Our body consists of many cells, and each of them performs its own functions. Understanding the diversity of such particles is not so easy. However, having understood their properties and characteristics, we can draw conclusions about the principles by which the organs and systems of our body function, understand the causes of disturbances in their activity, and even determine how such problems can be eliminated. One of the most important systems of our body is the immune system, and its proper functioning depends on many factors. The activity of the immune system is largely determined by the activity of macrophages, let's talk at www..

Macrophages are special blood cells that are necessary for the normal activity of the body's defenses. From Greek, this term can be translated literally as “big devourer.” In order to understand their role in the implementation of the immune response, it is necessary to understand their origin and structural features.

The production of macrophages begins in the bone marrow; in this organ, dividing stem cells form a cell called a monoblast. Its division results in the birth of a promonocyte, and its direct descendant is the monocyte, also known as a type of white blood cell.

The monocyte is transported from the bone marrow to the blood cells, where it can remain for twelve to twenty-four hours. Next, the monocyte leaves the bloodstream and moves into the tissue. Just at this time, a macrophage is produced from it.

Macrophage cells are actually large in size, although they are not visible to the human eye. Such particles are characterized by an irregular floating shape; their membrane is capable of forming spoonpods.
The nucleus is located directly inside the macrophage; particles of red blood cells and other cells, droplets of fat, various fragments of bacteria, etc. can be found in it. How do they penetrate there?

Main functions of a macrophage

When foreign objects, represented by microbes or foreign bodies, penetrate into the human body, the immune system immediately begins to work actively. Such aggressive particles are attacked by phagocytes. Among these cells are macrophages; they begin to recognize, capture and devour strangers who can threaten the well-being of the entire organism.

Macrophages also effectively destroy dead cells that have ended their existence by apoptosis (programmed, natural, normal death). In addition, macrophages provide some antitumor immunity, as they detect the occurrence of atypical, oncological cells in the human body. Macrophages attack and eat them.

There are several types of macrophages

Macrophages can be classified as tissue phagocytes; they live in different types of tissues. Since alveolar macrophages are located inside the walls of the alveoli of the lungs, such particles effectively clean the air inhaled by a person from all kinds of pollutants and aggressive substances.

Kupffer cells are located inside the liver. These macrophages are responsible for destroying old blood cells.

Histiocytes are a common type of macrophage. These cells can be found in all organs, because they are connective tissue cells that form the framework of almost all structures of the body. In certain cases, histiocytes become true macrophages.

Also among such cells are splenic macrophages, as the name suggests, they are located in the spleen, or more precisely, in its sinusoidal vessels. Such macrophages catch dead cells from the blood and destroy them.

Scientists also identify dendritic cells-macrophages, which are located directly under the mucous membranes, as well as in the skin. Peritoneal macrophages live in the peritoneum. Also known particles of this type are lymph node macrophages, which are naturally found in lymph nodes. It is these macrophages that serve as filters that cleanse the lymph.

Macrophages and immunity

Macrophage cells are not only capable of mindlessly destroying aggressive objects, as if splitting them into separate fragments. Such cells also carry out the process of presenting their antigens. And antigens are molecules of aggressive particles; they carry information about their foreignness and cause the appearance of a corresponding protective reaction on the part of the immune system. Antigens are not capable of causing infection or harming the body in any other way, but they are a mark of an alien.

Thanks to this property, the body perceives their appearance as an attack and responds to this with a defensive reaction.

During phagocytiosis, macrophages present the antigens of destroyed enemies, exposing them on the surface of their membranes. In addition, they form cytoxins, which carry data about the destroyed aggressor.

Macrophages provide such invaluable information to lymphocytes. They seem to teach the immune system the correct behavior when a carrier of the same antigen re-enters the body. Thanks to this property, the body is able to maintain full combat readiness in relation to specific aggressive particles.

Macrophages are extremely important immune cells that are necessary to fully protect the body from aggressive influences.

Literally translated, the definition of "macrophage" has a rather sinister and frightening meaning: "macro" in Greek means "large", and "phagos" means devourer. “Big Eater”... The imagination pictures some kind of monster, but we are just talking about blood cells. However, if we judge macrophages at the cellular level, then they fully justify their name.

