Which Russian scientist is the author of the theory of immunity. Who is considered the creator of the cellular theory of immunity? Stages of development of phagocytosis

4.13 Physiology, medicine

4.13.091 Mechnikov’s phagocytic theory of immunity

Zoologist, embryologist, physiologist, bacteriologist, immunologist, pathologist; lecturer, propagandist; founder of the first Russian school of microbiologists, immunologists and pathologists; professor at Novorossiysk University; honorary doctorate from the University of Cambridge; honorary member of the St. Petersburg Academy of Sciences, member of the French Academy of Medicine, the Swedish Medical Society and other foreign Academy of Sciences, scientific societies and institutes; organizer and director of the first Odessa bacteriological station in Russia to combat infectious diseases; founder and head of the laboratory at the Pasteur Institute (Paris), deputy director of this institute; laureate of the K. Baer Prize (together with A.O. Kovalevsky), Nobel Prize in Physiology and Medicine (together with P. Ehrlich); winner of the Copley Medal of the Royal Society of London and other awards and distinctions - Ilya Ilyich Mechnikov (1845-1916) is one of the founders of evolutionary embryology, the creator of the comparative pathology of inflammation, the discoverer of phagocytosis and intracellular digestion, the founder of scientific gerontology.

The outstanding achievement of the biologist was his phagocytic theory of immunity.

Convinced and more than once taught by bitter experience that “in Russia, good officials in departments are preferable to the most outstanding scientists,” I.I. Mechnikov carried out his scientific and pedagogical activities mostly outside our country in voluntary exile in Italy, Germany, and France.

Nevertheless, Ilya Ilyich dedicated all his works to Russia, published them in Russian in Russian publications, maintained constant contact with Russian scientists, founded the first Russian scientific school of microbiologists, immunologists and pathologists, from which many outstanding researchers emerged.

The scientist’s multifaceted activities touched upon a variety of areas of biology and medicine, but Mechnikov achieved the most impressive scientific results in embryology and gerontology, as well as in immunology and related pathology. Let's briefly talk about the first two and dwell in more detail on the biologist's works on immunity.

For research on the embryology of invertebrates (cephalopods, insects, ciliated worms - planarians) subordinated to the ultimate task - proof of evolution, Mechnikov, together with zoologist A.O. Kovalevsky received the prestigious K. Baer Prize.

Scientists established the unity of development of vertebrate and invertebrate animals and laid the foundations for a new branch of biology - evolutionary embryology.

Mechnikov also put forward the theory of “parenchymella” (phagocytella) - an extinct ancestor of multicellular animals, which played a large role in the development of evolutionary teaching.

While clarifying the issues of human aging, Mechnikov established several causes influencing premature aging and death. First of all, it is self-poisoning of the body with microbial and other poisons. To improve the intestinal flora, the biologist proposed a number of proven ones, incl. and on yourself, measures: sterilization of food, fermented milk products (Bulgarian yogurt - curdled milk fermented with a Bulgarian stick, Caucasian kefir), live culture of microorganisms - probiotics, limiting meat consumption, etc.

Mechnikov believed that a person’s life should be long and happy and end in a “calm natural death.” To do this, you need one skill - “to live correctly.” The scientist called this condition orthobiosis. (“Studies on Human Nature”, 1903; “Studies of Optimism”, 1907).

For most people, this teaching is more of a utopia, but for its adherents it is a panacea for many diseases and premature decline.

Mechnikov's path to the phagocytic theory of immunity was long and difficult. In addition, it was accompanied by continuous wars with opponents of this approach.

It began in Messina (Italy), where a scientist observed starfish larvae and sea fleas. The pathologist noticed how the wandering cells (he called them phagocytes - cell eaters) of these creatures surround and absorb foreign bodies, and at the same time resorb (dissolve) and destroy other tissues no longer needed by the body.

Mechnikov came to the idea of phagocytes earlier while studying intracellular digestion in motile connective tissue cells of invertebrates (amoebas, sponges, etc.), when the cells capture solid food particles and gradually digest them. In higher animals, typical phagocytes are white blood cells - leukocytes.

