THE ROLE OF IMMUNOLOGICAL TOLERANCE IN MAINTAINING HOMEOSTASIS
Immunological tolerance plays an important role in maintaining the antigenic homeostasis of the body. Immunological tolerance is a state of areactivity with an antigen that occurs as a result of the previous contact with this antigen. The most important thing for a person is tolerance to own antigens (autotolerance) since the non-response of the immune system to own antigens protects the body from autoagression. The mechanisms of the immune system that allow blocking aggression against own cells and tissues are divided into central and peripheral. Central tolerance is induced in the central organs of immunogenesis (thymus and bone marrow) and limits the autoreactivity of T- and B-lymphocytes. In addition to the central one, there are several levels of peripheral tolerance (suppression of potentially autoreactive T- and B-cells in peripheral tissues). Each level has its own molecular and cellular mechanisms. A special type of tolerance is observed at mother to fetal antigens during its gestation. Areactivity to foreign antigens (artificial immunological tolerance) can be induced in various ways. There are two types of artificial tolerance: high-dose and low-dose. The induction of such tolerance has great practical importance. It is used to solve many important medical problems, such as organ and tissue transplantation, suppression of autoimmune reactions, and treatment of allergic diseases.