [the percentage of some leukocytes is even less than 1%, so it is desirable to count at least 100 leukocytes].

Leukocytes are divided into two groups according to the presence of granularity in the cytoplasm:

1) Granular (granulocytes). The cytoplasm contains small dust-like granules, poorly distinguishable by conventional microscopy, containing a large number of enzymes (peroxidase, alkaline phosphatase, etc.). These granules are stained with various dyes, this is the basis for their division into:

a) neutrophilic;

b) eosinophilic;

c) basophilic.

2) Non-granular (agranulocytes):

a) lymphocytes

b) monocytes.

Azur-II-eosin is used for staining (Romanovsky-Giemsa method).

According to the degree of differentiation, neutrophils are divided into young, stab and segmented.

Segmented leukocytes (45-70%) are mature neutrophils, the nucleus consists of 3-5 segments connected by thin bridges. In some nuclei, there may be an outgrowth in the form of a drumstick - a condensed X chromosome, the presence of such chromosomes indicates that the blood is female.

Stab leukocytes (1-3-5%) are younger cells. Their core is S-shaped, but other shapes, such as C-shaped, are also common.

Young leukocytes, or meta-leukocytes (0-0.5%). They have a bean-shaped nucleus

According to the ratio of these forms in the leukocyte formula, a shift to the right or a shift to the left is judged.

A shift to the left - the predominance of young and rod-shaped - indicates irritation of the red bone marrow, a shift to the right - more mature (segmented) and almost absent young and rod-shaped - indicates the suppression of leukocytopoiesis, which is a poor prognostic sign. Since all these stages have different forms, they are referred to as polymorphonuclear leukocytes.

Neutrophilic leukocytes make up 50–75% (of the number of leukocytes). Their size in a smear is 10–12 µm. Contain fine dusty neutrophilic granularity.

The development cycle is about 8 days: the hematopoietic phase is about 6 days, the vascular phase is 6–10 hours, and the tissue phase is about 2 days. The neutrophilic leukocyte goes beyond the vessel, and, having a positive chemotaxis, moves with the help of pseudopodia to the focus of irritation, where it plays the role of a microphage: it phagocytizes toxic substances and microorganisms. The phagocytic activity of neutrophils is 70–99%, the phagocytic index (i.e., the ability to capture a certain number of microorganisms) is 12–25.

Neutrophils form a leukocyte shaft around the focus of inflammation or come to the surface of the epithelial layer at the joints in order to protect the body from damage. Either way, they die.

Eosinophilic leukocytes (2-5%) have a smear size of 12-14 microns. Slightly oxyphilic stained, large eosin-stained granules (lysosomes) containing a number of biologically active substances, enzymes and other substances that can affect certain cells of the population are determined in the cytoplasm. They have a bilobed core (like a bunch of boxing gloves). Life cycle reaches 5-6 days in the hematopoietic organs, 6 or less in the bloodstream, and several days - the tissue phase. Eosinophilic leukocytes are microphages, but they are specialized to engulf antigen-antibody complexes that form during a humoral response to a foreign substance or during an allergic reaction.

The number of eosinophils increases with helminth infestations, eczema, childhood infections, especially their number increases in those places where the greatest number of antibody-antigen complexes are formed, i.e. along the respiratory tract and intestines.

Basophilic leukocytes (0–0.5%) are in many ways similar to the previous ones, but differ in the content of biologically active substances. Their sizes are 11–13 µm.

The life cycle also consists of three phases: hematopoietic (in the red bone marrow) - 2-4 days; vascular - several hours; tissue - 10 hours or more. The cytoplasm is oxyphilic, the nucleus is S-shaped, has several lobes. In the cytoplasm, the lysosomal apparatus is well expressed, large basophilic granules containing histamine and heparin, which change the permeability of the walls of blood vessels. An increase in the content of basophilic leukocytes is associated with severe systemic lesions or intoxications.

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Physiology of blood 4

Leukocytes, or white blood cells, are colorless cells containing a nucleus and protoplasm. Their size is 8-20 microns. In the blood of healthy people at rest, the number of leukocytes ranges from 4.0-9.0-109 / l (4000-9000 in 1 mm3). An increase in the number of leukocytes in the blood is called leukocytosis, a decrease is called leukopenia.

Leukocytes are divided into two groups: granular leukocytes, or granulocytes, and non-granular, or agranulocytes.