In this struggle between the phagocytes of the body and microbes arriving from outside, and in the inflammation accompanying this struggle, Mechnikov saw the essence of any disease, its philosophy, if you like.

The biologist's experiments were brilliant in their simplicity. By artificially introducing foreign bodies into the larvae's body (for example, a rose thorn), the scientist demonstrated their capture, isolation or destruction by phagocytes. The rather transparent (like a starfish) arguments of the Russian scientist, although they excited the scientific community, also turned it against this interpretation of the body’s disease.

The fact is that many biologists (especially German ones - R. Koch, G. Buchner, E. Behring, R. Pfeiffer) were champions of the so-called biologist that emerged at the same time. the humoral theory of immunity, according to which foreign bodies are destroyed not by leukocytes, but by other blood substances - antibodies and antitoxins. As it turned out, this approach is legitimate and consistent with the phagocytic theory.

Studying phagocytes for decades, Mechnikov at the same time studied cholera, typhus, syphilis, plague, tuberculosis, tetanus, and other infectious diseases and their causative agents. It was the study of immunity in infectious diseases of humans and animals - from protozoa to higher vertebrates, from the standpoint of cellular physiology, that experts considered the main merit of the Russian scientist.

Moreover, the results of his research became the foundation of a new branch of biology and medicine - comparative pathology, and the issues of bacteriology and epidemiology solved by Mechnikov’s school became the basis of modern methods of combating infectious diseases.

Mechnikov made the first report in a series of numerous works devoted to the phagocytic (cellular) theory, “On the healing powers of the body,” at the 7th Congress of Russian Naturalists and Doctors in Odessa in 1883.

In his “Lectures on the comparative pathology of inflammation” (1892), the biologist substantiated the idea of pathological processes as reactions of the body, its “norm”.

The result of many years of research into immunity was Mechnikov’s classic work “Immunity in Infectious Diseases” (1901). In a serious struggle of ideas, the scientist managed to defend his theory.

“Biology and medicine owe it to A.I. Mechnikov... significant broad generalizations that laid the foundation for a number of the most progressive areas of modern biology and medicine" (http://nplit.ru/). And we are all consumers of the scientific achievements of the Russian scientist - also by his thoughts about life, death, physical and moral health of a person. “The solution to the problem of human life must inevitably lead to a more precise definition of the foundations of morality. The latter should have as its goal not immediate pleasure, but the completion of the normal cycle of existence.”

P.S. In 1908 I.I. Mechnikov was awarded the Nobel Prize in Physiology or Medicine “for his work on immunity.” The welcoming speech said that “Metchnikoff laid the foundation for modern research in... immunology and had a profound influence on the entire course of its development.”

Since by that time the scientist had already lived in France for more than 20 years and worked at the Pasteur Institute, the Nobel Committee made an official request - whether the future Nobel laureate was Russian or French. “Ilya Ilyich proudly answered that he has always been and continues to be Russian” (D.F. Ostryanin).

Immunological reactivity

The expression “immunological reactivity” comes from the word “immunity”, which came to medicine from ancient legal sciences. In ancient Rome, “immune” meant “exempt from paying taxes.” People who have recovered from one or another contagious disease and are not susceptible to recurrent disease have also come to be called immune. They were used during epidemics of plague, cholera and other diseases to care for the sick and clean up corpses.

Immunological reactivity is the most important expression of reactivity in general. This concept combines a number of interrelated phenomena.

Immunity of humans and animals to contagious (infectious) diseases, or immunity in the proper sense of the word.

Reactions of biological incompatibility of tissues:

Hypersensitivity reactions (anaphylaxis and allergies).

Phenomena of addiction to poisons of various origins.

All these seemingly heterogeneous phenomena are united by the following characteristics.

All of these phenomena and reactions occur in the body when “foreign” living beings (microbes, viruses), normal or diseased tissues, more or less denatured proteins, various antigens, toxins, alkaloids, etc. enter it. A special place is occupied by reactions between embryonic tissues, the foreignness of which to each other is determined by the stage of development of the embryo.

