Decreased immunity - Causes, symptoms and treatment. MF.

Immunity is the main body system that provides its protection against everything that carries the signs of genetically alien information.
Immunology is a relatively young science, the age of which slightly exceeds 120 years. Its founder is considered to be Louis Pasteur.

Currently, the immune system is seen as a control system that ensures the individuality and integrity of the body. Immunity is based on the ability to distinguish the body's own structures from genetically alien, as well as destroy and eliminate the latter.

Which structures can carry the signs of genetically alien and, accordingly, be attacked by the immune system.
In the first place, of course, are different microorganisms: bacteria, viruses, fungi, protozoa, etc. If the immune system does not cope with its protective role, then they begin to multiply within a person, causing various infectious diseases.

The second place in the list of immunity targets is located mutant or tumor cells. The body is constantly generating a sufficiently large number of mutant cells, many of which can cause the development of cancer. And immunity is precisely responsible for their timely recognition and destruction.

This, of course, the list is not limited. Carriers of foreign genetic information can be food, medicinal substances, transplants, etc.

This is normal. If the immunity is malfunctioning, it is possible to develop an immune attack on the cells, organs and tissues of one's own organism. Such pathological immune response is the primary cause of the development of autoimmune diseases. Abnormalities in the development of the immune response can also lead to the development of allergic diseases.

Providing immunity in the body

The ability of an organism to distinguish "one's own" from "another's" exists for hundreds of millions of years. However, only in vertebrates the lymphoid system was formed into the morphological basis of the immune system, and plays a leading role in the immune defense of the body. The only cells of the immune system( by the immunocytes ) are only lymphocytes.

Currently, two main populations of lymphoid cells are distinguished: B-lymphocytes and T-lymphocytes( their properties and functions are slightly lower).They and only they are able to recognize the antigen( the structure directly on which the immune response develops).The remaining cells involved in the immune response( blood cells - neutrophils, monocytes, basophils, eosinophils, blood vessel cells, dendritic cells, etc.) - only contribute to lymphocytes in the performance of their function, as it were, cooperate with them. In the development of the immune response, various protein systems( eg, proteins of the complement system), regulatory molecules( interleukins) also actively participate.

Anatomical basis of the immune system is lymphoid tissue. It forms the organs of immunity, which in turn are divided into central and peripheral.

In the central organs of the immune system, the main stages of lymphocyte development occur. In peripheral organs, lymphocytes mature and produce receptors for a particular foreign agent, that is, as it were, pulling a clone of lymphocytes into a specific antigen.
The central organs include the thymus and bone marrow. In the thymus there is a first stage of development of T-lymphocytes, in the bone marrow - B-lymphocytes.
The peripheral lymphoid organs include: spleen, lymph nodes, tonsils, appendix, adenoides, etc.

Types of immunity

Currently, there are two main variants of the immune response: cellular and humoral .

The humoral immune response of is realized by the activity of B-lymphocytes that produce antibodies( immunoglobulins).This type of immune response is directed primarily against extracellular antigens. This is primarily bacteria. That is, we can say that this is an antibacterial immune response. In case of failure of this link in human immunity, frequent bacterial infections begin to disturb( angina, acute respiratory infections, sinusitis, bronchitis, furuncles, etc.).The central orane immune system responsible for the humoral immune response is the bone marrow.

is based on the activity of various T-lymphocyte subpopulations based on the cellular immune response. The central organ of this type of immunity is the thymus. The cellular immune response is focused on combating intracellular antigens. Thus, this type of immune response is the basis of antiviral, antitumor, antifungal immunity and transplant rejection. Accordingly, in the pathology of this type of immune response, the patient is often concerned about frequent viral infections( eg, frequent recurrences of herpes), increased risk of cancer formation, etc.

In addition, the immune response can be primary and secondary. The primary immune response is the immune response that occurs upon first contact with the antigen. Secondary immune response is the immune response to repeated contact with the same antigen. The development of a secondary immune response was made possible by the appearance of immune memory cells.

Both the humoral and cellular immune response have a certain rate and, upon repeated exposure to the agent, develop much faster and have qualitative characteristics.