Granular leukocytes differ from non-granular ones in that their protoplasm has inclusions in the form of grains that can be stained with various dyes. Granulocytes include neutrophils, eosinophils, and basophils. According to the degree of maturity, neutrophils are divided into myelocytes, metamyelocytes (young neutrophils), rod-nuclear and segmented. The bulk of the circulating blood is made up of segmented neutrophils. Myelocytes and metamyelocytes are not found in the blood of healthy people.

Agranulocytes do not have inclusions in their protoplasm. These include lymphocytes and monocytes.

The percentage ratio between individual types of leukocytes is called the leukocyte formula

In a number of diseases, the nature of the leukocyte formula changes. In acute inflammatory processes (acute bronchitis, pneumonia), the number of neutrophilic leukocytes (neutrophilia) increases. In allergic conditions (bronchial asthma, hay fever), the content of eosinophils (eosinophilia) mainly increases. Eosinophilia is also observed in helminthic invasions. Indolent chronic diseases (rheumatism, tuberculosis) are characterized by an increase in the number of lymphocytes (lymphocytosis). Thus, the analysis of the leukocyte formula has a diagnostic value.

properties of leukocytes. Amoeba mobility - the ability of leukocytes to actively move due to the formation of protoplasmic outgrowths - pseudopodia (pseudopodia). Diapedesis should be understood as the property of leukocytes to penetrate through the capillary wall. In addition, leukocytes can absorb and digest foreign bodies and microorganisms - phagocytosis.

Leukocytes that absorb and digest microorganisms are called phagocytes. Leukocytes absorb not only bacteria that have entered the body, but also dying cells of the body itself.

Functions of leukocytes. One of the most important functions performed by leukocytes is protective. Leukocytes are able to produce special substances - leukins, which cause the death of microorganisms that have entered the human body. Some leukocytes (basophils, eosinophils) form antitoxins - substances that neutralize the waste products of bacteria, and thus have a detoxifying property. Leukocytes are capable of producing antibodies. Antibodies can remain in the body for a long time, so that a person becomes infected again. Finally, leukocytes (basophils, eosinophils) are related to the processes of blood coagulation and fibrinolysis - the protective reactions of the body.

Leukocytes stimulate regenerative (restorative) processes in the body, accelerate wound healing.

Monocytes take an active part in the processes of destruction of dying cells and body tissues due to phagocytosis.

enzymatic function. Leukocytes contain various enzymes necessary for the process of intracellular digestion.

Immunity - the body's immunity to infectious and non-infectious agents and substances that have antigenic properties. The immune system is the totality of all lymphoid organs (thymus gland, spleen, lymph nodes) and the accumulation of lymphoid cells. The main element of the lymphoid system is the lymphocyte.

Distinguish between humoral and cellular immunity. Humoral immunity is provided mainly by B-lymphocytes. B-lymphocytes as a result of complex interactions with T-lymphocytes and monocytes turn into plasma cells - cells that produce antibodies. As a result of the development of humoral immunity, the body is freed from foreign substances (bacteria, viruses, etc.) that enter it from the environment. Cellular immunity (rejection of transplanted tissue, destruction of genetically degenerated cells of one's own body) is provided mainly by T-lymphocytes. Macrophages (monocytes) can also take part in the reactions of cellular immunity.

platelets.

Platelets, or platelets, are oval or rounded formations with a diameter of 2-5 microns. The number of platelets in the blood is 180-320 x 109 / l (180,000-320,000 in 1 mm3). An increase in the content of platelets in the peripheral blood is called thrombocytosis, a decrease is called thrombocytopenia.

properties of platelets. Platelets are capable of phagocytosis and movement due to the formation of pseudopodia (pseudopodia). The physiological properties of platelets also include their ability to stick to a foreign surface and stick together under the influence of various reasons. Platelets are very easily destroyed. They are able to secrete and absorb some biologically active substances: serotonin, adrenaline, norepinephrine. All the considered features of platelets determine their participation in stopping bleeding.

Functions of platelets. Platelets take an active part in the process of blood coagulation and fibrinolysis (blood clot dissolution).

Biologically active compounds were found in the plates, due to which they are involved in stopping bleeding (hemostasis).

