Leukocytes are able to move with the help of. Indicators of leukocytes in the blood: what does their increase or decrease mean? How do leukocytes learn that a virus has entered the body?

Translated from Greek it sounds like “white blood cells”. They are also called white blood cells. They capture and neutralize bacteria, so the main role of white blood cells is to protect the body from disease.

Antonina Kamyshenkova / “Health-Info”

When your white blood cell count changes

Slight fluctuations in your white blood cell count are completely normal. But the blood reacts very sensitively to any negative processes in the body, and in a number of diseases the level of white blood cells changes dramatically. A low level (below 4000 per 1 ml) is called leukopenia, and it can be a consequence, for example, of poisoning with various poisons, radiation, a number of diseases (typhoid fever), and also develop in parallel with iron deficiency anemia. And an increase in white blood cells - leukocytosis - can also be a consequence of certain diseases, for example, dysentery.

If the number of white blood cells increases sharply (up to hundreds of thousands in 1 ml), then this means leukemia - acute leukemia. With this disease, the process of hematopoiesis in the body is disrupted, and many immature white blood cells are formed - blasts, which cannot fight microorganisms. This is a deadly disease, and if left untreated, the patient is at risk.

The phagocytic activity of leukocytes directly affects the level of resistance of the body to foreign microflora. Make an appointment for a free appointment with a doctor. A specialist will conduct a consultation and interpret the test results. Comfort is above all! Get tested without leaving your home or choose the laboratory that is most conveniently located. In order for the test results to be as reliable as possible, it is necessary to properly prepare for their delivery. Save on medical examination by becoming a member of a special discount program. Quality control of clinical laboratory tests, carried out according to international standards, is a guarantee of an accurate diagnosis.

Indicators of leukocytes in the blood: what does their increase or decrease mean?

Thanks to the coordinated work of all systems, our body is protected like a real fortress. Leukocytes are fearless soldiers who are the first to repel harmful microorganisms trying to penetrate the “fortress”. How do we know if everything is okay with our “steadfast knights”? Are there enough of them in the body to protect us from diseases?

In this article, we'll talk about what white blood cells are and find out how to interpret the results of a white blood cell test.

The role of leukocytes in the blood

In English, the word “leukocyte” is translated as “white blood cell” (White Blood Cells, WBC). However, in fact, this is not entirely true. Under a microscope you can see that the cells have different shades: pinkish, bluish, purple. They vary in form and function, but they all have a core in common. White blood cells are produced in the bone marrow and lymph nodes and are round or irregular in shape. Their size ranges from 6 to 20 microns.

The main function of leukocytes is to protect the body and ensure its immunity. The protective properties of cells are based on their ability to move through the walls of capillaries and penetrate into the intercellular space. There, absorption and digestion of foreign particles occurs - phagocytosis.

Interesting fact
The phenomenon of phagocytosis was discovered by the Russian scientist Ilya Mechnikov. For this he was awarded the Nobel Prize in 1908.

The mechanism of action of protective cells - phagocytes - is similar to inflating a balloon. The cell absorbs harmful microorganisms, swelling like a ball. But no longer able to absorb foreign elements, the particle bursts like a balloon filled too much with air. When phagocytes are destroyed, substances are released that cause inflammatory processes in the body. Other leukocytes immediately rush to the lesion. Trying to restore the defense line, they die in large numbers.

As we have already noted, leukocytes have various functions. And while some are directly involved in the “battle” against bacteria and viruses, others “work in the rear,” developing “weapons” for the “army,” or work in “intelligence.”

Types of blood leukocytes and their levels in women, men and children

At the beginning of the 20th century, German biologist Paul Ehrlich discovered different types of leukocytes: neutrophils, lymphocytes, monocytes, eosinophils, basophils. He divided them into two groups: granulocytes and agranulocytes.

Substances of the first group (these include neutrophils, basophils and eosinophils) have a granular structure, a large nucleus and special granules in the cytoplasm. The second group - non-granular leukocytes (monocytes and lymphocytes) - do not contain granules in the cytoplasm.

Let's take a closer look at each type.