These phenomena and reactions in a broad sense are reactions of biological protection aimed at preserving and maintaining the constancy, stability, composition and properties of each individual integral animal organism. Even severe hypersensitivity reactions in the form of anaphylactic shock are accompanied by destruction and cleansing of the body from the agent that caused the shock. Local hypersensitivity reactions are always accompanied by fixation of the pathogenic agent at the site of the reaction, which protects the body from the entry of this agent into the blood.

The doctrine of I. I. Mechnikov about phagocytosis. Phagocytosis (from the Greek phago - devour and cytos - cell) is the process of absorption and digestion of microbes and animal cells by various connective tissue cells - phagocytes. The doctrine of phagocytosis was created by the great Russian scientist - embryologist, zoologist and pathologist I. I. Mechnikov, who should be considered the founder of the doctrine not only of phagocytosis, but also of immunity.

For the first time, I. I. Mechnikov approached the question of phagocytosis based on observations of the absorption of food particles and microbes by endo- and mesoderm cells of lower invertebrate animals (sponges, coelenterates, intestinal turbellaria). In phagocytosis, he saw the basis of the inflammatory reaction, expressing the protective properties of the body.

I. I. Mechnikov first demonstrated the protective activity of phagocytes during infection using the example of infection of daphnia with a yeast fungus. Subsequently, I. I. Mechnikov convincingly demonstrated the importance of phagocytosis as the main mechanism of immunity in various infections of humans and animals. For humans, I. I. Mechnikov proved the correctness of his theory when studying the phagocytosis of streptococci in erysipelas. Subsequently, the phagocytic mechanism of immunity was established for tuberculosis, relapsing fever and many other infections.

PHAGOCYTIC THEORY OF IMMUNITY
immunity to infectious diseases, an outstanding discovery of the Russian scientist I.I. Mechnikov, made in 1901.

Source: Encyclopedia "Russian Civilization"

See what "PHAGOCYTIC THEORY OF IMMUNITY" is in other dictionaries:

I Medicine Medicine is a system of scientific knowledge and practical activities, the goals of which are to strengthen and preserve health, prolong the life of people, prevent and treat human diseases. To accomplish these tasks, M. studies the structure and... ... Medical encyclopedia

- (1845 1916), biologist and pathologist, one of the founders of comparative pathology, evolutionary embryology, immunology, creator of the scientific school of Russian microbiologists and immunologists; corresponding member (1883), honorary member (1902) of the St. Petersburg... ... Encyclopedic Dictionary

Famous scientist. Born 1845; studied at the 2nd Kharkov gymnasium and at the department of natural sciences of Kharkov University. Abroad (1864-67) he worked in Giessen, Göttingen and Munich. He received his master's degree in zoology in 1867 and... ... Biographical Dictionary

IMMUNITY- IMMUNITY. Contents: History and modern times. the state of the doctrine of I. . 267 I. as a phenomenon of adaptation........ 283 I. local..................... 285 I. to animal poisons...... ........ 289 I. during protozoan. and spirochete infections. 291 I. k… …

Zoologist and pathologist; genus. in 1845; studied at the 2nd Kharkov gymnasium, in 1862 he entered the department of natural sciences at Kharkov University, where he graduated from the course in 1864. Abroad (1864-67) he worked in Giessen, Göttingen and Munich. Degree… … Large biographical encyclopedia

GONORRHEA- GONORRHOEA. Contents: Historical data..............686 Biology of gonococcus in the body........6 87 Clinical immunity and reinfection.....689 Laboratory diagnosis of G.... .........690 G. as a general disease............695 General pathology... ... Great Medical Encyclopedia

- (from Latin immunis free, liberated, freed from something + Greek λόγος knowledge) medical biological science that studies the body’s reactions to foreign structures (antigens), the mechanisms of these reactions, their manifestations, normal course and outcome and ... Wikipedia

Books

Immunity in infectious diseases. Issue No. 14, I.I. Mechnikov. Readers are invited to the fundamental work of the outstanding Russian biologist I.I. Mechnikov (1845-1916), which examines the issues of immunity to diseases and substantiates...
Immunity in infectious diseases, I. I. Mechnikov. Readers are invited to the fundamental work of the outstanding Russian biologist I. I. Mechnikov, which examines the issues of immunity to diseases and substantiates...