What are macrophage cells and where do they come from?

Functions of macrophages:

When a foreign object enters the body, be it a microbe or a foreign body, the immune system immediately “unleashes the dogs” on it: it is attacked by phagocytes. These cells, including macrophages, recognize, capture and devour strangers who threaten the well-being of the body's internal environment.

In addition, macrophages destroy dead cells that have completed their existence through the process of apoptosis (programmed, natural, normal cell death). Also, the functions of macrophages are to provide antitumor immunity: having detected the appearance of atypical cancer cells in the body, macrophages attack and eat them.

Types of macrophages:

7. Where are the m acrophages of lymph nodes, is clear from the name. It is thanks to them that the lymph nodes are known as filters that cleanse the lymph.

Macrophages and the immune system:

Macrophage cells do not just mindlessly destroy harmful objects: by breaking them down into fragments, they carry out the process of presenting their antigens. Antigens are molecules of harmful particles that indicate their genetic foreignness and cause an appropriate protective reaction from the immune system. By themselves, they do not pose a threat of infection or other negative impact, but they are a mark of a stranger, so the body reacts to their presence with a defensive reaction, as if it were a full-fledged aggressor.

During the process of phagocytosis, macrophages present the antigens of killed “enemies” - they expose them to the surface of their membranes. They also form cytokines - information molecules that carry data about the defeated aggressor.

With this invaluable cargo, macrophages are sent to representatives of another part of the immune system - lymphocytes. They transmit information to them and teach them what to do if a carrier of the same antigen ever enters the body again. As a result, the immune system remains fully combat-ready against it.

Unfortunately, sometimes the personal experience of our macrophages or other phagocytes is not enough for the immune system to work properly and respond correctly to harmful objects. To increase its effectiveness and at the same time improve your overall health, it is recommended to take the drug Transfer Factor. It contains cytokines that carry data about all kinds of pathogens, toxins and other harmful agents. The drug trains the immune system to function fully, which immediately and favorably affects the course of existing diseases, the state of metabolism and organ function. The product can be used for therapeutic and prophylactic purposes.

Macrophages are members of the immune system that are vital for the development of nonspecific defense mechanisms that provide the first line of defense against. These large immune cells are present in almost all tissues and actively remove dead and damaged cells, bacteria, and cellular debris from the body. The process by which macrophages engulf and digest cells and pathogens is called.

Macrophages also assist in cellular or adaptive immunity by capturing and presenting information about foreign antigens to immune cells called lymphocytes. This allows the immune system to better defend against future attacks by the same invaders. In addition, macrophages are involved in other important functions in the body, including hormone production, immune regulation, and wound healing.

Macrophage phagocytosis

Phagocytosis allows macrophages to get rid of harmful or unwanted substances in the body. Phagocytosis is a form in which a substance is taken up and destroyed by a cell. This process is initiated when a macrophage targets a foreign substance with the help of antibodies. Antibodies are proteins produced by lymphocytes that bind to a foreign substance (antigen), bringing it into the cell for destruction. Once the antigen is detected, the macrophage sends projections that surround and engulf the antigen (dead cells, etc.), surrounding it in a vesicle.

The internalized vesicle containing the antigen is called a phagosome. in the macrophage they merge with the phagosome, forming a phagolysosome. Lysosomes are membrane sacs of hydrolytic enzymes formed that are capable of digesting organic material. The enzyme contents in the lysosomes are released into the phagolysosome, and the foreign substance is quickly degraded. The degraded material is then expelled from the macrophage.

Macrophage development

Macrophages develop from white blood cells called monocytes. Monocytes are the largest type of white blood cell. They have a large solitary, which is often kidney-shaped. Monocytes are produced in the bone marrow and circulate in one to three days. These cells exit the blood vessels, passing through the endothelium of the blood vessels to enter the tissues. Once they reach their destination, monocytes turn into macrophages or other immune cells called dendritic cells. Dendritic cells help in the development of antigenic immunity.

Macrophages, which differ from monocytes, are specific to the tissue or organ in which they are localized. When there is a need for more macrophages in a particular tissue, living macrophages produce proteins called cytokines, causing monocytes to respond to develop into the required type of macrophage. For example, macrophages that fight infection produce cytokines that promote the development of macrophages that specialize in fighting pathogens. Macrophages, which specialize in wound healing and tissue repair, develop from cytokines produced in response to tissue damage.