Neutrophils

They are segmented and rod-shaped. The first subtype got its name due to constriction segments in the nucleus of mature cells. In immature cells, the nucleus elongates and becomes rod-like - hence the name of the second subtype. Segmented neutrophils predominate in number over band neutrophils. The intensity of hematopoiesis is judged by the ratio of both. When there is a large loss of blood, the body requires more of these cells. Neutrophils do not have time to fully mature in the bone marrow and therefore enter the bloodstream immature. The main function of neutrophils is considered to be phagocytosis. The size of neutrophils is 12 microns. Their lifespan is no more than 8 days.

Lymphocytes

There are 3 groups of lymphocytes. The cells of the three groups are similar in appearance, but differ from each other in function. Thus, B cells recognize foreign structures, producing antibodies. T-killers stimulate the production of antibodies and are responsible for immunity. And NK lymphocytes are cells that provide innate immunity, reducing the risk of developing tumor diseases. Collectively, they are all the main components of the human immune system. Most lymphocytes are at rest; these cells circulate in the blood, controlling the entry of antigen into the body. As soon as the antigen is recognized, lymphocytes are activated, increase in size and prepare an immune response.

Monocytes

These cells are able to move quickly thanks to cytoplasmic outgrowths - pseudopodia. Monocytes reach the site of the inflammatory process, where they secrete active substances - endogenous pyrogens, interleukin-1 and others that provide antiviral protection. When monocytes leave the bloodstream, they become macrophages, which means they engulf microorganisms. This is their function. Due to their large size (about 15 microns), monocytes are able to absorb large foreign particles.

Eosinophils

They fight foreign objects that cause allergies. Their amount in the blood is insignificant, but when a disease occurs, especially of an allergic nature, it increases. They are microphages, that is, they are able to absorb small harmful particles.

Basophils

The cytoplasm of these cells includes histamine and peroxidase - “recognizers” of inflammation that cause an immediate allergic reaction. They are also called “scout cells” because they help other white blood cells detect harmful particles. Basophils can move, but this ability is severely limited. In addition to the listed functions, basophils regulate blood clotting.

For normal human life, it is necessary that the content of leukocytes in the blood does not go beyond normal limits. A general blood test can determine their number. The reference value of leukocytes in the blood depends on the person’s age:

in the first days of life in newborns, the number of leukocytes varies from 9 to 30x10 9 cells/l;
from 1 to 2 weeks - 8.5–15x10 9 cells/l;
from 1 month to six months - 8–12x10 9 cells/l;
from six months to 2 years - 6.6–11.2x10 9 cells/l;
from 2 to 4 years - 5.5–15.5x10 9 cells/l;
from 4 to 6 years - 5–14.5x10 9 cells/l;
from 6 to 10 years - 4.5–13.5x10 9 cells/l;
from 10 to 16 years - 4.5–13x10 9 cells/l;
from 16 years old - 4–10x10 9 cells/l.

In the absence of pathologies and diseases, the number of leukocytes fluctuates depending on the state of the body and the time of day.

The percentage of types of leukocytes is called leukocyte formula. To make the correct diagnosis and prescribe treatment, the doctor studies the number of leukocytes in the blood and this formula. Each type of cell performs its own specific function, so a significant change in their total number and deviation from the norm indicates that a malfunction has occurred in the body. For example, the number of band neutrophils in the blood should be about 1–6%, and segmental neutrophils should be 47–72%, lymphocytes should be 19–37%, monocytes should be 3–11% of the total number of leukocytes, and eosinophils and basophils even less - 0–1% and 0.5–5%, respectively.

What is pus?
When cells actively fight against foreign microflora that have entered the body, they die in large numbers. The “graveyard” of leukocytes is pus. It remains at the site of inflammation, just as dead soldiers remain on the battlefield after a battle.

When examining the blood of children, doctors sometimes use the concept of “leukocyte crossover.” What it is? In an adult, the white blood cell count changes, but not significantly, while in children there are very strong fluctuations due to the development of childhood immunity. The number of lymphocytes and neutrophils especially “jumps”. If we depict their readings in the form of curves, then the intersection will be observed on the 3rd–5th day of the child’s life and between 3 and 6 years. The cross cannot be classified as a deviation, so parents can breathe out calmly and not worry about their child.

Elevated leukocytes in the blood. What is the reason?

