Immunity (lat. Immunitas "liberation") is the defense that the body is capable of when antigens (substances foreign to the genes) penetrate it. They can be of exogenous and endogenous origin, homeostasis of the organism, biological individuality of each and the species as a whole are protected from them.
An optimal and simpler definition of immunity is a way to protect the genetic constancy of homeostasis from substances or bodies with foreign genetic information. It determines the body's ability to resist, is responsible for its genetic integrity.
Immune system properties
She has the ability to distinguish between her and someone else's pathogenic body, keeps a memory of them after the first contact with them: they become antigens for her. It has separate groups of cells, each of which has the ability to respond only to a separate type of pathogen.
Defense bodies
The immunity system consists of central and peripheral organs. What does this mean? It does not occur on its own, but is the result of the coordination of the work of the red bone marrow, lymph nodes, thymus and spleen. In the central organs of the immune system, lymphocytes are the hosts, as they can recognize antigens of any kind.
The central (primary) organs of immunity include:
- the precursor of blood elements is red bone marrow, it contains stem cells with T- and B-leukocytes;
- in children thymus lymphocytes specialize here;
- peripheral organs, T- and B-lymphocytes are formed in them.
These systems are in the way of pathogens, such as tonsils.
Peripheral organs:
- lymph nodes - are on the path of lymph and filter it, removing extraneous antigens;
- lymphoid tissues in the skin and mucous membranes of some organs also act as barriers;
- spleen - forms a response to pathogens that have entered the bloodstream.
And one more remark: not only immunity decides everything. The body itself is configured for its own safety. What it is? The organs themselves protect themselves from external influences. For example, saliva contains lysozyme, tears and urine have bactericidal properties, there are cleansing cilia in the nose, the skin is covered with antibacterial substances, if foreign pollen or bacteria enter the respiratory tract, a cough occurs, etc.
Kinds
First of all, immunity is divided into congenital and acquired.
Congenital, or species (it is hereditary), genetic, constitutional - the immunity of any species and its individuals (humans) to any antigen (or microorganism) is inherited. An example is the fact that a person does not suffer from some diseases of domestic animals and birds, for example, cattle plague, horse smallpox, dog pyroplasmosis, chicken cholera, etc. Another example is anthroponoses (measles, smallpox, leprosy, AIDS, gonorrhea and pertussis, typhoid fever and syphilis, cholera, etc.).
Congenital immunity is absolute and relative. With the latter, in the presence of certain factors, the body begins to respond to things to which it was previously insensitive.
For example, frogs do not respond to tetanus toxin, but they will also respond to its introduction when their body temperature rises - this is relative species immunity. When absolute, no additional factors can cause susceptibility to pathology.
Acquired immunity is immunity to an antigen that appears after a natural encounter with it, for example, after a disease. Unlike acquired as a result of a previous infection, artificial immunization with antigens is often used in medicine to develop immunity to them. This includes vaccination, the introduction of specific immunoglobulins, serums. Such immunity is called "post-vaccination."
He can be active and passive. Active - this is a vaccine well known to everyone when the body's reaction is active, and the passive is formed by the introduction of ready-made antibodies into the body. Such immunoreagents include specific immunoglobulins and serums.
Passive immunity in newborns is created by immunoglobulins received from the mother through the placenta.
Active is divided into: cellular, humoral, cell-humoral.
Cellular and humoral immunity is specific. It includes antitumor, anti-tuberculosis, transplantation. The leading role here belongs to killer T-lymphocytes, which destroy infected cells. The mechanism of manifestation of active immunity is different: the humoral one manifests itself through biological fluids of the body, releasing antibodies (immunoglobulins) of classes G, A, M, E, D into the blood.
Cellular is associated with phagocytosis - the process of digesting microbes by macrophages. The nature of the protection according to the properties of the antigen: antitoxic, against viruses, fungi, bacteria, protozoa, transplantation, antitumor, etc.
Finally, active immunity can persist either in the absence or only in the presence of the pathogen in the body. In the first case we are talking about sterile immunity, the second case is non-sterile.
An example of a sterile one is post-vaccination protection of an organism with the introduction of killed vaccines, and non-sterile one is immunity for tuberculosis.
And finally, it can be generalized (systemic) and local, when certain tissues and organs have a more pronounced resistance. It includes skin protection, mucous membranes of ENT organs, etc.
Congenital immunity: features
This is a genotypic trait of an organism; it is transmitted hereditarily. It means that it exists even before the first encounter with the pathogen, i.e., it is not specific. Based on phagocytosis. At the first encounter with pathogens, it activates faster, but recognizes a foreign body with less accuracy. This means that the response does not occur to specific specific antigens, but to certain classes of antigens (virus proteins, products of the metabolism of worms, etc.).
