Humoral immunity immunoglobulins. Humoral and cellular immunity. Humoral specific and nonspecific immunity

Our body has the ability to protect itself from pathogens, chemical agents, as well as from one’s own sick and substandard cells.

The biological meaning of immunity is to ensure the integrity and maintain the constancy of the composition of the body at the genetic and molecular level throughout its life.

Immunity is realized thanks to the immune system, which consists of central and peripheral organs. They form immunocompetent cells. The central organs include the bone red marrow and thymus gland(thymus). Peripheral organs are the spleen, lymph nodes, and lymphoid tissue, located in some organs. Immune defense is complex. Let's figure out what forms, types and mechanisms of immunity exist.

1. Nonspecific immunity is directed against all microorganisms, regardless of their nature. It is carried out by various substances that are secreted by the glands of the skin, digestive and respiratory tract. For example, the environment in the stomach is highly acidic, due to which a number of microbes die. Saliva contains lysozyme, which has strong antibacterial effect etc. Nonspecific immunity also includes phagocytosis - the capture and digestion of microbial cells by leukocytes.
2. Specific immunity is directed against a specific type of microorganism. Specific immunity is achieved through T-lymphocytes and antibodies. The body produces its own antibodies for each type of microbe.

There are also two types of immunity, each of them, in turn, is divided into two more groups.

1. Natural immunity is inherited or acquired after illness. It is, accordingly, divided into congenital and acquired.
2. A person acquires artificial immunity after vaccinations - the administration of vaccines, serums and immunoglobulins. Vaccination promotes the emergence of active artificial immunity, since either killed or weakened microbial cultures enter the body, and the body then itself develops immunity to them. This is how vaccines against polio, tuberculosis, diphtheria and some others work. infectious diseases. Active immunity is developed for years or for life.

When serums or immunoglobulins are administered, ready-made antibodies enter, which circulate in the body and protect it for several months. Since the body receives ready-made antibodies, this type of artificial immunity is called passive.

Finally, there are two main mechanisms by which immune reactions occur. These are humoral and cellular immunity. As the name suggests, humoral immunity is realized through the formation of certain substances, and cellular immunity is realized through the work of certain cells of the body.

Humoral immunity

This mechanism of immunity manifests itself in the formation of antibodies to antigens - foreign chemical substances, as well as microbial cells. B lymphocytes play a fundamental role in humoral immunity. They are the ones who recognize foreign structures in the body, and then produce antibodies against them - specific protein substances, which are also called immunoglobulins.

The antibodies that are produced are extremely specific, that is, they can only interact with those foreign particles that caused the formation of these antibodies.

Immunoglobulins (Ig) are found in the blood (serum), on the surface of immunocompetent cells (surface), and also in secretions gastrointestinal tract, tear fluid, breast milk (secretory immunoglobulins).

In addition to being highly specific, antigens also have other biological characteristics. They have one or more active centers that interact with antigens. More often there are two or more. The strength of the connection between the active center of an antibody and an antigen depends on the spatial structure of the substances involved in the connection (i.e., antibody and antigen), as well as the number of active centers in one immunoglobulin. Several antibodies can bind to one antigen at once.

Immunoglobulins have their own classification using Latin letters. In accordance with it, immunoglobulins are divided into Ig G, Ig M, Ig A, Ig D and Ig E. They differ in structure and function. Some appear immediately after infection, while others appear later.

The antigen-antibody complex activates the complement system (protein substance), which promotes further absorption of microbial cells by phagocytes.

Immunity is formed due to antibodies after past infections, and also after. They help neutralize toxins entering the body. Antibodies in viruses block receptors, preventing them from being absorbed by the body's cells. Antibodies are involved in opsonization (“wetting of microbes”), making antigens easier to ingest and digest by macrophages.

Cellular immunity

As already mentioned, cellular immunity is carried out by immunocompetent cells. These are T-lymphocytes and phagocytes. And if the body’s protection against bacteria occurs mainly due to humoral mechanism, then antiviral, antifungal, as well as antitumor protection - due to cellular immunity mechanisms.

• T lymphocytes are divided into three classes:
• Killer T cells (directly contact with foreign cells or damaged cells own body and destroy them)
• T helper cells (produce cytokines and interferon, which then activate macrophages)
• T-suppressors (control the strength of the immune response and its duration)

As you can see, cellular and humoral immunity are interconnected.

