Children's immunity: features of formation, signs and causes of weakened functioning. Formation of immunity At what age does a child develop immunity?

Vaccinated people are 70% to 90% less likely to get sick or have complications if they become infected.

You can find out how the flu progresses in vaccinated people by reading the statistics. Every year, about 10% of the world's population gets sick with influenza (that's 700 million people), and about 2 million die. At the same time, statistics show that among those who died from influenza and its complications, there are practically no vaccinated people.

Statistics show that the flu in vaccinated people is much milder than in people without vaccination.

Despite all the advances in medicine, influenza still remains one of the most dangerous infections, and by far the most common. Approximately every seventh person becomes ill during an epidemic. Out of 500 people who get sick, 1 dies. These numbers may be higher or lower depending on the characteristics of the pathogen strain causing the epidemic. But general idea Based on the given data, it is possible to determine what kind of disease this is.

Most people killed by influenza are infants, the elderly, and those with chronic illnesses. Adults, social active people flu is easier to tolerate. But every season they also lose, on average, from 10 to 15 days of working capacity (if the course is uncomplicated). In this case, it costs about 1–2 thousand rubles for treatment and an additional whole month for recovery.

Such losses can be prevented or significantly reduced by vaccination. After 2–4 weeks, when immunity develops after a flu shot, a person acquires a kind of insurance against these troubles. Of course, there can be no 100% guarantee. Meet special cases when post-vaccination immunity is not fully formed, a particularly aggressive virus is encountered, or the person finds himself in an environment that is too contagious. But even if infection occurs, the way the flu is tolerated after vaccination in any case provides evidence in favor of vaccination.

Immunity after a flu shot begins to develop after 2-4 weeks

Features of the formation of post-vaccination immunity

Any vaccination is done so that the body “prepares” for a meeting with a real pathogen, having undergone a kind of training on its harmless analogue. To do this, an inactivated virus, bacterium, or part of a microbial cell (this can be an isolated antigen) is introduced into the body, triggering an immune response.

The body reacts to the introduction of a vaccine in the same way as to the introduction of a pathogen. In this case, the destructive effect that the pathogen has is absent - the disease does not develop. However, after vaccination, immunity is developed, as if the person had been truly ill. This is how immunity is formed after a flu shot.

In general, the following features of post-vaccination immunity can be distinguished:

1. To produce it, there is no need to contact with a “wild” pathogen. It is formed from contact of the body with the immunogenic (immune-causing) part of the virus. Contact with the pathogenic part ( causing disease) not happening.
2. After vaccination, the disease does not develop, but immunity is still formed. An increase in temperature to low-grade levels and body aches that may appear are not a disease, but a manifestation of involvement immune system.
3. Thanks to vaccination, you can control which strain of influenza antibodies will be formed to. IN modern vaccines antigens of the most common and dangerous strains are included.
4. Another parameter of the immune response that the flu shot allows you to control is how long it takes for immunity to develop, as well as how intense it is. The dose of the vaccine can be calculated in such a way that the immune system is sufficiently stressed without exposing the person to unnecessary stress. In case of illness, the number of viruses attacking the body, and, accordingly, the strength of the immune response, cannot be controlled.

It should be noted that with vaccination, as with the flu, a sufficient number of antibodies are not developed immediately. It takes some time for the immune system to become sufficiently tense. How long immunity develops after a flu shot depends on several factors. This includes the dose, the patient’s weight, the state of his immune system, as well as general state body.

A person who has been vaccinated gets rid of viral bacteria much faster due to strengthened immunity.

If the calculation is done correctly, the vaccine dose is selected adequately, and the human body does not have serious deviations from the norm, then it is possible to determine quite accurately how much immunity is developed after a flu shot. Antibodies begin to be actively synthesized by the end of the first week, and their number reaches its peak by 3–4 weeks. For 6–9 months, sufficient immune tension remains to ensure protection. After this, the protection begins to weaken and disappears by 10–12 months.

The course of the infectious process without vaccination

The flu vaccine protects against infection by 70–90%, and the chance of complications is reduced by approximately the same amount. This is due to the fact that the vaccinated person already has ready-made antibodies in his blood.

If the body encounters the virus for the first time (and has not been vaccinated against it), then several days pass before a specific immune reaction will turn on. Antibodies begin to work in about 7–10 days. This is when recovery begins. During the time it takes for antibodies to develop, the pathogen manages to cause serious damage to health. Therefore, recovery may take longer.

Schematically, the entire infectious process can be divided into several stages (they partially overlap each other):

1. When the pathogen enters the body - the moment of infection.
2. The pathogen has begun to multiply, but there is not enough of it - this is incubation period, the person still feels healthy.
3. The number of microbes increases, and the first symptoms of general ill-being appear - malaise. This period is called prodromal.
4. The mass of microbes is large, and a detailed picture of the disease appears. There is an immune response, but it is nonspecific.
5. B-lymphocytes appear, which have already become “acquainted” with the virus, they begin to produce antibodies, the immune system takes control of the infection - a specific immune response develops, and improvement occurs.
6. There are many antibodies, they defeat the virus, and recovery occurs.
7. The recovery period is when the body heals the damage received.
8. Post-infectious immunity - circulates in the blood immune cells, which “remember” the virus, they ensure the production of specific protective antibodies.

Vaccination also helps prevent complications that often cause serious consequences of the flu.

Quite often with the flu, while the body is weakened and the mucous membranes respiratory tract damaged, a bacterial infection occurs. Then patients develop sinusitis, otitis, bronchitis, and even pneumonia. The cause of death of patients with influenza in 75% of cases is complications. An associated bacterial infection aggravates the condition, lengthens the period of disability, and increases the cost of treatment.

Features of influenza in vaccinated patients

The way the flu progresses in a vaccinated person is clearly illustrated by the same stages. Vaccination, of course, does not protect against contact with the pathogen. But once the virus enters the body, it does not have the opportunity to “freeze” there. It is immediately met by antibodies that inactivate it. That is, after infection, the stage of a specific immune response immediately begins. Therefore, in most cases the disease does not develop.

Sometimes vaccinated people also become infected. However, the course of influenza in vaccinated patients differs significantly from the course of the disease in unvaccinated patients. Infection occurs when there are few antibodies or a lot of the pathogen gets on the mucous membrane at once. At the same time, a certain amount of viruses still “breaks through” into the blood. But since the blood already contains immunocompetent cells that are “familiar” with the virus, they immediately trigger the synthesis of the missing antibodies.

