MACROPHAGES (grech, makros big + phagos devouring) — the connective tissue cells having active mobility, adhesiveness and the expressed ability to phagocytosis. M are opened by I. I. Mechnikov; he for the first time established their role in defense and other reactions of an organism and offered the term «macrophages» underlining differences of these cells from cells of the smaller size — the «microphages» (i.e. segmentoyaderny leukocytes, neutrophils) englobing only fine alien particles, napr, microbes. M described under different names: Ranvye's klazmatotsita, ragiokrinny cells, adventitious cells, aletocytes at rest, pirrolovy cells, polyblasts, amoeboid, metallophilic cells, macrophagocytes, histiocytes. The majority of these terms has only historical interest.
M, as well as all connective tissue cells, have a mezenkhimny origin, and in post-natal ontogenesis are differentiated from a stem hemopoietic cell (see. Hemopoiesis ), passing in marrow consistently stages of a monoblast, a promonocyte and a monocyte. The last circulate in blood, and, being moved in fabric, turn into M. Razlichayut M. free (migrating) and fixed in fabrics. M also subdivide on hematogenous, formed of the monocytes which are just moved from blood, and gistiogenny which were present at fabrics earlier. Depending on localization distinguish M. of friable connecting fabric — histiocytes (see), a liver — star-shaped retikuloendoteliotsita (a kupferova of a cell), a lung — alveolar M., serous cavities — peritoneal and pleural M., M. of marrow and lymphoid bodies, glial macrophages of c. N of page (microglia). From M. there are, apparently, also osteoclasts.
M, being the last stage of a differentiation of one-nuclear phagocytes, do not share a mitosis. An exception, perhaps, M. in the centers hron make, inflammations. On the basis of homogeny from a stem hemopoietic cell, a structure and function M. and their progenitors (monocytes, etc.), according to the classification published in the Bulletin of WHO (1973) are included in system of mononuclear phagocytes. Unlike it reticuloendothelial system (see) combines the cells having various origin and having ability to phagocytosis: reticular macrophages, endothelial cells (in particular sinusoidny capillaries of the hemopoietic bodies) and other elements.
M.'s structure differs in the variety depending on phagocytal activity, properties of the absorbed material and so forth (fig. 1). Unlike the predecessors of monocytes (see. Leukocytes ) M have the big sizes (20 — 100 microns), contain many dense cytoplasmatic granules and mitochondrions; in slabobazofilny (sometimes oxyphilic) the remains of fagotsitirovanny material are quite often visible to cytoplasm. Kernel of spherical, fabiform or irregular shape. At observation in a phase contrast microscope in M. the characteristic undulating cellular membrane making undulations comes to light. At a submicroscopy in M. well developed lamellar complex is visible (see. Golgi complex ), usually small amount of a granular endoplasmic reticulum. Reflection of phagocytal activity are dense cytoplasmatic granules — lysosomes (see), phagosomas, multivesicular residual little bodies — so-called myelin figures (fig. 2). Also microtubules and bunches microfilament are observed.
Value of macrophages in immunity
M. are a peculiar store coming to an organism antigens (see) which are in it in the form of determinants (the sites of a molecule of antigen defining its specificity) consisting not less than of 5 peptides. Antigens subject to special processing: interacting with receptors of a membrane of M. antigens cause activation of their lizosomalny enzymes and increase in synthesis of DNA.
M play very essential role in induction of antibodyformation, for a cut all three types of cells are necessary (macrophages, T - and V-lymphocytes). The antigen connected with various fractions M. (membranes, lysosomes), is much more immunogene, than native antigen. After processing antigens come to M. to T - and to B-lymphocytes (see. Immunocompetent cells ). The m containing antigen react with T-cells in the beginning, and only after that «V-cells get into gear». M.'s interaction with T-cells is regulated by N-antigens or a product of the gene connected with system of genes of histocompatability (see. Immunity transplant ).
The V-cells activated by antigen develop opsonins (see), improving M.'s contact with antigenic material; at this Fab - fragments antibodies (see) interact with determinants of antigen, a Fc - fragments are attached to M. Eto's surface stimulates synthesis of adenyl cyclase and strengthens products 3', 5' - AMF promoting proliferation and a differentiation of V-lymphocytes.
