Phagocytosis- the process of active absorption by cells of the organism of microbes and other alien particles (Greek. Phagos - devouring + Kytos cell), including its own dead cell cells. I.I. Mechnikov - the author of the phagocytic theory of immunity - showed that the phenomenon of phagocytosis is the manifestation of intracellular digestion, which in lower animals, for example, in AmeB, is a power method, and the highest organisms phagocytosis is a protection mechanism. Phagocytes exempt the organism from microbes, and also destroy the old cells of their own organism.
According to Mesnikov, all phagocytic cells are divided into macrophages and microphages. Microphams include polymorphonuclear blood granulocytes: neutrophils, basophiles, eosinophils. Macrophages are blood monocytes (free macrophages) and macrophages of various organism tissues (fixed) - liver, lung, connective tissue.
Microphages and macrophages occur from a single predecessor - bone marrow stem cell. Blood granulocytes are mature short-lived cells. Monocytes of peripheral blood - immature cells and, leaving the bloodstream, fall into the liver, spleen, lungs and other organs, where ripen in tissue macrophages.
Phagocytes perform a variety of functions. They absorb and destroy alien agents: microbes, viruses, dying cells of the organism itself, tissue decay products. Macrophages take part in the formation of an immune response, firstly, by presenting (presentation) of antigenic determinants (epitopes on its membrane and, secondly, the method of producing biologically active substances - interleukins, which are necessary for regulating the immune response.
In the process of phagocytosis, several stages distinguish:
1) Approximation and addition of phagocyte to the microbe - carried out due to chemotaxis - the movement of phagocyte in the direction of the alien object. Movement is observed due to lowering the surface tension of the cell membrane of phagocyte and the formation of pseudoenia. The addition of phagocytes to the microbe occurs due to the presence of receptors on their surface,
2) the absorption of the microbe (endocytosis). The cell membrane begins, prying is formed, as a result we form a phaagosome -Fagocyrtic vacuol. This process) is sewn with the participation of complement and specific antibodies. For phagocytosis of microbes with antiphaganic activity, the participation of these factors is necessary;
3) intracellular inactivation of the microbe. The phagemy is poured with a lysosome cell, a phagelicosome is formed, in which bactericidal substances and enzymes accumulate, as a result of which the microbial death nominates;
4) the digestion of the microbe and other phagocyted particles occurs in phagelicosomes.
Phagocytosis, which leads to the inactivation of the microbe, that is, includes all four stages, called completed. Incorrect phagocytosis does not lead to death and digestion of microbes. The microbes captured by phagocytes survive and even multiply inside the cell (for example, gonococci).
In the presence of an acquired immunity to this microbe, the OpOson antibodies specifically enhances phagocytosis. Such phagocytosis is called immune. With regard to pathogenic bacteria with anti-phakocyte activity, for example, staphylococci, phagocytosis is possible only after OPSonization.
Antigens.
Antigens (Greek Anti - Against, Genos - Birth) - Genetically alien substances that are caused by an immune response when entering the body. Specific immune reactions that may occur in response to the antigen, this: antibody synthesis, the appearance of immune lymphocytes, allergic reactions, immunological tolerance, immunological memory.
Full antigenshave two properties: immunogenicity and specificity. Under immunogeneity, the ability of the antigen cause 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 is connected only with those antibodies and immune lymphocytes that arose in response to its introduction.
Defective antigens or haptendo not have immunogenicity, but can be connected with ready-made antibodies for them. Antibodies, specific for hapten, are produced by the administration of Gapten with protein into the body.
In order to act as antigens, substances should be recognized by macroorganism as alien, "not their own", since the antibodies to "their" proteins are not formed. Antigens can be bioolymer substances, alien for a given organism, with a large molecular weighthaving a rigid chemical structure forming a colonium solution. This is basically proteins. Among the antigens of microbial origin there are neochny antigens - these are lipopolysaccharides (LPS) of the cell wall of gram-negative bacteria.
Specificity of antigenit is determined determinant groups.These are small sections of the antigen molecule (epitons) located on its surface. It is they who are recognized as alien lymphocytes (antigensic, immunocompetent cells). By chemical nature Determinant groups are carbohydrates, peptides, lipids, nucleic acids. If you separate them from the carrier molecule, they behave like haptins.
Immunogenicityit increases with the introduction of antigens with adjuvants (lat. Adjuvantis - auxiliary). As an adjuvant, aluminum hydroxide is often used - A1 (OH) 3.