In this case, the stages when the pathogen accumulates, a nonspecific response is formed, and specific (antibody-producing) lymphocytes are formed are also skipped. The virus does not have time to cause significant damage to health, complications do not arise, so the recovery period is also reduced.

People who have been vaccinated can also get the flu, but they are much less likely to develop complications.

Thus, the answer to the question - is the flu easily tolerated after vaccination - the answer is clear. It is much easier to tolerate than in unvaccinated people. Flu develops much less frequently in vaccinated people, lasts much less, and proceeds without complications. Besides, recovery period and treatment costs are also reduced. These features indicate the undeniable benefits of vaccination.

Before we talk about the time and stages of formation children's immunity, it is worth knowing what immunity is, how it works and how immunity is formed in a child.

Immunity is a combination of various vital systems of the body that are aimed at fighting various foreign infections and microbes, and serves as a natural shield between the body and the environment. The human immune system begins to form even when the child is in the womb. Thus, the human immune system begins to work even before birth, which helps ensure that the child does not get sick immediately after birth.

Immunity is divided into two types - congenital (nonspecific) and acquired (specific). The formation of the immune system in children occurs in stages.

Innate immunity

As the name implies, a person already has innate immunity from birth, and it is thanks to it that a newborn baby is protected from negative influences environment. Innate immunity begins its work from the moment the baby is born, but despite this, it still does not work fully. The immune system and the body are formed in stages over time, and it is at this moment that the child most of all needs breast milk and additional protection.

As mentioned earlier, from the very birth of a child, the immune system is already able to protect the newborn baby from diseases such as bronchitis, sore throat, otitis media, and inflammation of the upper respiratory tract. After infection enters children's body the first barrier that becomes its path is our mucous membrane.

Thanks to the special acidic environment, which does not promote the development of harmful infections and bacteria, the infection cannot penetrate deeper into the body. In this case, the mucous membrane begins to secrete substances that have bactericidal properties. Thus, it is thanks to our mucous membrane that most pathogens and harmful microbes are stopped and destroyed.

If the infection and harmful microbes somehow managed to bypass the human mucosa, then on its way there is another layer of protection, namely phagocytes. Phagocytes are cells that protect our body from infections, being located both in the mucous membrane and skin, and in our blood. Thanks to the influence of special protein complexes, phagocytes begin to exert an effect that destroys and “disinfects” our body from the effects of various infections. This method protection stops any infection in 99.9% of cases, which makes it no less effective and efficient.

Acquired immunity

Unlike innate immunity, acquired immunity begins to develop gradually. As we fall ill with a particular disease, our body becomes more and more protected each time. This is due to the fact that during illness, the immune system produces certain cells that fight precisely this infection.

In the future, when the disease recurs, the body already knows which cells need to be produced, thanks to which we get sick much less and recover faster. A good option for strengthening a specific immune system is vaccination. When vaccinated, weakened viruses and infections are introduced into the human body, and it will be much easier for the body to cope with them than it would have to fight the real virus of the disease.

So, we will answer this interesting question: how immunity is formed in children.

Immunity in newborns

Throughout life, a person has to deal with countless harmful and dangerous microorganisms, for each of which the body must develop its own medicine. In this regard, the body of a newborn child is the most vulnerable, since its acquired immunity cannot give a worthy response to diseases due to its inexperience.

The formation of immunity in the fetus begins to occur around the fourth or fifth birthday, because it is during this period that the liver, which is responsible for the production of B-lymphocytes, begins to form. Around the sixth or seventh week, the thymus gland begins to form, which is responsible for the production of T-lymphocytes. At approximately the same time, immunoglobulins gradually begin to be produced.

In the third month of pregnancy, group B lymphocytes produce a full set of immunoglobulins, which will participate in protecting the newborn baby in the first weeks of his life. An important stage is the formation of the spleen, since thanks to it the body produces the lymphocytes we need. However, lymph nodes that contribute to protection and delay foreign bodies in our body, they begin to work in full force only when...

It is worth remembering that any nutritional disorders, diseases of various infectious diseases in the first five months of pregnancy provide negative impact on the formation of the spleen and liver, which is fraught with a significant deterioration in the child’s health at birth. Therefore, during this dangerous period, you need to avoid crowded places, hospitals, and communication with infected people.

First period of development

The first critical period in the development of a child’s immunity is the immediate moment of birth. The fact is that during childbirth the immune system is specifically suppressed, working at 40-45%. This can be explained by the fact that when a child passes birth canal he comes into contact with millions of new bacteria unknown to him, and when he is born, this number increases to billions.

If the child’s immune system were fully functioning, the body would not be able to cope with such pressure from unknown organisms and would die. In this regard, during birth the baby is most vulnerable to various infections, and only thanks to the mother’s cells (immunoglobulins) the body continues to function fully. After birth, the baby’s gastrointestinal tract is filled with many beneficial intestinal bacteria, and when the baby is directly fed breast milk and formula, the baby’s immune system begins to gradually recover.

Second period in development

At approximately 6-7 months of age, the resulting maternal cells and antibodies almost completely leave the child’s body. This is due to the fact that by this age the child’s body must have learned to produce immunoglobulin A on its own. It is also obtained through vaccination, however, due to the lack of memory in the cells of this immunoglobulin, at six months of age it is necessary to undergo the vaccination process again.

An excellent method of strengthening the immune system during such a difficult period is hardening. To do this, during the reception water procedures pour warm water over the child, which differs from body temperature by 2-3 degrees. It is recommended to reduce the water temperature by 1 degree weekly. The water should not be colder than 28 degrees Celsius.

Third period

The third critical moment in the development of a child’s immunity is the period when the child is two to three years old. It is during this period that the formation of acquired immunity occurs most effectively. This is due to the fact that it is at this age that the child begins to actively contact other children, adults, various representatives of the animal world, be it parrots, as well as the fact that the child is attending kindergarten for the first time.

This period is extremely important and responsible, since the child begins to get sick quite often, and in many cases one illness can flow over or be replaced by another. However, you should not panic too much because of the child’s weakened immunity, since it is at this moment that the child comes into contact with microorganisms and microbes, which is necessary for normal development immune system. On average, it is considered normal that a child gets sick from eight to twelve times a year.

You also need to know that during this period of your child’s life, you should never give children drugs that stimulate the effect, as this can not only interfere with the development of acquired immunity, but also completely worsen his condition.

The fourth period

An important period is the period that falls at the age of 6-7 years. At this stage of life, the child already has the necessary lymphocytes necessary for healthy functioning. However, there is still not enough immunoglobulin A in the body, and therefore it is during this period that children quite often acquire new chronic diseases affecting the upper respiratory tract.