In addition, platelets perform a protective function due to agglutination of bacteria and phagocytosis, they are able to produce certain enzymes (amylolytic, proteolytic, etc.) that are necessary not only for the normal functioning of the plates, but also for the process of stopping bleeding. Platelets affect the state of histohematic barriers by changing the permeability of the capillary wall (the release of serotonin and a special protein, protein S, into the bloodstream).

Leukocytes, or white blood cells, are colorless cells containing nuclei of various shapes. 1 mm 3 of the blood of a healthy person contains about 6000-8000 leukocytes.

When examining a stained blood smear under a microscope, one can notice that leukocytes have a variety of color shapes. tab. II). There are two groups of leukocytes: granular and non-granular. The former have small grains (granules) in the cytoplasm, stained with different dyes in blue, red or purple. Non-granular forms of leukocytes do not have such grains.

Among nongranular leukocytes, there are lymphocytes- round cells with very dark rounded nuclei - and monocytes- larger cells with irregularly shaped nuclei.

Granular leukocytes react differently to different dyes. If the grains of the cytoplasm are better stained with basic (alkaline) paints, then such forms are called basophils if sour - eosinophils(eosin is an acidic dye), and if the cytoplasm is stained with neutral dyes - neutrophils.

There is a certain ratio between the individual forms of leukocytes. The ratio of various forms of leukocytes, expressed as a percentage, is called leukocyte formula(Table 3).

In some diseases, characteristic changes in the ratio of individual forms of leukocytes are observed. In the presence of worms, the number of eosinophils increases, with inflammation, the number of neutrophils increases. In tuberculosis, an increase in the number of lymphocytes is usually noted.

Often the leukocyte formula changes during the course of the disease. In the acute period of an infectious disease, with a severe course of the disease, eosinophils may not be detected in the blood, and with the onset of recovery, even before visible signs of an improvement in the patient's condition, they are clearly visible under a microscope.

Some drugs also affect the leukocyte formula. With prolonged treatment with penicillin, streptomycin and other antibiotics, the number of eosinophils in the blood may increase, which should alert the doctor regarding the further use of these drugs.

Leukocytes are counted in the same way as erythrocytes (see experiment 6).

Experience 9

When counting leukocytes, dilute blood 10 or 20 times. At a 20-fold dilution, draw blood into the WBC mixer to the 0.5 mark, and then pump the dilution solution to the 11 mark.

Dilute the blood with 3% acetic acid stained with methylene blue. Acetic acid is necessary in order to destroy red blood cells, the presence of which would interfere with the count of leukocytes, and methylene blue tints the nuclei of leukocytes, which serve as the main reference point in the count.

Count white blood cells at low magnification of the microscope. For greater accuracy, count white blood cells in 25 large squares, which corresponds to 400 small squares. The formula for counting the number of leukocytes:

where L is the number of leukocytes in 1 mm 3 of blood;

n is the number of leukocytes in 400 small (25 large) squares;

20 - dilution of blood.

The blood of different people contains an unequal number of leukocytes. The body of an adult contains an average of 60 billion leukocytes. The number of white blood cells in the blood can change. After eating, heavy muscle work, the content of these cells in the blood increases. Especially a lot of leukocytes appear in the blood during inflammatory processes.

Leukocytes live 2-4 days. They are formed in the red bone marrow, spleen and lymph nodes.

Unlike erythrocytes, leukocytes are able to move independently in the body.

The value of leukocytes

The main function of leukocytes is to protect the body from microorganisms, foreign proteins, foreign bodies penetrating into the blood and tissues.

Leukocytes have the ability to move independently, releasing pseudopods (pseudopodia). They can leave the blood vessels, penetrating through the vascular wall, and move between the cells of various body tissues.

In blood vessels, leukocytes move along the walls, sometimes even against the flow of blood. The speed of movement of different leukocytes is not the same. The most rapidly moving neutrophils - about 30 microns in 1 min; lymphocytes and basophils move more slowly. In diseases, the rate of movement of leukocytes, as a rule, increases. This is due to the fact that pathogenic microbes that have entered the body as a result of their vital activity emit substances that are toxic to humans - toxins. They cause the accelerated movement of leukocytes.

Approaching the microorganism, leukocytes wrap it with pseudopods and draw it into the cytoplasm (Fig. 9.). One neutrophil can absorb 20-30 microbes. After 1 hour, all of them are digested inside the neutrophil. This happens with the participation of special enzymes that destroy microorganisms.

