Phagocytosis is the main mechanism of the immune system. Cells capable of phagocytosis include Bacterial cell capable of phagocytosis

More often than not, we learn from adults raised on TV shows that the immune system lives in the gut. It is important to wash everything, boil, eat right, saturate the body beneficial bacteria and everything like that.

But this is not the only thing that matters for immunity. In 1908, the Russian scientist I.I. Mechnikov received the Nobel Prize in Physiology, telling (and proving) to the whole world about the presence in general and the importance in particular of phagocytosis in work

Phagocytosis

Our body's defense against harmful viruses and bacteria occurs in the blood. General principle the work is as follows: there are marker cells, they see the enemy and mark him, and the rescue cells find the stranger by the marks and destroy him.

Phagocytosis is the process of destruction, that is, the absorption of harmful living cells and non-living particles by other organisms or special cells - phagocytes. There are 5 types of them. And the process itself takes about 3 hours and includes 8 stages.

Stages of phagocytosis

Let's take a closer look at what phagocytosis is. This is a very orderly and systematic process:

First, the phagocyte notices the object of influence and moves towards it - this stage is called chemotaxis;

Having caught up with the object, the cell is firmly glued, attached to it, that is, it adheres;

Then it begins to activate its shell - the outer membrane;

Now the actual phenomenon itself begins, marked by the formation of pseudopodia around the object;

Gradually, the phagocyte encloses the harmful cell inside itself, under its membrane, so a phagosome is formed;

On the this stage fusion of phagosomes and lysosomes occurs;

Now you can digest everything - destroy it;

On the final stage it remains only to throw out the products of digestion.

Everything! The process of destruction of the harmful organism is completed, it died under the influence of strong digestive enzymes of the phagocyte or as a result of a respiratory explosion. Ours won!

Jokes aside, but phagocytosis is a very important mechanism of the body's defense system, which is inherent in humans and animals, moreover, in vertebrate and invertebrate organisms.

Characters

Not only phagocytes themselves are involved in phagocytosis. Although these active cells are always ready to fight, they would be absolutely useless without cytokines. After all, the phagocyte, so to speak, is blind. He himself does not distinguish between his own and others, more precisely, he simply does not see anything.

Cytokines are signaling, a kind of guide for phagocytes. They just have excellent "vision", they perfectly understand who is who. Having spotted a virus or bacterium, they glue a marker on it, by which, as if by smell, the phagocyte will find it.

The most important cytokines are the so-called transfer factor molecules. With their help, phagocytes not only find out where the enemy is, but also communicate with each other, call for help, wake up leukocytes.

When we get vaccinated, we train exactly cytokines, we teach them to recognize a new enemy.

Types of phagocytes

Cells capable of phagocytosis are divided into professional and non-professional phagocytes. Professionals are:

monocytes - belong to leukocytes, have the nickname "wipers", which they received for their unique ability to absorb (so to speak, they have a very good appetite);

Macrophages are big eaters that consume dead and damaged cells and promote the formation of antibodies;

Neutrophils are always the first to arrive at the site of infection. They are the most numerous, they neutralize enemies well, but they themselves also die at the same time (a kind of kamikaze). By the way, pus is dead neutrophils;

Dendrites - specialized in pathogens and work in contact with environment,

Mast cells are progenitors of cytokines and scavengers of Gram-negative bacteria.

He conducted his research in Italy, on the coast of the Strait of Messina. The scientist was interested in whether individual multicellular organisms the ability to capture and digest food, as unicellular organisms, such as amoeba, do. Indeed, as a rule, in multicellular organisms, food is digested in the alimentary canal and ready-made nutrient solutions are absorbed. observed starfish larvae. They are transparent and their contents are clearly visible. These larvae do not have a circulating, but wandering larva throughout the larva. They captured particles of red carmine paint introduced into the larva. But if these absorb paint, then maybe they capture any foreign particles? Indeed, the rose thorns inserted into the larva turned out to be surrounded by carmine-colored ones.

They were able to capture and digest any foreign particles, including pathogenic microbes. called wandering phagocytes (from the Greek words phages - devourer and kytos - receptacle, here -). And the very process of capturing and digesting different particles by them is phagocytosis. Later he observed phagocytosis in crustaceans, frogs, turtles, lizards, and also in mammals - guinea pigs, rabbits, rats and humans.