The level of leukocytes in the blood can be used to judge the state of immunity. When there are too many of these cells, we talk about a condition called leukocytosis. Note that it can also be found in completely healthy people. Thus, some foods can significantly increase the level of leukocytes in the blood. These include: cereals, vegetables, fruits, fermented milk products, seafood, tinctures based on plantain, motherwort and sweet clover.

There are two types of leukocytosis:

physiological - occurring during significant emotional and physical stress, after taking a special food or a hot bath, during pregnancy, before menstruation;
pathological - associated with allergies, cancer, viral infections, diseases accompanied by cell necrosis, inflammatory and purulent processes, etc. It is especially pronounced in sepsis.

Symptoms of leukocytosis may include:

labored breathing;
decreased vision;
temperature increase;
sweating;
loss of appetite and sudden weight loss;
pain in the abdominal area;
dizziness and loss of consciousness.

The first point in treating leukocytosis is to visit a doctor and find out the reasons for this deviation. The specialist prescribes an examination, and only then determines the necessary therapy. These could be medications aimed at relieving inflammatory processes, antibiotics to prevent sepsis, etc.

Causes of low leukocytes

A low number of these cells is called leukopenia. Leukopenia means a decrease in the body's immune functions. If leukopenia is not cured quickly, the consequences can be very serious, including death. As in the case of leukocytosis, this condition has two types - physiological and pathological.

The causes of leukopenia can be:

leukemia;
tumor lesions of the brain;
enlarged spleen;
infectious diseases (measles, rubella, influenza, viral hepatitis);
radiation sickness;
lack of substances for the formation of new cells (vitamins B1, B9, B12); stress;
taking certain medications.

External symptoms of leukopenia include: chills, rapid pulse, headaches, enlarged tonsils.

Having determined the cause of the deviation, you can proceed to treatment. The hematologist necessarily prescribes, among other things, a diet and the intake of vitamins B1, B9 and B12, as well as iron supplements.

Leukocytes play an important role in protecting the body from the penetration of viruses and bacteria, therefore deviations in their concentration from the norm reduce the immune functions of the body and affect our condition as a whole. The content of each type of leukocyte can indicate to a specialist the presence of a particular disease.

Where can I donate blood for a leukocyte test?

Leukocytes in the blood are determined by performing a general analysis. You can donate biomaterial at any medical institution - public or private. The advantage of private clinics is that you do not need a referral from your doctor or therapist, and you will receive results in a short time in any convenient way: in person, by fax, telephone or e-mail. In such an institution, you will not only receive a form with the indicators, but also hear an interpretation from a specialist.

You can obtain such services, for example, from an independent laboratory. The clinic conducts a wide range of laboratory tests. Analysis preparation time is 1 working day. The cost of a general blood test (including determination of hemoglobin concentration, hematocrit value, concentration of erythrocytes, leukocytes, platelets, as well as calculation of erythrocyte indices) here will be 310 rubles. For an additional fee of 300 rubles, specialists will calculate the leukocyte formula. If necessary, you will receive an answer within 2 hours after blood sampling.

Wednesday, 03/28/2018

Editorial opinion

In order to obtain reliable results of a blood test for leukocytes, you should follow a few simple rules. Firstly, you need to donate biomaterial on an empty stomach. Secondly, on the eve of the procedure you should avoid drinking alcohol, as well as fatty and spicy foods. And thirdly, you should not expose yourself to emotional and physical overload before taking the analysis.

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

When examining a smear of stained blood through a microscope, you will notice that leukocytes have a variety of shapes and colors. table II). There are two groups of leukocytes: granular and non-granular. The former have small grains (granules) in the cytoplasm that are stained with different dyes in blue, red or violet. Non-granular forms of leukocytes do not have such grains.

Among non-granular leukocytes, a distinction is made between lymphocytes - round cells with very dark, rounded nuclei - and monocytes - larger cells with irregularly shaped nuclei.

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

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

Table 3. Leukocyte formula of the blood 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; in inflammation, the number of neutrophils increases. With 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, but with the onset of recovery, even before visible signs of improvement in the patient’s condition, they are clearly visible under a microscope.

Some medications also affect the leukocyte formula. With long-term 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 the blood 10 or 20 times. When diluting 20 times, draw blood into the leukocyte mixer to the 0.5 mark, and then pump the dilution solution to the 11 mark.