If a foreign body is larger than a leukocyte, then groups of neutrophils accumulate around it, forming a barrier. Digesting or destroying this foreign body together with surrounding tissues, leukocytes die. As a result, an abscess forms around the foreign body, which after a while breaks and its contents are thrown out of the body.

Absorption and digestion by leukocytes of various microbes, protozoa and any foreign substances that enter the body is called phagocytosis, while the leukocytes themselves phagocytes.

The phenomenon of phagocytosis was studied by I. I. Mechnikov.

Leukocytes play an important role in the release of the body from dead cells. In the human body, the process of aging and death of cells and the birth of new cells is constantly going on. If dead cells were not destroyed, then the body would be poisoned by decay products and life would become impossible. Leukocytes gather around dead cells, draw them inward and, with the help of enzymes, break them down into simpler compounds that are used by the body.

Phagocytosis is a protective reaction of the body, contributing to the preservation of the constancy of its internal environment.

Form and number of leukocytes., or white blood cells, are colorless cells containing nuclei of various shapes. 1 mm 3 of the blood of a healthy person contains about 6000-8000 leukocytes.

When examining a smear of stained blood under a microscope, one can notice that they have a variety of shapes (color. Table XI). There are two groups of leukocytes: grainy and non-granular. The former have small grains (granules) in the cytoplasm, stained with different dyes in blue, red or purple. Non-granular forms of leukocytes do not have such grains.

Among nongranular leukocytes, there are lymphocytes(round cells with very dark, rounded nuclei) and monocytes larger cells with irregularly shaped nuclei).

Grainy by: Treat different dyes differently. If the grains of the cytoplasm are better stained with basic (alkaline) paints, such forms are called basophil nor, if sour eosinophils (eosin is an acidic dye), and if the cytoplasm is stained with neutral dyes - neutrophils.

Rice.48. Phagocytosis of a bacterium by a leukocyte (three successive stages)

There is a certain ratio between the individual forms of leukocytes. The ratio of various forms of leukocytes, expressed as a percentage, is called leukocyte formula (tab. 9 ).

Table 9

Leukocyte formula of the blood of a healthy person

Granular leukocytes			Nongranular leukocytes
basophils	eosinophils	neutrophils	lymphocytes	monocytes
	(in absolute	quantities in	1 mm 3 blood)
0-1	3-5	57-73	25-35	3-5
	(in absolute quantities in 1 mm 3 of blood)
35-70	I 140-350	4200-5250	1750-2450	350-560

In some diseases, characteristic changes in the ratio of individual forms of leukocytes are observed. In the presence of worms, the number of eosiiophils increases, with inflammation, the number of neutrophils increases, with tuberculosis, an increase in the number of lymphocytes is often noted.

Often the leukocyte formula changes during the course of the disease. In the acute period of an infectious disease, with a severe course of the disease, eosinophils may not be detected in the blood, and with the onset of recovery, even before visible signs of improvement in the patient's condition, they are clearly visible under a microscope.

They affect the leukocyte formula and some drugs. With prolonged treatment with penicillin, streptomycin and other antibiotics, the number of eosinophils in the blood may increase, which should alert the doctor regarding the further use of these drugs.

Leukocytes are counted in the same way as. when counting white blood cells, dilute 10 or 20 times. For a 20-fold dilution, draw up to the 0.5 mark in the WBC mixer, and then pump the dilution solution into the mixer to the 11 mark.

Dilute with 3% methylene blue tinted acetic acid. Acetic acid is necessary in order to destroy, the presence of which would interfere with the count of leukocytosis, and methylene blue tints the nuclei of leukocytes, which serve as the main reference point in counting.

Count leukocytes at low magnification of the microscope (eyepiece 7x). For greater accuracy, count white blood cells in 25 large squares, which corresponds to 400 small squares. Formula for counting the quantityproperties of leukocytes:

L \u003d (n 4000 20): 400

where L - the number of leukocytes in 1 mm 3 blood; P - the number of leukocytes in 400 small (25 large) squares; 20 - dilution of blood.

The body of an adult contains an average of 60 billion leukocytes. The number of white blood cells in the blood can change. After eating, heavy muscle work, the content of these cells in the blood increases. Especially a lot of leukocytes appear in the blood during inflammatory processes.