Phagocytes are special. Digestion of captured particles is not necessary for them to feed, like amoebas and other unicellular organisms, but to protect the body. In starfish larvae, phagocytes wander throughout the body, while in higher animals and humans they circulate in the vessels. This is one of the types of white blood cells, or leukocytes - neutrophils. It is they who, attracted by the toxic substances of microbes, move to the site of infection (see). Having left the vessels, such leukocytes have outgrowths - pseudopodia, or pseudopodia, with the help of which they move in the same way as an amoeba and wandering starfish larvae. Such leukocytes capable of phagocytosis are called microphages.

However, not only constantly moving leukocytes, but also some sedentary ones can become phagocytes (now they are all combined into single system phagocytic mononuclear cells). Some of them rush to dangerous areas, for example, to the site of inflammation, while others remain in their usual places. Both of them are united by the ability to phagocytosis. These tissue (histocytes, monocytes, reticular and endothelial) are almost twice as large as microphages - their diameter is 12-20 microns. Therefore, they called them macrophages. Especially a lot of them in the spleen, liver, lymph nodes, bone marrow and in the walls of blood vessels.

Microphages and wandering macrophages themselves actively attack the “enemies”, while immobile macrophages wait for the “enemy” to swim past them in the current or lymph. Phagocytes “hunt” for microbes in the body. It happens that in an unequal struggle with them they are defeated. Pus is the accumulation of dead phagocytes. Other phagocytes will approach it and begin to deal with its elimination, as they do with all sorts of foreign particles.

Phagocytes are cleansed of constantly dying and are involved in various restructuring of the body. For example, during the transformation of a tadpole into a frog, when, along with other changes, the tail gradually disappears, whole hordes of phagocytes destroy the tadpole's tail.

How do particles get inside the phagocyte? It turns out that with the help of pseudopodia, which capture them, like an excavator bucket. Gradually, the pseudopodia lengthen and then close over foreign body. Sometimes it seems to be pressed into the phagocyte.

He suggested that phagocytes should contain special substances that digest the microbes and other particles captured by them. Indeed, such particles were discovered 70 years after the discovery of phagocytosis. They contain capable of breaking down large organic molecules.

Now it has been found out that, in addition to phagocytosis, they are predominantly involved in the neutralization of foreign substances (see). But for the process of their production to begin, the participation of macrophages is necessary. They capture foreign

Specify organisms whose cells are capable of phagocytosis:
a) bacteria;
b) mushrooms; c) plants; d) animals.
3. Name the organisms in the composition cell wall which includes glycoca-
lix:
a) bacteria; b) mushrooms; c) plants; d) animals.
4. Specify the compounds of which the chromosomes mainly consist:
a) proteins and
lipids; b) proteins and DNA; c) proteins and RNA; d) lipids and RNA.
5. What is the name of the scientist who proposed the term "cell":
a) R. Hooke;
b) T. Schwann; c) M. Schleiden; d) R. Virchow.
CHOOSE FROM THE PROPOSED ANSWERS TWO CORRECT
1. Name the organisms in whose cells there are vegetative and generative
kernels:
a) yeast; b) ulotrix; c) foraminifera; d) ciliates.
2. Name the cells that do not have nuclei:
a) erythrocytes of most mammals
feeding; b) epithelial cells; c) leukocytes; d) mammalian platelets.
3. Name the organisms whose cells have a nucleus:
a) cyanobacteria; b) peni-
cill; c) mucor; d) E. coli.
4. Name the structures located inside the nucleus:
a) ribosome subunits;
b) chromatin threads; c) plastids; d) mitochondria.
5. Name the mechanisms of passive transport of substances into the cell:
a) diffusion;
b) change in the spatial structure of proteins penetrating the membrane;
c) potassium-sodium pump; d) phagocytosis.
6. Name the properties plasma membrane:
a) semipermeability; b) spo-
ability to self-renewal; c) rigidity; d) the ability to synthesize own
natural proteins.
COMPLIANCE TASKS
1. Determine the belonging of chromosomes to one or another type.
Types of chromosomes Names of chromosomes
A) similar in size and structure
B) differ in size and structure
B) sex
D) non-sexual
1 Heterochromosomes
2 Autosomes
3 Politenny
4 Homologous
5 Non-homologous
2. Determine the correspondence of organelles and cell structures to groups of organisms,
in which they are presented.
Groups of organisms Organelles and structures
A) erythrocytes of most mammals
B) cyanobacteria
B) Plant skin cells
D) Cells of ciliates
1 Nuclei are not differentiated
for vegetative and generative
2 Absence of a nucleus in mature cells
3 Nucleoid
4 Nuclei vegetative and generative
5 Sieve plates
3. Establish a correspondence between the names of scientists and their contribution to development
cytology.
Surnames of scientists Contribution to the development of cytology
A) R. Hooke
B) A. van Leeuwenhoek
B) T. Schwann
D) I. Mechnikov
1 Discovered the phenomenon of phagocytosis
2 Discovered the phenomenon of pinocytosis
3 Coined the term "cell"
4 Discovered and described bacterial cells
5 Laid the foundations cell theory
HARD QUESTIONS
1. How does the absence of a nucleus affect the properties of a cell? Justify the answer.
2. How can one explain that some eukaryotic cells devoid of a nucleus?
Give examples of such cells.
3. What is the importance of studying the karyotypes of organisms for taxonomy? Answer
justify.
4. What is common and different between the hereditary material of prokaryotic cells and
eukaryotes?
5. What is common and different between the processes of pinocytosis and phagocytosis? Cells
what organisms can carry out these processes?
6. What is the relationship between the entry of water into the cell and maintaining it
forms? Justify your answer