The second group of immunocompetent cells involved in cellular immune reactions are phagocytes. In fact, these are leukocytes different types, which are either in the blood (circulating phagocytes) or in tissues (tissue phagocytes). Granulocytes (neutrophils, basophils, eosinophils) and monocytes circulate in the blood. Tissue phagocytes are found in connective tissue, spleen, lymph nodes, lungs, endocrine cells of the pancreas, etc.

The process of destruction of antigen by phagocytes is called phagocytosis. It is extremely important to ensure immune defense body.

Phagocytosis occurs in stages:

• Chemotaxis. Phagocytes are directed to the antigen. This can be facilitated by certain complement components, some leukotrienes, as well as products secreted by pathogenic microbes.
• Adhesion (gluing) of phagocytes-macrophages to the vascular endothelium.
• Passage of phagocytes through the wall and exit beyond it
• Opsonization. Antibodies envelop the surface of a foreign particle and are assisted by complement components. This facilitates the uptake of antigen by phagocytes. The phagocyte then attaches to the antigen.
• Actually phagocytosis. The foreign particle is absorbed by the phagocyte: first, a phagosome is formed - a specific vacuole, which then connects with the lysosome, where lysosomal enzymes that digest the antigen are located).
• Activation of metabolic processes in the phagocyte, promoting phagocytosis.
• Antigen destruction.

The process of phagocytosis can be completed or incomplete. In the first case, the antigen is phagocytosed successfully and completely, in the second - not. Some people take advantage of the incompleteness of phagocytosis pathogenic microorganisms for their own purposes (gonococci, mycobacterium tuberculosis).

Find out how you can support your body's immunity.

Immunity – the most important process our body, helping to maintain its integrity, protecting it from harmful microorganisms and foreign agents. Cellular and humoral are two mechanisms that, acting harmoniously, complement each other and help maintain health and life. These mechanisms are quite complex, but our body as a whole is a very complex self-organizing system.

Protecting the body from penetration various kinds pathogenic agents are formed mainly by two means. They are cellular and humoral immunity. Let's look at them in more detail next.

T lymphocytes

They provide cellular immunity. T-lymphocytes are formed from stem elements migrating from the bone (red) marrow. Penetrating into the blood, these cells create up to 80% of its lymphocytes. They also settle in peripheral organs. These primarily include the spleen and lymph nodes. Here T lymphocytes form thymus-dependent zones. They become active areas of proliferation. In them, T-lymphocytes multiply outside the thymus. Further differentiation is carried out in three directions.

T-killerash

These cells constitute the first group of daughter elements of T lymphocytes. They are able to react and destroy foreign antigen proteins. They can be their own mutants or pathogens. "Killer cells" are distinguished by their ability, without additional immunization, on our own, without connecting protective plasma complement and antibodies, perform lysis - destruction by dissolving cell membranes - “targets”. It follows from this that killer T cells represent a separate branch of differentiation of stem elements. They are intended to form the primary antitumor and antiviral barrier.

T-suppressors and T-helpers

These two populations carry out cellular protection by regulating the degree of functioning of T lymphocytes in the structure of humoral immunity. “Helpers” (helpers), when antigens appear in the body, contribute to the active reproduction of effector elements - performers. Helper T cells are divided into two subtypes. The former secrete specific 1L2 interleukins (hormone-like molecules), β-interferon. The second T helper cells secrete IL4-1L5. They interact with T cells predominantly of humoral immunity. Suppressors have the ability to regulate the activity of T- and B-lymphocytes relative to antigens.

Humoral immunity

It has its own characteristics. Humoral immunity is provided by lymphocytes that differentiate not in the stem elements of the brain, but in other areas. In particular, these include the large intestine, pharyngeal tonsils, The lymph nodes and others. The structures that form humoral immunity are called B lymphocytes. They make up up to 15% of the total leukocyte volume.

Protection activity

The mechanism of humoral immunity is as follows: when they first encounter an antigen, T-lymphocytes that are sensitive to it begin to multiply. Some children differentiate into protective memory structures. In the area of ​​the lymph nodes, the £-zones pass into plasma cells, after which they gain the ability to form humoral antibodies. These processes are actively promoted by T-helpers.

Antibodies

They are included in humoral immunity and are presented in the form of large protein molecules. Antibodies have a specific affinity for one or another antigen (in accordance with chemical structure). They are called immunoglobulins. Each molecule includes two chains - heavy and light. They are connected to each other by disulfide bonds and are able to activate antigen membranes by attaching plasma complement. This humoral component of immunity has two triggering pathways. The first is classic - from immunoglobulins. The second way of activation is alternative - from drugs and toxic substances or endotoxins.

