Immunology is the science of the molecular and cellular mechanisms of the immune response and its role in various pathological conditions of the body. To one of the most pressing problems they munologii include immunological reactivity – the most important expression of reactivity in general, that is, the properties of a living system to respond to the effects of various external and internal factors. The concept of immunological reagent vnosti includes 4 taken Aimo related phenomena: 1) immunity to infectious disease, or immune system in the proper sense of the word, and 2) reacting the biological tissue incompatibility, and 3) increased sensitivity reaction NOSTA (allergy and anaphylaxis) 4) habituation phenomenon to poisons of various origins.
All these phenomena combine the following signs with each other: 1) they all occur in the body when alien living creatures (microbes, viruses) or painfully modified tissues, various antigens, toxins get into it. 2) these phenomena and reactions are biological defense reactions, aimed at maintaining and maintaining consistency, stability, composition and properties of each individual whole organism; 3) in the mechanism of most reactions themselves, the processes of interaction of antigens with antibodies are essential.
Antigens (Greek anti -. V., Genos – genus origin) – alien substances to the organism that cause the formation of antibodies in the blood and other tissues. Antibodies are proteins of a group of immunoglobulins that are formed in the body when certain substances (antigens) get into it and neutralize their harmful effects.
Immunological tolerance – complete or partial lack of immunological reactivity, i.e. loss (or decrease) in the body’s ability to produce antibodies or immune lymphocytes in response to antigenic irritation. It can be physiological, pathological and artificial (curative). Physiological immunological tolerance is manifested by the tolerance of the body’s own proteins by the immune system. The basis of this tolerance is the “memorization” by the cells of the immune system of the protein composition of the organism. An example of pathological immunological tolerance is the tolerance of a tumor by the body. In this case, the immune system reacts weakly to cancer cells that are foreign to the protein composition, with which not only tumor growth can be associated, but also its occurrence. Artificial (curative) immunological tolerance is reproduced by means of influences that reduce the activity of the organs of the immune system, for example, by administering immunosuppression , by ionizing radiation . The weakening of the activity of the immune system ensures the tolerance of the body of transplanted organs and tissues (heart, kidney)
Immunity (lat immunitas -. Exemption from anything deliverance) – this body immunity against pathogen or certain poisons.Immune reactions are directed not only against pathogens and their poisons (toxins), but also against all alien: foreign cells and tissues that have genetically changed as a result of mutation of their own cells, including cancer cells.In every organism, there is an immunological surveillance that ensures the recognition of “one’s own” and “of another’s” and the destruction of the “other’s.” Therefore, under the immunity understand not only immunity to infectious diseases, but also a way to protect the body from living beings and substances carrying signs of foreignness. Immunity is the ability of an organism to defend itself from genetically alien bodies and substances. According to the method of origin, innate (species) and acquired immunity are distinguished.
Congenital immunity is a hereditary trait for this type of animal. By strength or durability it is divided into absolute and relative. Absolute immunity is very durable: no effects of the external environment weaken the immune system (in dogs and rabbits it is not possible to cause the disease by polio during their cooling, fasting, injury). The relative species immunity is in contrast to the absolute less durable, depending on the effects of the external environment (birds (chickens, pigeons) are normally immune to anthrax, but if they are weakened by cooling, starvation, they become ill).
Acquired immunity is acquired in the process of life and is divided into naturally acquired and artificially acquired. Each of them is divided into active and passive by the way of occurrence.
Naturally acquired active immunity occurs after the transfer of the corresponding infectious disease. The naturally acquired passive immunity (congenital, or placental, immunity) is due to the transfer of protective antibodies from the mother’s blood through the placenta to the fetal blood. Protective antibodies are produced in the mother’s body, but the fetus gets them ready. In this way, newborn babies are immune to measles, scarlet fever, diphtheria. After 1-2 years, when antibodies obtained from the mother are destroyed and partially excreted from the child’s body, its susceptibility to these infections increases dramatically. Passively, immunity can be less transmitted with mother’s milk. Artificially acquired immunity is reproduced by humans in order to prevent contagious diseases. Active artificial immunity is achieved by inoculating healthy people with cultures of killed or weakened pathogenic microbes, weakened toxins (toxoids) or viruses. For the first time, artificial active immunization was performed by E. Jenner by vaccinating vaccinia against children. This procedure L. Pasteur was called vaccination, and vaccination material – vaccine. Passive artificial immunity is reproduced by injecting human serum containing antibodies against microbes and their toxins. Especially effective anti-toxic serum against diphtheria, tetanus, botulism, gas gangrene. Serums are also used against snake venoms (cobra, viper). These sera are obtained from horses that are immunized with a toxin.