Dilute the blood with a 3% acetic acid solution tinted with methylene blue. Acetic acid is necessary to destroy red blood cells, the presence of which would interfere with the counting of leukocytes, and methylene blue tints the nuclei of leukocytes, which serve as the main reference point for counting.

Count leukocytes at low microscope magnification. For greater accuracy, count white blood cells in 25 large squares, which corresponds to 400 small squares. 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 - blood dilution.

The blood of different people contains different numbers of leukocytes. The body of an adult contains an average of 60 billion leukocytes. The number of white blood cells in the blood may change. After eating or heavy muscular work, the content of these cells in the blood increases. Especially many 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 red blood cells, white blood cells are able to move independently in the body.

The meaning of leukocytes

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

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

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

In blood vessels, leukocytes move along the walls, sometimes even against the blood flow. The speed of movement of different leukocytes is not the same. Neutrophils move the fastest - about 30 microns per minute; lymphocytes and basophils move more slowly. In diseases, the speed 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 release substances that are toxic to humans - toxins. They cause accelerated movement of leukocytes.

Approaching the microorganism, leukocytes envelop 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 occurs with the participation of special enzymes that destroy microorganisms.

If the foreign body is larger in size than a leukocyte, then groups of neutrophils accumulate around it, forming a barrier. By digesting or destroying this foreign body along with the tissues surrounding it, leukocytes die. As a result, an abscess forms around the foreign body, which after some time ruptures and its contents are thrown out of the body.

The absorption and digestion of various microbes, protozoa and any foreign substances entering the body by leukocytes is called phagocytosis, and the leukocytes themselves are called phagocytes.

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

Leukocytes also play an important role in ridding the body of dead cells. In the human body, the process of aging and cell death and the birth of new cells constantly occur. If dead cells were not destroyed, the body would be poisoned by decay products and life would become impossible. White blood cells gather around dead cells, draw them inside themselves 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 that helps maintain 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 per liter. However, their number is subject to fluctuations: even when eating, their quantity changes. Leukocytes are mobile cells: they can freely move through the wall of blood vessels (they are able to pass between vascular endothelial cells and epithelial cells, through basement membranes) into the connective tissue of organs, where they perform basic protective functions. The movement of cells is carried out as a result of changes in viscosity like an amoeba and through the formation of an inducing membrane at the front 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.

Leukocytes have a well-developed cytoskeleton, represented by actin filaments and microtubules, which ensure 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 granularity, granulocytes are divided into neutrophilic, eosinophilic and basophilic leukocytes. Non-granular leukocytes lack specific granularity and contain unsegmented nuclei. Non-granular leukocytes include lymphocytes and monocytes.

The percentage of all leukocytes in a person's blood is called the leukocyte formula. The content of different types of leukocytes changes with various diseases, with physical and emotional stress. For example, during acute bacterial infections, the content of neutrophils in the blood increases. With viral and chronic infections, the content of lymphocytes increases, and with helminthic infestations, eosinophilia is observed.

Leukocytes perform a protective function, since almost all white blood cells are capable of phagocytosis. Lymphocyte cells take an active part in the implementation of humoral and cellular immunity. Finally, leukocytes determine the blood group based on leukocytes. There are currently 92 known blood groups based on leukocytes. The last blood group was discovered in Shanghai (СSh3); it is detected mainly in eastern peoples. Blood groups based on leukocytes must be taken into account when determining consanguinity, as well as when transplanting bone marrow and various organs.

Granular leukocytes

Neutrophils are the most numerous group of leukocytes in peripheral blood: their number is 40-75%. Their diameter in a living 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, which is why 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 of sex chromatin (X chromosome) in the majority of neutrophils in the form of a drumstick - Barr body. In the peripheral blood of an adult there are also young neutrophils whose 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, in the blood there are band neutrophils, which contain a nucleus in the form of a rod or the letter S. The content of such cells in the peripheral blood ranges from 2-5%. Juvenile and band neutrophils are poorly differentiated neutrophils. The number of young neutrophils increases during blood loss or inflammation, when hematopoiesis in the bone marrow increases and immature neutrophils are released into the blood.