Phagocytosis- the process of active absorption by the cells of the body of microbes and other foreign particles (Greek phagos - devouring + kytos - cell), including the body’s own dead cells. I.I. Mechnikov, the author of the phagocytic theory of immunity, showed that the phenomenon of phagocytosis is a manifestation of intracellular digestion, which in lower animals, for example, amoebas, is a method of nutrition, and in higher organisms phagocytosis is a defense mechanism. Phagocytes free the body from microbes and also destroy old cells of their own body.

According to Mechnikov, all phagocytic cells are divided into macrophages and microphages. Microphages include polymorphonuclear blood granulocytes: neutrophils, basophils, eosinophils. Macrophages are blood monocytes (free macrophages) and macrophages of various body tissues (fixed) - liver, lungs, connective tissue.

Microphages and macrophages originate from a single precursor - a bone marrow stem cell. Blood granulocytes are mature, short-lived cells. Peripheral blood monocytes are immature cells and, leaving the bloodstream, enter the liver, spleen, lungs and other organs, where they mature into tissue macrophages.

Phagocytes perform a variety of functions. They absorb and destroy foreign agents: microbes, viruses, dying cells of the body itself, tissue breakdown products. Macrophages take part in the formation of the immune response, firstly, by presenting antigenic determinants (epitopes) on their membrane and, secondly, by producing biologically active substances - interleukins, which are necessary for regulating the immune response.

There are several stages in the process of phagocytosis:

1) the approach and attachment of the phagocyte to the microbe - is carried out due to chemotaxis - the movement of the phagocyte in the direction of a foreign object. Movement is observed due to a decrease in the surface tension of the phagocyte cell membrane and the formation of pseudopodia. The attachment of phagocytes to the microbe occurs due to the presence of receptors on their surface,

2) absorption of the microbe (endocytosis). The cell membrane bends, an invagination is formed, and as a result, a phagosome is formed - a phagocytic vacuole. This process is carried out with the participation of complement and specific antibodies. For the phagocytosis of microbes with antiphagocytic activity, the participation of these factors is necessary;

3) intracellular inactivation of the microbe. The phagosome merges with the lysosome of the cell, a phagolysosome is formed, in which bactericidal substances and enzymes accumulate, as a result of which the death of the microbe occurs;

4) digestion of the microbe and other phagocytosed particles occurs in phagolysosomes.

Phagocytosis, which leads to the inactivation of the microbe, that is, includes all four stages, is called complete. Incomplete phagocytosis does not lead to the death and digestion of microbes. Microbes captured by phagocytes survive and even multiply inside the cell (for example, gonococci).

In the presence of acquired immunity to a given microbe, opsonin antibodies specifically enhance phagocytosis. This type of phagocytosis is called immune. In relation to pathogenic bacteria with antiphagocytic activity, for example, staphylococci, phagocytosis is possible only after opsonization.

Antigens.

Antigens (Greek anti - against, genos - birth) are genetically foreign substances that, when they enter the body, cause an immune response. Specific immune reactions that can occur in response to an antigen are: the synthesis of antibodies, the appearance of immune lymphocytes, allergic reactions, immunological tolerance, immunological memory.

Complete antigens have two properties: immunogenicity and specificity. Immunogenicity is understood as the ability of an antigen to provoke an immune response in the body, in particular, the formation of antibodies and immune lymphocytes. The specificity of the antigen is expressed in the fact that it binds only to those antibodies and immune lymphocytes that arose in response to its administration.

Defective antigens or haptens They do not have immunogenicity, but can combine with ready-made antibodies specific for them. Antibodies specific for hapten are produced when a hapten with protein is introduced into the body.