Function and location of macrophages

Macrophages are found in almost all tissues of the body and perform a number of functions outside of the immune system. Macrophages help in the production of sex hormones in the male and female reproductive organs. They promote the development of networks of blood vessels in the ovary, which is vital for the production of the hormone progesterone. Progesterone plays an important role in the implantation of the embryo into the uterus. Additionally, macrophages present in the eye help develop the networks of blood vessels necessary for proper vision. Examples of macrophages that are found elsewhere in the body include:

• Central nervous system: microglia are glial cells found in nervous tissue. These extremely small cells patrol the brain and spinal cord, removing cellular waste and protecting against microorganisms.
• Adipose tissue: Macrophages in fat tissue protect against microbes and also help fat cells maintain the body's sensitivity to insulin.
• Integumentary system: Langerhans cells are macrophages in the skin that serve immune function and help in the development of skin cells.
• Kidneys: macrophages in the kidneys help filter microbes from the blood and promote the formation of ducts.
• Spleen: Macrophages in the red pulp of the spleen help filter damaged red blood cells and microbes from the blood.
• Lymphatic system: macrophages stored in the central region of the lymph nodes filter lymph containing microbes.
• Reproductive system: macrophages help in the development of germ cells, the embryo and the production of steroid hormones.
• Digestive system: Macrophages in the intestine control the environment that protects against microbes.
• Lungs: alveolar macrophages, remove germs, dust and other particles from respiratory surfaces.
• Bone: macrophages in bone can develop into bone cells called osteoclasts. Osteoclasts help reabsorb and assimilate bone components. Immature cells from which macrophages are formed are found in the non-vascular parts of the bone marrow.

Macrophages and diseases

Although the primary function of macrophages is defense against, sometimes these pathogens can evade the immune system and infect immune cells. Adenoviruses, HIV, and the bacteria that cause tuberculosis are examples of pathogens that cause disease by infecting macrophages.

In addition to these types of diseases, macrophages have been linked to the development of diseases such as cardiovascular disease, diabetes, and cancer. Macrophages in the heart contribute to cardiovascular disease by helping in the development of atherosclerosis. In atherosclerosis, artery walls become thick due to chronic inflammation caused by white blood cells.

Macrophages in adipose tissue can cause inflammation, which induces insulin resistance in fat cells. This can lead to the development of diabetes. Chronic inflammation caused by macrophages can also contribute to the development and growth of cancer cells.

Macrophages is a heterogeneous specialized cell population of the body's defense system. There are two groups of macrophages - free and fixed. Free macrophages include macrophages of loose connective tissue, or histiocytes; macrophages of serous cavities; macrophages of inflammatory exudates; alveolar macrophages of the lungs. Macrophages are able to move throughout the body. The group of fixed macrophages consists of macrophages of bone marrow and bone tissue, spleen, lymph nodes, intraepidermal macrophages, macrophages of placental villi, and the central nervous system.

The size and shape of macrophages vary depending on their functional state. Typically macrophages have one nucleus. Macrophage nuclei are small, round, bean-shaped or irregular in shape. They contain large clumps of chromatin. The cytoplasm is basophilic, rich in lysosomes, phagosomes and pinocytotic vesicles, contains a moderate amount of mitochondria, granular endoplasmic reticulum, Golgi apparatus, inclusions of glycogen, lipids, etc.

Forms of manifestation of the protective function of macrophages: 1) absorption and further breakdown or isolation of foreign material; 2) neutralizing it upon direct contact; 3) transfer of information about foreign material to immunocompetent cells capable of neutralizing it; 4) providing a stimulating effect on another cell population of the body’s defense system.

The number of macrophages and their activity especially increase during inflammatory processes. Macrophages produce factors that activate the production of immunoglobulins by B lymphocytes and the differentiation of T and B lymphocytes; cytolytic antitumor factors, as well as growth factors that influence the reproduction and differentiation of cells of their own population, stimulate the function of fibroblasts. Macrophages are formed from HSCs, as well as from promonocytes and monocytes. Complete renewal of macrophages and loose fibrous connective tissue in experimental animals occurs approximately 10 times faster than fibroblasts. One type of macrophage is multinucleated giant cells, which were previously called “foreign body giant cells”, as they can form, in particular, in the presence of a foreign body. Multinucleated giant cells are symplasts containing 10-20 nuclei or more, arising either by endomitosis without cytotomy. Multinucleated giant cells contain a developed synthetic and secretory apparatus and an abundance of lysosomes. The cytolemma forms numerous folds.