In the inner part of the cytoplasm there are organelles: the Golgi apparatus, granular endoplasmic reticulum, and single mitochondria. The neutrophil contains a large number of glycogen inclusions. The energy obtained through 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 survive for long.

Neutrophils have two types of granularity: specific and azurophilic. The number of grains in each neutrophil can reach 200. The specific granules are very fine (pulverized), distributed evenly throughout the cytoplasm and stained lilac with a mixture of acidic and basic dyes. Specific granularity contains proteins that have bacteriostatic and bacteriocidal properties: lactoferin (it binds iron ions, which promotes the adhesion of bacteria), lysozyme, which has a bacteriocidal effect.

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

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

Thus, neutrophils perform a protective function due to active phagocytosis: they phagocytose tissue decay products, microorganisms, which is why 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 population of white blood cells than neutrophils. The blood of an adult contains 2-5% eosinophils. Their number varies throughout the day and is maximum in the morning. They circulate in the peripheral blood for only 5-8 hours, and then, as a rule, are released into tissues that come into contact with the external environment (mucous membranes of the respiratory, genitourinary and intestinal tracts). In a living drop, the size of eosinophils is 8-10 µm, and in a smear – 12–14 µm. Life expectancy is 8-14 days.

A few mitochondria, the Golgi apparatus and the cell center are found in the cytoplasm. The granular endoplasmic reticulum is poorly developed. The nucleus of eosinophils is lobular and consists, as a rule, of two segments connected by a bridge. Kernels with three and four segments are less common.

Eosinophils have positive chemotaxis to histamine released 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 the degranulation of mast cells. In addition, eosinophils absorb histamine granules produced by mast cells, binding it using receptors. That is why in allergic diseases, bronchial asthma, allergic rhinitis, food allergies, allergic dermatitis, the number of eosinophils increases sharply.

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

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

Basophils have sizes ranging from 10-12 microns. The lifespan of these cells is not precisely established. The nuclei of basophils 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 throughout the cytoplasm and stained purple with the main dye due to the high content of sulfated glycosaminoglycans.

Mitochondria, a relatively poorly developed secretory apparatus, ribosomes, and the Golgi apparatus are revealed in the cytoplasm.

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 participate in the regulation of blood coagulation processes due to heparin, and due to histamine they participate in the regulation of the permeability of the vascular wall. They perform a protective function due to their ability to phagocytose. Thus, it has been established that basophils are able to phagocytose sensitized erythrocytes and foreign compounds. Basophils are involved in regulating the intensity of allergic inflammatory reactions (immediate 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 plasmalemma of the basophil and mast cells. Re-entry of the allergen into the body causes the development of a secretory reaction within a few minutes - 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 - 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 gender, age, ecology and other factors.

Leukocytes go through three phases:

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

2) blood circulation (only a few hours);

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

For some cells, recirculation is possible - return to the lumen of blood 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 the total number of leukocytes found in the smear [the percentage of some leukocytes is even less than 1%, so it is advisable to count at least 100 leukocytes].

Based on the presence of granularity in the cytoplasm, leukocytes are divided into two groups:

1) Granular (granulocytes). The cytoplasm contains small dust-like granules, difficult to distinguish with conventional microscopy, containing a large number of enzymes (peroxidase, alkaline phosphatase, etc.). These granules are colored 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, band 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 a drumstick-shaped outgrowth - a condensed X chromosome; the presence of such chromosomes indicates that the blood is female.

Band 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 kernel

Based on 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 - a predominance of young and rod-shaped - indicates irritation of the red bone marrow, a shift to the right - more mature (segmented) and almost no young and rod-shaped - indicates suppression of leukocytopoiesis, which is a poor prognostic sign. Since all these stages have different forms, they are classified as polymorphonuclear leukocytes.

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

The development cycle is about 8 days: the hematopoietic phase is about 6 days, the vascular phase is 6–10 hours, the tissue phase is about 2 days. The neutrophilic leukocyte leaves the vessel and, having positive chemotaxis, moves with the help of pseudopodia to the source of irritation, where it plays the role of a microphage: phagocytoses 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 source of inflammation or come to the surface of the epithelial layer in the area of \u200b\u200bthe junctions in order to protect the body from damage. In any case, they die.

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

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

Basophilic leukocytes (0–0.5%) are largely similar to the previous ones, but differ in the BAS they contain. Their sizes are 11–13 microns.