In order to act as antigens, substances must be recognized by the macroorganism as foreign, “not its own,” since antibodies to “self” proteins are usually not formed. Antigens can be biopolymeric substances, foreign to a given organism, with a large molecular weight, having a rigid chemical structure, forming a colloidal solution. These are mainly proteins. Among the antigens of microbial origin, there are also non-protein antigens - these are lipopolysaccharides (LPS) of the cell wall of gram-negative bacteria.

Antigen specificity determined by it determinant groups. These are small sections of the antigen molecule (epitons) located on its surface. They are recognized as foreign by lymphocytes (antigen-recognizing, immunocompetent cells). By chemical nature, determinant groups are carbohydrates, peptides, lipids, and nucleic acids. If separated from the carrier molecule, they behave like haptens.

Immunogenicity increases with the introduction of antigens with adjuvants (Latin adjuvantis - auxiliary). Aluminum hydroxide, A1(OH)3, is often used as an adjuvant.

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Discovery of phagocytosis by I. I. Mechnikov. Discovery of humoral immunity factors. (P. Ehrlich, E. Bering, E. Roux, etc.). Obtaining therapeutic serums.

The third stage in the development of microbiology is immunological, from the end of the 19th century. until the middle of the 20th century. During this period, the state of the body's defenses aimed at combating pathogenic microorganisms was studied. The Russian scientist I.I. Mechnikov developed the doctrine of phagocytosis, i.e., the role of white blood cells against foreign factors, and developed the foundations of cellular immunity. German the scientist P. Ehrlich discovered the phenomenon of humoral immunity, i.e. the presence of antibodies, and also mistakenly assumed that the humoral mechanism was the body’s only defense. E. Bering was the first to use passive immunization by reintroducing living microorganisms from a recovered organism into a healthy one. E. Roux studied the causative agent of diphtheria that produces the toxin and its effect, discovered anti-diphtheria serum and anti-botulism serum.

The fourth stage is modern from the mid-20th century. to this day. Its main tasks:

1. Development of the science of virology.

2. Creation of new vaccines.

3. Creation of new antibiotics.

4. Creation of immunomodulators (immunostimulants - increase immunity, immunosuppressants - suppress the immune response. (used in transplantology)).

6. The role of domestic scientists in the development of microbiology (I. I. Mechnikov, G. N. Gabrichevsky, D. K. Zabolotny, N. F. Gamaleya, L. A. Zilber, Z. V. Ermolyeva, P. F. Zdradovsky , V.D. Timakov, etc.)

I. I. Mechnikov (see question 5)

G. N. Gabrichevsky - he is responsible for the creation of honey. Institute in Moscow, St. Petersburg. Publishing textbooks on microbiology.

N. F. Gamaleya - studied the causative agent of the plague, developed preventive measures and the doctrine of the epidemiology of diseases.

L. A. Zilber is the founder of the viral genetic theory of tumors. He proved experimentally that certain types of viruses cause oncogenic degeneration of cells.

Z.V. Ermolyeva - created the first domestic antibiotic, developed accelerated methods for diagnosing cholera (express diagnostics).

P. F. Zdradovsky - studied rickettsia, the epidemiology of typhus.

V.D. Timakov - compiled a textbook on microbiology, which we now use.

7. D. I. Ivanovsky – founder of virology. Development of virology in the second half of the 20th century. The role of domestic scientists.

Virology is the science of precellular life forms - viruses. Virology originated in 1892. After the contribution made by 5th year student of the St. Petersburg Botanical Academy D.I. Ivanovsky, he reported on mosaic disease of tobacco and concluded that it is caused by something smaller than bacteria and is contagious. Live start filtered through bacterial filters and can infect healthy plants. A mute entered into an argument with him. chemist Beyering, he stated that this something is a poison (Virus from Latin poison, toxin). D.I. Ivanovsky proved the living nature of viruses in an experiment on the passage of infectious material through susceptible organisms. Each new plant became sick and died faster. than the previous one, i.e. living beginning accumulated and increased its pathogenicity, while the poison would decrease its concentration.