Concept of the macrophage system. This system includes the totality of all cells that have the ability to capture foreign particles, dying cells, non-cellular structures, bacteria, etc. from the tissue fluid of the body. Phagocytosed material undergoes enzymatic cleavage inside the cell, due to which agents harmful to the body that arise locally or penetrate from the outside are eliminated. I.I. Mechnikov was the first to come to the idea that phagocytosis, which arises in evolution as a form of intracellular digestion and is assigned to many cells, is at the same time an important protective mechanism. He substantiated the feasibility of combining them into one system and proposed calling it macrophage. The macrophage system is a powerful protective apparatus that takes part in both general and local protective reactions of the body. In the whole organism, the macrophage system is regulated both by local mechanisms and by the nervous and endocrine systems.

4. Dense connective tissue. Classification, structural features and differences from loose tissue. Tendon structure. A common feature for PVST is the predominance of the intercellular substance over the cellular component, and in the intercellular substance the fibers predominate over the main amorphous substance and are located very close to each other (densely) - all these structural features are reflected in a compressed form in the name of this tissue. PVST cells are represented overwhelmingly by fibroblasts and fibrocytes; macrophages, mast cells, plasmacytes, poorly differentiated cells, etc. are found in small numbers (mainly in layers of PVST).
Dense fibrous connective tissues are characterized by a relatively large number of densely arranged fibers and a small amount of cellular elements and basic amorphous substance between them. Depending on the location of the fibrous structures, this tissue is divided into dense unformed and dense formed connective tissue. Dense, unformed connective tissue is characterized by a disordered arrangement of fibers. In dense, structured fibrous connective tissue, the arrangement of fibers is strictly ordered and in each case corresponds to the conditions in which the organ functions. Formed fibrous connective tissue is found in tendons and ligaments, in fibrous membranes. Tendon. It consists of thick, densely lying parallel bundles collagen fibers. Between these bundles are located fibrocytes and a small amount of fibroblasts and ground amorphous material. Thin lamellar processes of fibrocytes enter the spaces between the fiber bundles and are in close contact with them. Fibrocytes of tendon bundles are called tendon cells.

Each bundle of collagen fibers, separated from the adjacent layer of fibrocytes, is called first order beam. Several bundles of the first order, surrounded by thin layers of loose fibrous connective tissue, make up second order beams. Layers of loose fibrous connective tissue separating second-order bundles are called endotenonium. From beams of the second order they are composed third order beams, separated by thicker layers of loose connective tissue - peritenonium. Large tendons may also have fourth-order bundles.

The peritenonium and endotenonium contain blood vessels that supply tendons, nerves, and proprioceptive nerve endings. Dense, shaped fibrous connective tissue also includes nuchal ligament.

Fibrous membranes. This type of dense fibrous connective tissue includes fascia, aponeuroses, tendon centers of the diaphragm, capsules of some organs, dura mater, sclera, perichondrium, periosteum, as well as the tunica albuginea of ​​the ovary and testicle, etc. Fibrous membranes are difficult to stretch. In addition to bundles of collagen fibers, fibrous membranes contain elastic fibers. Fibrous structures such as periosteum, sclera, tunica albuginea, joint casulas, etc.

5.Cartilage tissue. General morpho-functional characteristics. Classification. Development and structural features of various cartilaginous tissues. Perichondrium. Growth of cartilage, regeneration capabilities and age-related changes in cartilage tissue.

Cartilage tissue is part of the organs of the respiratory system, joints, intervertebral discs, and consists of cells – chondrocytes and chondroblasts and intercellular substance.Classification: There are three types of cartilage tissue: hyaline, elastic, fibrous.

