Specific defense mechanisms of the immune system. Humoral and cellular immunity: features and differences Natural and artificial immunity

Cellular immune response is formed during transplantation of organs and tissues, infection with viruses, malignant tumor growth. TC (TC) is involved in cellular immunity, reacting with an antigen in combination with class I MHC glycoproteins in the plasma membrane of the target cell. A cytotoxic T cell kills a virus-infected cell if it recognizes, through its receptors, fragments of viral proteins bound to MHC class I molecules on the surface of the infected cell. The binding of Tc to targets leads to the release by cytotoxic cells of pore-forming proteins called perforins, which polymerize in the plasma membrane of the target cell, turning into transmembrane channels. It is believed that these channels make the membrane permeable, which contributes to cell death.

Mechanism of humoral immunity

The humoral immune response is provided by B-lymphocytes with the participation of Tx and macrophages (antigen-presenting cells).

The antigen that enters the body is absorbed by the macrophage. The macrophage cleaves it into fragments, which, in combination with class II MHC molecules, appear on the cell surface. This processing of an antigen by a macrophage is called antigen processing.

The participation of Tx is necessary for the further development of the immune response to the antigen. But before Tx must be activated themselves. This activation occurs when the antigen processed by the macrophage is recognized by Tx. “Recognition” of the “antigen + MHC class II molecule” complex on the surface of a macrophage by a Th-cell (i.e., the specific interaction of the receptor of this T-lymphocyte with its ligand) stimulates the secretion of interleukin-1 (IL-1) by the macrophage. Under the influence of IL-1, the synthesis and secretion of IL-2 by the Tx cell are activated. The release of IL-2 by the Th-cell stimulates its proliferation. Such a process can be regarded as autocrine stimulation, since the cell reacts to the agent that it synthesizes and secretes. An increase in the number of Tx is necessary for the implementation of an optimal immune response. Tx activate B cells by secreting IL-2.

Activation of the B-lymphocyte also occurs with direct interaction of the antigen with the immunoglobulin receptor of the B-cell. The B-lymphocyte processes the antigen itself and presents its fragment in combination with the class II MHC molecule on the cell surface. This complex recognizes Tx already involved in the immune response. Recognition by the Th-cell receptor of the “AG + class II MHC molecule” complex on the surface of the B-lymphocyte leads to the secretion of interleukins by the Th-cell, under the influence of which the B-cell multiplies and differentiates with the formation of plasma cells and memory B-cells. Thus, IL-4 initiates B-cell activation, IL-5 stimulates the proliferation of activated B-cells, IL-6 causes the maturation of activated B-cells and their transformation into antibody-secreting plasma cells. Interferon attracts and activates macrophages, which begin to phagocytize more actively and destroy invading microorganisms.

The transfer of a large number of antigens processed by the macrophage ensures the proliferation and differentiation of B-lymphocytes towards the formation of plasma cells that produce specific antibodies for a specific type of antigen.

In order to begin producing antibodies, B cells must turn into plasma cells. The process of plasmacytogenesis is accompanied by a loss of the ability of cells to divide and move and a decrease in the amount of surface immunoglobulins in the cytolemma. The life span of plasma cells is several weeks. Lymphoblasts and immature plasma cells from the lymph nodes where they form are able to enter the efferent lymphatic vessels and colonize neighboring lymph nodes. Some of the small cells formed from them, resembling lymphocytes in appearance, penetrate into the blood vessels. They have a centrally located nucleus, surrounded by a narrow rim of the cytoplasm, in which a developed granular endoplasmic reticulum is visible. These cells are called lymphoplasmocytes.

T-suppressors (Tc) suppress the ability of lymphocytes to participate in the production of antibodies and thus provide immunological tolerance, i.e. insensitivity to certain antigens. They regulate the number of plasma cells formed and the amount of antibodies synthesized by these cells. It turned out that a special subpopulation of B-lymphocytes, which are called B-suppressors, can also inhibit the production of antibodies. It has been shown that T- and B-suppressors can also suppress the reactions of cellular immunity.

At present, it has been proven that the guarantee of human health and vital activity to a greater extent depends on the state of immunity. At the same time, not everyone knows what the presented concept is, what functions it performs and what types it is divided into. This article will help you to get acquainted with useful information on this topic.

