Immune tolerance

Definition

Immune tolerance is the state in which the immune system does not mount a response against specific antigens, particularly those that are self-derived, preventing autoimmune reactions. This is a crucial mechanism that helps maintain homeostasis and protects the body from damaging inflammatory responses against its own tissues while allowing for a functional immune response to pathogens.

5 Must Know Facts For Your Next Test

1. Immune tolerance is essential for preventing autoimmune diseases, where the body mistakenly targets its own tissues.
2. Central tolerance primarily occurs in the thymus for T cells and in the bone marrow for B cells, eliminating self-reactive lymphocytes during their development.
3. Peripheral tolerance refers to mechanisms that prevent activation of self-reactive lymphocytes that have escaped central tolerance, often involving regulatory T cells.
4. Failure of immune tolerance can lead to conditions such as lupus, rheumatoid arthritis, and type 1 diabetes, where the immune system attacks healthy tissues.
5. Therapeutic strategies aimed at inducing immune tolerance are being researched for organ transplantation and treatment of autoimmune diseases.

Review Questions

• How does immune tolerance function to prevent autoimmune diseases?
  • Immune tolerance works by ensuring that the immune system does not respond aggressively to self-antigens, which are components of the body's own tissues. This prevention occurs through mechanisms like central and peripheral tolerance, where self-reactive immune cells are either eliminated or kept inactive. By maintaining this balance, immune tolerance prevents the immune system from attacking the body’s own cells, thereby reducing the risk of autoimmune diseases.
• Discuss the roles of central and peripheral tolerance in maintaining immune homeostasis.
  • Central tolerance is established during lymphocyte development in primary lymphoid organs, like the thymus for T cells and bone marrow for B cells, where self-reactive lymphocytes are deleted or rendered non-functional. Peripheral tolerance complements this by regulating those lymphocytes that escape central tolerance in secondary lymphoid organs. This dual mechanism is vital for maintaining immune homeostasis and preventing inappropriate immune responses against self-tissues.
• Evaluate potential therapeutic approaches aimed at inducing immune tolerance in autoimmune diseases and organ transplantation.
  • Inducing immune tolerance presents a promising therapeutic approach to treating autoimmune diseases and improving organ transplantation outcomes. Strategies include using regulatory T cells to suppress harmful immune responses or employing specific antigens to retrain the immune system. Additionally, manipulating costimulatory signals can help prevent activation of self-reactive lymphocytes. These methods aim to establish a state of immune tolerance that could potentially lead to lasting remission in autoimmune disorders or successful acceptance of transplanted organs without the need for lifelong immunosuppression.

Related terms

Autoimmunity: A condition in which the immune system mistakenly attacks the body's own cells, leading to tissue damage and disease.

Treg Cells: Regulatory T cells that play a key role in maintaining immune tolerance by suppressing excessive immune responses.

Central Tolerance: The process during lymphocyte development where self-reactive cells are eliminated or rendered inactive to prevent autoimmune responses.