Antibody classes

There are five of them: E, A, C, M, D. Humoral factors of immunity differ in their functional abilities. For example, immunoglobulin M is usually the first to be turned on in response to an antigen. It activates plasma complement, promoting the absorption of the “foreigner” by macrophages or triggers lysis. Immunoglobulin A is located in areas where antigens are most likely to appear. These are areas such as mother's milk, adenoids, sweat, salivary and lacrimal glands, lymph nodes of the digestive system and others. This immunoglobulin forms a strong barrier, triggering phagocytosis of antigens. lg D is involved in the reproduction (proliferation) of lymphocytes against the background of infectious lesions. T cells recognize antigens using gammaglobulin embedded in the membrane. The process of reproduction of activated T- and B-lymphocytes occurs quite quickly. They also intensively trigger humoral immunity and die en masse. At the same time, some activated lymphocytes are transformed into B- and T-memory elements that have a long lifespan. During a secondary attack by infection, they recognize the structure of the antigen and quickly turn into active (effector) cells. They stimulate the plasma elements of the lymph nodes to form the appropriate antibodies. With repeated contact with certain antigens, reactions may sometimes occur, accompanied by increased capillary permeability and blood circulation, bronchospasm and itching. In this case, they talk about allergic reactions.

Protection classification

Immunity can be specific and nonspecific. In turn, they are divided into acquired (formed as a result of past pathologies) and congenital (transmitted from the mother). Humoral nonspecific immunity is caused by the presence of “natural” antibodies in the blood. They are often formed through contact with intestinal flora. There are nine compounds that form protective complement. Some of these substances can neutralize viruses, others can suppress the vital activity of microorganisms, others can destroy viruses and suppress the reproduction of their cells in tumors, and so on. Protection is also determined by the activity of special elements - neutrophils and macrophages. They are able to destroy (digest) foreign structures.

Artificial protection

Such immunization of the body can be carried out in the form of vaccination. In this case, a weakened pathogen is introduced. It activates immunity (cellular and humoral) for the formation of appropriate antibodies. A passive response is also triggered. In this case, vaccinations are given against specific diseases. Serums are administered, for example, against rabies or after the bite of a poisonous animal.

Newborn's defenses

According to Bobritskaya, infant there are about 20 thousand of all leukocyte forms per 1 mm3 of blood. During the first days of a person’s life, their number increases, sometimes reaching 30 thousand. This is due to the resorption of decay products of tissue hemorrhages occurring at birth. After 7-12 first days of life, the number of leukocytes decreases to 10-12 thousand/1 mm3. This volume persists throughout the first year from birth. Subsequently, there is a further decrease in the number of leukocytes. By the age of 13-15, their number is established at the adult level (about 4-8 thousand). Until the age of seven, the majority of leukocytes are lymphocytes. The ratio levels off by 5-6 years. In children 6-7 years old it is found big number immature neutrophils. This causes the relatively low protective ability child's body towards infectious pathologies. Ratio different forms Leukocytes in the blood are called the leukocyte formula. It changes significantly with age. The volume of neutrophils increases, and the percentage of mono- and lymphocytes decreases. By the age of 16-17, the leukocyte formula has the same composition as an adult.

Invasion of the organism

Its consequence is always inflammatory process. Its acute course is usually caused by antigen-antibody reactions. During them, a few hours after damage, plasma complement is activated, reaching a maximum after 24 hours and fading after 42-48 hours. Inflammation chronic type due to the influence of antibodies on the T-lymphocyte system. It usually appears after 1-2 days, reaching its peak after 2-3 days. The temperature rises at the site of inflammation. This occurs due to vasodilation. Swelling also appears. On the background acute course the tumor is caused by the release of phagocytes and proteins into intercellular space, in chronic cases, infiltration of macrophages and lymphocytes occurs. Also characteristic feature inflammation is considered pain. It is associated with an increase in tissue pressure.

Finally

There are four main categories of immune diseases. These include: primary and secondary failure, malignant formations, dysfunction, infectious lesions. The latter, for example, include the well-known herpes virus. This infection has spread throughout the world at an alarming rate. HIV is also deadly. It is based on damage to the T-helper chain of the lymphocytic system. This leads to an increase in the volume of suppressors and a violation of the ratio of these elements. Pathologies of the immune system are quite dangerous for the body. They often lead to death because the body becomes virtually unprotected.