What is immunity?

Immunity is the ability of the human body to provide protective functions, preventing the reproduction of bacteria and viruses. The peculiarity of the immune system is to maintain the constancy of the internal environment.

Main functions:

• Elimination of the negative impact of pathogens - chemicals, viruses, bacteria;
• Replacement of non-functioning, spent cells.

The mechanisms of the immune system are responsible for the formation of a protective reaction of the internal environment. The correctness of the implementation of protective functions determines the state of health of the individual.

Mechanisms of immunity and their classification:

Allocate specific and non-specific mechanisms. Impact of specific mechanisms aimed at ensuring the protection of the individual against a particular antigen. Non-specific mechanisms resist any pathogens. In addition, they are responsible for the initial protection and viability of the organism.

In addition to the listed types, the following mechanisms are distinguished:

• Humoral - the action of this mechanism is aimed at preventing antigens from entering the blood or other body fluids;
• Cellular - a complex type of protection that affects pathogenic bacteria through lymphocytes, macrophages and other immune cells (skin cells, mucous membranes). It should be noted that the activity of the cell type is carried out without antibodies.

Main classification

Currently, the main types of immunity are distinguished:

• The existing classification divides immunity into: natural or artificial;
• Depending on the location, there are: General- provides general protection of the internal environment; Local- whose activities are aimed at local protective reactions;
• Based on origin: congenital or acquired;
• According to the direction of action, there are: infectious or non-infectious;
• The immune system is also divided into: humoral, cellular, phagocytic.

natural

Currently, the types of immunity in humans are: natural and artificial.

The natural type is an inherited susceptibility to certain foreign bacteria and cells that have a negative effect on the internal environment of the human body.

The noted varieties of the immune system are the main ones and each of them is divided into other types.

As for the natural appearance, it is classified into congenital and acquired.

Acquired Species

acquired immunity represents a specific immunity of the human body. Its formation occurs during the period of individual development of a person. When it enters the internal environment of the human body, this type helps to counteract pathogenic bodies. This ensures the course of the disease in a mild form.

Acquired is divided into the following types of immunity:

• Natural (active and passive);
• Artificial (active and passive).

Natural active - produced after a disease (antimicrobial and antitoxic).

Natural passive - produced by the introduction of ready-made immunoglobulins.

artificial acquired- this type of immune system appears after human intervention.

• Artificial active - formed after vaccination;
• Artificial passive - manifests itself after the introduction of serum.

The difference between the active type of the immune system and the passive one lies in the independent production of antibodies to maintain the viability of the individual.

Congenital

What type of immunity is inherited? An individual's innate susceptibility to disease is inherited. It is a genetic trait of an individual that contributes to countering certain types of diseases from birth. The activity of this type of immune system is carried out at several levels - cellular and humoral.

Congenital susceptibility to diseases has the ability to decrease when exposed to negative factors - stress, malnutrition, severe illness. If the genetic species is in a weakened state, the acquired protection of the person comes into play, which supports the favorable development of the individual.

What type of immunity arises as a result of the introduction of serum into the body?

A weakened immune system contributes to the development of diseases that undermine the human internal environment. If necessary, to prevent the progression of diseases, artificial antibodies contained in the serum are introduced into the body. After vaccination, artificial passive immunity is produced. This variety is used to treat infectious diseases and remains in the body for a short time.

The mechanisms of immunity are processes that allow the formation of a protective reaction against the ingress of foreign microorganisms into the human body. The correctness of their work directly affects the health and functioning of the body. All mechanisms of immunity can be divided into two groups: non-specific and specific.

Specific mechanisms are processes that work towards a specific antigen, thereby protecting the body from it, not just for a long time, but throughout a person's life. Nonspecific mechanisms of immunity can be attributed to the class of universal ones, since they begin to act only at the moment when certain foreign agents enter the body. In addition, they allow you to effectively protect a person until antigen-specific reactions come into play.

Humoral and cellular immunity

Historically, in the process of learning the immune system, there was a division into cellular and humoral immunity. Cellular immunity is able to work only because of phagocytes and lymphocytes, but at the same time it does not need antibodies at all, which are actively involved in humoral mechanisms.