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

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Blood Physiology 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 per 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 leukocytes in that their protoplasm has inclusions in the form of grains that can be stained with various dyes. Granulocytes include neutrophils, eosinophils and basophils. Neutrophils according to the degree of maturity are divided into myelocytes, metamyelocytes (young neutrophils), rod-nuclear and segmented. The bulk of the circulating blood consists 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 predominantly increases (eosinophilia). Eosinophilia is also observed with helminthic infestations. Sluggish chronic diseases (rheumatism, tuberculosis) are characterized by an increase in the number of lymphocytes (lymphocytosis). Thus, analysis of the leukocyte formula has diagnostic value.

Properties of leukocytes. Amoeboid motility is the ability of leukocytes to actively move due to the formation of protoplasmic outgrowths - pseudopods (pseudopodia). Diapedesis should be understood as the property of leukocytes to penetrate the capillary wall. In addition, white blood cells can absorb and digest foreign bodies and microorganisms - phagocytosis.

Leukocytes that absorb and digest microorganisms are called phagocytes. Leukocytes absorb not only bacteria that enter 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 capable of producing special substances - leukins, which cause the death of microorganisms that enter the human body. Some leukocytes (basophils, eosinophils) form antitoxins - substances that neutralize bacterial waste products, and thus have detoxification properties. Leukocytes are capable of producing antibodies. Antibodies can remain in the body for a long time, making it impossible for a person to become ill again. Finally, leukocytes (basophils, eosinophils) are related to the processes of blood coagulation and fibrinolysis - the body's protective reactions.

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

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

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

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

There are humoral and cellular immunity. Humoral immunity is provided primarily by B lymphocytes. B-lymphocytes, as a result of complex interactions with T-lymphocytes and monocytes, turn into plasmacytes - 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 (the reaction of rejection of transplanted tissue, the destruction of genetically degenerated cells of one’s own body) is provided mainly by T-lymphocytes. Macrophages (monocytes) can also take part in cellular immune reactions.

Platelets.

Platelets, or blood platelets, are oval or round-shaped 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 platelet content in 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 pseudopods (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 destroyed very easily. They are able to secrete and absorb some biologically active substances: serotonin, adrenaline, norepinephrine. All the considered features of blood platelets determine their participation in stopping bleeding.

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

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

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

Our body is an amazing thing. It is capable of producing all the substances necessary for life, coping with many viruses and bacteria, and finally providing us with a normal life.

Where are leukocytes formed in humans?

Human blood consists of formed elements and plasma. Leukocytes are one of these formed elements along with red blood cells and platelets. They are colorless, have a nucleus and can move independently. They can be seen under a microscope only after preliminary staining. From the organs where leukocytes are formed, they enter the bloodstream and body tissues. They can also freely pass from vessels to adjacent tissues.

Leukocytes move in the following way. Having secured itself on the wall of the vessel, the leukocyte forms a pseudopodia (pseudopod), which it pushes through this wall and clings to the tissue from the outside. Then it squeezes through the resulting gap and actively moves among other cells of the body that lead a “sedentary” lifestyle. Their movement resembles the movement of an amoeba (a microscopic single-celled organism from the category of protozoa).

Basic functions of leukocytes

Despite the similarity of leukocytes to amoebas, they perform complex functions. Their main tasks are to protect the body from various viruses and bacteria and destroy malignant cells. White blood cells chase bacteria, envelop them and destroy them. This process is called phagocytosis, which is Latin for “eating something by cells.” Destroying the virus is more difficult. During illness, viruses settle inside the cells of the human body. Therefore, in order to get to them, leukocytes need to destroy cells with viruses. Leukocytes also destroy malignant cells.

Where are leukocytes formed and how long do they live?

While performing their functions, many white blood cells die, so the body constantly reproduces them. Leukocytes are formed in organs that are part of the human immune system: in the bone marrow, lymph nodes, tonsils, spleen and in the lymphoid formations of the intestine (in Peyer's patches). These organs are located in different places in the body. It is also the place where leukocytes, platelets, and red blood cells are formed. It is believed that white blood cells live for about 12 days. However, some of them die very quickly, which happens when they fight with a large number of aggressive bacteria. Dead leukocytes can be seen if pus appears, which is a collection of them. They are replaced from organs related to the immune system, where leukocytes are formed, new cells emerge and continue to destroy bacteria.

