key term - Central tolerance

Definition

Central tolerance is a crucial mechanism in the immune system that helps prevent the body from attacking its own tissues by eliminating or inactivating self-reactive immune cells during their development in the thymus and bone marrow. This process is essential for maintaining self-tolerance and preventing autoimmune diseases, ensuring that the adaptive immune response can effectively target foreign pathogens without causing harm to the host's own cells.

5 Must Know Facts For Your Next Test

1. Central tolerance primarily occurs in the thymus for T cells and in the bone marrow for B cells, where developing lymphocytes are screened for self-reactivity.
2. During central tolerance, self-reactive T cells undergo apoptosis, while some B cells can become anergic or undergo receptor editing to avoid attacking self-antigens.
3. Failure of central tolerance mechanisms can lead to autoimmune diseases, where the immune system targets the body's own tissues, resulting in inflammation and damage.
4. Central tolerance is only one part of a larger tolerance network that includes peripheral tolerance mechanisms that further regulate immune responses to self-antigens outside of the primary lymphoid organs.
5. Research has shown that enhancing central tolerance could be a therapeutic strategy for treating autoimmune diseases by promoting the elimination or inactivation of self-reactive immune cells.

Review Questions

• How does central tolerance contribute to the overall functioning of the adaptive immune response?
  • Central tolerance plays a vital role in shaping the adaptive immune response by eliminating or inactivating self-reactive lymphocytes during their development. This process ensures that only those immune cells that can recognize foreign antigens without reacting against the body’s own tissues are released into circulation. By preventing autoimmunity, central tolerance allows the adaptive immune system to efficiently target pathogens while minimizing harmful responses against self.
• Discuss the processes involved in central tolerance and their implications for T cell and B cell maturation.
  • In T cell maturation within the thymus, central tolerance involves positive and negative selection processes. During positive selection, T cells that can moderately bind to self-MHC molecules are allowed to survive, while those that do not are eliminated. Negative selection eliminates T cells that strongly react with self-antigens, thereby preventing autoimmunity. Similarly, in B cell maturation, self-reactive B cells can undergo receptor editing or become anergic. These processes are crucial as they shape a functional immune repertoire capable of defending against pathogens without attacking the host.
• Evaluate how failures in central tolerance mechanisms can lead to autoimmune diseases and what therapeutic strategies might address these issues.
  • Failures in central tolerance mechanisms can result in an increased population of self-reactive lymphocytes that attack healthy tissues, leading to autoimmune diseases such as lupus or rheumatoid arthritis. Understanding these mechanisms has opened avenues for therapeutic strategies aimed at enhancing central tolerance. Approaches like developing drugs that promote apoptosis of self-reactive cells or enhance regulatory T cell function could potentially restore proper immune regulation. By targeting these pathways, it may be possible to prevent or treat autoimmune conditions effectively.

Related terms

self-tolerance:

The ability of the immune system to recognize and not attack the body's own cells and tissues.

thymus:

An organ where T cells mature and undergo selection processes, including central tolerance.

autoimmunity:

A condition in which the immune system mistakenly attacks the body's own healthy cells, often due to failures in tolerance mechanisms.