In 1882-1883. the famous Russian zoologist I. I. Mechnikov conducted his research in Italy, on the shores of the Strait of Messina. The scientist was interested in whether individual cells of multicellular organisms retained the ability to capture and digest food, as unicellular organisms, such as amoeba, do. Indeed, as a rule, in multicellular organisms, food is digested in the alimentary canal and the cells absorb ready-made nutrient solutions.

Mechnikov observed starfish larvae. They are transparent and their contents are clearly visible. These larvae do not have circulating blood, but have cells wandering throughout the larva. They captured particles of red carmine paint introduced into the larva. But if these cells absorb paint, then maybe they capture any foreign particles? Indeed, the rose thorns inserted into the larva turned out to be surrounded by cells stained with carmine.

The cells were able to capture and digest any foreign particles, including pathogenic microbes. Mechnikov called wandering cells phagocytes (from the Greek words phagos - eater and kytos - receptacle, here - cell). And the very process of capturing and digesting different particles by them is phagocytosis. Later, Mechnikov observed phagocytosis in crustaceans, frogs, turtles, lizards, and also in mammals - guinea pigs, rabbits, rats and humans.

Phagocytes are special cells. Digestion of captured particles is not necessary for them to feed, like amoebas and other unicellular organisms, but to protect the body. In starfish larvae, phagocytes wander throughout the body, while in higher animals and humans they circulate in the vessels. This is one of the types of white blood cells, or leukocytes, - neutrophils. It is they, attracted by the toxic substances of microbes, that move to the site of infection (see Taxis). Having left the vessels, such leukocytes have outgrowths - pseudopodia, or pseudopodia, with the help of which they move in the same way as amoeba and wandering cells of starfish larvae. Mechnikov called such phagocytic leukocytes microphages.

This is how the particle is captured by the phagocyte.

However, not only constantly moving leukocytes, but also some sedentary cells can become phagocytes (now they are all combined into a single system of phagocytic mononuclear cells). Some of them rush to dangerous areas, for example, to the site of inflammation, while others remain in their usual places. Both of them are united by the ability to phagocytosis. These tissue cells (histocytes, monocytes, reticular and endothelial cells) are almost twice as large as microphages - their diameter is 12-20 microns. Therefore, Mechnikov called them macrophages. Especially a lot of them in the spleen, liver, lymph nodes, bone marrow and in the walls of blood vessels.

Microphages and wandering macrophages themselves actively attack the “enemies”, while immobile macrophages wait for the “enemy” to swim past them in the blood or lymph flow. Phagocytes “hunt” for microbes in the body. It happens that in an unequal struggle with them they are defeated. Pus is the accumulation of dead phagocytes. Other phagocytes will approach it and begin to deal with its elimination, as they do with all sorts of foreign particles.

Phagocytes clean tissues from constantly dying cells and are involved in various restructuring of the body. For example, during the transformation of a tadpole into a frog, when, along with other changes, the tail gradually disappears, whole hordes of phagocytes destroy the tissues of the tadpole's tail.

How do particles get inside the phagocyte? It turns out that with the help of pseudopodia, which capture them, like an excavator bucket. Gradually, the pseudopodia lengthen and then close over the foreign body. Sometimes it seems to be pressed into the phagocyte.