Immunological reactivity
The expression "immunological reactivity" comes from the word "immunity", which came to medicine from the ancient legal sciences. In ancient Rome, "Immune" meant "released from payment of filters." Immune began to be called people who have suffered by one or another infectious disease and not susceptible to re-illness. They were used at the epidemics of plague, cholera and other diseases to care for sick and cleaning corpses.
Immunological reactivity is an essential expression of reactivity in general. This concept combines a number of interrelated phenomena.
Unresponsibility of man and animals to infectious (infectious) diseases, or immunity in his own sense of the word.
Reactions biological incompatibility Tissues:
Reactions increased sensitivity (anaphylaxis and allergies).
Phenomena of addictive to poisons of various origin.
Unite all these at first glance, heterogeneous phenomena with each other the following signs.
All indicated phenomena and reactions occur in the body when "alien" living beings (microbes, viruses), normal or painfully altered tissues, more and less denatured proteins, various antigens, toxins, alkaloids, etc., occasionally occupied by Tissues, the alienity of which is determined by each other's stage of the development of the embryo.
These phenomena and reactions are widely understood are reactions of biological protection aimed at preserving and maintaining constancy, stability, composition and properties of each individual integrity of the animal. Even severe well-sensitivity reactions in the form of anaphylactic shock are accompanied by the destruction and purification of the body from the agent that caused the shock. Local reactions of increased sensitivity are always accompanied by fixing the pathogen agent at the reaction site, which protects the body from this agent to the blood.
The teachings of I. I. Mesnikov about phagocytosis. Phagocytosis (from Greek. Phago - devout and cytos cell) is called the process of absorption and digestion of microbes and animal cells by various connective tissue cells - phagocytes. The doctrine of Phagocytosis created a great Russian scientist - an embryologist, a zoologist and a pathologist I. I. Mesnikov, who should be considered the founder of the teachings not only about phagocytosis, but also on immunite.
For the first time, I. I. Mechnikov approached the question of phagocytosis on the basis of observation of the absorption of endo and mesoderma cells of the lower invertebrate animals (sponges, intestinal, dry turbellarium) particles of food and microbes. In Phagocytosis, he saw the basis of an inflammatory reaction expressing the protective properties of the body.
Protective activities of phagocytes in infection I. I. Smestov first showed on the example of a yeast fungus infection. In the future, I. I. Meschnikov, the value of phagocytosis as the main mechanism of immunity was convincingly shown in various human and animal infections. For a person, the correctness of his theory of I. I. Mesnikov proved in the study of Phagocytosis streptococci during his face. In the future, the phagocytarial mechanism of immunity was installed for tuberculosis, return title and many other infections.
The process of the formation and development of immunity science was accompanied by the creation of various kinds of theories, which laid the foundation of science. Theoretical teachings acted as an explanation of the complex mechanisms and processes of the person's internal environment. Consider the main concepts of the immune system, and the presented publication will help to familiarize themselves with their founders.
What is the theory of immunity?
Theory of immunity - It is a teaching summarized by experimental studies, which, based on the principles and mechanisms of immune protection in the human body.
The main theories of immunity
Immunity theories created and developed for a long period of time I.I. Mechnikov and P. Erlich. The founders of the concepts laid the foundation for the development of immunity science - immunology. Consider the principles for the development of science and features will help basic theoretical teachings.
The main theories of immunity:
- The fundamental concept in the development of immunology was made the theory of Russian scientist Minkov I.I. In 1883, the representative of the Russian scientific community proposed the concept according to which mobile cell elements are present in the inner medium. They are able to collect all the bodies and digest foreign microorganisms. Cells were called - macrophages and neutrophils.
- The ancestor of the theory of immunity, which was developed in parallel with the theoretical teaching of Mechnikov became concept of German scientist P. Erlich. According to the teachings of P. Erlich, it was found that in the blood of animal bacteria, microelements appear, destroying foreign particles. Protein substances received the name - antibodies. A characteristic feature of antibodies is their focus on resistance to a specific microbe.
- Teaching M. F. Berenet. The basis of its theory lay the assumption that immunity is an antibody reaction aimed at recognizing and separation of their and dangerous trace elements. Acts as a creator clonal - breeding theory of immune defense. In accordance with the concept presented, one clone of lymphocytes reacts to one particular trace element. The designated theory of immunity was proved and as a result, it was revealed that the immune response acts in relation to any alien organisms (graft, tumor).
