tolerantsusmehhanismid

Tolerantsusmehhanismid refers to the biological processes that prevent an organism's immune system from attacking its own tissues. This is crucial for maintaining self-tolerance and avoiding autoimmune diseases. These mechanisms are established during development and maintained throughout life.

One primary mechanism is central tolerance, which occurs in the primary lymphoid organs, the thymus for T cells and the bone marrow for B cells. Immature lymphocytes that strongly recognize self-antigens are eliminated through apoptosis (programmed cell death) or are functionally inactivated. This process ensures that the repertoire of mature lymphocytes circulating in the body is largely composed of cells that do not target self.

Peripheral tolerance mechanisms act as a backup to central tolerance and operate in secondary lymphoid organs and other tissues. These include anergy, where lymphocytes are rendered unresponsive upon encountering self-antigens without proper co-stimulatory signals. Another mechanism is the induction of regulatory T cells (Tregs), which actively suppress the activity of self-reactive lymphocytes. Ignorance, where self-antigens are sequestered from the immune system, is also considered a form of peripheral tolerance, although it is less actively maintained. Disruption of these tolerantsusmehhanismid can lead to the development of autoimmunity.