Along with this, among T-lymphocytes there are immunological memory cells that live for decades. If a lymphocyte meets, for example, such a monster as the Ebola virus, it will remember it for the rest of its life. When they encounter this virus again, lymphocytes are transformed into large lymphoblasts, which have the ability to multiply quickly. Then they turn into killer lymphocytes (killer cells), which block the familiar dangerous virus from entering the body. This indicates existing immunity to this disease.

How do white blood cells know that a virus has entered the body?

Every human cell contains an interferon system, which is part of the innate immune system. When a virus enters the body, interferon is produced - a protein substance that protects uninfected cells from the penetration of viruses into them. At the same time, interferon is one of the types of leukocytes. From the bone marrow, where white blood cells are produced, they travel to infected cells and destroy them. In this case, some viruses and their fragments fall out of the destroyed cells. The dropped viruses try to penetrate into uninfected cells, but interferon protects these cells from their penetration. Viruses outside cells are not viable and die quickly.

The fight against viruses against the interferon system

In the process of evolution, viruses have learned to suppress the interferon system, which is too dangerous for them. Influenza viruses have a strong suppressive effect on it. This system is even more oppressed. However, all records were broken by the Ebola virus, which practically blocks the interferon system, leaving the body practically defenseless against a huge number of viruses and bacteria. More and more cells emerge from the spleen, lymph nodes and other organs related to the immune system, where white blood cells are formed. But, having not received a signal to destroy the virus, they remain inactive. In this case, the human body begins to decompose alive, many toxic substances are formed, blood vessels rupture, and the person bleeds to death. Death usually occurs in the second week of the disease.

When does immunity occur?

If a person has had one or another disease and recovered, then he develops a stable acquired immunity, which is provided by leukocytes belonging to the groups of T-lymphocytes and B-lymphocytes. These white blood cells are formed in the bone marrow from progenitor cells. Acquired immunity also develops after vaccination. These lymphocytes know well the virus that has entered the body, so their killing effect is targeted. The virus is practically unable to overcome this powerful barrier.

How do killer lymphocytes kill cells that have become dangerous?

Before you kill a dangerous cell, you need to find it. Killer lymphocytes tirelessly search for these cells. They focus on the so-called histocompatibility antigens (tissue compatibility antigens) located on cell membranes. The fact is that if a virus gets into a cell, then this cell, in order to save the body, dooms itself to death and, as it were, throws out a “black flag”, signaling the introduction of the virus into it. This “black flag” is information about the invading virus, which in the form of a group of molecules is located next to the histocompatibility antigens. This information is “seen” by the killer lymphocyte. He acquires this ability after training in the thymus gland. Control over learning outcomes is very strict. If a lymphocyte has not learned to distinguish a healthy cell from a diseased one, it itself will inevitably be destroyed. With this strict approach, only about 2% of killer lymphocytes survive, which subsequently leave the thymus gland to protect the body from dangerous cells. When the lymphocyte determines that the cell is infected, it gives it a “lethal injection” and the cell dies.

Thus, white blood cells play a huge role in protecting the body from pathogenic agents and malignant cells. These are small, tireless warriors of the body's main defenses - the interferon and immune systems. They die en masse in the fight, but from the spleen, lymph nodes, bone marrow, tonsils and other organs of the immune system, where leukocytes are formed in humans, they are replaced by many newly formed cells, ready, like their predecessors, to sacrifice their lives in the name of saving the human body. Leukocytes ensure our survival in an external environment filled with a huge number of different bacteria and viruses.

table II). There are two groups of leukocytes: granular and non-grainy. The former have small grains (granules) in the cytoplasm that are stained with different dyes in blue, red or violet. Non-granular forms of leukocytes do not have such grains.

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

Granular leukocytes respond differently to different dyes. If cytoplasmic grains are better stained with basic (alkaline) dyes, 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 relationship between the individual forms of leukocytes. The ratio of different forms of leukocytes, expressed as a percentage, is called leukocyte formula(Table 3).

Experience 9

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

20 - blood dilution.