During the development of cartilage tissue from mesenchyme a cartilaginous differential is formed:
1. Stem cell
2. Semi-stem cell
3. Chondroblast
4. Chondrocyte
Stem and semi-stem cells are poorly differentiated cambial cells, mainly localized around the vessels in the perichondrium. By differentiating they turn into chondroblasts and chondrocytes, i.e. necessary for regeneration.
Chondroblasts are young cells located in the deep layers of the perichondrium singly, without forming isogenic groups. Under a light microscope, blasts are flattened, slightly elongated cells with basophilic cytoplasm. Under an electron microscope, the granular ER, Golgi complex, and mitochondria are well expressed in them, i.e. protein-synthesizing complex of organelles because The main function of x/blasts is the production of the organic part of the intercellular substance: proteins collagen and elastin, glycosaminoglycans (GAG) and proteoglycans (PG). In addition, ch/blasts are capable of reproduction and subsequently turn into chondrocytes. In general, x/blasts provide appositional (superficial) growth of cartilage from the side of the perichondrium.
Chondrocytes are the main cells of cartilage tissue, located in the deeper layers of cartilage in cavities - lacunae. Cells can divide by mitosis, while the daughter cells do not separate, but remain together - so-called isogenic groups are formed. Initially, they lie in one common lacuna, then an intercellular substance is formed between them and each cell of a given isogenic group has its own capsule. X/cytes are oval-round cells with basophilic cytoplasm. Under an electron microscope, the granular ER, Golgi complex, and mitochondria are well defined, i.e. protein synthesizing apparatus, because The main function of cartilage tissue is the production of the organic part of the intercellular substance of cartilage tissue. The growth of cartilage due to the division of cells and their production of intercellular substance is ensured by interstitial (internal) growth of cartilage.
The intercellular substance of cartilage tissue contains collagen, elastic fibers and ground substance. The intercellular substance is highly hydrophilic, the water content reaches 75% of the mass of the cartilage, this determines the high density and turgor of the cartilage. Cartilaginous tissues in the deep layers do not have blood vessels; nutrition is diffuse through the vessels of the perichondrium.

The source of development of cartilage tissue is mesenchyme. In the first stage, in some parts of the body of the embryo, where cartilage is formed, mesenchymal cells lose their processes, multiply vigorously and, tightly adjacent to each other, create a certain tension - turgor. Such areas called chondrogenic primordia, or chondrogenic islets. The stem cells they contain differentiate into chondroblasts, cells similar to fibroblasts. In the next stage, the formation of primary cartilaginous tissue, the cells of the central region round, increase in size, granular EPS develops in their cytoplasm, with the participation of which the synthesis and secretion of fibrillar proteins occurs. Along the periphery of the cartilaginous anlage, at the border with the mesenchyme, a perichondrium
The perichondrium is a layer of connective tissue covering the surface of the cartilage. In the perichondrium, there is an outer fibrous layer (from a dense, unformed SDT with a large number of blood vessels) and an inner cellular layer containing a large number of stem, semi-stem cells and f/blasts. In the process of secreting synthesis products and layering onto existing cartilage along its periphery, the cells themselves are “embedded” in the products of their activity. This is how cartilage grows by applying.
The difference between the 3 types of cartilage. The differences mainly concern the structure of the intercellular substance:
Hyaline cartilage –

Covers all articular surfaces of bones, is contained in the sternal ends of the ribs, in the airways. The main difference between hyaline cartilage and other cartilages is in the structure of the intercellular substance: the intercellular substance of hyaline cartilage in preparations stained with hematoxylin-eosin appears homogeneous and does not contain fibers. In fact, in the intercellular substance there is a large number of collagen fibers, whose refractive index is the same as the refractive index of the main substance, so collagen fibers are not visible under a microscope, i.e. they are camouflaged. The second difference of hyaline cartilage is that there is a clearly defined basophilic zone around the isogenic groups - the so-called territorial matrix. This is due to the fact that x/cytes secrete a large amount of GAG with an acidic reaction, so this area is stained with basic dyes, i.e. basophilic. The weakly oxygenic areas between the territorial matrices are called the interterritorial matrix.
Elastic cartilage

present in the auricle, epiglottis, corniculate and sphenoid cartilages of the larynx. The main difference between elastic cartilage is the intercellular substance except collagen fibers there are a large number of randomly located elastic fibers, which gives elasticity to the cartilage. Elastic cartilage contains less lipids, chondroethinsulfates and glycogen. Elastic cartilage does not calcify.
Fibrous cartilage

located at the attachment points tendons to bones and cartilage, in the symphysis and intervertebral discs. In structure it occupies an intermediate position between densely formed connective and cartilaginous tissue. Difference from other cartilages: in the intercellular substance there are much more collagen fibers, and the fibers are oriented - they form thick bundles, clearly visible under a microscope. Cells often lie singly along the fibers, without forming isogenic groups.

