Infection HIV Phagocytosis Immunity Antibacterial Antiviral Antifungal Antiparasitic Antitumor Transplantation symptoms prevention treatment shop of folk medicine. Worms Tumor cells Infestations prevention treatment at home by health extracts.
Immune system protects against infectious agents, removes foreign, malignant or altered, aging cells, ensures the process of fertilization and fetal development, promotes the beginning of the birth act, and implements the aging program.
In accordance with the clinical orientation, the types of immunity are usually divided into:
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antibacterial immunity;
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antiviral immunity;
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antifungal immunity;
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antiparasitic immunity;
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antitumor immunity;
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transplant immunity.
Antibacterial immunity.
Anti-bacterial immunity is directed against both bacteria and their toxins. It includes the antibacterial protection of mucosal membranes provided by secretory immunoglobulins Ida2, which bind to bacteria and prevent their penetration into the body.
The main mechanism of antibacterial immunity is phagocytosis. The complex mechanism of immune responses involves the participation of antibacterial and antitoxic antibodies. Antibodies directly or with the participation of the complement system envelop and then destroy the outer membrane of the cell envelope, presenting (demonstrating) microbial antigen to activated phagocytes.
Phagocytes (macrophages and neutrophils) destroy bacteria using reactive oxygen species, nitrogen oxide, cationic antimicrobial proteins, and other mechanisms.
Some intracellular pathogens (mycobacterium tuberculosis, leprosy, and others) can survive in phagocytes, and then the mechanism of cellular immunity is activated with the activation of T-helpers, cytotoxic T-lymphocytes and macrophages.
Antiviral immunity.
The peculiarity of antiviral immunity is determined by the fact that viruses are intracellular parasites with a peculiar way of reproduction. The early stage of infection usually consists of the virus fighting with the host's defense systems.
The very first protective barrier is the skin and mucous membranes of the body.
In case of violation of their integrity, the mechanism of emergency non – specific protection comes into effect-factors of innate immunity, among which a special role belongs to the antiviral activity of interferon, EC cells (natural killers) and macrophages.
Antiviral effect of interferon.
Cells infected with the virus cause the synthesis of interferon, which activates the protective mechanisms of neighboring cells that ensure their resistance to viral infection.
Interferon activates the synthesis of two enzymes that inhibit the synthesis of viral proteins and destroy the main life structure of the virus (viral and RNA), in addition, interferon activates EC cells (natural killers) and macrophages.
The antiviral effect of NK-cells and macrophages.
The activity of EC cells manifests itself within two days after infection of the host body with the virus. EC cells and macrophages destroy infected cells. If the virus manages to overcome the barriers of innate defense, it causes the attachment of a specific immune response involving T-helpers, T-killers, and specific antibodies.
Antiviral protection acquires a specific character aimed at fighting a specific viral infection, this process is accompanied by the formation of acquired (adaptive) antiviral immunity, that is, resistance to this type of viral infection.
The spread of viruses in the body is blocked mainly by antibodies. During the development of specific immunity, antibodies to most virus antigens are synthesized. The way to eliminate infected viral particles depends on their localization: extracellular or intracellular.
The extracellular form of the virus - virion is a full-fledged viral particle located outside of a living cell of the host body, consisting of a nucleic acid and a capsid (protein, less often a lipid shell).
Viruses can only cause disease if they enter the cell. To attach to it, they use cellular receptors, which the cell uses for its own physiological purposes. The virus recognizes specific cell receptors and attaches itself to them using its attachment proteins, which act as a kind of pilot that directs the movement of the virus into the cell.
In some viruses, these molecules are located in hidden places - crevices, canyons, that is, in depressions on the surface of the virion, so the antibody cannot contact the virus's pilot protein and block it.
The effect of antibodies, in addition to neutralizing extracellular viruses, is that they cause the destruction of virus-infected cells.
Mechanisms for avoiding viruses from the host's immune surveillance, i.e. recognition by their antibodies, are very diverse. The most effective mechanism is the change of antigens in viral proteins.
Antigenic variability is observed in human immunodeficiency virus (HIV) and influenza viruses. So, in the flu virus, it is called antigenic drift (gradual change) and shift (abrupt change). This does not allow us to count on the long-term effect of vaccination for these types of viral diseases.