The meaning of leukocytes

In blood vessels, leukocytes move along the walls, sometimes even against the blood flow. The speed of movement of different leukocytes is not the same. Neutrophils move the fastest - about 30 microns per minute; lymphocytes and basophils move more slowly. In diseases, the speed 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 release substances that are toxic to humans - toxins. They cause accelerated movement of leukocytes.

The absorption and digestion of various microbes, protozoa and any foreign substances entering the body by leukocytes is called phagocytosis, and the leukocytes themselves - phagocytes.

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Leukocytes move with the help of

6. Leukocytes [Human Physiology]

Leukocytes, or white blood cells, are colorless cells containing nuclei of various shapes. 1 mm3 of blood from a healthy person contains about 0 leukocytes.

Among non-granular leukocytes, a distinction is made between lymphocytes - round cells with very dark, rounded nuclei - and monocytes - larger cells with irregularly shaped nuclei.

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

Table 3. Leukocyte formula of the blood of a healthy person

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

Experience 9

When counting leukocytes, dilute the blood 10 or 20 times. When diluting 20 times, draw blood into the leukocyte mixer to the 0.5 mark, and then pump the dilution solution to the 11 mark.

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 - blood dilution.

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

Unlike red blood cells, white blood cells are able to move independently in the body.

The meaning of leukocytes

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

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

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

The absorption and digestion of various microbes, protozoa and any foreign substances entering the body by leukocytes is called phagocytosis, and the leukocytes themselves are called phagocytes.

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

Phagocytosis is a protective reaction of the body that helps maintain the constancy of its internal environment.

Leukocytes

Leukocytes have a well-developed cytoskeleton, represented by actin filaments and microtubules, which ensure the formation of pseudopodia and the movement of leukocytes.

Granular leukocytes

Neutrophils are the most numerous group of leukocytes in peripheral blood: their number is 40-75%. Their diameter in a living drop is 8-10 microns, and in a smear - km. Life expectancy is 8–10 days. The nucleus of a mature neutrophil consists of several segments connected by thin bridges, which is why 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 of sex chromatin (X chromosome) in the majority of neutrophils in the form of a drumstick - Barr body. In the peripheral blood of an adult there are also young neutrophils whose 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, in the blood there are band neutrophils, which contain a nucleus in the form of a rod or the letter S. The content of such cells in the peripheral blood ranges from 2-5%. Juvenile and band neutrophils are poorly differentiated neutrophils. The number of young neutrophils increases during blood loss or inflammation, when hematopoiesis in the bone marrow increases and immature neutrophils are released into the blood.

Neutrophils are capable of active migration and active phagocytosis. The main activity of neutrophils occurs outside the vascular bed. They enter the connective tissue and accumulate in areas of inflammation, where they actively phagocytose microbes. The destruction and digestion of absorbed particles occurs with the help of lysosomes, which gradually disappear. After all lysosomes disappear, the neutrophil dies. The phagocytic activity of neutrophils gradually decreases with age. Phagocytic activity is most pronounced in aged neutrophils.

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

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

Mitochondria, a relatively poorly developed secretory apparatus, ribosomes, and the Golgi apparatus are revealed in the cytoplasm.

Leukocytes (white blood cells)

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

Leukocytes go through three phases:

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

2) blood circulation (only a few hours);

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

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

Based on the presence of granularity in the cytoplasm, leukocytes are divided into two groups:

2) Non-granular (agranulocytes):

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

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

Band 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 kernel

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

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

Eosinophilic leukocytes (2–5%) have a smear size of 12–14 µm. Stained weakly oxyphilic, large eosin-stained granules (lysosomes) are detected in the cytoplasm, containing a number of biologically active substances, enzymes and other substances that can affect certain cells of the population. They have a bilobed nucleus. The life cycle reaches 5-6 days in the hematopoietic organs, 6 or less in the bloodstream, and several days in the tissue phase. Eosinophilic leukocytes are microphages, but they are specialized to absorb antigen-antibody complexes that are formed during the humoral response to a foreign substance or during an allergic reaction.

Basophilic leukocytes (0–0.5%) are largely similar to the previous ones, but differ in the BAS they contain. Their sizes are 11–13 microns.

Blood Physiology 4

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

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

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

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

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

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

Platelets.

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

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

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