White blood cells – Leukocyte functions

Neutrophilic granulocytes

The bulk of the white blood cells make up neutrophilic granulocytes. Mature cells of this series - segmented neutrophilic granulocytes - mobile, highly differentiated and highly specialized blood cells, which respond to functional thin organic and changes in the body, completing the phagocytic and bactericidal function.

The total number of mature and maturing neutrophilic cells in the bone marrow of a number of 61,6-1010, and the number of neutrophils in the peripheral blood on average equal to 2,3-1010 cell, t. it is. almost 30 times less, than in bone marrow.

Under physiological conditions, neutrophilic granulocytes in the blood stream are divided into two approximately equal parts - the parietal (marginal) a pool and a central, located in the center of the flow. If emotional stress, postprandial, the introduction of a number of hormones (catecholamine, glucocorticosteroids, etioholonalona et al.) It is going redistributive leykoditoz, t. it is. leukocytes from marginal pool enters the central.

The lifespan of neutrophil granulocytes average 14 days, of them five or six days they mature and remain in the bone marrow sinuses, from 30 min to two days circulate in peripheral blood, Six to seven days are tissues, where they do not come back and bloodstream. Established, that with complete cessation of proliferation marrow is able to maintain the number of neutrophils in the peripheral blood at a normal level for six days.

The most important function of neutrophilic granulocytes – phagocytosis, and the ability to develop a number of enzymes, has a bactericidal effect, as well as their ability to pass through the basal membrane, between cells and navigate inoglia.

As phagocytosis, and the movement of granulocytes - active processes, associated with energy costs, which are provided through the glycogen reserves in the body and the presence of glycolytic enzymes in these cells. Phagocytosis of neutrophils is their specific function and is performed only when the maturation of cells.

Mieloblastov hardly exhibit phagocytic activity. For promyelocytic phagocytic activity indicator approaches 10,8%, and more mature forms - myelocytes - it is four times higher. The index of neutrophil phagocytic activity is meta myelocytes 67 %, which is close to the figures, peculiar stab and mature segmented neutrophils. When the involution of mature neutrophils ability to phagocytosis almost disappears, According to reports, phagocytic activity of mature white blood cells of healthy people on average 86 %.

Neutrophil granulocytes are highly metabolic activity. Their specific grain contains about 35 different enzymes, capable of destroying the main classes of biological compounds. Expected, that the release of lysosomal enzymes into the environment occurs by increasing the permeability of lysosomal membranes, destruction and death of the cell by phagocytosis or. Near experimental works shown, that substance, secreted by granulocytes during the life go at break, possess a broad spectrum of activity. Some enhance the mitotic activity of cells and motor, enhance regenerative processes in tissues.

The biological significance of neutrophil granulocytes It is, they brought to the focus of inflammation wide variety of proteolytic enzymes, play an important role in the resorption of necrotic tissue. Numerous studies have proven the ability of the decay products of neutrophils stimulate leykotsittpoez seen before, and enhanced proliferation and differentiation of granulocytic cells and bone marrow. Besides, circulating blood leukocytes decomposition products may affect the release of mature granulocytes from bone marrow

Recent studies have shown, that granulocytes can also be released into the blood substances, having bacterial and antitoxic properties, and a pyrogenic substance, causing fever, and substance, supporting the inflammatory process.

When studying allergic reactions Much attention is paid segmented neutrophils. With modern techniques of investigation set, neutrophilic granulocytes that do not produce antibodies, but, adsorbing them in its shell, can be delivered to the homes of infection. Besides, capturing antigen antibody, they digest the whole complex, while they themselves are subject to alteration, followed by lysis and the release of biologically active substances, dramatically increases the permeability of the vessel walls.

The neutrophils are found substances, having thromboplastin activity, and the presence of cathepsin and trypsin promotes participation in the process of fibrinolysis.

Eosinophilic granulocytes

Eosinophil granulocytes in the peripheral blood contained in a small amount. In a large and abundant grain of their cytoplasm contains proteins, lipids, phosphorus, iron, histamine, RNA, and enzymes, involved in redox processes and immune.

Grit eosinophilic granulocytes resistant to autolytic enzymes, trypsin, but soluble in concentrated acids and alkalis. It is believed, that it is a cytoplasmic vacuoles, crystalloid substances containing mitochondrial origin.

The main functions of eosinophilic granulocytes are not carried out in the bloodstream, and tissue.

Eosinophilic granulocytes is quite mobile and, leaving the blood stream, form clusters in tissues and organs. They also exhibit phagocytic activity, which is considerably weaker, than neutrophilic granulocytes.

Eosinophilic granulocytes participate in immune reactions is, they prevent an immune response generalization, limiting the body's immune response process at the level of local or submucosal layer subepithelial. Eosinophilic granulocytes suppress hypersensitivity reactions of immediate type, allocating a number of inactivating enzymes (gistaminazu, арилсульфатазу B, фосфолипазу D, And простагландины₁ and E₂ and etc.). Participation of eosinophilic granulocytes in the development of immunity helminthoses It is a killer (cytotoxic) effect of these cells, therefore hypereosinophilia helminthiasis should be regarded as a protective response.

Basophil granulocytes

Basophilic granulocytes are found when counting leukogram not all surveyed.

Granules basophilic granulocytes soluble in water, contain fat and enzymes - peroxidase and oxidase, A takjye heparin E histamine, participate in the formation of serotonin. Considering, basophil granulocyte that contain the active mediators of vascular reactions and coagulation processes, regulators of vascular tone, Study them has diagnostic significance in hemorrhagic diathesis, allergic diseases, vascular permeability disorders of various origins.