Macrophages, T - and V-lymphocytes interact with each other by means of the various soluble factors allocated by these cells after an antigen challenge. It is suggested that the majority of soluble factors is distinguished with T lymphocytes. The chemical nature of these factors is not studied. Transfer immunol, information to a lymphocyte comes from M. at direct contact of these cells. The mechanism of this transfer consists in M.'s «sticking» to a lymphocyte that is followed by protrusion of cytoplasm M., edges then merges with an outgrowth of cytoplasm of a lymphocyte. M synthesize a large number of nonspecific factors of immunity: transferrin, a complement, a lysozyme, interferon, pyrogens, etc., being antibacterial factors.
M play a large role in antimicrobic and anti-virus cellular immunity that is promoted also by rather big life expectancy of these cells (approximately from one to several months), and also in development of an immune response of an organism. They carry out the major function on release of an organism from alien antigens. Digestion of microbes or not microbic agents, pathogenic fungi, protozoa, products of own changed cells and fabrics is carried out by means of lizosomalny enzymes M.
As numerous researches, I. I. Mechnikov's idea about value of phagocytal cells show in immunity (see) it is fair in the relation not only of bacteria, but also viruses. M, especially immunizirovanny animals, take active part in destruction of virions (see. Viruses ), in spite of the fact that viruses are steadier against effect of enzymes and process of their destruction goes less vigorously, than process of destruction of bacteria. M perform protective function at various stages inf. process: they are a barrier on site of entrance infection atriums and at a stage of a viremiya when restriction of spread of a virus is interfered by M. to a liver, spleens and limf, nodes. By means of M. process of removal of a virus of an organism, more precisely, than a complex antigen — an antibody accelerates (see. Antigen — an antibody reaction ). The m received from neimmunizirovanny and immunizirovanny animals actively englobe influenza viruses, variolovaccines, myxomas, ektromeliya. From immune M. the influenza virus could be allocated only within several hours while from not immune M. it was isolated within several days.
Blocking in M.'s experiment anti-macrophagic serum, silicon, karraginany (a high-molecular polygalactose) leads to burdening of a current of a number of bacterial and viral infections. However at some viral diseases of M. appeared not only incapable to prevent an infection, but, moreover, supported a reproduction of viruses (e.g., viruses of a lymphocytic choriomeningitis) which it is long remained in an organism, promoting development of autoimmune diseases.
The researches which showed M.'s participation in cytotoxic action of sensibilized lymphocytes on target cells are conducted. In an experiment it is shown that removal of m from population of immune lymphocytes caused considerable weakening of cytotoxic action of leukocytes on cells of some tumors and that the forecast of a disease of that is more favorable, than more active M. contain in regional to a tumor limf, nodes. Studying of reactions of immune system of the recipient at organ and tissue transplantation showed that M. participate in graft rejection and in elimination of alien cells from an organism (see. Transplantation ).
See also Connecting fabric .
Bibliography: Burnett F. M. Cellular immunology, the lane with English, M., 1971; In and N Fyurt R., etc. System of mononuclear phagocytes, new classification of macrophages, monocytes and their cells-pre-shestvennikov, Bulletin WHO, t. 46, No. 6, page 814, 1973, bibliogr.; Zdrodovsky P. F. Problems of an infection, immunity and allergy, M., 1969, bibliogr.; P. N. jambs and P about in N about in and 3. I. Virus-induced immunity, M., 1972; Petrov R. V. Immunology and immunogenetics, M., 1976, bibliogr.; The teacher I. Ya. Makrofagi in immunity, M., 1978; And 1 1 i s about and A. S. Interactions of antibodies complement components and various cell types in immunity against viruses and pyogenic bacteria, Transplant. Rev., v. 19, p. 3, 1974, bibliogr.; Carr I. The macrophage, L. — N.Y., 1973; Gordon S. a. With o h n Z. The macrophage, Int. Rev. Cytol., v. 36, p. 171, 1973, bibliogr.; Immunobiology of the macrophage, ed. by D. S. Nelson, N. Y., 1976; Mononuclear phagocytes in immunity, ed. by R. van Furth, Oxford, 1975; Wahl S. M. a. o. The role of macrophages in the production of lymphokines by T and B lymphocytes, J. Immunol., v. 114, p. 1296, 1975.
H. G. Hrushchov; M. S. Berdinsky (immunol.).