This type of immunity is able to protect the body not only from infections, but also from cancerous tumors. Cellular immunity is based on lymphocytes, which are formed inside the bone marrow, after which they pass into the thymus, and sometimes into the thymus gland, where their final formation takes place. That is why they are called thymus-dependent, or T-lymphocytes. Throughout their life, lymphocytes several times go beyond the lymphoid organs, enter the blood, and after work they return to their place again.

This mobility allows cells to move to sites of inflammation very quickly. T-lymphocytes meet three types. Naturally, each of them plays an important role. T-killers are cells capable of eliminating antigens. T-helpers are the first cells that understand that there is a danger inside the body. In addition, they express their reaction to the invasion by creating special enzymes that allow you to increase the number of killer T-cells and B-cells. The last type is T-suppressors. They are necessary to suppress the active immune response, if at the moment it is not required. This process plays an important role in stopping the development of autoimmune reactions. In fact, it is simply impossible to distinguish between cellular and humoral immunity. And all because cells take part in the creation of antigens, and a large number of cellular immunity reactions simply cannot proceed without the participation of antibodies.

Humoral immunity works by creating antibodies suitable for every antigen that can appear in the human body from the outside. This is a kind of combination of proteins found in the blood, as well as some biological fluids. They are interferons, which help cells remain immune to the effects of any viruses. The C-reactive protein in the blood triggers the complement system. Lysozyme is an enzyme that allows you to harm the walls of foreign microorganisms, thereby dissolving them. All of these proteins are part of nonspecific humoral immunity. True, there is still a specific one. They are considered interleukins. There are also specific antibodies and a number of other formations.

Cellular and humoral immunity are closely related to each other. Therefore, even the slightest failure in one of these categories can lead to serious consequences in another category of immunity.

Infectious and antiviral immunity

Infectious immunity in some situations can be called non-sterile. The essence of such immunity lies in the fact that a person will no longer be able to get sick a second time with that disease, the causative agent of which is already present in the body. It can be a congenital or acquired disease. Moreover, the acquired disease can be both passive and active.

Infectious immunity is present in our body only as long as antigen and antibodies walk through the blood. After recovery, this protection becomes unnecessary, a person re-opens himself to diseases that until recently sat inside him. Infectious immunity is divided into short-term and long-term, or lifelong. For example, short-term immunity manifests itself during the flu, and long-term immunity can also exist with typhoid fever, while measles, chickenpox give your body lifelong immunity.

Antiviral immunity already at the first stage acquires barriers in the form of mucous membranes and skin. Their damage, as well as dryness, can help viruses enter the body. After penetration, the enemy begins to damage the cells, so it is very important at this moment to start producing the required amount of interferons that can organize immunity to viral effects.

At the next stage, antiviral immunity works due to the call of dying cells. When they die, they release cytokines into the body, which mark the site of inflammation. This call attracts leukocytes, which provide the creation of a focus of inflammation. Approximately on the fourth day of the disease, antibodies are produced. It is they who will eventually be proclaimed the winners of viruses. But they also have assistants called macrophages. These are special cells that activate the process - phagocytosis, as well as the destruction and digestion of destructive cells. Antiviral immunity is a complex process that involves a huge amount of immune system resources.

Unfortunately, not all immune responses work the way biology textbooks tell you. For the most part, certain processes are violated, leading the body to problems and various complications. During the lowering of the immune response, a person should take drugs that raise immunity. They can be created by nature itself or purchased in a pharmacy, but their safety and effectiveness remain the most important.

Activation of immune defense is required for people of different ages, including the elderly and children. Unfortunately, these groups of our population require a gentler and safer way of treatment. Modern remedies that raise immunity, for the most part, do not correspond to these parameters. They are not only capable of causing side effects, but also because of them there is a withdrawal syndrome, addiction. Naturally, the question arises: are they really necessary for a person? Naturally, if, after a medical examination, a specialist prescribes you immunity boosters, then, of course, you should take them. But it is better not to allow cases with self-medication.