Monocytes

Monocytes - quite numerous cells of peripheral blood, having high metabolic activity of. In their cytoplasm found lipase, Proteolytic enzymes, peroxidase, karʙoangidraza, RNA. Using cytochemical reactions identified glycogen, lipids, phospholipids. Specific enzyme monocytes, as macrophages, является a-нафтилацетатэстераза, suppressed sodium fluoride.

Due to the high content of lipase monocytes, macrophages are active in the microorganisms are lipid enveloped. The ability of monocytes to independent amoeboid movement, phagocytic cell debris, small foreign bodies, malaria parasites, Mycobacterium tuberculosis determines the role of these cells in the compensatory and protective reactions of the organism. Monocytes are blood to three days, capable of recycling and freely exchange with a large pool of extravascular (mainly, in the spleen and lung), in which 25 times the number of monocytes in the blood.

Lymphocytes

Lymphocytes are moved fairly rapidly and have the ability to invade other tissues, where there may be a long time. They are central to the specific immunological reactions as precursors of antibody-forming cells, and as carriers of immunological memory.

Lymphocytes are involved in graft rejection and local allergic reactions. There is a point of view, in the body cells of information is transmitted lymphocytes, supporting function and constant level of differentiation of tissue cells, carry trophic and reparative processes, involved in the excretion of toxic products of protein metabolism. There is also evidence of the protective role of lymphocytes in the tumor process, However, these issues are still subject to further study.

According to current data, lymphocytes, circulating in the blood, perform different functions. Most of them belong to the T-lymphocytes (thimic-dependent) -50-70 %, make up a smaller portion of B-15-25 limfotsity- %.

T-lymphocytes are mainly involved in cellular reactions, and B-lymphocytes - humoral immunity. Морфологически T- and B-lymphocytes in humans indistinguishable. In recent years, methods have been developed, distinguishing T- and B-lymphocytes are a number of features. So, for T-lymphocyte response characteristic of spontaneous rosette formation with sheep red blood cells and blast transformation in the presence of PHA (PHA), high electrophoretic mobility. B-lymphocytes are characterized by the immunoglobulin receptors on the cell surface, lower electrophoretic mobility, the ability to synthesize antibodies.

T-lymphocytes

Depending on the participation in immune reaction T-lymphocytes are divided into four groups:

• cell immunological memory, t. it is. recognizing a foreign antigen and give a signal to start an immunological response (antigen- responsive cells);
• effectors, carrying out an immune response (antibody producers, effectors of delayed-type hypersensitivity); basic cells in this group are T-killers - cytotoxic cells, destroying cell transplant and mutant cells in the body, including tumor;
• T-хелперы, providing education effectors, and determining the direction and intensity of the immune response;
• suppressor, inhibiting the immune response and the beginning of the end of the exercising of this reaction.

Thus, T-lymphocytes are functionally heterogeneous group of cells, although they have a common ancestor. Precursors of T-lymphocytes, getting into the cortex of the thymus gland, They multiply rapidly and become timocity. Ripening, thymocytes undergo stages of development T₁-lymphocytes, T₂-lymphocytes, finally, mature lymphocytes.

Common to all of the T-lymphocytes is the presence at their surface of thymic human leukocyte antigen (HLA или OCT 1, or Leu-1). This T-antigen is found on all thymocytes, and in peripheral blood - 50-90 % lymphocytes.

In the early stages of maturation of T-lymphocytes appear specific antigens OKT10, OKT9 and a number of other antigens, which disappear as lymphocyte maturation and their exit from the thymus into the peripheral blood. Some T-lymphocytes has a high migration rate, and unlike the B-lymphocytes. Another part - settled, It is constantly in the peripheral lymphatic organs.

B-lymphocytes

B-lymphocytes develop from bone marrow progenitors. In the process they undergo maturation stage g pre-preB lymphocyte, not having a receptor for immunoglobulin, stage nreI lymphocyte, having cytoplasmic μ-heavy chain, and the stage of early B-lymphocyte, having on the cell membrane IgM. Further maturation of B-lymphocytes in the peripheral blood occurs.

The B-lymphocytes of all degrees of maturity found Ia-like antigen (HLA-DR2 и HLA-DR3), which plays an important role in the relationship between the cells. Ia-antigen concentration is gradually reduced until the complete disappearance of plasma cells.

The differentiation of B-lymphocytes antigenozavisnmyh like cells occurs in the germinal centers of follicles peripheral lymphatic organs, which appear immediately after birth. It is mainly settled cells, migrating significantly less T-lymphocytes. Functionally B-lymphocytes also are a heterogeneous group of cells. Among these are antibody producers (producing immunoglobulins) - The most numerous group, and the killer, suppressor cells and immunological memory.

Natural killer cells

Natural killer cells (null cells) comprise peripheral blood 5-10 % total lymphocytes. This cell, non-T- and B-markers. Expected, this group includes the bone marrow stem cells, early progenitor T- and B-lymphocytes.

Cytochemical and biochemical studies have established, that lymphocytes contain cathepsin, nucleases, amilazu, lipase, neutral non-specific esterase, b-глюкуронидазу, kisluju fosfatazu, sukcinatdegidrogenazu, cytochrome oxidase, arginine, gistidin, glycogen.

For lymphocytes characterized by a high exchange of RNA and proteins. T-lymphocytes, Unlike B-lymphocytes, contain adenosine deaminase and purine nucleoside phosphorylase.

Plasma cells

Plasma cells are actively involved in the synthesis and secretion of the protein. Average number of plasma cells in a punctate sternum does not exceed 0,25-0,8 % the total number of myelokaryocytes. In some pathological processes (chronic purulent inflammation, tuberculosis, visceral syphilis, Kidney Cancer), differing duration for a number of plasma cells in the bone marrow can make 6 8 %.

When agranulocytosis, aplastic anemia, bone marrow can be observed not only increase the number of plasma cells, but also the emergence of multi-core cell.