During this period, it would not be a bad idea to resort to the help of multivitamin complexes, but his attending pediatrician should tell him what vitamins the child needs. It is recommended to use drugs that stimulate the child’s immune system only after a thorough examination by a doctor and an immunogram, which will show which part of your child’s immune system is weakened and which needs to be strengthened.

Fifth period

The last critical period in the formation of the immune system is teenage years. For girls, this period begins a little earlier - from 12-13 years old, while for boys it begins approximately at the age of 14-16 years. It is characterized by the fact that the body is rebuilt due to the action of hormones, as well as due to rapid growth. All this entails that the lymph nodes decrease in size, exposing the child’s body to danger.

It is also during this period that old chronic diseases make themselves felt, but with a new, more dangerous force. also in adolescence children are influenced by other people, which entails borrowing bad habits, which are also quite a serious test for the immune system and the entire body as a whole.

Thus, you should know that the development of the immune system in children occurs gradually, in five stages. Each of these stages is extremely important and requires careful monitoring by parents.

Video

Let's figure out how the basic mechanisms of immunity are formed. How is it that some people have effective immunity, while others have weak immunity?

The thing is that even before the formation of the fetus, when the egg begins to form and its fertilization occurs, the parental genes are combined, as a result of which genetic information is inherited, which is closely related to the capabilities of the immune system.

It is curious that humans have more than 36,000 genes, and about half of them are in their own way related to the functioning of both the immune system and the entire biological protection body. From this fact we can conclude how great importance has an immune system.

At some levels of fetal development, various genetic programs are activated, thanks to which central ones are first created, and then peripheral organs immune system. Over time, these organs fill with cells that are created first in the liver and then in the bone marrow. From these cells, after several differentiation operations, cells are formed that form the immune system, primarily lymphocytes, divided into two groups.

The first group is the largest. This is a group of T lymphocytes, which are cells from bone marrow, which move to thymus gland(aka thymus). Since the word "thymus" begins with the letter "t", these cells are called T lymphocytes. In the thymus, which is the main organ of the immune system, lymphocytes undergo a stage of maturation, training and profile change, after which they are transmitted into the blood. Lymphocytes travel through the blood throughout the body and implement the work of immunity at the cellular level.

All lymphocytes that have undergone training in the thymus can react in a special way to any specific irritant agent. The cells are completely ready to defend the “Motherland”, i.e. our body. In other words, these are absolutely mature lymphocytes, but they still have a certain amount of “naivety”, since they have never encountered their real enemy, namely, an agent of infection.

Another group of lymphocytes is smaller, it includes B-lymphocytes (from the first letter of the phrase “bone marrow” - bone marrow). B lymphocytes move from the bone marrow to the spleen and lymph nodes, after which they are constantly on duty throughout the body. Such lymphocytes are also naive guys, since they do not yet have sufficient experience in their work.

The third group of cells heads the immune defense squad and controls the work of both T- and B-lymphocytes. These cells include monocytes and dendritic cells. Such cells have an excellent ability to neutralize various agents through the procedure of phagocytosis. In this case, cells capture foreign agents, are processed with enzymes, cut and destroyed. The resulting processed information is further transmitted to T- and B-lymphocytes. The latter have special receptors on their membrane, with the help of which they recognize a foreign structure (peptide) and act in a special way on these fragmented elements (usually short polypeptides consisting of ten or more amino acids). In this case, B-lymphocytes are activated, moving to a special section of the lymph nodes, as well as special B-dependent zones. Similar zones are present in the spleen.

After contact with macrophages, monocytes or dendritic cells, T lymphocytes are also transferred to the nearest lymph node, but to its own area, which is designated as the T-dependent zone. There, lymphocytes begin to transform into more specialized cells designed to perform specific protective missions.

This is what the initial process looks like, from which the professional, joint work of three types of cells is activated. Upon subsequent interaction with antigens from viruses and bacteria, these special cells increase in size and then divide repeatedly, creating offspring from a single cell, also called a “clone.”

Each clone is specifically designed to combat specific agents: helminths, protozoa, viruses and bacteria. Moreover, agents are selected not only by the type of their structure, but also by individual elements, such as nucleoproteins, proteins, polysaccharides, etc. At this stage, immunity is created. Consequently, immunity is determined by the number of cells of all three types, their ability to instantly respond to foreign agents, recognize them and create antibodies.

An ordinary person has no idea how violent and fascinating processes occur in his body. What is associated with the immune system can be regarded as a confrontation between two programs. Let's study this using the example of an infectious disease.

An infection agent has one program and task. It must penetrate the body and multiply as quickly as possible. The second program, namely, the genetic program of the immune system, is required to quickly respond and use all available protective equipment to combat the multiplying agent. The immune system uses its “soldiers” in the form of T- and B-lymphocytes, which are equipped with special “machine guns” that shoot infection agents with “bullets”, which are special molecules.

If a person’s immunity is in perfect order and has a worthy squad of defenders, then soldiers can easily find enemies in any area of ​​the body, be it circulatory system, bronchopulmonary region, urogenital tract or intestines. Lymphocytes will search every corner to detect, destroy and remove strangers from the body. Their main goal is to clear the territory of the enemy, to cleanse the body of gangs of hostile agents. Unfortunately, in most cases, a person is not able to reliably avoid infection, so the body’s entire defense relies on the immune system. The body must be able to stand up for itself.

After the battle is won and the territory is liberated, the B- and T-lymphocytes almost die with the honor of the brave, but acquire and store in “memory” for a long time information about the agent of infection and its characteristics. This process is called immunological memory. In the future, if the agent has the courage to return, the memory will help in deploying a defensive response that will be 2-3 times faster and more effective than before. This way, the immune system will fight off the attack again.

This is how the immune system is created and works, striving to create resistance (immunity) of the body to infectious agents various types, promptly identifying and eliminating identified threats to human life. Such information can, of course, be provided by medical centers in Moscow, but isn’t it better to receive it in expanded form, with detailed explanations and illustrations?

Infectious agent – ​​salmonella (group of Escherichia coli):

Why does the child weak immunity? To understand this issue, we have collected information that explains the principle of operation, the peculiarities of the formation of immunity in children and the reasons for its decline in babies under one year old and older children. From the article, parents will also learn what signs can be used to determine that a child has a weak immune system.

What is immunity and how does it work?

When in human body When various viral or bacterial infections creep in, he begins to actively fight them. The ability of the immune system to fight various types infections that enter the body is called immunity.