Thus, the main mechanisms of antiviral immunity are reduced to blocking the spread of viral particles and destroying virus-infected cells, which are actually factories for the production of new viruses. In chronic (dormant, slow) infections, viruses can remain in cells indefinitely, without having a characteristic damaging effect.
Under the influence of provoking factors (cooling, exposure to ionizing radiation, stress, etc.), a hidden asymptomatic infection becomes an obvious disease.
Increased immunity to viral infections is achieved by vaccination, the use of interferons, their inducers and immunomodulators.
Antifungal immunity.
Most fungi that are pathogenic to humans are widespread in nature. Infection occurs when spores carried by air enter the lungs or sinuses of the nose, as well as when spores or mycelium are introduced into the skin and cornea.
Infection from other individuals and animals is extremely rare, since fungi are so-called opportunistic pathogens. Infections caused by them occur when the immune system is violated and do not occur in a person with a normally functioning immune system.
Each type of fungus is characterized by a certain path of introduction and destruction of certain tissues. Dermatophytes, ringworm and Piedra are infections of the epidermis, nails and hair.
Sporotrichosis and mycetoma develop due to the ingress of the pathogen into the subcutaneous tissue. Deep mycoses occur when the pathogen enters the respiratory tract.
After contact with fungi, an immune system can be formed, which will later partially protect against infection. Where certain fungal infections are common, local residents get sick with them less often than visitors.
Antifungal immunity is characterized by a variety of manifestations, due to the complexity of the antigenic composition of fungi and their variability, which depends on the conditions of existence, form and stage of mycosis.
If the fungal antigen comes into contact with cellular components of the immune system, delayed hypersensitivity develops (type IV allergic reactions).
Delayed allergic reactions occur 24-48 hours after contact with the allergen. They occur on conditionally pathogenic organisms, including fungal antigens, and are the basis of diseases such as infectious and allergic bronchial asthma, rhinitis, and contact dermatitis.
Antiparasitic immunity.
Pathogens of parasitic infections are protozoa and parasitic worms-helminths. Among the simplest few (less than 20 species) can invade, that is, invade the human body, but among them four parasites are the greatest danger to it, causing severe diseases.
These are the pathogens of malaria, African and American Trypanosoma and Leishmania.
The simplest ones use the same mechanisms as bacteria and viruses, but they are more advanced. In the course of evolution, such parasites have developed many mechanisms for evading the host's immunological surveillance.
They are spread over long distances by insect vectors, parasitize intracellularly, can change like the flu virus and, like the human immunodeficiency virus (HIV), have immunosuppressive properties, that is, they can inhibit the immune defense.
As a result, full-fledged immunity to protozoa is very rare, and the role of the immune system is reduced to limiting the number of parasites (non-sterile immunity) and preserving the life of the host body (and therefore parasites).
Rational vaccination, accordingly, is ineffective, because some symptoms of parasitic protozoal infections develop as a result of immune damage, and not the impact of the parasite as such.
Protozoa that affect the intestines cause fairly mild forms of the disease, provided the immune system is functioning normally. However, no matter how easy these diseases may seem, in combination with parasitic worms in the intestines, they provoke a serious additional load on the human body in tropical countries.
In protozoic infestations (malaria, trypanosomes), when the pathogen is in the blood, humoral factors determine immunity, and when parasites multiply in tissues – cellular.
Cavity parasites located on the surface of the mucous membrane - these include amoebas, Giardia, and Trichomonas-also cause an immune response, but it is insufficient to destroy them because there is limited contact between the parasite's antigens and the host's immune system cells.
In protozoic infestations, as a rule, there is a parasite-bearing activity, accompanied by immune and allergic reactions.
Parasitic worms of all three classes: trematodes, cestodes, and nematodes – cause many diseases in humans, the most unpleasant of which are onchocerciasis, elephantiasis, and cystosomiasis. These diseases are common in tropical countries and are spread by insects, shellfish and other vectors.
Other diseases that cause cestodes and worms are ubiquitous and are transmitted with food infected with eggs, larvae, or parasite cysts.
Worms are characterized by a complex life cycle and circular migration, during which they often populate certain organs.
