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Immunity and its forms (essay)

1. The concept of immunity, its form

The human body or animals may not accept the action of pathogenic microbes. This stage is called immunity. In other words, the body is able to withstand the proliferation of microorganisms and disinfect toxins (poisons).

Immunity (Latin immunitas — dismissal) — a manifestation aimed at preserving the sustainability of the internal environment of the protective reactions of the body against the genetic foreign substances (antigens). If the antigens are microorganisms or toxins, an infectious, or antitoxic, immunity develops; during transplantation of foreign cells, tissues and organs — transplantation immunity; in response to the onset of tumors — antitumor immunity, etc. Often, the term «immunity» means immunity to pathogens of infectious diseases.

Immunity is natural (inherited and acquired) and artificial. Hereditary immunity is due to the protective function of a number of tissues, such as skin, mucous membranes. The skin not only inhibits the pathogenic microbes on the surface but also releases substances that destroy them. Bactericidal properties are endowed with saliva and human gastric juice. Acquired immunity occurs in people who have suffered an infectious disease or after the administration of vaccines and serums.

In order to acquire artificial immunity, use a vaccine (active immunity) — a drug with a weakened virulence of microorganisms and serum (passive) — ready-made protective substances (antibodies).

Natural immunity — immunity to infectious diseases, which was inherited from the mother from the mother (born) or arose after the transfer of the disease (acquired).

Currently developed methods to create artificial immunity.

Active artificial immunity is produced by the introduction into the body of weakened or killed pathogens of infection. This causes a mild form of the disease, during which specific antibodies are formed in the body and the person becomes immune for a long time before the disease against which the vaccine was made. This vaccine is used against poliomyelitis, tularemia, pertussis and other diseases.

Preventive vaccination plays an important role in the fight against infectious diseases.

Passive immunity is created by introducing into the body therapeutic serums containing ready-made antibodies against pathogens. This immunity is retained for several months. Therapeutic serums extract from the blood of animals (often horses), which gradually introduce more and more doses of infectious material. In blood, animals accumulate antibodies. From time to time such blood is taken out and manufactured from therapeutic serum.

2. Characteristics of the basic forms of immunity

Congenital (species or hereditary) immunity — the resistance of the organism to certain pathogenic agents, which is inherent in this species and transmitted hereditary. It is believed that this type of immunity is associated with the peculiarities of the genotype of this particular type of macroorganism (human susceptibility to plague cattle, chicken cholera, and animals — to scarlet fever, bark).

Specific immunity is a consequence of the long evolution of the relationship between the organism and the pathogen. It can be absolute and relative and depends on those biological features of these organisms, which were formed in the process of historical development during the natural selection, variability and genetic adaptation to environmental conditions.

The basis of the mechanisms of innate immunity to infections is the absence of cells in the macroorganism of the receptors and substrates, which are necessary for the adsorption and reproduction of the pathogen, the presence of substances that block its reproduction, the ability of the host organism to synthesize various inhibitors in response to the penetration of pathogenic microorganisms.

Under the acquired immunity are understood the specific protection against the genetic foreign substances (antigens), which is carried out by the immune system of the body through the development of antibodies or the accumulation of sensitized lymphocytes. Acquired immunity is produced as a result of a transmitted disease or vaccination of a healthy body.

Distinguish natural and acquired artificial immunity. Natural is active and passive. Natural active immunity may occur after the infection is transmitted and last for months, years or throughout life. Natural passive immunity has a newborn body, gaining it from the mother during the period of prenatal development.

Acquired artificial immunity is produced as a result of active or passive immunization of the body. Artificial active immunity is formed under the influence of vaccines and can last from a few months to several years. Immunity due to the introduction into the body of the finished protective substances (antibodies) in the form of serums, took the name of the acquired artificial passive immunity.

Acquired immunity is not inherited. It is formed in relation to a specific type of pathogenic microbe as a result of contact with it, that is, it is strictly specific. This type of immunity is very stable; for example, after a smallpox, it is saved all life, and after a bark, typhoid fever — long years.

Non-specific resistance of the organism is determined by such factors of protection as barrier function of the skin, mucous membranes, lymph nodes, bactericidal substances of saliva, blood, excretory system, temperature reaction, etc. These factors do not require special rearrangement, but neutralize bodies and substances altogether mainly due to mechanical or physical-chemical action.

Distinguish antibacterial and antitoxic, antiviral and antiparasitic forms of immunity (depending on the fact that against which agents the protective forces of the body are directed). However, it should be borne in mind that absolutely autonomous forms of immunity does not exist, they are all interconnected and exhibit their effects in the body with the participation of all its systems.

In infectious diseases, the pathogens of which are pathogenic bacteria, an antibacterial immunity is formed. In the blood and lymphoid-macrophage system of the bacterium undergoes cellular and humoral factors. The state of immunity, in which the body completely released from the pathogen, got the name of sterile immunity. In tuberculosis and other infections that have a long course, relative immunity coincides with a certain period of time with the presence of pathogens in the body of the infection. Such an immunity is called non-sterile.

Immunity, which is produced in the body in response to the release of exotoxins by pathogenic microbes, is called antitoxic. Consequently, in the process of evolution of protective reactions, the organism has developed the ability to neutralize not only microbes, but also their poisons — toxins.

With viral infections, the body uses all its protective forces to neutralize the virus and neutralize its toxins. Antiviral protective reactions of the organism are divided into nonspecific and specific. An integral part of the first is interferon — an inducible protein, opened in 1957. It withstands low temperatures, heating and ultraviolet irradiation, does not lose activity under the influence of acids and alkalis, non-toxic, is formed by the system of limpous organs and cells. Interferons are synthesized by UIITO and UIUO in response to the action of natural (viruses, endotoxins, intracellular parasites) and synthetic (high and low molecular weight) inductors. Interferon acts on the intracellular stages of reproduction of a wide range of RNA and DNA-containing viruses, suppressing the translation of viral information RNAs and their biosynthesis.

It has been shown that interferon digests the gene for an antiviral protein, which is localized in cells of the human body in chromosome 21, the virus does not act as an interferon itself, but an antiviral protein, the synthesis of which in cells is induced by interferon (F. I. Iershov, A. S. Novohatsky , 1980).

Specific cellular protection of the organism is associated with the participation of sensitized T-lymphocytes that do not act on the virus, and with the help of lymphotoxins destroys infected cell viruses.

The immunity of the organism to pathogenic parasites (malarial plasmodia, trypanosomes, etc.) has been called parasitic-immune immunity. The development of such immunity depends on the localization of the parasite. This form of immunity is determined by the protective effect of IgE and increased activity of phagocytes.

In addition to the above-mentioned forms of protection, there are concepts of collective (group) immunity, transplantation immunity, etc.

Currently developed methods to create artificial immunity. Active artificial immunity is produced by the introduction into the body of weakened or killed pathogens of infection. This causes a mild form of the disease, during which specific antibodies are formed in the body and the person becomes immune for a long time before the disease against which the vaccine was made. This vaccine is used against poliomyelitis, tularemia, pertussis and other diseases.

Preventive vaccination plays an important role in the fight against infectious diseases.

Passive immunity is created by introducing into the body therapeutic serums containing ready-made antibodies against pathogens. This immunity is retained for several months. Therapeutic serums extract from the blood of animals (often horses), which gradually introduce more and more doses of infectious material. In blood, animals accumulate antibodies. From time to time such blood is taken out and manufactured from therapeutic serum.

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