For many years, scientists have been working, trying to create special pills for immunity that would help restore a person's immune function. About 50 years ago, experts conducted a small study, after which it turned out that these miracle pills had become a reality. This study included the study of transfer factors, that is, special compounds with information that can teach the cells of the immune system, to make explanations in which cases and how to work. As a result of the long work of immunologists and scientists, pills for immunity were born. They are able to regulate and even restore the functions of the immune system, although some time ago they could only dream of this.

These pills were called Transfer Factor. This is a special drug that helps fill in some of the gaps in immune information. This process became possible only thanks to the informational compounds present in the composition, obtained from cow colostrum. None of the tablets for immunity, in addition to the Transfer Factor, are able to provide safety, high efficiency and, at the same time, be natural.

This drug is the best tool that exists in the modern world to restore immunity. It can be used both as a prophylactic and as a therapeutic agent, as well as during the recovery period. For infants, the elderly and pregnant women, doctors prescribe this drug without fear, as it does not cause side effects, addiction, and, therefore, is safe.

Immunity, as an important component of the human system, is very diverse in its structure, classification of immunological phenomena and certain forms of immunity, mechanism and several other types of features.

The mechanisms of immunity are conditionally divided into several groups:

skin and mucous barriers, inflammation, phagocytosis, reticuloendothelial system, barrier function of lymphatic tissue, humoral factors, reactivity of body cells.

Also, to simplify and better understand the mechanisms of immunity can be divided into groups: humoral and cellular.

Humoral mechanism of immunity

The main effect of humoral immunity occurs at the moment when antigens penetrate the blood and other body fluids. At this point, antibodies are produced. Antibodies themselves are divided into 5 main classes, different in function, however, they all provide protection for the body.

Antibodies are proteins, or a combination of proteins, these include interferons that help cells resist viruses, C-reactive protein helps launch the complement system, lysozyme is an enzyme that can dissolve the walls of antigens.

The above proteins belong to a non-specific type of humoral immunity. Interleukins are part of the specific humoral mechanism of immunity. In addition, there are other antibodies.

One of the components of immunity is humoral immunity. In turn, in its actions it is very closely related to cellular immunity. Humoral immunity is based on the work performed by B-lymphocytes to produce antibodies.

Antibodies are proteins that enter and constantly interact with foreign proteins - Antigens. The production of antibodies occurs according to the principle of full compliance with the antigen, i.e. for each type of antigen, a strictly defined type of antibody is produced.

Violations of humoral immunity include the presence of long-term respiratory diseases, chronic sinusitis, otitis media, etc. Immunoglobulins are often used for treatment.

Cellular mechanism of immunity

The cellular mechanism is provided by the presence of lymphocytes, macrophages and other immune cells, but all their activity occurs without antibodies. Cellular immunity is a combination of several types of protection. First of all, these are also skin cells and mucous membranes, which are the first to prevent the penetration of antigens into the body. The next barrier is blood granulocytes, which tend to adhere to a foreign agent. The next factor of cellular immunity is lymphocytes.

Throughout their existence, lymphocytes move almost constantly throughout the body. They represent the largest grouping of immune cells, are produced in the bone marrow, and undergo "training" in the thymus gland. Hence they are called thymus-dependent lymphocytes, or T-lymphocytes. T-lymphocytes are divided into 3 subgroups.

Each has its own tasks and specialization: T-killers, T-helpers, T-suppressors. T-killers themselves are able to destroy foreign agents, T-helpers provide destruction to a greater extent, they are the first to raise the alarm about the penetration of viruses. T-suppressors provide a decrease and stop the immune response when it is no longer necessary in a certain specific case.

Much work on the destruction of foreign agents is carried out by macrophages, directly absorbing them, and then, by releasing cytokines, they “notify” other cells about the enemy.

For all their differences, humoral immunity and cellular immunity constantly interact very closely to ensure the protection of the body.

Infectious and antiviral immunity

Consider another conditional division of the types of immunity. Infectious immunity, it is also non-sterile, the basis of this immunity is that a person who has been ill or infected with a certain virus cannot have a recurrence of the disease. In this case, it does not matter whether the disease is passive or active.