Mechnikov suggested that phagocytes should contain special substances that digest the microbes and other particles captured by them. Indeed, such particles - lysosdma were discovered 70 years after the discovery of phagocytosis. They contain enzymes that can break down large organic molecules.

It has now been clarified that, in addition to phagocytosis, antibodies are predominantly involved in the neutralization of foreign substances (see Antigen and antibody). But for the process of their production to begin, the participation of macrophages is necessary. They capture foreign proteins (antigens), cut them into pieces and expose their pieces (the so-called antigenic determinants) on their surface. Here, those lymphocytes that are able to produce antibodies (immunoglobulin proteins) that bind these determinants come into contact with them. After that, such lymphocytes multiply and secrete many antibodies into the blood, which inactivate (bind) foreign proteins - antigens (see Immunity). The science of immunology deals with these issues, one of the founders of which was I. I. Mechnikov.

A person carries out an important process, which is called phagocytosis. Phagocytosis is the process of absorption of foreign particles by cells. Scientists believe that phagocytosis is the most ancient form of macroorganism defense, since phagocytes are cells that carry out phagocytosis and are found in both vertebrates and invertebrates. What is phagocytosis and what is its function at work immune system human? The phenomenon of phagocytosis was discovered in 1883 by I.I. Mechnikov. He also proved the role of phagocytes as protective cells of the immune system. For this discovery I.I. Mechnikov was awarded in 1908 Nobel Prize in physiology. Phagocytosis is an active capture and absorption of living cells and inanimate particles by unicellular organisms or special cells of multicellular organisms - phagocytes, which consists of successive molecular processes and lasts several hours. Phagocytosis is the first reaction of the body's immune system to the introduction of foreign antigens that can enter the body as part of bacterial cells, viral particles, or in the form of a high molecular weight protein or polysaccharide. The mechanism of phagocytosis is of the same type and includes eight consecutive phases:
1) chemotaxis (directed movement of the phagocyte towards the object);
2) adhesion (attachment to an object);
3) activation of the membrane (actin-myosin system of the phagocyte);
4) the beginning of phagocytosis itself, associated with the formation of pseudopodia around the absorbed particle;
5) the formation of a phagosome (the absorbed particle is enclosed in a vacuole due to the pushing of the plasma membrane of the phagocyte on it like a zipper);
6) fusion of phagosomes with lysosomes;
7) destruction and digestion;
8) release of degradation products from the cell.

Cells phagocytes

Phagocytosis is carried out by cells phagocytes- this important cells immune system. Phagocytes circulate throughout the body, looking for "aliens". When the aggressor is found, it is tied up with receptors. After the phagocyte absorbs the aggressor. This process takes about 9 minutes. Inside the phagocyte, the bacterium enters the phagosome, which merges with a granule or lysosome containing enzymes within a minute. The microorganism dies under the influence of aggressive digestive enzymes or as a result of a respiratory explosion, in which free radicals. All phagocyte cells are in a state of readiness and can be called to a certain place where their help is needed, with the help of cytokines. Cytokines are signaling molecules that play important role at all stages of the immune response. Transfer factor molecules are one of the most important cytokines of the immune system. With the help of cytokines, phagocytes also exchange information, call other phagocytic cells to the source of infection, and activate "sleeping" lymphocytes.
Human and other vertebrate phagocytes are divided into "professional" and "non-professional" groups. This section is based on the efficiency with which cells participate in phagocytosis. Professional phagocytes are monocytes, macrophages, neutrophils, tissue dendritic cells and mast cells.

Monocytes are the body's "wipers"

Monocytes are blood cells that belong to the group of leukocytes. Monocytes called "wipers of the body" because of their amazing opportunities. Monocytes engulf cells of pathogenic agents and their fragments. At the same time, the number and size of absorbed objects can be 3-5 times greater than those that are capable of absorbing neutrophils. Monocytes can also absorb microorganisms, being in an environment with hyperacidity. Other leukocytes are not capable of this. Monocytes also absorb all the remnants of the "fight" with pathogenic microbes and thereby create favorable conditions for tissue repair in areas of inflammation. Actually, for these abilities, monocytes were called "wipers of the body."