Immunity is a set of physiological processes and mechanisms aimed at maintaining the body’s antigenic homeostasis from biological active substances and creatures carrying genetically foreign antigenic information or from genetically foreign protein agents.

Immunity classification

Distinguish congenital ( species) and acquired immunity . Specific (congenital, hereditary) immunity is inherited by the baby. Acquired immunity accumulates throughout a person’s life and is divided into natural and artificial.

Natural (acquired) immunity divided into active and passive. Active natural immunity accumulates gradually after successful fight against a particular infection. Not all past diseases contribute to the formation of lifelong immunity. A child can suffer some diseases several times after the next interaction with a microbe. If a child has had rubella or rubella, then in almost all cases he will acquire stable, lifelong immunity against these diseases. The duration of immunity depends on the ability of the microbe to cause an immune response. Passive natural immunity is formed due to antibodies that are transmitted from mother to child through the placenta during pregnancy and through milk during breastfeeding.

Artificial acquired immunity divided into passive and active. Active immunity is formed after the . Passive immunity appears after special serums with antibodies are introduced into the human body. The duration of such immunity is measured in several weeks, and after the end of this period it disappears.

The concept of an immune response and its types

Immune response- this is the body’s reaction to the ingress of any foreign microbes or their poisons.

Types of immune response:

• Nonspecific immune response is activated almost instantly as soon as the microbe enters the child’s body. Its goal is to destroy the microbe by forming a focus of inflammation. Inflammatory reaction- a universal protective process aimed at preventing an increase in the field of microbial activity. The overall resistance of the body directly depends on nonspecific immunity. Children with weakened nonspecific immunity are most susceptible to various diseases.
• Specific immune response T - the second stage of the body’s defense reactions. At this stage, the body tries to recognize the microbe and develop protective factors that will be aimed at eliminating a specific type of microbe. Specific and nonspecific immune responses invariably overlap and complement each other.

The specific immune response is divided into cellular and humoral:

• When it works cell specific immune response , clones of lymphocytes are formed that seek to destroy targets whose membranes contain foreign materials, such as cellular proteins. Cellular immunity helps eliminate viral infections, as well as some types bacterial infections(for example, tuberculosis). In addition, activated lymphocytes are an active weapon in the fight against cancer cells.
• Specific humoral immune response acts through B lymphocytes. Once a microbe is recognized, they actively synthesize antibodies according to the principle of one type of antigen - one type of antibody. During all infectious diseases Antibodies always begin to be produced. The humoral immune response develops over several weeks, during which time the necessary amount of immunoglobulins is formed in the body in order to completely neutralize the source of infection. Lymphocyte clones are able to remain in the body for quite a long time, so upon repeated contact with microorganisms they give a powerful immune response.

There are several types of antibodies (immunoglobulins):

• Antibodies type A (IgA) needed to provide local immunity. They try to prevent germs from entering through skin or mucous membranes.
• Antibodies type M (IgM) are activated immediately after the child has had contact with the infection. They are able to bind several microbes at the same time. If type M antibodies (IgM) were detected during a blood test, then they are evidence of the occurrence and proliferation of acute infectious process in organism.
• Immunoglobulins type G (IgG) capable of protecting the body from the penetration of various microorganisms for a long time.
• Antibodies type E (IgE) - protecting the body from the penetration of microbes and their poisons through the skin.

How immunity is formed in children: five critical periods in the life of children

The baby’s immune system begins to form even during intrauterine development, when strong connections are established between the body of mother and child. The baby begins to produce small amounts of its own M antibodies around the twelfth week of pregnancy, and their number becomes greater immediately before birth.

In addition, by the 12th week of pregnancy, T-leukocytes appear in the baby’s body, the number of which increases on the fifth day of the baby’s life. In the first months of a child’s life, maternal antibodies protect the child, since the baby’s body is practically incapable of synthesizing its own immunoglobulins. The required amount of type M antibodies approaches adult levels only at 3-5 years of a child’s life.

There are five critical periods in the life of children that influence the process of formation of the immune system:

1. Neonatal period (up to the 28th day of a child’s life). The baby is protected by the mother's immune system, while his own immune system is just beginning to form. The child's body is susceptible to the effects various kinds viral infections, especially those from which the mother did not pass on her antibodies to the baby. At this time, it is extremely important to establish and maintain breast-feeding, since breast milk is best protection for the baby.
2. The period from 3 to 6 months of a child’s life. At this time, maternal antibodies are destroyed in the baby’s body, and active immunity is formed. During this period, ARVI viruses begin to act especially actively. In addition, babies can easily catch an intestinal infection and suffer inflammatory diseases respiratory organs. The baby may not acquire antibodies to diseases such as whooping cough, rubella, and chickenpox from the mother if she does not have vaccinations or did not have them in childhood. Then there is a high risk that these diseases may develop in a rather severe form in the baby. There is a high probability of recurrence of the disease, because the infant’s immunological memory has not yet formed. There is also a high risk of allergies in a child, primarily to food.
3. The period from 2 to 3 years of the baby’s life. The child actively learns about the world around him, but the primary immune response still predominates in the work of his immunity, and the system of local immunity and the production of type A antibodies remains rather immature. Children during this period are most susceptible to bacterial rather than viral infections, which can be repeated several times.
4. Age 6-7 years. During this period, the child already has luggage with accumulated active immunity. However, parents should worry that the disease may become chronic. In addition, there is a high risk of allergic reactions.
5. Adolescence. In girls it begins at 12-13 years old, in boys a little later - at 14-15 years old. At this time, rapid growth and hormonal changes in the body occur, which are combined with a decrease in lymphoid organs. Chronic diseases make themselves felt with renewed vigor. In addition, the child's immune system is tested if the teenager encounters bad habits.

Weak immunity: main signs

Signs reduced immunity in children of different ages :

• in young years.
• The child often experiences prolonged acute otitis, and a runny nose will certainly turn into sinusitis or sinusitis. Problems arise with the adenoids, as well as the palatine tonsils.
• Constant tearfulness and irritability, poor short-term sleep.
• Poor appetite.
• Pale skin.
• Poor bowel function. The stool is irregular or too small, or loose, or it is difficult for the baby to have a bowel movement.
• It takes a very long time for a child to recover after being ill.
• Frequent occurrence of fungal infections.

Factors that reduce children's immunity

Causes of reduced immunity in infants:

1. Trauma during passage through the birth canal.
2. Difficult pregnancy.
3. Poor heredity and predisposition to infectious diseases.
4. The baby refused breast milk before reaching six months of age.
5. Incorrect complementary feeding with excess or deficiency of essential nutrients.
6. Malfunction of the gastrointestinal tract.
7. Drug overdose.
8. Severe psychological trauma.
9. Poor ecology, especially in areas with high radiation.

