IMMUNOPATHOLOGY

From Big Medical Encyclopedia

IMMUNOPATHOLOGY (immuno [logiya] + pathology) — the section of immunology studying a role of reactions antigen — an antibody or disturbances of cellular mechanisms of immunity in a pathogeny of various diseases. To patol, to states which emergence is the cornerstone immunol factors and mechanisms, the allergy, a disease of cell-bound immune complexes, autoimmune processes, etc. belong.

Allergy — specific hypersensitivity of an organism to various antigens (allergens). The most various substances of plant and animal origin, medicinal and other drugs can be allergens.

Allergens — poor immunogens, and only at the people predisposed to an allergy it is formed rather more, than normal, immunoglobulins of the class IgE (reagins). Reagins join Fc-fragments of their molecules superficial membranes of basophiles, mast cells, etc., however active centers their (Fab-fragments) at the same time remain free and can specifically interact with allergen. At secondary intake of allergen he unites to active centers of the reagins fixed on cells that leads to change of permeability of cellular membranes and release from these cells to the environment of a histamine, the serotonin, heparin and other mediators causing reduction of smooth muscles and others functional patofiziol and patoanatomichesky disturbances (see. Allergy ).

External manifestations of allergic reactions are extremely various: bronchial asthma, hay fever, small tortoiseshell, Quincke's disease of Quincke, acute anaphylaxis, etc. Unequally and participation in them of cellular and humoral factors. At an imediate-type allergy on the first place specific antibodies act, to-rymi can passively be sensibilizirovan an organism of the healthy person. At reactions of the slowed-down type to the first place sensitized cells by means of which transfer it is possible to carry out transfer of a condition of hypersensitivity to a certain allergen act. Despite these features, all allergic reactions combines immunol, the mechanism which is the cornerstone of their emergence and development. Specific diagnosis, prevention and therapy of allergic diseases are based hl. obr. on immunol, the principles.

K I. belongs as well immunohematology (see) — undressed the wedge, immunology studying the diseases of blood connected with immunol, reactions of an organism. Among these diseases the greatest value hemolitic anemias, leukopenias, thrombocytopenia, a hemolitic disease of newborns, posttransfusion have complications. Factors and mechanisms — group antigens of erythrocytes, leukocytes, thrombocytes, proteins of plasma, immunocompetent cells and antibodies are the cornerstone of these diseases immunol. As it is established, under action from - or autoantibodies (see) there is a sensitization of uniform elements of blood, as leads to acceleration of destruction them both in a blood channel, and in macrophages of a spleen, liver, limf, nodes, marrow. Various on the wedge, to manifestations patol, states are a consequence of these immune responses.

Establishment immunol, the nature of many diseases of blood, specifics participating in these patol processes of antigens and antibodies opened opportunities for their more perfect diagnosis, immunoprevention and therapy.

Section I. the diseases caused by autoantibodies (autoimmunization) are. Normal antibodies are formed to the antigens (viruses, bacteria and other foreign proteins) which are absent in an organism, interacting with to-rymi, they promote their inactivation and destruction. However antibodies and in relation to own not changed antigens of cells and fabrics, i.e. true autoantibodies in certain cases can be developed. Connect many with emergence of such autoantibodies immunopato by l. states (see. Autoallergichesky diseases ). A classical example of such true autoimmune disease is the acquired hemolitic anemia. On a surface of erythrocytes of the persons having this disease in many cases are found direct breakdown of Koombs (see. Koombs reaction ) specific antibodies to group antigens e, with, E, the D systems a Rhesus factor. At the patients suffering from a paroxysmal cold haemoglobinuria found antibodies to P1 and P2 antigens of erythrocytes. Less often at the acquired hemolitic anemia autoantibodies to isoantigens I and i meet (see. Blood groups , Rhesus factor ).

The autoimmune mechanism of such disease as Hashimoto's thyroiditis does not raise doubts. At this disease the thyroid gland is surprised not only autoantibodies, but also lymphocytes, infiltriruyushchy its fabric.

Particularly complex autoimmune processes are observed at a system lupus erythematosus. For this disease existence at the patient of autoantibodies to antigens of kernels of neutrophils is considered pathognomonic. In blood preparations from such patients neutrophilic leukocytes with fagotsitirovanny kernels from other neutrophils (LE-cell) are found, i.e. process of self-phagocytosis of these cells takes place.