Depending on the direction of action, antitoxic, antimicrobial and antiviral immunity are also distinguished. Anti- toxic immunity is aimed at neutralizing microbial poisons, while antitoxins play a leading role in it. Antimicrobial (antibacterial) immunity is aimed at the destruction of microbial bodies themselves. A large role in it belongs to the antibodies, as well as phagocytes. Antiviral immunity is manifested by the formation in the cells of the lymphoid series of a special protein – interferon, which suppresses the multiplication of viruses. However, the action of interferon is not specific.
The mechanisms of immunity are divided into non-specific, i.e.general protective devices, and specific immune mechanisms.Nonspecific mechanisms prevent from penetrating germs and foreign substances in the body, specific mechanisms begin to work when the body appear foreign antigens.
Mechanisms of nonspecific immunity include a number of protective barriers and devices. 1) Intact skin is a biological barrier for most microbes, and mucous membranes have devices (ciliary movements) for mechanical removal of microbes. 2) Destruction of microbes using natural fluids (saliva, tears – lyso- Zim , gastric juice – hydrochloric acid.) 3) The bacterial flora contained in the large intestine, the mucous membrane of the nasal cavity, mouth, genital organs, is the antagonist of many pathogenic micro bov.4) Blood-brain barrier (endothelium of capillaries of the brain and choroid plexuses of its ventricles) protects the central nervous system from infection and foreign substances in it.5) Fixation of microbes in tissues and their destruction by phagocytes.6) Source of inflammation at the site of microbes penetration through the skin or the mucous membrane plays the role of a protective barrier.7) Interferon is a substance that inhibits the intracellular multiplication of the virus. It is produced by various cells of the body. Being formed under the influence of one type of viruses, it is also active with respect to other viruses, i.e. is a nonspecific substance.
The specific immune mechanism of immunity includes 3 interconnected components: A-, B- and T-systems. 1) A-system is able to perceive and distinguish the properties of antigens from the properties of its own proteins. The main representative of this system is monocytes. They absorb antigen, accumulate it and transmit a signal (antigenic stimulus) Executive immune cells sistemy.2) The executive branch of the immune system – The system includes lymph B – cytes (they mature birds in the bursa of Fabricius (Latin bursa -. Bag) – diverticulum cloaca). In mammals and in humans, an analogue of the factory bag was not found, suggesting that its function is performed either by the hematopoietic tissue of the bone marrow itself or by the Peyer’s ileal plaques. After receiving an antigenic stimulus from monocytes, B-lymphocytes are transformed into plasma cells that synthesize antibodies specific for the antigen — immunoglobulins of five different classes: IgA , IgD , IgE , IgG , IgM . The B-system provides for thedevelopment of humoral immunity. 3) The T-system includes T-lymphocytes (maturation depends on the thymus gland). After receiving an antigenic stimulus, T-lymphocytes are transformed intolymphoblasts , which multiply vigorously and mature. As a result, immune T-lymphocytes are formed that are able to recognize the antigen and interact with it. There are 3 types of T-lymphocytes: T-helpers, T- suppressors and T-killers. T helper (assistant) help B lympho – tsitam, increasing the activity and turning them into plasma cells. T- suppressors (oppressors) reduce the activity of B-lymphocytes. T-killers (killers) interact with antigens — worse than native cells and destroy them. The T-system ensures the formation of cellular immunity and graft rejection reactions, preventing the formation of op- choles in the body , creating anti-tumor resistance, and therefore its violations can contribute to the development tumors.
