Immunity is a complex of protective factors that ensure the body's ability to withstand the negative effects of external agents. The latter, for example, include bacteria, poisons, viruses, foreign bodies. In science, two types of immunity are distinguished: specific and nonspecific. The latter will be discussed in the article.
General characteristics
Non-specific immunity is directed against any antigen. When a foreign substance penetrates, the body forms an adequate response. The reaction can be at the humoral or cellular level. In the first case, the response is formed due to the production of bactericidal compounds. Non-specific cellular immunity ensures the capture of foreign substances and the cytotoxic effect.
Elements
Non-specific protection factors (immunity) are presented in the form of anatomical barriers, secretory molecules and other components. The former include epithelial mucous layers, skin, fluctuations of bronchopulmonary cilia and bowel contraction. Non-specific immunity is considered innate.
Mechanical structures
Physical factors of non-specific cellular immunity form various barriers for foreign agents. Epithelial surfaces act as one of the most effective barriers. These barriers are practically impenetrable to most agents. The first barrier is the skin. Desquamation (peeling) of the epithelium helps to remove bacteria and other infectious bodies. Intestinal peristalsis, movement of cilia ensure the release of the respiratory system and gastrointestinal tract from microorganisms. Saliva and tears, washing the mouth and eyes, help prevent infections. The mucosa of the respiratory tract and gastrointestinal tract also provides protection.
Chemical compounds
Non-specific immunity is provided in a variety of ways. Of no small importance in this case are chemical compounds formed during the penetration of agents. Thus, the development of bacteria slows down under the influence of sweat fatty acids. Phospholipase and lysozyme present in nasal secretions, tears and saliva have a destabilizing effect on the membrane of pathogenic microorganisms. Bacterial growth is also slowed down by low pH of gastric secretions and sweat. Low molecular weight proteins (defensins) present in the gastrointestinal tract and lungs have antimicrobial activity. The normal flora of the skin and in the gastrointestinal tract is able to prevent the colonization of pathogenic agents by producing toxic compounds or by competing with bacteria for attachment tosurfaces or nutrients.
Non-specific immunity: humoral level
Certainly, anatomical barriers are very effective in preventing the colonization of surfaces by pathogenic agents. However, if they are damaged, the barriers are broken. This allows harmful compounds to enter the body. In such cases, nonspecific immunity is activated at the humoral level. Its elements are present in the serum or accumulate in the site of infection.
Systems
When pathogenic agents enter the body, defense mechanisms are activated. One of them is the complement system. Its activation is accompanied by the mobilization of phagocytes, lysosomes, and an increase in vascular permeability. Another mechanism is the clotting system. It is activated depending on the severity of tissue damage. Some products of the system provide a non-specific protective response by increasing vascular permeability. They act as chemoattractants - substances that, when attached to agents, provoke their movement. In addition, some products have an antimicrobial effect. These include, for example, beta-lysine. This protein is produced by platelets during the clotting process. It lyses many Gram-positive bacteria. Transferrin and lactoferrin bind iron necessary for microbes, limiting their growth. Interferons have the ability to limit replicationviruses. Lysozyme acts destructively on the bacterial membrane.
Cells of nonspecific immunity
Mobilization of polymorphonuclear eosinophils, neutrophils, macrophages is part of the reaction to infection. They move to the site of localization of bacteria. These cells are considered the main line of defense of nonspecific immunity. Neutrophils - polymorphonuclear leukocytes go to the site of infection and capture bacteria. Immunity cells can destroy them intracellularly or move them to extracellular traps. In addition, neutrophils are involved in tissue repair after the infection has been eliminated.
Macrophages
These elements also have the ability to phagocytize (capture) pathogenic elements and destroy them. Agents are deactivated at the intracellular level. Macrophages have some special features. For example, they have the ability to extracellular (extracellular) self-destruction. In addition, the elements are involved in tissue remodeling.
Extra
In addition to the above cells, the nonspecific immune system contains natural and lymphokine-activated killers. These elements are capable of destroying tumor agents infected with infection. Killer cells are not considered part of the inflammatory response. However, they play a significant role in nonspecific immunity. Eosinophils are also present in the system. The proteins in their granules are effective against a number of parasites.
Inflammation
Basicthe task of this reaction is the separation of pathogenic organisms and their toxins that have penetrated the tissues, and then their destruction. Of particular importance in the inflammatory process are histamine, serotonin and other biologically active components. They increase the permeability of capillaries, providing the development of edema. In the fluid present at the site of accumulation of agents, there are neutrophils, macrophages, antibodies, complement. They provide neutralization of bacteria and their toxins. Phagocytes are concentrated in the focus of inflammation. They form a kind of barrier that prevents the spread of infection. This is where fibrinogen begins to accumulate. Turning into fibrin, it provides thrombosis of small lymphatic and blood vessels. As a result, a barrier is created for the spread of infection through them. In the inflammatory focus, blood supply is disturbed. Due to this, acidic products of metabolic processes begin to accumulate and the pH decreases. This adversely affects the growth and reproduction of microorganisms.