Reasons for decreased immunity in school-age children:

1. Recurrent diseases of the ear, nose and throat.
2. Poor nutrition, including eating foods that contain excess nitrates or pesticides.
3. Stress and constant nervous tension.
4. The emergence of conflicts leading to misunderstanding and rejection in the team.
5. Abuse of TV, computer, and other modern gadgets.
6. The child spends a minimum amount of time outside and does not rest. Fatigue and overwhelming loads: school plus many additional clubs and sections.
7. Allergies worsen every year in spring and autumn.

If a child’s immunity is weak, then it is necessary to strengthen it. The article “How to Strengthen the Immunity” will tell you how to do this.

Anatomical and physiological features, reserve capabilities.

The development of the body's immune system continues throughout childhood. During the growth of a child and the development of his immune system, “critical” periods are distinguished, which are periods of maximum risk of developing inadequate or paradoxical reactions of the immune system when the child’s immune system encounters an antigen.

The first critical period is the neonatal period (up to 29 days of life). During this period of postnatal adaptation, the formation of the immune system is just beginning. The child's body is protected almost exclusively by maternal antibodies obtained through the placenta and breast milk. The sensitivity of a newborn baby to bacterial and viral infections during this period is very high.

The second critical period (4 - 6 months of life) is characterized by the loss of passive immunity received from the mother due to the catabolism of maternal antibodies in the child's body. The child’s ability to form his own active immunity develops gradually and during this period is limited to the predominant synthesis of immunoglobulin M - antibodies without the formation of immunological memory. The insufficiency of local protection of the mucous membranes is associated with the later accumulation of secretory immunoglobulin A. In this regard, the child’s sensitivity to many airborne and intestinal infections during this period is very high.

The third critical period (2nd year of life), when the child’s contacts with outside world and with infectious agents. The child’s immune response to infectious antigens remains defective: the synthesis of immunoglobulins M predominates, and the synthesis of immunoglobulins G suffers from insufficient production of one of the most important subclass G2 for antibacterial protection. Local mucosal protection is still imperfect due to the low level of secretory IgA. The child's sensitivity to respiratory and intestinal infections is still high.

The fifth critical period is adolescence (for girls from 12 to 13 years old, for boys from 14 to 15 years old), when the pubertal growth spurt is combined with a decrease in the mass of lymphoid organs, and the beginning of the secretion of sex hormones (including androgens) causes depression cellular mechanisms of immunity. At this age, external, often unfavorable, effects on the immune system increase sharply. Children of this age are characterized by high sensitivity to viral infections.

In each of these periods, the child is characterized by anatomical, physiological and regulatory features of the immune system.

At birth, neutrophils predominate in the child’s blood, often with a shift in the leukocyte count to the left to myelocytes. By the end of the first week of life, the number of neutrophils and lymphocytes levels off - the so-called “first crossover” - with a subsequent increase in the number of lymphocytes, which in the next 4 - 5 years of life remain the predominant cells among the child’s blood leukocytes. The “second crossover” occurs in a child aged 6–7 years, when the absolute and relative number of lymphocytes decreases and leukocyte formula takes on the appearance characteristic of adults.

Granulocytes of newborns are characterized by reduced functional activity and insufficient bactericidal activity. The functional deficiency of neutrophils in newborn children is to some extent compensated by a large number of these cells in the blood. In addition, granulocytes of newborns and children of the first year of life differ from granulocytes of adults in a higher level of receptors for IgG, necessary for the cleansing of bacteria from the body mediated by specific antibodies.

The absolute number of blood monocytes in newborns is higher than in older children, but they are characterized by low bactericidal activity and insufficient migration ability. The protective role of phagocytosis in newborns is limited by the underdevelopment of the complement system, which is necessary to enhance phagocytosis. Monocytes of newborns differ from monocytes of adults in their higher sensitivity to the activating effect of interferon gamma, which compensates for their initial low functional activity, because Interferon gamma activates all protective functions of monocytes. promoting their differentiation into macrophages.

The content of lysozyme in the serum of a newborn exceeds the level of maternal blood already at birth; this level increases during the first days of life, and by the 7th - 8th day of life it decreases slightly and reaches the level of adults. Lysozyme is one of the factors that ensures the bactericidal properties of the blood of newborns. In the tear fluid of newborns, the content of lysozyme is lower than in adults, which is associated with an increased incidence of conjunctivitis in newborns.

In umbilical cord blood at the birth of a child, the total level of hemolytic activity of complement, the content of complement components C3 and C4, and factor B are about 50% of the level of maternal blood. Along with this, the level of membrane attack complex components C8 and C9 in the blood of newborns barely reaches 10% of the level of adults. The low content of factor B and component C3 in the blood of newborns is the cause of insufficient auxiliary activity of the blood serum when interacting with phagocytic cells. The above-described defects in the phagocytic activity of granulocytes and monocytes in the newborn are associated with this. By approximately the 3rd month of postnatal life, the content of the main components of complement reaches levels characteristic of an adult organism. In conditions of inability to develop effective specific immunity in children early age The main burden in the processes of cleansing the body from pathogens falls on the alternative pathway of activation of the complement system. However, in newborns, the alternative complement activation system is weakened due to deficiency of factor B and properdin. Only by the second year of life does the production of components of the complement system finally mature.

The content of natural killer cells in the blood of newborns is significantly lower than in adults. Natural killer cells in children's blood are characterized by reduced cytotoxicity. A decrease in the secretory activity of natural killer cells in a newborn is indirectly evidenced by the weakened synthesis of interferon gamma.

As can be seen from the above, in newborn children all the basic mechanisms of nonspecific defense of the body against pathogenic bacteria and viruses are sharply weakened, which explains the high sensitivity of newborns and children of the first year of life to bacterial and viral infections.

After birth, the child’s immune system receives a strong stimulus for rapid development in the form of a flow of foreign (microbial) antigens entering the child’s body through the skin, mucous membranes of the respiratory tract, and gastrointestinal tract, which are actively populated by microflora in the first hours after birth. The rapid development of the immune system is manifested by an increase in the mass of lymph nodes, which are populated by T and B lymphocytes. After the birth of a child, the absolute number of lymphocytes in the blood increases sharply already in the 1st week of life (the first crossover in the white blood formula). Physiological age-related lymphocytosis persists for 5 to 6 years of life and can be considered compensatory.