The number of leukocytes in 1 mm 3 of blood in children, nursery, preschool and younger school age higher than in adults. The leukocyte blood formula in these ages is also different.

A high content of lymphocytes and a low number of neutrophils in the first years of a child's life gradually level off, reaching almost the same numbers by the age of 5-6. After that, the percentage of neutrophils steadily increases, and the percentage of lymphocytes decreases.

The low content of neutrophils, as well as their insufficient maturity, partly explains the relatively high susceptibility of children younger ages to infectious diseases.

In children of the first years of life, the phagocytic activity of neutrophils is also the lowest.

During the period of rapid growth of the body, hematopoietic organs are characterized by increased sensitivity to adverse effects. external environment. Insufficient exposure of children to the air, excessive load and other violations of hygiene requirements often lead to anemia.

Improper use (overdose) of sunbathing or artificial radiation has a negative effect on the body of children, in particular on their bone marrow. The latter begins to produce a large number of immature blood cells.

The life expectancy of most forms of leukocytes is 2-4 days. Leukocytes are formed in the red bone marrow, spleen and lymph nodes. The process of cell formation blood is coming continuously throughout a person's life. Its intensity is dictated by the needs of the body.

The value of leukocytes

The main function of leukocytes is to protect the body from microorganisms, foreign proteins, foreign bodies penetrating into the blood and tissues.

Leukocytes have the ability to move independently, releasing pseudopods (pseudopodia). They can leave the blood vessels, penetrating through the vascular wall, and move between the cells of various body tissues. Atslowing down the movement of blood, leukocytes adhere to the inner surface of the capillaries and leave the vessels in large numbers, squeezing between the cells of the capillary endothelium. Along the way, they capture and subject microbes and other foreign bodies to intracellular digestion. Leukocytes actively penetrate through intact vascularwalls that easily pass through the membranes, move in the connective tissue under the action of various chemicals formed in the tissues.

AT In blood vessels, leukocytes move along the walls, sometimes even against the flow of blood. Not all cells move at the same speed. Neutrophils move most rapidly - about 30 microns per minute, lymphocytes and basophils move more slowly. In diseases, the rate of movement of leukocytes, as a rule, increases. This is due to the fact that pathogenic microbes that have entered the body, as a result of their vital activity, emit toxins that are poisonous to humans. They cause the accelerated movement of leukocytes.

Approaching the microorganism, leukocytes wrap it with pseudopods and draw it into the cytoplasm (Fig. 48). One neutrophil can absorb 20-30 microbes. An hour later, all of them are digested inside the neutrophil. This happens with the participation of special enzymes that destroy microorganisms.

If a foreign body is larger than a leukocyte, groups of neutrophils accumulate around it, forming a barrier. Digesting or melting this foreign body together with the tissues surrounding it, the leukocytes die. As a result, an abscess forms around the foreign body, which after a while breaks and its contents are thrown out of the body.

FROM Destroyed tissues and dead leukocytes also throw out foreign bodies penetrating into the body.

Absorption and digestion by leukocytes of various microbes, protozoa and any foreign substances that enter the body is called phagocytosis and the leukocytes themselves phagocytes.

The phenomenon of phagocytosis was studied by I. I. Mechnikov. I. I. Mechnikov made his first observation on relatively simple organisms - starfish larvae. He noted thatsplinter in the body of the larva starfish quickly surrounded by mobile cells.

The same thing happens with a person who has stuck his finger. A large number of white blood cells accumulate around the splinter, and outwardly this is manifested by the formation of a white vesicle, consisting of an accumulation of dead leukocytes - pus.

An even more important observation was made by II Mechnikov on freshwater daphnia. He found that if spores of a microscopic fungus penetrate the intestinal wall and enter the body cavity, then mobile cells rush to them, which capture and digest them. As a result, the disease does not develop. If the spore enters the body of daphnia a lot, then the phagocytes do not cope with their task, the spores germinate, which leads to illness and death of the animal.