In the mid-40s. invented an electron microscope and were able to examine viruses and determine their structure. In the first 50 years, 100 viral diseases were discovered. and for 10 years of the second half of the 20th century. already 1000 viruses.

Modern virology studies:

1. New viruses (HIV. Ebola).

2. Creates vaccines against viral diseases.

3. Creates antiviral drugs.

4. Studies the genome of viruses with the aim of using genetic engineering to obtain microorganisms with new properties.

Basic principles of taxonomy of microorganisms according to Bergey. Taxonomic categories; genus, species, strain. Intraspecific identification of bacteria; serovar, phagovar, biovar, ecovar, pathovar.

The Bergey classification was created in 1927. Since then, it has gone through 9 editions, because many microorganisms were discovered later. The classification is based on morphology, physiology, biological and antigenic properties. According to Bergey, all microorganisms are divided into three kingdoms:

1. Eukaryotes (presence of a separate nucleus) are fungi and protozoa.

2. Prokaryotes (lack of a separate nucleus) are bacteria, mycoplasmas, actinomycetes, rickettsia, chlamydia, spirochetes.

3. Viruses (DNA and RNA containing).

Bacteria are divided according to morphology into cocci, rods and convoluted ones. According to Gram staining ability (Gr+ and Gr-).

Taxometric categories. A species is a collection of individuals of the same genotype with different phenotypic manifestations and having the same evolutionary ancestor. A genus is a collection of individuals of different species, but having one evolutionary ancestor. (Example: Salmonella – Genus, Salmonella Typhy – Species). A strain is a microorganism of the same species isolated from different sources or at different times. Strains are designated by numbers (Example: E. coli-Strain No. 1).

Species identification term

Serovar– a serological variant with different antigenic structure within the same species.

Biovar– a serological variant with different degrees of sensitivity to bacteriophages.

Ecovar- a representative of one species isolated from different environmental environments.

Patovar– a pathological variant of a representative of the species – the causative agent of the disease.

9. Study of the morphology of microorganisms. Microscopy and staining methods. Structural features of Gr+ and Gr- bacteria.

1.Light immersion microscopy allows you to view a colored object. A light microscope, immersion oil (1) and immersion objective (2) with a magnification of x90 are used. The principle of the immersio method is immersion. Immersion oil is applied to the preparation, the immersion lens is immersed in it, as a result of which there is no scattering of the rays.

Disadvantages of the method: the resolution of the microscope is at least 0.2 microns.

Who discovered the phenomenon of phagocytosis: answer the question

at a wavelength of ½ l.

2. Phase contrast microscopy for studying living, unpainted objects. A light immersion microscope and a phase plate are used, which converts phase oscillations invisible to the eye (1) into visible amplitude ones (2), by moving the wave passing through the object by ¼ l. right or left. (A) by phase (negative contrast). (B) antiphase (positive contrast). X is amplitude, T is time.

3. Luminescence microscopy to study the glow of objects painted with fluorochromes. A fluorescent microscope and illumination source (UFL) are used. The rays do not pass through the object, but fall on it. Ultraviolet radiation causes electrons to escape from orbitals. Energy is released visible as a glow. Advantages: high resolution, possibility of specific luminescence (RIF). Disadvantages: high cost, inaccessibility for practical laboratories.

4. Electron microscopy the most advanced method, unlimited resolution, even the atomic structure can be considered. The principle of the method: the electric flow passing through the object between the cathode and the anode loses speed at the anode. For recording, a photographic plate or photocell connected to an oscilloscope is fixed in front of the anode. Disadvantages: inaccessibility for practical laboratories.

Coloring methods.

Simple coloring - using one dye (fuchsin or methylene blue).

Complex coloring - the use of two or more dyes and additional ingredients (according to Gram, according to Ziehl-Neelsen).