Allergy (Greek . Allos – another, ergon – action) – an altered (perverse) reactivity of the organism to repeated effects of any substances or to components of its own tissues.The basis of the allergy is an immune response that occurs with tissue damage.
Upon initial introduction of antigen into the body, called an allergen, noticeable changes occur, but accumulate antibodies or immune cells to this Aller a genius. After some time, against the background of a high concentration of antibodies or immune lymphocytes, the same allergen reintroduced causes a different effect — pronounced disorders of vital activity, and sometimes death of the organism. In allergies, the immune system in response to ingress of allergens actively produces antibodies and immune lymphocytes that interact with the allergen. The result of this interaction is damage at all levels of organization: cellular, tissue, organ.
Typical allergens include various types of grass and flower pollen, pet dander, synthetic products, detergent powders, cosmetics, food substances, medicines, various dyes, foreign blood serum, household and industrial dust. In addition to these ekzoallergenov penetrating from outside the body in different ways (through the respiratory tract, the mouth, skin, mucous membranes, by injection), in a sick body formedendoallergeny (autoallergens) of its own proteins and under the influence of various damaging factors. These endoallergens cause various auto-allergic (autoimmune, or auto-aggressive ) human diseases.
All allergic reactions are divided into two groups: 1) delayed-type allergic reactions (delayed-type hypersensitivity), 2) immediate-type allergic reactions (immediate-type hypersensitivity ). In the onset of the first reactions, the main role is played by the interaction of allergen with sensitized T-lymphocytes, the occurrence of the second – the disruption of the B-system and the participation of humoral allergic antibodies-immunoglobulins.
By delayed type allergic reactions include tuberculin type reaction (bacterial allergy), allergic contact type (contact dermatitis), some forms of drug allergies, many autoimmune diseases (encephalitis,thyroiditis, systemic lupus erythematosus, rheumatoid arthritis, systemic scleroderma), aller- GIC reactions of graft rejection. Allergic reactions of immediate type include: anaphylaxis, serum sickness, bronchial asthma, urticaria, pollinosis (hay fever), G. Quincke’s edema .
Anaphylaxis (Gr ana -. Again, aphylaxis – vulnerability) – immediate allergic reaction that occurs in the parenteral administration of the allergen (anaphylactic shock, serum sickness). Anaphylactic shock is one of the most severe forms of allergies. This condition can occur in humans with the introduction of therapeutic sera, antibiotics, sul-fanilamidov , novocaine, vitamins. Serum sickness occurs in humans after the introduction of therapeutic sera (anti-diphtheria, tetanus toxoid ), as well as gamma globulin with therapeutic or prophylactic purposes. It is manifested by an increase in body temperature, the occurrence of pain in the joints, their edema, skin itching, rashes on the skin. For the prevention of anaphylaxis use a method for desensitizing A.M.Bezredka: 2-4 hours its small dose is administered (0.5-1 ml) before introducing the required amount of serum, then no response is administered rest.
Bronchial asthma is a chronic disease characterized by asthma attacks with difficulty exhaling, which are caused by spasm of the bronchioles and swelling of their mucous membranes. Urticaria – a sudden appearance on the skin and mucous membranes of itchy blisters, similar in appearance to the blisters after touching nettle and disappearing. May be accompanied by headache, malaise and fever. G. Quincke’s edema ( angioedema , giant urticaria) is a form of urticaria characterized by a sudden development of limited or diffuse edema of the subcutaneous tissue and mucous membranes. The process can spread to the brain’s rims and brain matter.
Allergies include idiosyncrasy (Greek . Idios – peculiar, siynkrasis – blending) – the body’s hypersensitivity to certain foods (fish, milk, strawberries), medicines (iodine, bromine, quinine ), inhaled pollen from flowers, cosmetic products. Idiosyncrasy differs from anaphylaxis in that it occurs immediately after the first injection, without prior sensitization. When exposed to a diosyncrasy- causing agent, antibodies are formed. There is an idiosyncrasy with general malaise, a rash and swelling of the skin.