Substances of some own bodies and fabrics which do not have in normal conditions of contact with immune system can be at their penetration into a blood channel the cause of formation of true autoantibodies. It is established concerning proteins of lens, spermatozoa. The true autoantibodies which arose thus can have the specific damaging effect on appropriate authorities and fabrics. Cases of damage of a liver, kidneys, a stomach, cardiovascular system and other bodies and fabrics in which as believe, autoimmune mechanisms take part are described.

The question of the reasons and mechanisms of formation of autoantibodies is studied a little, and all offered explanations have still hypothetical character. One researchers consider formation of autoantibodies result of an immune response of an organism on cross reacting antigens, i.e. alien antigens having antigenic determinants, similar to an organism. E.g., try to explain these participation of immune mechanisms in damage of heart at a streptococcal infection as the activator has an antigenic community with tissues of a muscle of heart. Other researchers consider emergence of autoimmune reactions as a result of vegetative mutation of immunocompetent cells and emergence of a new clone them which is deprived immunol, tolerances (see. unresponsiveness ) to own antigens. According to this hypothesis the changed cells eliminirutsya by the system of lymphocytes exercising genetic control of cellular structure. During the weakening of this controlling function there will be a development of abnormal clones of the cells which are not possessing immunol, tolerance in relation to own antigens of cells and fabrics. There are instructions on close connection of autoimmune diseases with a hereditary factor, in particular with the gene of an immunoreactivity (Ir) defining expressiveness of an immune response and also with the genes controlling antigens of histocompatability and factors of a complement which are located on one chromosome.

Immunol, mechanisms can be the cause of many diseases, however their true autoimmune nature admits not all researchers. So, at the diseases connected with the damaging action on cells and body tissues of various exogenous agents (viruses, bacteria, toxins and physical. - chemical factors), the formed gaptenny substances can report new antigenic specificity to erythrocytes, leukocytes, thrombocytes and other cells. The same mechanism of immunogene action and at some medicines. It is established that enzymes of viruses and bacteria can affect cells and lead to emergence of antigens, new, alien for an organism. Sialidazny activity of an influenza virus can be an example, a cut in cells new antigens of Tomsen result, and in serum then there are also antibodies corresponding to them participating in damage of cells. Many viruses, both Oncogenous, and not oncogenous, are capable to induce in cells products of the new antigens specifically different as from antigens of a virus, and antigens of a normal cell. The antibodies which are formed to these new antigens with the participation of a complement will directly destroy cells producers of this antigen or to opsonize them and to make more available for macrophages and lymphocytes. Antibodies to the new antigens arising in the cells infected with viruses cannot be referred to category of true autoantibodies as they are directed to products of alien genetic information, certainly.

At true autoimmune processes of an aberration undergo not antigens of the damaged cells and fabrics, and immunol, function of immunocompetent cells. Therefore apply ingibition to treatment of true autoimmune diseases) immunol, functions of an organism various immuno-depressants, hormones etc.

of Immunopato of l. the phenomena caused by exogenous factors, napr medicines, are liquidated after they cease to be applied while ability of development of antibodies to the antigens changed by drugs for some term remains.

Antibodies to the new antigens which arose in cells under the influence of physical. - chemical or biol, factors, is the defense immune response of an organism directed to release from the changed cells and fabrics which became alien. True autoimmune reactions are a deep pathology as they are directed against own cells which are not changed in the antigenic relation.

Cellular and humoral factors of immunity can damage also the cells infected with viruses. Existence in cells, including and their superficial membranes, viral antigens leads to adsorption on them specific antiviral antibodies and a complement therefore there is a cytolysis of the infected cells. In destruction of the last accept having speeded up also lymphocytes, sensibilized to a viral antigen, and macrophages (see. virus-induced immunity ).

The antibodies neutralizing toxins, viruses, bacteria and other antigens perform the major protective function. The complexes neutralized by antibodies antigen — an antibody — a complement are absorbed by the barrier fixing systems of a spleen, liver, lungs, limf, nodes, etc. where there is their destruction. However at excessive formation of cell-bound immune complexes in the conditions of excess of antigens there is an adjournment of complexes on basal membranes of the smallest vessels of a kidney, lungs etc. that leads to their damage (see. Inflammation ).