The relative number of T lymphocytes in newborns is reduced compared to adults, but due to age-related lymphocytosis, the absolute number of T lymphocytes in the blood of newborns is even higher than in adults. The functional activity of T-lymphocytes in newborns has its own characteristics: high proliferative activity of cells is combined with a reduced ability of T-lymphocytes to respond by proliferation to contact with antigens. A feature of T-lymphocytes in newborns is the presence in their blood of about 25% of cells bearing signs of the early stages of intrathymic differentiation of T-cells. This indicates the release of immature thymocytes into the bloodstream. Lymphocytes of a newborn have increased sensitivity to the action of interleukin-4, which predetermines the predominance of Th2 differentiation in them.

In a newborn, the thymus is fully formed during the first year of life and reaches its maximum size (Fig. 3-6). The intense functioning of the thymus, in which all T-lymphocytes undergo maturation, persists during the first 2 to 3 years of life. During these years, there is a constant proliferation of thymocytes in the thymus - the precursors of T-lymphocytes: of the total number of 210 8 thymocytes, 20-25% (i.e. 510 7 cells) are newly formed daily during their division. But only 2-5% (i.e. 110 6) of them enter the blood daily in the form of mature T-lymphocytes and settle in lymphoid organs. This means that 50 10 6 (i.e. 95-98%) thymocytes die every day in the thymus, and only 2-5% of cells survive. From the thymus, only T-lymphocytes that carry receptors capable of recognizing foreign antigens in combination with their own histocompatibility antigens enter the bloodstream and lymphoid organs. These mature T lymphocytes respond to antigen recognition by proliferation, differentiation and activation protective functions during a specific immune response. The rapid increase in thymus mass in the first 3 months of life continues at a slower pace until 6 years of age, after which the thymus mass begins to decline. From the age of two, the production of T-lymphocytes also begins to decline. The process of age-related involution of the thymus accelerates during puberty. During the first half of life, true thymic tissue is gradually replaced by adipose and connective tissue (Fig. 3-6). It follows from this that the thymus manages to carry out its main function of forming a pool of T-lymphocytes in the first years of life.

In the first years of life, against the background of maximum intensity of the maturation processes of T-lymphocytes in the thymus, primary contacts of the body with antigens of pathogenic microorganisms occur, which leads to the formation of clones of long-lived T-cells of immunological memory. During the first three years of life, children are routinely vaccinated against all the most dangerous and common infectious diseases: tuberculosis, polomyelitis, diphtheria, tetanus, whooping cough, measles. At this age, the body’s immune system responds to vaccination (killed or weakened pathogens, their antigens, their neutralized toxins) by producing active immunity, i.e. formation of clones of long-lived memory T cells.

A significant defect in T-lymphocytes in newborns is reduced quantity they have receptors for cytokines: interleukins 2, 4, 6, 7, tumor necrotizing factor-alpha, interferon gamma. A feature of T-lymphocytes in newborns is the weak synthesis of interleukin-2, cytotoxic factors and interferon gamma. In newborns, the activity of mobilizing T-lymphocytes from the bloodstream is reduced. This explains the weakened or negative results of T-dependent skin allergy tests (for example, tuberculin test) in young children. In contrast, a rapid increase in the levels of proinflammatory cytokines (tumor necrotizing factor alpha, interleukin-1) in the blood of newborns during the development of sepsis indicates early maturation of the mechanisms of production and secretion of proinflammatory cytokines.

Absolute and relative lymphocytosis in the blood of children up to the prepubertal period reflects the process of accumulation of clones of lymphocytes that have specific receptors for recognizing various foreign antigens. This process is completed mainly by 5-7 years, which is manifested by a change in the blood formula: lymphocytes cease to dominate and neutrophils begin to predominate (Fig. 3-7).

The lymphoid organs of a young child respond to any infection or any inflammatory process with severe and persistent hyperplasia (lymphadenopathy). At birth, a child has mucosal associated lymphoid tissues (MALT), potentially capable of responding to antigenic stimuli. Children in the first years of life are characterized by a response to infections with hyperplasia of MALT, for example MALT of the larynx, which is associated with an increased frequency and danger of rapid development of edema in the larynx in children during infections and allergic reactions. MALT gastrointestinal tract, in children of the first years of life remains immature, which is associated with a high risk of intestinal infections. The low efficiency of the immune response to infectious antigens entering through the mucous membranes in children of the first years of life is also associated with delayed maturation of the population of dendritic cells - the main antigen-presenting cells of MALT. Postnatal development of MALT in children depends on the feeding system, vaccination, and infection.

In terms of the number of B-lymphocytes in the blood of newborns and their ability to produce a proliferative response to antigens, no significant differences from B-lymphocytes of adults were detected. However, their functional inferiority is manifested in the fact that they give rise to antibody producers that synthesize only immunoglobulin M and do not differentiate into memory cells. This is related to the peculiarities of the synthesis of antibodies in the body of newborns - only class M immunoglobulins accumulate in their bloodstream, and immunoglobulin G in the blood of a newborn is of maternal origin. The content of immunoglobulin G in the blood of a newborn does not differ from the level of this immunoglobulin in the blood of the mother (about 12 g/l); all subclasses of immunoglobulin G pass through the placenta. During the first 2 - 3 weeks of a child's life, the level of maternal immunoglobulin G decreases sharply as a result of their catabolism. Against the background of a very weak child’s own synthesis of immunoglobulin G, this leads to a decrease in the concentration of immunoglobulin G between the 2nd and 6th months of life. During this period, the antibacterial protection of the child’s body is sharply reduced, because IgG are the main protective antibodies. The ability to synthesize one’s own immunoglobulins G begins to appear after 2 months of age, but only by the prepubertal period does the level of immunoglobulins G reach the level of adults (Fig. 3-8).

Neither immunoglobulin M nor immunoglobulin A have the ability to transfer transplacentally from the mother's body to the child's body. Immunoglobulin M synthesized in the child's body is present in the newborn's serum in a very small amount (0.01 g/l). An increased level of this immunoglobulin (over 0.02 g/l) indicates an intrauterine infection or intrauterine antigenic stimulation of the fetal immune system. The level of immunoglobulin M in a child reaches adult levels by the age of 6 years. In the first year of life, the child’s immune system responds to various antigenic influences by producing only immunoglobulin M. The immune system acquires the ability to switch the synthesis of immunoglobulins from Ig M to Ig G as it matures, as a result of which, in the prepubertal period, a balance of different classes of immunoglobulins is established in the blood, characteristic for adults and provides antibacterial protection to both the bloodstream and body tissues.