To destroy parasites, you need to influence several immune factors at once. The most important of these is eosinophils. They recognize the parasite by the IgE antibody released by it and produce substances that destroy the helminth shell.
This process attracts immune cells, which causes the development of an allergic reaction.
The subsequent immune response can lead to the destruction of the parasite or the expulsion of helminths from the intestine. However, in General, many parasites, although they always cause an immune response, are quite resistant to its effector factors and can survive for a long time in the body.
Chronic blood circulation of parasite antigens that are resistant to the immune response can cause tissue damage. For example, nephrotic syndrome, granulomatous liver damage and autoimmune heart diseases develop.
Parasite-induced immune suppression increases the body's sensitivity to bacterial and viral infections.
Antigenic variability during the life cycle of protozoa, as well as the low activity of protective antibodies and specific cellular mechanisms for removing parasites from the body have not yet allowed to create any effective vaccines against parasitic infections.
Intradermal tests or laboratory tests are used to diagnose many parasitic infestations. In recent years, in connection with the development of highly sensitive serological tests (enzyme immunoassay and radioimmune analysis), the determination of specific IgM and IgG antibodies is increasingly used.
Thus, the mechanisms of antiparasitic immunity are diverse and depend on the type of pathogen, its properties, dose, as well as on the state of immunological reactivity of the body.
Antitumor immunity.
The reason for the development of neoplastic (tumor) processes are genetic rearrangements of the cell, leading to changes in its structure and function. The growth of tumors depends on the development of their vascular network. In small neoplasms, there is a low level of nutrients and oxygen entering the tumor by diffusion (moving through cell membranes).
A feature of immune response in tumor growth is that tumor cells synthesize cancer proteins and growth factors that stimulate their division and have an immunosuppressive effect.
In this case, the genes that suppress division in tumor cells are absent or blocked. Tumor cells, unlike normal cells, do not secrete substances that inhibit cell division.
The autonomy of the tumor reaches its maximum at the stage of metastasis, when tumor cells acquire the ability to penetrate into blood or lymph vessels, migrate to them, maintaining viability, and take root in a new place in a new microenvironment.
Ability to metastasize also depends on the synthesis of specific enzymes by tumor cells.
There are complex relationships between tumor cells and the host organism that encompass the body's response to tumor growth and the effect of the tumor itself on the body. The immune system is able to respond the appearance of transformed (altered) cells in the body, because they produce unique tumor antigens.
With the emergence of neoplastic processes in the body are beginning to form all classes of antibodies.
Antitumor immunity is provided by T-killers, EC-cells (normal killers) and macrophages, direct intercellular contacts of immunocompetent cells with tumor cells. The development of this process is also influenced by hormones and cytokines – immune molecules that cause intercellular interactions in various pathological processes.
Transplant immunity.
Transplant immunity is an immune response of the body directed against foreign tissue (graft) transplanted into it.
Knowledge of the mechanisms of transplantation immunity is necessary to solve one of the most important problems of modern medicine – organ and tissue transplantation.
Many years of experience have shown that the success of organ and tissue transplantation in the vast majority of cases depends on the immunological compatibility of the donor and recipient tissues. The reactivity of immunocompetent cells of the recipient undergoing transplantation is directed against foreign antigens located on the surface of the membranes of cells of the donor graft.
Transplantology is a separate branch of medicine that studies the specifics of implementation, feasibility, consequences and prospects of transplantation.
Therefore, the characteristic features and problems of transplant immunity are of a purely professional nature and are described in the medical literature intended for specialists.
Immunological reactivity.
Immunological reactivity is the property of the body to selectively respond to the effects of various stimuli, applying to each of them the most effective response.
It determines the ability of an animal or person to adapt to environmental conditions, aimed at preserving and maintaining the constancy of their own internal environment of the body.
Adaptive changes in immunological reactivity are the basis for the survival of an organism in a constantly changing external world.
In different periods of life (childhood, old age, pregnancy) and in other cases, there are significant changes in the degree of expression of the immune mechanisms of protection of the body in the form of strengthening or reducing their activity, which is a physiological reaction of adaptation, and not evidence of the presence of any pathological processes.
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