Congenital immunity can be hereditary (species) and individual. It also needs to be supported, because in some cases it may decline. This is noted during stress or during hypovitaminosis, as a result of exhaustion, prolonged somatic or infectious diseases, weakening nutrition, poor ecology, poor social conditions, and in an unfavorable climate. The penetration of pathogens during this period into the blood causes a change in immunity: the acquired protection is connected and begins its work.
All types of immunity are interconnected, and therefore they speak of a multi-level defense system.
Features of acquired protection
Acquired immunity is a phenotypic trait, resistance forms after vaccination or infection. Long-term resistance to some kind of re-infection is called permanent protection.
If the immunity is short-term, this is a temporary protection, for example, after the administration of serum.
Artificial Defense
It is acquired with the use of medications. The vaccine always contains weakened or killed microorganisms. It can only be introduced into a healthy body and prevents diseases in the future.
Serum is a plasma drug with ready-made antibodies to a specific pathogen. It is administered to a sick person if his body cannot produce antibodies in sufficient quantities.
Infectious immunity
It is directed against pathogens of infection and its toxins. Accordingly, it is divided into antimicrobial and antitoxic. The first, in turn, can be antiviral, fungal, antibacterial, protozoan. Antimicrobial is also divided into sterile infectious non-sterile immunity. And antitoxic fights with toxins that produce microorganisms.
Non-sterile and sterile protection
It studies any type of immunity (sterile and non-sterile) microbiology, namely its section such as immunology. The body's resistance consists of a number of mechanisms and reactions to the removal of a pathogen from body cells. At the same time, most of the pathogenic objects completely die and are eliminated. This outcome is considered a sterile form of immunity.
Features of sterile body protection
What is the difference between sterile immunity and non-sterile? Microbes do not remain in the body after recovery completely (for example, hepatitis A or vaccination). When the pathogen is no longer in the body, but resistance to it remains, this is sterile immunity. You can talk about this method of protection after chickenpox and smallpox, measles, whooping cough, diphtheria; It can also occur after vaccination.
Non-sterile protection
Non-sterile immunity - what is it? It is completely impossible to destroy some antigens; they are strong and remain deep in the cellular structure. Then the protective system partially kills the pathogen, and partially blocks inside the Taurus, preventing them from showing their aggression and sharing. This type of immunity is called non-sterile immunity when the pathogen sits in the cells but is inactive. This means that the disease can recur again, but will be quickly suppressed.
Features of non-sterile protection
Examples of non-sterile immunity: develops with certain infections - malaria, herpes, luez, tuberculosis, typhus, brucellosis, rickettsial. When a person has been ill with them, there is a constant presence of these pathogenic particles in the body. While immunity is at its best, pathogens are suppressed, but with a decrease in the body's resistance to diseases, they are activated and work to the detriment. This is “premunition” (in immunology, non-sterile immunity passes under the name premonition) and this co-existence is called in harmony and without the struggle of the microbe and the host.
The body is resistant to the microbe that lives inside the cells. They coexist on mutually beneficial conditions: the pathogen has nutrition in use for its life, and the owner has protection against reinfection.
All this until the first turn. The level of resistance changes and friendliness leaves: the pathogen is activated. Therefore, non-sterile immunity has some time limits - it exists in parallel with the living microbe.
Resistance after infection develops rapidly, symptoms appear in the initial period. Thanks to this phenomenon, it is impossible to relive all the primary symptoms once again after 10 days or 2 weeks. The peak occurs in the secondary period.
It is important to note in the definition of "non-sterile immunity" - this is that this type cannot be eternal, it is limited. It exists exactly until the microbe is in the body. When there is no pathogen in the body, the body loses its ability to resist this disease in the future.
With infectious non-sterile immunity, the infection can be reactivated. This means that a person can be infected with a previous infection repeatedly, but the body already knows how to deal with it. The disease becomes localized, therefore, it is suppressed without difficulty.
Tuberculosis immunity: features
Non-sterile immunity occurs with tuberculosis (it does not happen sterile with this infection). A newborn receives natural resistance or a predisposition to the disease from parents. But just one innate immunity is not enough to fight tuberculosis, therefore, WHO has developed a vaccination schedule requiring mandatory tuberculosis vaccination (BCG). After it is carried out for 3 weeks, specific anti-tuberculosis antibodies are formed that perform a barrier function. Thus, innate immunity is complemented by acquired. At the same time, the body is producing antibodies, and the memory of the protective response program is formed. That is, natural anti-tuberculosis immunity is produced as a result of contact with an antigen.
This combination of susceptibility to MBT and resistance is a feature of immunity in tuberculosis. With reactivation, the body's defense can defeat the disease much faster.