Infectious immunity can also be divided into several types: antimicrobial (antibacterial), antiviral and antitoxic, in addition, it can be divided into short-term and long-term. It can also be divided into innate and acquired immunity.

Infectious immunity develops when pathogens multiply in the body. It has the basic mechanisms of both cellular and humoral.

Antiviral immunity is a highly complex process that uses a significant amount of immune system resources.

The first stage of antiviral immunity is represented by the skin and mucous membranes of the body. If the virus manages to penetrate further into the body, parts of the humoral and cellular immunity mechanism come into play. The production of interferons begins, which contribute to ensuring the immunity of cells to viruses. Further, other types of body defense are connected.

At the moment, there are a huge number of other drugs, but for the most part they have either contraindications for use, or they cannot be used for a long time, which cannot be said about the Transfer Factor immunomodulator. Means for raising immunity in many respects lose to this immunomodulator.

For not always known reasons, sometimes there are failures in the work of antiviral and infectious immunity. The right step in this case would be to strengthen the immune system, although we do not always need to strengthen the immune system.

It would be more correct to say that immunity modulation is necessary - some optimization of immunity and all its types: antiviral and infectious; its mechanisms - humoral and cellular immunity.

It is best to start using the Transfer Factor immunomodulator for these purposes, unlike other similar products, it is not a product of pharmaceutical companies, and not even a plant product, but these are sets of amino acids similar to ours, taken from other types of vertebrates: cows and chickens.

Use in the complex treatment of any diseases: whether it is an immune or autoimmune disease; accelerates the rehabilitation process and positive dynamics during the treatment period, relieves side effects of drugs, restores the immune system.

Immunity is a word that for most people is almost magical. The fact is that each organism has its own genetic information peculiar only to it, therefore, each person's immunity to diseases is different.

So what is immunity?

Surely everyone who is familiar with the school curriculum in biology roughly imagines that immunity is the body's ability to protect itself from everything foreign, that is, to resist the action of harmful agents. Moreover, both those that enter the body from the outside (microbes, viruses, various chemical elements), and those that are formed in the body itself, for example, dead or cancerous, as well as damaged cells. Any substance that carries alien genetic information is an antigen, which literally translates as "against genes." and the specific is ensured by the integral and coordinated work of the organs responsible for the production of specific substances and cells that are able to recognize in a timely manner what is their own for the body and what is alien, and also adequately respond to the invasion of the foreign.

Antibodies and their role in the body

The immune system first recognizes the antigen, and then tries to destroy it. In this case, the body produces special protein structures - antibodies. It is they who stand up for protection when any pathogen enters the body. Antibodies are special proteins (immunoglobulins) produced by leukocytes to neutralize potentially dangerous antigens - microbes, toxins, cancer cells.

By the presence of antibodies and their quantitative expression, it is determined whether the human body is infected or not, and whether it has sufficient immunity (nonspecific and specific) against a particular disease. Having found certain antibodies in the blood, one can not only conclude that an infection or a malignant tumor is present, but also determine its type. It is on the determination of the presence of antibodies to pathogens of specific diseases that many diagnostic tests and analyzes are based. For example, in an enzyme-linked immunosorbent assay, a blood sample is mixed with a pre-prepared antigen. If a reaction is observed, it means that antibodies to it are present in the body, and therefore this agent itself.

Varieties of immune defense

According to their origin, the following types of immunity are distinguished: specific and non-specific. The latter is innate and directed against any foreign substance.

Nonspecific immunity is a complex of protective elements of the body, which, in turn, is divided into 4 types.

1. To mechanical elements (skin and mucous membranes, eyelashes are involved, sneezing, coughing appears).
2. To chemical (sweat acids, tears and saliva, nasal secretions).
3. To the humoral factors of the acute phase of inflammation, blood coagulation; lactoferrin and transferrin; interferons; lysozyme).
4. To cellular (phagocytes, natural killers).