Immunoglobulin A in the blood of newborns is either absent or present in small quantities (0.01 g/l), and only at a much older age reaches the level of adults (after 10 - 12 years). Class A secretory immunoglobulins and the secretory component are absent in newborns, but appear in secretions after the 3rd month of life. Typical adult levels of secretory immunoglobulin A in mucosal secretions are reached by the age of 2–4 years. Until this age, local protection of the mucous membranes, depending mainly on the level of secretory IgA, remains sharply weakened in children. During breastfeeding, the insufficiency of local mucosal immunity is partially compensated by the intake of secretory immunoglobulin A with mother's milk.

Despite the early start of the formation of elements of the immune system in ontogenesis (on the 40th day of pregnancy), by the time the child is born, his immune system remains immature and unable to provide full protection of the body from infections. In a newborn, the mucous membranes of the respiratory and gastrointestinal tracts are poorly protected - the entrance gates for most infections. Lack of mucosal protection associated with the late onset of immunoglobulin A synthesis and secretory IgA production throughout childhood remains one of the reasons for the increased sensitivity of children to respiratory and intestinal infections. The weakened anti-infective defense of the child’s body is aggravated during periods of decreased levels of protective IgG in the bloodstream (between the second and sixth months of life). At the same time, in the first years of a child’s life, primary contact with the majority of foreign antigens occurs, which leads to the maturation of organs and cells of the immune system, to the accumulation of the potential of T- and B-lymphocytes, which can subsequently respond with a protective immune response to pathogens entering the body. microorganisms. All four critical periods of childhood - the neonatal period, the period of loss of maternal protective antibodies (3 - 6 months), the period of a sharp expansion of the child’s contacts with the outside world (2nd year of life) and the period of the second crossover in the content of blood cells (4 - 6 years ) are periods high risk development of infections in the children's body. Inadequacy of both cellular and humoral immunity makes it possible to develop chronic recurrent infections, food allergies, various atopic reactions and even autoimmune diseases. Individual characteristics of the development and maturation of the immune system during childhood determine the immune status of an adult. It is in childhood, during the heyday of the thymus functions, that specific antimicrobial immunity and the corresponding immunological memory are formed, which should be sufficient for the rest of life.

Reserve capabilities for protecting the newborn's body are associated with breastfeeding. With mother's milk, ready-made antibacterial and antiviral antibodies - secretory IgA and IgG - enter the child's body. Secretory antibodies act directly on the mucous membranes of the gastrointestinal and respiratory tracts and protect these mucous membranes of the child from infections. Due to the presence of special receptors on the mucous membrane of the gastrointestinal tract of the newborn, immunoglobulins G penetrate from the child’s gastrointestinal tract into his bloodstream, where they replenish the supply of maternal IgG previously received through the placenta. The reserve capabilities of protecting the child’s body are associated with an increased number of leukocytes circulating in the body, which partially compensates for their functional inferiority.

Risk factors.

The above-described signs of immaturity of the immune system of a child in the first years of life indicate imperfection of anti-infective protection. That's why infections represent the most important risk factor for the immune system of children. The group at increased risk of developing infections among newborns are premature infants, and among them are low birth weight infants who suffer from the most pronounced and persistent immunological defects. In children of the first years of life, an inability to develop a full immune response to polysaccharide antigens, which are widespread in pathogenic bacteria (Streptococcus pneumonie, Klebsiella pneumonie), was revealed. The insufficiency of local mucosal immunity in children leads to the possibility of penetration of microorganisms - pathogens of respiratory and intestinal infections. The weakness of cellular defense mechanisms makes children especially sensitive to viral and fungal infections, protection against which requires the participation of functionally complete T-lymphocytes. It is precisely due to the defectiveness of cellular defense mechanisms that a high risk of tuberculosis remains throughout childhood due to the widespread circulation of the tuberculosis pathogen. Sensitivity to many infections increases sharply in children after 6 months of life, from the moment of loss of passive immunity - antibodies received from the mother. The risk of developing infections in childhood against the background of an underdeveloped immune system is associated not only with a danger to the child’s life, but also with the danger of long-term consequences. Thus, many neurological diseases of adults are etiologically associated with infections suffered in childhood: measles, chicken pox and others, the pathogens of which are not removed from the body due to the low efficiency of cellular immunity in children, remain in the body for a long time, becoming triggers for the development of autoimmune diseases in adults, such as multiple sclerosis, systemic lupus erythematosus.

Table 3-3.

Risk factors affecting the immune system of children

RISK FACTORS	PREVENTION MEASURES
Infections	Specific vaccination. Breast-feeding
Malnutrition	Breast-feeding. Design of infant formula. Balanced children's diets.
Acquisition hypersensitivity to environmental antigens, allergization	Prevention of prenatal contacts with allergens. Rational baby food.Complexes of vitamins and microelements. Breast-feeding
Environmental troubles	Rational baby food. Complexes of vitamins and microelements.
Psycho-emotional stress	Explanatory work with parents, educators, teachers. Complexes of vitamins and microelements.
Excessive insolation (UV exposure)	Strict adherence to the daily routine, limiting the time of sun exposure for children

The gradual colonization of the child’s mucous membranes with microorganisms contributes to the maturation of his immune system. Thus, the microflora of the airways comes into contact with the MALT of the respiratory tract, microbial antigens are captured by local dendritic cells and macrophages, which migrate to regional lymph nodes and secrete proinflammatory cytokines, which increases the production of interferon gamma and Th1 differentiation. Microorganisms penetrating through the gastrointestinal tract are the main drivers of postnatal maturation of the child’s entire immune system. As a result, an optimal balance of Th1 and Th2, responsible for the cellular and humoral immune response, is established in the maturing immune system.

As the child’s immune system matures and the mechanisms of a specific immune response improve, the risk of an overreaction of his immune system to contact with environmental and developmental antigens increases. allergic reactions. Even prenatal contact of the fetus with pollen allergens inhaled by the mother leads to the subsequent development of atopic reactions and diseases in the newborn. The high risk of developing atopic reactions in children of the first years of life is associated with the predominance of Th2 differentiation in them, which controls the synthesis of immunoglobulin E and increased secretion of histamine by basophils and mast cells. The low level of secretory IgA on the mucous membranes of children facilitates the unhindered penetration of allergens through the mucous membranes of the respiratory and gastrointestinal tract. A feature of atopic reactions in children of the first years of life can be considered a higher frequency of food and lower frequency of dust/pollen allergies compared to adults. Children are often allergic to cow's milk (2 - 3% of children in industrialized countries). Cow's milk contains more than 20 protein components, and many of them can cause the synthesis of immunoglobulin E. The widespread occurrence of such allergies makes it difficult to artificially feed children, forcing them to look for adequate substitutes (for example, soy products).