The Gram stain method differentiates bacteria into two groups based on the structure and biochemistry of the cell wall

Differences in wall structure:

Gram stain scheme:

Ziehl-Neelsen staining:

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The issue of protecting the body from unfavorable conditions has always interested humans, so it is difficult to establish when immunology first appeared. It is known that already in the first millennium BC. In China, inoculations of the contents of smallpox papules were used to instill immunity in healthy people. In the 11th century, Avicenna mentioned acquired immunity, and based on his theory, the Italian author Girolamo Fracastoro wrote a large-scale treatise “Contagion” (1546).

Development of the theory of immunity

At the end of the 19th century, thanks to the work of Louis Pasteur, a breakthrough occurred in the development of immunology. In 1881, he succeeded in vaccinating animals against anthrax, but his theory lacked acceptable scientific basis. At the same time, the German Emil von Berning proved the formation of antitoxins in people who had suffered from tetanus or diphtheria, as well as the effectiveness of blood transfusions from such people for the formation of immunity in healthy people. Berning also investigated the mechanisms of serum therapy, and his works laid the foundation for the study of the theory of humoral immunity.

However, neither Pasteur nor Berning were able to offer a sufficiently substantiated theory describing the mechanisms of immunity. The foundations of the modern scientific approach to the study of immunity were laid by the Russian scientist Ilya Mechnikov, who laid the foundation for the phagocytic theory of immunity. For his research into immunity in infectious diseases in 1908, Mechnikov was awarded the Nobel Prize, albeit jointly with P. Ehrlich (author of the humoral theory of immunity).

Cellular immunology Mechnikov

Mechnikov proved the existence in the body of special amoeboid cells capable of absorbing pathogenic microorganisms.

Observing the moving cells of a starfish under a microscope, Ilya Ilyich discovered that they not only participate in the digestion process, but also perform protective functions in the body, enveloping and absorbing foreign particles. Mechnikov gave them the name “phagocytes”, and the process itself was called “phagocytosis”.

In his theory, the scientist described three main properties of phagocyte cells:

The ability to protect the body from infections, as well as cleanse it of toxins (including breakdown products of healthy tissues).
The ability of phagocytes to produce enzymes and biologically active substances.
The presence of antigens on the membrane of phagocyte cells.

Mechnikov identified two groups of phagocytes - granular blood cells (microphages) and mobile leukocytes (macrophages).

Due to the fact that immunocompetent cells are able to remember the antigen presented by macrophages, the body develops immunity against foreign elements of a certain type. Therefore, when the infection is re-infected, there is an appropriate immune response that prevents the development of pathogenic processes.

Main tasks of immunology of the 21st century

Despite a significant breakthrough in studies of the structure and interaction of body cells, the phagocytic theory proposed by Mechnikov remains the main basis of modern immunology.

In 1937, work began on the electrophoresis of blood proteins, which laid the foundation for the study of immunoglobulins; the main classes of antibodies (immunoglobulins) capable of identifying and neutralizing foreign elements were soon discovered. All these studies only develop the theory proposed by Mechnikov, exploring its mechanisms at a more detailed level.

The main challenges to which the phagocytic theory must find an answer are issues of immunodeficiency, treatment of cancer, development of new vaccines and antiallergens.

Promising directions are the study of the mechanisms of response of infectious microorganisms to means of combating them.

Discovery of phagocytes by Metchnikoff

What their modifications trigger, how this process occurs at the biochemical level, how the mechanisms of immunity are affected by the mental and emotional state and other additional factors - these and other questions remain poorly understood and await their discoverers.

Today 8.07.2018

Diseases Phagocytosis

During the development of inflammation, another universal tissue mechanism of nonspecific defense is implemented - phagocytosis. The phenomenon of phagocytosis was discovered and studied by the great Russian scientist I.I. Mechnikov (1883). The result of these many years of work was the phagocytic theory of immunity, for the creation of which Mechnikov was awarded the Nobel Prize.

I.I. Mechnikov divides all cells with phagocytic activity into microphages and macrophages.

Microphages: polymorphonuclear granulocytes - neutrophils, eosinophils, basophils.

Macrophages: blood monocytes, cells of the reticuloendothelial system, combining migrating and fixed cells of the liver, spleen, bone marrow, which are united in a system of mononuclear phagocytes.