- Instructive theory of immunity The creation date is considered to be in 1930. Founders were performed by F. Branel and F. Gaurovits. According to the concept of scientists, the antigen is a place to connect antibodies. The antigen is also a key element of the immune response.
- The theory of immunity was also designed M. Heidelberg and L. Polingom. According to the presented teaching, compounds of antibodies and antigens in the form of a lattice are formed. The creation of the lattice will only be possible in the presence of three determinants in the antibody molecule for the antigen molecule.
- Immunity concept Based on which the theory was developed natural selection N. Erne. The founder of the theoretical teaching suggested that in the human body there is a molecule complimentary to foreign microorganisms, which fall into the internal environment of a person. The antigen does not connect and does not change the existing molecules. It contacts the appropriate antibody in the blood or a cell and combines it.
The presented immunity theories laid the foundation for immunology and allowed scientists to develop historically established views regarding the functioning of the human immune system.
Cellic
The founder of the cell (phagocytic) theory of immunity is the Russian scientist I. Smestov. Studying marine invertebrates, the scientist found that some cell elements absorb alien particles penetrating into the inner medium. The merit of Mechnikov is to carry out an analogy between the observed process with the participation of invertebrates and the absorption process by white cellular elements of the blood of vertebrates. As a result, the researcher put forward the opinion according to which the process of absorption acts as a protective reaction of the body accompanied by inflammation. As a result of the experiment, cell immunity theory was nominated.
Cells carrying protective functions in the body were called phagocytes.
Distinctive features of phagocytes:
- Implementation of protective functions and withdrawal of toxic substances from the body;
- Representation of antigens on the cell membrane;
- Isolation of a chemical substance from other biological substances.
The mechanism of action of cellular immunity:
- In cell elements, the process of attaching phagocyte molecules to bacteria and viral particles occurs. The presented process contributes to the elimination of alien elements;
- Endocytosis affects the creation of phagocytic vacuole - the phagemsomas. Granules of macrophages and azurophilic and specific neutropyl granules move to the phaginomome, and combine with it, highlighting their contents into the fagosome tissue;
- In the process of absorption, generating mechanisms are enhanced - specific glycoliz and oxidative phosphorylation in macrophages.
Gumoral
The German researcher P. Earlich was spoken by the ancestor of the humoral theory of immunity. The scientist argued that the destruction of alien elements from the inner medium of a person is possible only with the help of protective blood mechanisms. The resulting conclusions were presented in a single theory of humoral immunity.
According to the author, the basis of humoral immunity is the principle of destruction of alien elements through fluids of the internal environment (through blood). Substances that carry out the process of eliminating viruses and bacteria are divided into two groups - specific and nonspecific.
Nonspecific immune system factors represent the stability of the human body to diseases obtained by inheritance. Nonspecific antibodies are universal and have an impact on all groups of dangerous microorganisms.
Specific factors of the immune system (protein elements). They are created in lymphocytes that form antibodies that recognize and destroy the foreign particles. The peculiarity of the process is the formation of immune memory, which prevents the invasion of viruses and bacteria in the future.
The merit of the researcher is to establish the fact of transferring antibodies by inheritance with Mother's milk. As a result, a passive immune system is formed. The duration of its action is six months. After the immune system of the child begins to function independently and produce its own cellular elements.
Familiarize yourself with the factors and mechanisms of the action of humoral immunity
During the second halves XIX. A century, the role of pathogenic microorganisms in the process of developing infectious diseases, as well as the possibility of forming artificial immunity to form artificial immunity to the doctors and biologists of that time. These studies led to the study of facts about the natural protection of the body from infections. Paster offered a scientific community the idea of \u200b\u200bthe so-called "exhaust force." According to this theory, viral immunity is such a state in which the human body is not a beneficial nutrient medium for infectious agents. However, this idea could not explain a number of practical observations.