It is called acquired or adaptive. It is directed against a selected foreign substance and manifests itself in two forms - humoral and cellular.

its mechanisms

Let us consider how both types of biological protection of living organisms differ from each other. Nonspecific and specific mechanisms of immunity are divided according to the reaction rate and action. Factors of natural immunity begin to protect immediately, as soon as the pathogen penetrates the skin or mucous membrane, and do not preserve the memory of the interaction with the virus. They work throughout the entire time of the body's battle with the infection, but especially effectively - in the first four days after the penetration of the virus, then the mechanisms of specific immunity begin to work. The main defenders of the body against viruses during the period of nonspecific immunity are lymphocytes and interferons. Natural killer cells identify and destroy infected cells with the help of secreted cytotoxins. The latter cause programmed cell destruction.

As an example, consider the mechanism of action of interferon. During a viral infection, cells synthesize interferon and release it into the space between cells, where it binds to receptors on other healthy cells. After their interaction in cells, the synthesis of two new enzymes increases: synthetase and protein kinase, the first of which inhibits the synthesis of viral proteins, and the second cleaves foreign RNA. As a result, a barrier of uninfected cells is formed near the focus of the viral infection.

Natural and artificial immunity

Specific and non-specific innate immunity is divided into natural and artificial. Each of them is active or passive. The natural comes naturally. Natural active appears after a cured disease. For example, people who had the plague did not become infected while caring for the sick. Natural passive - placental, colostral, transovarial.

Artificial immunity is detected as a result of the introduction of weakened or dead microorganisms into the body. Artificial active appears after vaccination. An artificial passive is acquired with a serum. When active, the body creates antibodies on its own as a result of illness or active immunization. It is more stable and long lasting, can persist for many years and even a lifetime. achieved with the help of antibodies artificially introduced during immunization. It is less long-lasting, acts a couple of hours after the introduction of antibodies and lasts from several weeks to months.

Specific and non-specific immunity differences

Nonspecific immunity is also called natural, genetic. This is a property of an organism that is genetically inherited by members of a given species. For example, there is human immunity to dog and rat distemper. Congenital immunity can be weakened by irradiation or starvation. Nonspecific immunity is realized with the help of monocytes, eosinophils, basophils, macrophages, neutrophils. Specific and non-specific factors of immunity are also different in time of action. Specific manifests itself after 4 days during the synthesis of specific antibodies and the formation of T-lymphocytes. At the same time, immunological memory is triggered due to the formation of T- and B-cells of memory for a specific pathogen. Immunological memory is stored for a long time and is the core of a more effective secondary immune action. It is on this property that the ability of vaccines to prevent infectious diseases is based.

Specific immunity aims to protect the body, which is created in the process of development of an individual organism throughout its life. When an excessive amount of pathogens enters the body, it can be weakened, although the disease will proceed in a milder form.

What is the immunity of a newborn baby?

A newly born baby already has non-specific and specific immunity, which is gradually increasing every day. The first months of a baby's life are helped by the mother's antibodies, which he received from her through the placenta, and then receives along with breast milk. This immunity is passive, it is not persistent and protects the child up to about 6 months. Therefore, a newborn child is immune to infections such as measles, rubella, scarlet fever, mumps and others.

Gradually, and also with the help of vaccination, the child's immune system will learn to produce antibodies and resist infectious agents on its own, but this process is long and very individual. The final formation of the child's immune system is completed at the age of three. In a younger child, the immune system is not completely formed, so the baby is more susceptible than an adult to most bacteria and viruses. But this does not mean that the body of a newborn is completely defenseless, it is able to withstand many infectious aggressors.

Immediately after birth, the baby encounters them and gradually learns to exist with them, producing protective antibodies. Gradually, microbes populate the baby's intestines, dividing into useful ones that help digestion and harmful ones that do not show themselves in any way until the balance of microflora is disturbed. For example, microbes settle on the mucous membranes of the nasopharynx and tonsils, and protective antibodies are produced there. If, when an infection enters, the body already has antibodies against it, the disease either does not develop or passes in a mild form. Prophylactic vaccinations are based on this property of the body.

Conclusion

It should be remembered that non-specific and specific immunity is a genetic function, that is, each organism produces the number of various protective factors necessary for it, and if this is quite enough for one, then it is not for another. And, on the contrary, one person can completely get by with the necessary minimum, while another person will need much more protective bodies. In addition, the reactions occurring in the body are quite variable, since the work of the immune system is a continuous process and depends on many internal and external factors.