After all, you hear this phrase quite often, especially within the walls of a medical institution. In this article we will take a closer look at what humoral immunity is.

Disputes about how our immune system works began to arise in the 19th century between such great scientists as Ilya Mechnikov and Paul Ehrlich. But, before delving into the classification of immunity and its differences from each other, let's remember what human immunity is.

What is human immunity?

If a person’s immunity decreases, then this is the cause of various diseases, ailments, inflammatory and infectious processes in organism.

Immunity is regulated in the human body at two levels – cellular and molecular. It is thanks to the increase protective forces organism, the existence and life of a multicellular organism, that is, a person, became possible. Before this, only single-celled individuals functioned.

Mechanism of immunity

After we realized that without immunity a person would constantly get sick and ultimately would not be able to exist in this world, since his cells were constantly eaten by infections and bacteria. Now, let's return to the scientists - Mechnikov and Erlich, whom we talked about above.

There was a dispute between these two scientists about how the human immune system works (the dispute lasted for several years). Mechnikov tried to prove that human immunity works exclusively on cellular level. That is, all the body’s defenses are manifested by the cells of the internal organs. The scientist Ehrlich made a scientific assumption that the body's defenses manifest themselves at the level of blood plasma.

As a result of numerous scientific research And huge amount days and years spent on experiments, a discovery was made:

Human immunity functions at the cellular and humoral levels.

For these studies, Ilya Mechnikov and Paul Ehrlich received the Nobil Prize.

Specific and nonspecific immune response

Exactly how our body reacts to pathogenic negative factors surrounding a person is called the immunity mechanism. Let’s take a closer look at what this means.

Today, specific and nonspecific reactions of the body to environmental factors are classified.

A specific reaction is one that is aimed at one particular pathogen. For example, a person once had chickenpox in childhood and after that he developed immunity to this disease.

This means that if a person has developed specific immunity, he can be protected from negative factors throughout his life.

Nonspecific immunity is universal protective function human body. If a person has nonspecific immunity, then his body immediately reacts to most viruses, infections, as well as foreign organisms, penetrating cells and internal organs.

A little about cellular immunity

To move on to consider humoral immunity, let's first consider cellular immunity.

In our body, cells such as phagocytes are responsible for cellular immunity. Thanks to cellular immunity, we can be reliably protected from the penetration of various viruses and infections into the body.

Lymphocytes, which act as the body's defense forces, are formed in the human bone marrow. Once these cells are fully mature, they move from the bone marrow to the thymus gland or thymus. It is for this reason that in many sources you can find such a definition as T-lymphocytes.

T lymphocytes - classification

Cellular immunity provides protection to the body through active T lymphocytes. In turn, T-lymphocytes are divided into:

• Killer T cells– that is, these are cells in the human body that are capable of completely destroying and fighting viruses and infections (antigens);
• T-helpers– these are “smart” cells that are immediately activated in the body and begin to produce specific protective enzymes in response to the penetration of pathogenic microorganisms;
• T-suppressors– they block the response of cellular immunity (of course, if there is such a need). T-suppressors are used in the fight against autoimmune diseases.

Humoral immunity

Humoral immunity consists entirely of proteins that fill the human blood. These are cells such as interferons, C-reactive protein, an enzyme called lysozyme.

How does humoral immunity work?

The action of humoral immunity occurs through a large number of various substances, which are aimed at inhibiting and destroying microbes, viruses and infectious processes.

All substances of humoral immunity are usually classified into specific and nonspecific.

Let's consider nonspecific factors humoral immunity:

• Blood serum (infection enters the bloodstream - activation begins C-reactive protein– the infection is destroyed);
• Secrets secreted by the glands affect the growth and development of microbes, that is, they do not allow them to develop and multiply;
• Lysozyme is an enzyme that is a kind of solvent for all pathogenic microorganisms.

Specific factors of humoral immunity are represented by B-lymphocytes. These useful material produce human internal organs, in particular - Bone marrow, Peyer's patches, spleen, and lymph nodes.

Most of the humoral immunity is formed during the development of the child in the womb and is then transmitted to the baby through breast milk. Some immune cells can be established during a person’s life through vaccination.

Summary!

Immunity is the ability of our body to protect us (that is, internal organs and important systems life activity) from the penetration of viruses, infections and other foreign objects.

Humoral immunity is built according to the type of constant formation in the human body of special antibodies, which are necessary for an enhanced fight against infections and viruses that penetrate the body.

Humoral and cellular immunity are one common link, where one element cannot exist without the other.