Phagocytes perform several functions in the body:

1) they remove dying cells from the body, absorb and inactivate microorganisms and their products, acting as a kind of orderly, scavenger.

2) synthesize some biologically active substances that provide resistance to the body - such as lysozyme, interferon, complement components, cytokines, etc.

Cytokines are hormone-like mediators produced by different cells of the body and can affect the function of these or other groups of cells. Cytokines that regulate the interactions of leukocytes with each other and other cells are called interleukins.

3) these cells participate in specific immunity by presenting antigen to immunocompetent cells.

Phagocytosis consists of several successive phases, stages:

1) chemotaxis—approximation of the phagocyte to the object;

2) adhesion - adsorption of a foreign substance absorbed by a microorganism on the surface of a phagocyte;

3) endocytosis - absorption of a foreign substance by invagination of the cell membrane with the formation of a phagosome.

4) intracellular digestion - fusion of the phagosome with the lysosome of the cell occurs, forming a phagolysosome and digestion of a foreign substance in the phagolysosome with the help of enzymes. (Table 7)

Intracellular lysosomes contain about 40 different enzymes that can digest almost any substance. These stages are characteristic of completed phagocytosis. Some bacteria, viruses, and protozoa block the enzymatic activity of the phagocyte and microorganisms not only do not die or are destroyed, but also multiply in the phagocytes. This process is usually called incomplete phagocytosis.

Factors stimulating phagocytosis - antibodies opsonins, complement, immunoglobulins, lymphokine mediators. Phagocytosis is also accelerated by electrolytes, Ca and Mg salts, adrenaline, and histamine. Phagocytosis is inhibited by acetylcholine, serotonin, antihistamines and corticosteroids.

During the second half of the 19th century, doctors and biologists of that time actively studied the role of pathogenic microorganisms in the development of infectious diseases, as well as the possibility of creating artificial immunity to them. These studies have led to the discovery of facts about the body's natural defenses against infections. Pasteur proposed to the scientific community the idea of the so-called “exhausted force.” According to this theory, viral immunity is a condition in which the human body is not a beneficial breeding ground for infectious agents. However, this idea could not explain a number of practical observations.

Mechnikov: cellular theory of immunity

This theory appeared in 1883. The creator of the cellular theory of immunity relied on the teachings of Charles Darwin and was based on the study of digestive processes in animals, which are located at various stages of evolutionary development. The author of the new theory discovered some similarities in the intracellular digestion of substances in endoderm cells, amoebas, tissue macrophages and monocytes. Actually, immunity was created by the famous Russian biologist Ilya Mechnikov. His work in this area continued for quite a long time. They began in the Italian city of Messina, where a microbiologist observed the behavior of larvae

The pathologist discovered that the wandering cells of the observed creatures surround and then absorb foreign bodies. In addition, they resorb and then destroy those tissues that the body no longer needs. He put a lot of effort into developing his concept. The creator of the cellular theory of immunity introduced, in fact, the concept of “phagocytes,” derived from the Greek words “phages” - to eat and “kitos” - cell. That is, the new term literally meant the process of eating cells. The scientist came to the idea of such phagocytes a little earlier, when he studied intracellular digestion in various connective tissue cells in invertebrates: sponges, amoebae and others.

In representatives of the higher animal world, the most typical phagocytes can be called white blood cells, that is, leukocytes. Later, the creator of the cellular theory of immunity proposed dividing such cells into macrophages and microphages. The correctness of this division was confirmed by the achievements of the scientist P. Ehrlich, who differentiated different types of leukocytes through staining. In his classic works on the pathology of inflammation, the creator of the cellular theory of immunity was able to prove the role of phagocytic cells in the process of eliminating pathogens. Already in 1901, his fundamental work on immunity to infectious diseases was published. In addition to Ilya Mechnikov himself, a significant contribution to the development and dissemination of the theory of phagocytic immunity was made by I.G. Savchenko, F.Ya. Chistovich, L.A. Tarasevich, A.M. Berezka, V.I. Isaev and a number of other researchers.