Normal immune response

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Cells, which then differentiate into the participants of the immune response, occur at a very early stage of individual development. Their stem, the primary elements appear in the yolk SAC, and then enter the liver is the body of blood formation of the embryo. Of embryonic liver these cells migrate in the thymus, and after a 4-month bone marrow remains a reservoir of lymphoid stem cells, which, as required, enter it in the blood and develop into Mature immunocompetent cells.
"Training" tells the thymus lymphocytes ability to distinguish the cells of his body from foreign or their cells, but modified. Receptors immature lymphocytes interact with the surface of epithelial cells of the thymus, which are antigens tissue compatibility that define the personality of the body. The relationship with these receptors stimulates the maturation of lymphocytes within the thymus. In the future, T-lymphocytes will show intolerance only to the foreign antigen, its individual molecules that are associated familiar with antigens of tissue compatibility. This is the determination of immune response to a complex of his and others. Separately their antigens (if they are not changed) and others (if they are not subjected to decomposition and is not integrated with its) immune response is not called.
T-cells, vasilishina of the thymus may be the man for weeks, months and even years. In response to antigen they greatly increase in size rapidly divide and produce several hormone-like proteins-lymphokines. Last contribute to the mobilization of other protective cells and removal from the body dangerous microbes and malfunctioning cells.
First of macrophage information about the antigen get T-cells, called helpers, or T-helper. The signal for their reproduction is soluble factor macrophages interleukin-1 (IL-1). It was opened in 1972 Geri (USA). IL-1 activates the inflammatory response in the body, in particular, helps to increase body temperature - adaptive response to inhibit the reproduction of microbes and atypical cells. Under the influence of IL-1 T-helpers begin to produce another hormone-like factor IL-2. Already after 6 hours after resting T cells become T-killers that provide specific cytotoxic effect on tumor target cells or cells infected by germs. Cytotoxic T-lymphocytes perceive signals from the T-helpers and T-helpers from macrophages) only if compatible with them to class II antigens (1A antigens), and its killing effect of T-lymphocytes have on the target, compatible with the class I antigens. This is very important restrictive mechanism immunological interactions received in the literature the name of immunological restrictions (limit, deterrence).
With age, the value of the thymus begins to diminish, as most veselishsya from him cells are T-reservations in other lymphoid organs and able for self-maintenance. But your vooruzhali T cells hormone Timosin the thymus gland produces up to extreme old age. Any damage to the body (whether emotional stress, depression or mechanical injury) causes a violent reaction on the part of the thymus. Thymus while temporarily atrophied, he seems to be reduced in size, becoming pale and anemic. Temporary involution of the thymus is called adrenal cortical substance which reacts to stress more quickly. Adaptive response in extreme influences captures and bone marrow, the thyroid gland, the hypothalamus and the pituitary gland.
In the bone marrow arise lymphocytes other classes, including B-lymphocytes, which received its name from Bursa - body birds governing the maturation of these cells. Bone marrow is located in the cavities of tubular and some flat bones, but despite anatomic variations, it functions as a single body. 1 hour from it checks out into the bloodstream 200-300 lymphoid stem cells, from which the further Matures T and B lymphocytes. Under special conditions (stress, microbial attack, radiation, and so on), the rate of maturation of stem cells is accelerated. Further specialization of immune cells occur in the spleen, lymph nodes, Meyerovich plaques intestines, pharyngeal tonsils. The Central organs of the immune system produce soluble mediators perceived on the periphery of T - and B-lymphocytes. Therefore, the thymus and bone marrow included in the total organismic system, endocrine organs.
B-cells are somewhat larger T-cells (8.5 and 6.5 microns).