Content leukocytes in the peripheral blood of an adult is 4 - 9 x 10 in 1 liter. However, their number is subject to fluctuations: even when eating, their number changes. Leukocytes are mobile cells: they can freely pass through the vascular wall (they are able to pass between vascular endothelial cells and epithelial cells, through basement membranes) into the connective tissue of organs, where they perform the main protective functions. The movement of cells is carried out as a result of a change in viscosity like an amoeba and by the formation of an inducing membrane at the anterior end of the cell due to the surface layers of the cytoplasm. At a temperature of 37 leukocytes move at a speed of 4-50 microns per minute. The speed of movement of leukocytes depends on temperature, chemical composition, pH, consistency of the medium, etc. The direction of movement of leukocytes is determined by chemotaxis under the influence of chemical stimuli - products of tissue decay.

Well developed in leukocytes cytoskeleton, represented by actin filaments and microtubules, which provide the formation of pseudopodia and the movement of leukocytes.

Leukocytes are a heterogeneous group of cells. Among them are distinguished granular (granulocytes) and non-granular (agranulocytes). In granular leukocytes, blood staining according to Romanovsky-Giemsa with a mixture of acidic and basic dyes reveals specific granularity (neutrophilic, eosinophilic and basophilic) and segmented nuclei. In accordance with the nature of the granularity, granulocytes are divided into neutrophilic, eosinophilic and basophilic leukocytes. In non-granular leukocytes, there is no specific granularity and contains non-segmented nuclei. Nongranular leukocytes include lymphocytes and monocytes.

The percentage of all white blood cells in human blood is called leukocyte formula. The content of various types of leukocytes changes with various diseases, with physical and emotional stress. For example, in acute bacterial infections, the content of neutrophils in the blood increases. With viral and chronic infections, the content of lymphocytes increases, and with helminthic invasions, eosinophilia is observed.

Leukocytes perform protective function, since almost all white blood cells are capable of phagocytosis. Lymphocyte cells are actively involved in implementation of humoral and cellular immunity. Finally, leukocytes determine blood type by leukocytes. There are currently 92 known leukocyte blood groups. The last blood type was found in Shanghai (CSH2), it is found mainly in eastern peoples. Blood groups by leukocytes must be taken into account when determining consanguinity, as well as during bone marrow and various organ transplantation.

Granular leukocytes

Neutrophils- the most numerous group of leukocytes in peripheral blood: their number is 40-75%. Their diameter in a live drop is 8-10 microns, and in a smear 10-12 microns. Life expectancy is 8-10 days. Nucleus mature neutrophil consists of several segments connected by thin bridges, therefore such neutrophils are called segmented. During the life of the cell, the number of segments in the nucleus increases. Women are characterized by the presence in most neutrophils of sex chromatin (X-chromosome) in the form of a drumstick - Barr's body. In the peripheral blood of an adult, there are also young neutrophils, in which the nucleus is round or slightly bean-shaped. The content of such neutrophils should not exceed 0.5% of the total number of leukocytes. In addition, they are found in the blood stab neutrophils, which contain a nucleus in the form of a stick or the letter S. The content of such cells in the peripheral blood ranges from 2-5%. Young and stab neutrophils are poorly differentiated neutrophils. The number of young neutrophils increases with blood loss or inflammation, when hematopoiesis in the bone marrow increases and immature neutrophils are released into the blood.

In the interior of the cytoplasm are organelles: Golgi apparatus, granular endoplasmic reticulum, single mitochondria. The neutrophil contains a large amount of glycogen inclusions. The energy obtained by glycolysis allows the cell to exist in oxygen-poor damaged tissues. The number of mitochondria and organelles required for protein synthesis is minimal, so neutrophils cannot exist for long.

There are two types of granularity in neutrophils: specific and azurophilic. The number of grains in each neutrophil can reach 200. Specific grain very small (pulverized), evenly distributed throughout the cytoplasm and stained with a mixture of acidic and basic dyes in lilac color. Specific granularity contains proteins with bacteriostatic and bactericidal properties: lactoferrin(it binds iron ions, which contributes to the adhesion of bacteria), lysozyme, with bactericidal action.

Azurophilic granularity represented by larger granules containing proteins with antibacterial action: myeloperoxidase(it produces molecular hydrogen from hydrogen peroxide, which has a bactericidal effect), cationic proteins and lysozyme and acid phosphatase. Azurophilic granules are primary lysosomes. In the process of differentiation in the bone marrow, azurophilic granules appear earlier, therefore they are called primary granularity, in contrast to secondary-specific.