Macrophages are "big eaters"

macrophages, literally "big eaters" are large immune cells that capture and then piecemeal destroy foreign, dead or damaged cells. In the event that the "absorbed" cell is infected or malignant, macrophages leave intact a number of its foreign components, which are then used as antigens to stimulate the formation of specific antibodies. Macrophages travel throughout the body in search of foreign microorganisms that have penetrated the primary barriers. Macrophages are found throughout the body in almost all tissues and organs. The location of a macrophage can be determined by its size and appearance. The lifespan of tissue macrophages is 4 to 5 days. Macrophages can be activated to perform functions that a monocyte cannot perform. Activated macrophages play an important role in the destruction of tumors by generating tumor necrosis factor alpha, interferon gamma, nitric oxide, reactive oxygen species, cationic proteins, and hydrolytic enzymes. macrophages perform the role of cleaners, ridding the body of worn-out cells and other debris, as well as the role of antigen-presenting cells that activate the links of the acquired human immunity.

Neutrophils - "pioneers" of the immune system

Neutrophils live in the blood and are the most numerous group of phagocytes, typically representing about 50%-60% total circulating leukocytes. These cells are about 10 micrometers in diameter and only live for 5 days. During acute phase Inflammatory neutrophils migrate to the site of inflammation. Neutrophils- These are the first cells that react to the source of infection. As soon as the appropriate signal arrives, they leave the blood within about 30 minutes and reach the site of infection. Neutrophils quickly absorb foreign material, but after that they do not return to the blood. The pus that forms at the site of infection is dead neutrophils.

Dendritic cells

Dendritic cells are special antigen-presenting cells that have long processes (dendrites). With the help of dendrites, the absorption of pathogens is carried out. Dendritic cells are located in tissues that are in contact with the environment. It is primarily skin inner shell nose, lungs, stomach and intestines. Once activated, dendritic cells mature and migrate to the lymphatic tissues and interact with T and B lymphocytes there. As a result, an acquired immune response arises and is organized. Mature dendritic cells activate T-helpers and T-killers. Activated T-helpers interact with macrophages and B-lymphocytes to activate them, in turn. Dendritic cells, in addition to all this, can influence the occurrence of one or another type of immune response.

mast cells

Mast cells engulf, kill Gram-negative bacteria and process their antigens. They specialize in processing fimbrial proteins on the surface of bacteria that are involved in tissue attachment. Mast cells also produce cytokines that trigger the inflammatory response. This is an important function in killing germs because cytokines attract more phagocytes to the site of infection.

"Unprofessional" phagocytes

Non-professional phagocytes include fibroblasts, parenchymal, endothelial and epithelial cells. For such cells, phagocytosis is not the main function. Each of them perform some other function. This is due to the fact that "non-professional" phagocytes do not have special receptors, thus, they are more limited than "professional".

Insidious deceivers

The pathogen leads to the development of infection only if it managed to cope with the protection of the macroorganism. Therefore, many bacteria form processes, the purpose of which is to create resistance to the effects of phagocytes. Indeed, a lot of pathogens got the opportunity to multiply and survive inside phagocytes. There are several ways in which bacteria avoid contact with cells of the immune system. The first is reproduction and growth in those areas where phagocytes are not able to penetrate, for example, into a damaged cover. The second way is the ability of some bacteria to suppress inflammatory reactions, Without which phagocyte cells unable to respond properly. Also, some pathogens can "trick" the immune system into thinking the bacterium is part of the body itself.

Transfer Factor - immune system memory

In addition to producing specialized cells, the immune system produces a number of signaling molecules called cytokines. Transfer factors are among the most important cytokines. Scientists have found that transfer factors have a unique efficiency regardless of the biological species of the donor and recipient. This property of transfer factors is explained by one of the key scientific principles - the more important for life support is one or another material or structure, the more universal they are for all living systems. Transfer Factors are indeed the most important immunoactive compounds and are found even in the most primitive immune systems. Transfer factors are unique means transmission of immune information from cell to cell within the human body, as well as from one person to another. We can say that transfer factors are the "language of communication" immune cells, the memory of the immune system. The unique action of transfer factors is to accelerate the response of the immune system to a threat. They increase immune memory, reduce the time to fight infection, and increase the activity of natural killers. Initially, it was thought that transfer factors could only be active when administered by injection. Today, bovine colostrum is considered to be the best source of transfer factors. Therefore, by collecting excess colostrum and isolating transfer factors from it, it is possible to provide the population with additional immune protection. The American company 4 life became the first company in the world to start isolating transfer factors from bovine colostrum with a special membrane filtration method, for which it received a corresponding patent. Today the company supplies the market with a line of Transfer Factor drugs, which have no analogues. The effectiveness of Transfer Factor preparations has been clinically confirmed. To date, more than 3,000 scientific works on the application of transfer factors for the most various diseases. AND