Age-related changes.As the body ages, the concentration of proteoglycans and the associated hydrophilicity in cartilage tissue decrease. The processes of reproduction of chondroblasts and young chondrocytes are weakened. After the death of chondrocytes, some of the gaps are filled with an amorphous substance and collagen fibrils. In some places, deposits of calcium salts are found in the intercellular substance, as a result of which the cartilage becomes cloudy, opaque, and becomes hard and brittle. Regeneration. Physiological regeneration of cartilage tissue is carried out due to unspecialized cells of the perichondrium and cartilage through reproduction and differentiation prechondroblasts and chondroblasts.Post-traumatic regeneration of cartilage tissue of extra-articular localization is carried out due to the perichondrium.

Currently, an understanding of the main cellular elements of the immune system has been formed. Along with its main structural units (T-, B-lymphocytes, MK), auxiliary cells are of great importance. These cells differ from lymphocytes in both morphological and functional properties. According to the WHO classification (1972), these cells are united into a mononuclear phagocytic system. It includes cells of bone marrow origin that have mobility (chemotaxis) and are able to actively phagocytose and adhere to glass. Motility, phagocytosis, adhesion.

Mon/mf form an MPS, which includes circulating monocytes and macrophages localized in various tissues. Morphology: compact, rounded nucleus (in contrast to granulocytic phagocytes, which have a polymorphonuclear structure). Cells contain a number of acid-type enzymes: hydrolases, peroxidases, etc., located in lysosomes, with which the function of intracellular destruction of phagocytic microorganisms is associated. The presence of a nonspecific esterase enzyme in the CK is a feature that distinguishes mon/mf cells from lymphocytes. They are larger in size than lf (diameter - 10-18 microns). In humans, monocytes make up 5-10% of peripheral blood leukocytes.

Phagocytes are represented by:

macrophages (circulating blood monocytes and tissue macrophages) – monononuclear

microphages (neutrophils, basophils, eosinophils) - polymorphonuclear phagocytes

The main biological functions of macrophages are: phagocytosis (absorption and digestion of foreign corpuscular particles); secretion of biologically active substances; presentation (supply, presentation) of antigenic material to T - and B-lymphocytes; as well as participation in the induction of inflammation, in cytotoxic antitumor immunity, in the processes of regeneration and involution, in intercellular interactions, in humoral and cellular immunity.

Macrophages from the bone marrow enter the blood - monocytes, which remain in the circulation for about a day, and then migrate into the tissue, forming tissue macrophages. The phagocytic ability of tissue macrophages is associated with the function of a given organ or tissue. Thus, alveolar macrophages actively phagocytose, freely located in the cavity of the alveoli; lysothelial cells - phagocytose only when serous cavities are irritated, thymic RES cells phagocytose only lymphocytes, osteoclasts - only bone tissue elements, etc. MFS include multinucleated giant cells, which are formed as a result of the fusion of mononuclear phagocytes. These cells are usually found in areas of inflammation. Like phagocytes, they can phagocytose red blood cells, absorb and kill microorganisms, produce O2- as a result of a respiratory burst, express the membrane la-molecule, and produce hydrolytic enzymes. The level of multinucleated giant cells changes in various pathological conditions, in particular in patients with AIDS; their number increases significantly in the central nervous system.

The process of transformation of monocytes into macrophages is accompanied by morphological, biochemical and functional changes. They increase in size, the organization of intracellular organelles becomes more complicated; the number of lysosomal enzymes increases. Like neutrophils, macrophages do not return to the circulation, but are eliminated through the mucous membranes of the intestines and upper respiratory tract

Ontogenesis of mononuclear phagocytes

PRM (macrophage growth factor)