Past infections have a persistent nonspecific effect on the nature of the child’s immune response to other antigens. For example, among children who have had measles, the incidence of atopy and allergy to house dust compared to children who did not have measles. The measles virus causes a systemic switch to Th1 differentiation. Mycobacteria, including the BCG vaccine, are also Th1 activators. After children are vaccinated with the BCG vaccine, the tuberculin skin test (an indicator of an active cellular immune response) becomes positive and children who had symptoms of atopy before revaccination lose them. In contrast, vaccination with diphtheria-tetanus-pertussis vaccine (DTP), which induces a Th2-mediated response, not only does not have a protective effect against atopy, but may increase the incidence of Th2-mediated atopic diseases in children.

A risk factor affecting the child's immune system is malnutrition of the mother during pregnancy or the child itself.. There is a relationship between malnutrition and infections in children: on the one hand, the low social status of parents, poor nutrition children contribute to a weakening of the immune system and increased sensitivity to infections, on the other hand, infections lead to loss of appetite, the development of anorexia, malabsorption, i.e. to deterioration of nutrition. In this regard, malnutrition and infections are considered as two interrelated major factors that determine the environmental background of morbidity in children, especially in developing countries. A direct correlation has been shown between the infectious morbidity of children in developing countries and the degree to which their body weight lags behind the age norm, with which the low efficiency of cellular immunity also correlates.

A risk factor for the immune system of children is stress. Long separation from the mother is stressful for a child in the first year of life. In children deprived of maternal attention early on, defects in cellular immunity have been identified, which persist throughout the first two years of the child’s life.. For children preschool age the most important are the socio-economic living conditions of the family, which can become the reason for them psychosocial stress. Stress, as a rule, is accompanied by temporary suppression of immune mechanisms, against the background of which the child’s sensitivity to infections sharply increases. In children living in the Far North, inhibition of nonspecific defense factors (phagocytic cells, natural killer cells), a change in the ratio of certain classes of immunoglobulins in the blood serum was revealed: an increase in the level of immunoglobulin M, a decrease in the content of immunoglobulins G, a decrease in the content of secretory immunoglobulin A in saliva and a decrease in tension specific anti-infective immunity formed in response to vaccination.

A stressful factor for children is the effect of light through the visual system on certain areas of the brain or through the skin. Visible light(400-700 nm) can penetrate the layers of the epidermis and dermis and act directly on circulating lymphocytes, changing their functions. Unlike the visible part of the spectrum, irradiation ultraviolet rays UV-B (280-320 nm), UV-A (320-400 nm), acting through the skin, can inhibit immunological functions. The most pronounced inhibition by ultraviolet irradiation of the mechanisms of cellular immunity, the production of certain cytokines and growth factors. These data force us to consider insolation as one of the risk factors affecting the immune system of children.

One of the reliable methods of activating the immune system and preventing infections in children is vaccination. To ensure passive immunity of a newborn in the first months of life, vaccination of pregnant women is quite effective: against tetanus, diphtheria, hepatitis B, staphylococcus, streptococcus. Newborn children are vaccinated against tuberculosis, whooping cough, diphtheria, tetanus, measles, and polio during the first year of life, followed by revaccination throughout childhood and adolescence.

Increasing the reserves of the immune system and preventing infections in newborns is achieved breastfeeding. Human milk contains not only a complex necessary for the child food components, but also the most important factors of nonspecific protection and products of a specific immune response in the form of secretory immunoglobulins of class A. Secretory IgA supplied with breast milk improves the local protection of the mucous membranes of the gastrointestinal, respiratory and even genitourinary tract of the child. Breastfeeding, through the introduction of ready-made antibacterial and antiviral antibodies of the SIgA class, significantly increases the resistance of children against intestinal infections, respiratory infections, and otitis media caused by Haemophilus influenzae. The mother's immunoglobulins and lymphocytes supplied with breast milk stimulate the baby's immune system, providing long-term antibacterial and antiviral immunity. Breastfeeding increases the immune response of children to administered vaccines. Breastfeeding hinders development allergic diseases and the autoimmune disease celiac disease. One of the components of breast milk, lactoferrin, is involved in stimulating immunological functions, being able to penetrate immunocompetent cells, bind to DNA, inducing transcription of cytokine genes. Components of breast milk such as specific antibodies, bacteriocidins, and bacterial adhesion inhibitors have direct antibacterial activity. All of the above requires a lot of attention in preventive work with pregnant women to explain the benefits of breastfeeding. Special educational programs that involve not only women, but also their husbands, parents and other persons who can influence a woman’s decision to breastfeed her child are useful (Fig. 3-9).

The task of designing infant formulas that can replace breastfeeding is very difficult not only in terms of nutritional value, but also by its stimulating effect on the child’s immune system. It is planned to introduce into such mixtures the necessary cytokines and growth factors obtained using genetic engineering technologies.

Rational baby nutrition is one of the universal ways to maintain the proper development and maturation of the immune system and prevent infections and other diseases in children, for example, the consequences of stressors on the child’s immune system. Lactic acid products containing live lactic acid bacteria serve as a safe source of antigens that act at the MALT level of the gastrointestinal tract, promoting the maturation of antigen-presenting cells and T lymphocytes. Use of nucleotides as food additives accelerates the maturation of the immune system in premature newborns. The following are recommended as food supplements for weakened children: glutamine, arginine and omega-3 fatty acid, helping to establish a balance between the cellular and humoral mechanisms of the immune response. The introduction of zinc as a dietary supplement is used to normalize body weight and immunological functions in children. In the serum of premature newborns, the concentration of vitamin A (retinol) is significantly lower than in full-term newborns, which is the basis for the use of vitamin A as a nutritional supplement for the former. Complexes of vitamins and microelements are recommended for permanent use children of the first years of life, which contributes to the maturation of their immune system (Table 3-3).

Children with severe manifestations of immunodeficiency are treated with replacement therapy. For example, they try to compensate for the lack of immunoglobulin G by introducing donor immunoglobulin. However, the injected donor IgG has an even shorter half-life of circulation in the child's body than maternal IgG. Prevention of infections in neutropenia in children is associated with the use of growth factor drugs: G-CSF and GM-CSF, which stimulate myelopoiesis and increase the number and activity of phagocytic cells in the child’s blood.