Formation of immunity in children. Part 1

Immunity provides the body's ability to recognize and destroy foreign substances - bacteria, viruses, parasites, their toxins, as well as their own altered cells. The immune system consists of a set of links, each of which performs a special task. All elements of this design can be divided into nonspecific, or congenital, and specific, that is, acquired. Innate immunity is always active, even in the absence of foreign substances. Specific begins to act only if the enemy enters the body. Innate immunity meets the "troublemakers" first. It begins to work as soon as the crumb appears on white light, but at full power it does not turn on right away. Innate immunity is considered a nonspecific system of protection against infection, it is the same in almost all people, and its main task is to prevent the development of most bacterial infections - for example, bronchitis, otitis, angina.

The first on the way "stranger" stand physiological barriers - skin and mucous membranes. They have a special acidic medium (pH level), which is disastrous for "pests" and is populated with microflora - bacteria-protectors. Mucous membranes also produce bactericidal substances. Both barriers detain most of the aggressively-tuned microorganisms.

"Strangers" who overcome such obstacles meet with the cellular link of innate immunity, that is, with specialized cells - phagocytes, which are found in the skin of mucous membranes and in blood cells. They act in cooperation with special types of proteins and protein complexes, for example, known to all interferons, possessing bactericidal or anti-etching action. Thanks to their joint efforts, only 0.1% of the "aggressors" remain alive.

Special forces team
Specific (or acquired) immunity is not formed immediately, but only after the birth of a crumb, and in several stages. Such protection is based on a more subtle mechanism of separating "one's own" from "alien" and immunological memory, that is, recognizing the "alien" that has already had to come into contact. If the enemy is not familiar, then the specific immunity will not react to him in any way. This protection is formed in the interaction of two very closely related factors - cellular (T- and B-lymphocytes) and humoral (immunoglobulins). Both T- and B-lymphocytes recognize alien substances (bacteria, viral) and if they meet with it again, they will immediately start attacking - so the memory of immunity manifests itself. In this case, the second time the infection does not occur at all or the disease proceeds in a lighter form. But if the T cells act on their own, the B-lymphocytes, in order to get rid of the enemy, synthesize specific antibodies - immunoglobulins. Immunoglobulins in the child are formed gradually, becoming as in adults only to a certain age.

A significant role in the formation of acquired immunity is played by vaccinations made at an early age, as well as natural encounters of the child with microbes and viral infections in the first 5 years of life. The richer will be the memory for infection, the better the crumb will be protected in the future.

Ready for battle
One of the components of specific immunity are immunoglobulins. By their level, one can judge the development of the disease and accurately determine the "enemy".

There are 5 types of immunoglobulins: A, M, G, D, E. Immunotubulin D is involved in the production of B-lymphocytes. Immunotubulin A (lgA) promotes the protection of mucous membranes. Elevated levels of lgA in the blood indicate an acute inflammatory process. Antibodies of the M (lgM) group are not remembered from the first time by the "stranger", but after colliding with it 2-3 more times, they begin to recognize and are already working for destruction. Due to this property, IgM vaccination was possible. When vaccinated in the blood of a child in tiny doses are introduced inactivating viruses in order that the body developed their antibodies. Antibodies of group M together with lgA fight infection at first. Elevated levels of lgM in newborns signal for intrauterine infection (toxoplasmosis, herpes). In older children - that the child first met the virus and is now frayed. Using lgG, the body "finishes" the infection. It takes 1-2 weeks to produce them. The presence in the body of antibodies of this class to a certain virus means that a person has been infected with an infection (measles, chickenpox) and immunity has been developed to it.

IgE is synthesized when parasites (helminths, worms) develop in the body, and these antibodies also react to allergic reactions. If a suspected allergy is prescribed, the blood test for IgE is common, and to determine sensitivity to allergens - lgE specific. The stronger the reaction to the allergen, the higher the level of the last indicator.

The beginning of the way
If adults have antibodies to hundreds of "pests", the kids only have to work out them. So at different stages of development, the immune system of crumbs has different possibilities. In many respects it influences on what diseases and at what age he is sick.

The immune system begins to form during pregnancy. At the 3rd-8th week, the liver is formed, B-lymphocytes appear in it. At the 5th-12th week the thymus is formed, where after the birth of the baby T-lymphocytes begin to mature. At the same time, the spleen and lymph nodes form. At the 21st week of pregnancy, the spleen also begins to produce lymphocytes. Lymph nodes, however, should hold bacteria and other foreign particles and keep them from getting inside. But this barrier function they begin to perform only to 7-8 years. If in 1-2 trimesters the expectant mother will suffer an infectious disease, it will be unbalanced to eat, there will be a risk of incorrect formation of these organs. In these terms, a woman should avoid contact with influenza and ARVI if possible, and do not overcool.

Between the 10th and 12th weeks of gestation, the future child begins to produce his own imunoglobulins, primarily class G. Some of the latter he also receives through the blood of his mother and placenta almost immediately after conception. But before the 6th month of pregnancy, maternal immunoglobulins are present in the blood of the unborn child only in very small amounts. For this reason, the risk of infection is very high for very premature babies.

After the 32nd week of pregnancy, antibodies begin to form rapidly, which will protect the baby from illnesses in the first months after birth.