For immune complex deposition change of permeability of vessels under the influence of vasoactive amines is essential. Cell-bound immune complexes interact with components of coagulant system of blood that leads to bleedings and thrombosis, activates function of some biologically active agents. The serum disease also belongs to the pathology connected with formation of cell-bound immune complexes. Introduction to an organism with to lay down. the purpose of rather large amount of serum, napr, horse, is followed by products of antibodies and their interaction from the rest of yet not destroyed antigens. The complexes formed thus antigen — an antibody are postponed in joints, an endocardium, kidneys, etc. These processes are followed by a small tortoiseshell, joint pains, increase limf, nodes, temperature increase and other symptoms. Peculiar immunol, the phenomenon is observed at a pseudorheumatism. Find cell-bound immune complexes in serum and synovial fluid of such patients (see. Rhematoid factor ), constructed of own molecules of immunoglobulins. At these patients as believe, self-aggregation of molecules of immunoglobulins thus takes place that Fc-chayet of one molecule connects to the Fab-frag-cop another, i.e. one molecule behaves as antigen, and another — as an antibody; this complex is absorbed by phagocytes. Identification of such phagocytes has diagnostic value.

Variously value of antibodies and in atrepsy (see. atrepsy ). On the one hand, antibodies is a factor of protection, with another — the factor promoting growth of a tumor. Still earlier it was known that small doses of antineoplastic serum stimulate growth of a tumor, and big oppress. By pilot studies it is established that specific humoral factors can brake activity of cellular immunity, giving thereby the chance of a tumor to avoid immunol, the control exercised by immunocompetent cells. It was suggested [by Hellstr (To. Hellstrom) et al., 1969] that antibodies, connecting to the new antigens localized on a surface of cancer cells do them unavailable to sensibilized lymphocytes. This phenomenon was explained with blockade by antibodies of receptors of tumor cells therefore they lost ability to be distinguished by lymphocytes as antigenic and alien educations. Further researches, however, showed that a point of application of the blocking factors are not tumor cells, but lymphocytes and that blockade is carried out not by(with) antibodies, and soluble cancer antigens. The complex of cancer antigen with the corresponding antibodies was more effective factor blocking cytotoxic functions of lymphocytes. Suppression of cytotoxic function of lymphocytes tumoral antigen or cell-bound immune complexes antigen — an antibody leads to decrease or loss of efficiency of cellular immunity. At organ and tissue transplantation also another can be observed immunopato by l. a phenomenon — the immune response of a transplant against the owner which is shown on condition of easing at the recipient of protective factors and mechanisms (see. Welt disease ), and also immune responses of the owner on a transplant (see. Immunity transplant ).

The big place in And. occupy the inborn and acquired defects of cellular and humoral factors of immunity that finds the manifestation in various forms patol, states. Different degree of an underdevelopment of the plasmocytes developing antibodies, or total absence of such cells is the cornerstone of these diseases.

Decrease in products of immunoglobulins leads to increase in a susceptibility to infections, their heavier current, a long persistention of microbes in an organism (see. Agammaglobulinemia , Immunological insufficiency ).

Dysfunction of plasmocytes can be shown also in increase or reduction of separate components of immunoglobulins, and also in change of their structure. At patients with a multiple myeloma, Valdenstrem's macroglobulinemia (see. Valdenstrema disease ) excess products of light chains of immunoglobulins are observed (see. Bens-Jones of squirrels ).

At a multiple myeloma and miotonichesky dystrophy in blood and urine products of abnormal synthesis of heavy chains of IgG — proteins of «a disease of heavy chains» which represent Fc-fragments of IgG with a small piece of gamma chains are found. Emergence of such proteins is result either of mutations of structural genes, or a consequence of disturbances in the course of a transcription of a V-gene responsible for synthesis of the variable site of IgG.

Peculiar immunopatol. a problem is incompatibility of mother and a fruit. The huge amount of isoantigen of century enters into structure of cells and body tissues of the person and animals. Combinations of isoantigens are so diverse that only unioval twins possess an identical set of isoantigens. As the fruit receives a half of genetic set from the father, mother and a fruit can be incompatible to a greater or lesser extent immunological. Nevertheless the fruit is not torn away as the ordinary gomotransplan-Tat, and develops certain time in an organism of mother. The nature of this mechanism is still not found out. Popular belief that protection of a fruit against influence immunol, factors of a maternal organism is connected with existence of a placental barrier. In case of disturbance of barrier function of a placenta and fetal membranes develops immunopatol. the conflict between an organism of mother and a fruit leading to disturbance of the normal course of an embryogenesis. Such conflict can lead to infertility of the woman, cause death of zygotes, cause a misbirth and a still birth. It is suggested about a role immunol, incompatibility of mother and a fruit in development of toxicoses of pregnancy.

One of manifestations immunol, the conflict is development hemolitic disease of newborns (see), the cut is the cornerstone incompatibility of a fruit and mother on a Rhesus factor, and sometimes and on other antigens of blood (see. Blood groups , Incompatibility immunological , Rhesus factor ).



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Item H. Jambs, 3. I. Rovnova, V. I. Sachkov.

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