Mistresses: Cellular theory of immunity
This theory appeared in 1883. The creator of the cell theory of immunity relied on the teaching of Charles Darwin and was based on the study of the processes of digestion in animals, which are located on various steps of evolutionary development. The author of the newly theory found some similarity in intracellular digestion of substances in Entoderm cells, ameb, fabric macrophages and monocytes. Actually, immunity created the famous Russian biologist Ilya Zdovnikov. His work in this area continued long enough. The beginning of them was laid in the Italian city of Messina, in which the microbiologist watched the behavior and larvae
The pathologist discovered that the wandering cells of the observed creatures of alien bodies surround and then absorb them. In addition, they are dissipated and trail destroy those tissues that do not need the organism more. He made a lot of effort to develop his concept. The creator of the cell theory of immunity introduced, in fact, the concept of "phagocytes", derived from the Greek words "FAGES" - to eat and "Kitos" - a cell. That is, the new term literally meant the process of eating cells. The scientist came to the idea of \u200b\u200bsuch phagocytes, when he studied intracellular digestion in various cells connective tissue Invertebrates: Sponges, Ameb and others.
Representatives of the highest animal world with the most typical phagocytes may be called white blood tales, that is, leukocytes. Later, the creator of the cell theory of immunity proposed to divide such cells on macrophages and microphages. The correctness of such separation confirmed the achievements of the scientist P. Erlich, which differentiated various types of leukocytes through coloring. In their classical work devoted to the pathology of inflammation, the creator of cell theory of immunity was able to prove the role of phagocytic cells in the process of elimination of pathogens. Already in 1901, his fundamental work on immunity to infectious diseases was published. In addition to Ilya, Mechnikov, a significant contribution to the development and distribution 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.
Russian biologist I.I.Technical is the founder of the theory of immunity. They have developed a phagocytic theory of immunity, which explains the complex work of the immunity system.
The swords studied how different pathogens in leukocytes behave (protective cells of blood) of man and monkeys behave. Numerous experiments became the basis for the creation of phagocytosis theory proposed by scientists.
Ilya Ilyich Mechnikov
According to the theory, all cells of the human body, which participate in phagocytosis, can be divided into macrophages and microphages.
TO microfhams Granular leukocytes (basophiles, neutrophils) are blood cells. Macrofagi - these are moving leukocytes (spleen cells, lymphs, monocytes) and stationary (epithelial cells lining from the inside of the walls of the vessels, cells of the spleen pulp).
The basis of phagocytic theory
The basis of the phagocytic theory of swords was put on three basic properties of phagocytes.
- Phagocytes are able to protect and purify from toxins, from infections, from tissue decay products.
- Phagocytes represent (have) antigens on cell membrane.
- Phagocytes have the ability to secrete enzymes and biologically active substances.
In the process of phagocytosis, five stages are distinguished:
- Activation or acceleration of energy exchange. Bacterial products, complement components, antibodies and cytokines can cause activation.
- Chemotaxis - directed phagocyte movement to a foreign cell or body.
- Adhesion - accession to a dangerous agent.
- Endocytosis is the absorption of the phagocyte of an alien agent and digesting it.
- The outcome of phagocytosis.
Adhesion becomes possible due to receptors on the surface of phagocytes. These can receptors for Fc fragments, to fibronectin, to the components of the compliment system. In addition, special opsonins are formed - substances that envelop the microorganism to which phagocyte is joined, and limit its mobility.
Phagocytes have pseudopodia - this is the cells of the cell membrane, which resemble the legs of Ameb. Phagocyt surrounds with these false peasons and absorbs it, the phagosome is formed. Then, a lysosome is joined to such a fagosome in which enzymes that are capable of digesting cellular structures. Fagalism is formed.
Phagocyte
It is known several outcomes of phagocytosis: phagocytosis completed, phagocytosis unfinished, antigens processing. With complete phagocytosis, the captured microorganism is completely digested inside the phagocytic cell.
The reasons why microorganisms do not die in phagocite, several. Toxoplasm, influenza virus, mycobacteria is able to block the fogosome fusion with lysosome.
Enzymes do not go to phagocyte and digestion does not occur. Staphylococci and gonococci are resistant to the action of lysosomal enzymes. Ricketcies are able to quickly leave the Fagosoma, which absorbed them, and to be long in the cytoplasm.
The bactericidal effect (the ability to kill microorganisms) of phagocytes is explained by the fact that in phagocytosis, the "oxidative explosion" occurs, as a result of which a lot is formed active forms oxygen. They completely destroy bacteria.
Macrophages are capable not only to participate in phagocytosis, move to an alien organism, destroy it, secreted by biologically active substances, but also to recycle the antigen, and then provide it with special immunocompetent cells. These cells "remember" the presented antigen, so that when it is repeated, it is necessary to answer properly.
As a result of phagocytosis, the biological object is not only destroyed by the alien organism, but also recognizes its antigens for further launch and inflammation reactions.