Neutrophils are capable of active migration and active phagocytosis. The main activity of neutrophils takes place outside the vascular bed. They enter the connective tissue and accumulate in the foci of inflammation, where they actively phagocytize microbes. The destruction and digestion of the absorbed particles occurs with the help of lysosomes, which gradually disappear. After the disappearance of all lysosomes, the neutrophil dies. The phagocytic activity of neutrophils gradually decreases with age. The most pronounced phagocytic activity in neutrophils at the age of 18-20 years.

Thus, neutrophils perform protective function due to active phagocytosis: they phagocytize tissue decay products, microorganisms, therefore they are called the main cellular elements of the body's nonspecific defense. In addition, neutrophils secrete biologically active compounds - cytokines (neutrophilokines), which stimulate the proliferation of lymphocytes and the production of immunoglobulins.

Eosinophils - it is a less common white blood cell population than neutrophils. The blood of an adult contains 2-5% of eosinophils. Their number varies during the day and maximum in the morning. In the peripheral blood, they circulate for only 5-8 hours, and then, as a rule, they go into tissues that are in contact with the external environment (mucous membranes of the respiratory, genitourinary tract and intestines). In a live drop, the size of eosinophils is 8-10 microns, and in a smear - 12-14 microns. Life expectancy is 8-14 days.

In the cytoplasm, a few mitochondria, the Golgi apparatus and the cell center are found. The granular endoplasmic reticulum is poorly developed. The nucleus of eosinophils is lobulated and usually consists of two segments connected by a bridge. Less common are nuclei with three and four segments.

Eosinophils have positive chemotaxis to histamine secreted by mast cells, as well as to lymphokines secreted by stimulated T-lymphocytes, and immune complexes.

Eosinophils suppress the intensity of the allergic inflammatory reaction, as they inactivate histamine(due to histaminase), suppress mast cell degranulation. In addition, eosinophils absorb histamine granules, produced by mast cells, binding it with the help of receptors. That is why with allergic diseases, bronchial asthma, allergic rhinitis, food allergies, allergic dermatitis, the number of eosinophils increases dramatically.

Eosinophils perform protective function due to the ability to phagocytosis of some products of tissue decay, bacteria. In addition, eosinophils are involved in regulation of the immune response: they are able to phagocytose some foreign compounds, secrete cytokines.

Basophils is a very small population of leukocytes. The blood of an adult contains only 0.5-1% of basophils. At the same time, in a number of animals the content of eosinophils is very high. For example, in birds they contain 3-4%, and in frogs, up to 23%. The content of basophils fluctuates even during the day: there are more of them in the second half of the day. Under stressful conditions, the number of basophils is significantly reduced.

Basophils have sizes in the range of 10-12 microns. The lifespan of these cells has not been precisely established. Basophil nuclei are also segmented and contain several segments, but the number of segments is always less than that of neutrophils.

The cytoplasm of basophils contains a specific granularity: large, unevenly located in the cytoplasm and stained with the main dye in purple due to the high content of sulfated glycosaminoglycans.

In the cytoplasm, mitochondria, a relatively poorly developed secretory apparatus, ribosomes, and the Golgi apparatus are detected.

Secretory granules of basophils contain proteoglycans, glycosaminoglycans (including heparin), vasoactive histamine, neutral proteases and other enzymes. In addition, like neutrophils, basophils produce prostaglandins and leukotrienes.

Basophils are involved in the regulation of the processes of the blood coagulation system due to heparin, and due to histamine participate in the regulation of vascular wall permeability. They perform protective function, due to the ability to phagocytosis. Thus, it has been established that basophils are able to phagocytize sensitized erythrocytes, foreign compounds. Basophils are involved in the regulation of the intensity of inflammatory reactions of an allergic nature(hypersensitivity of immediate type). When an antigen (allergen) first enters the body, plasma cells secrete IgE, which interact with numerous receptors for the Fc region of IgE on the basophil and mast cell plasmalemma. Re-entry into the body of the allergen causes the development within a few minutes of a secretory reaction - anaphylactic degranulation. As a result, under the influence of secreted substances, vasodilation occurs, the permeability of the vascular wall increases, and tissue damage occurs (for example, the epithelium of the bronchi and intestines). The rapid release of mediators by a large number of mast cells and basophils causes a sharp contraction of smooth muscles (bronchospasm) and the development of an attack of bronchial asthma, as well as allergic rhinitis, allergic dermatitis, food allergies, and in exceptional cases - to the development of anaphylactic shock.