🦠microbiology review

key term - Clonal Deletion

Definition

Clonal deletion is a process in which self-reactive T cells or B cells are eliminated from the immune system, preventing the development of autoimmune disorders. It is a crucial mechanism for maintaining self-tolerance and preventing the immune system from attacking the body\'s own healthy tissues.

5 Must Know Facts For Your Next Test

  1. Clonal deletion occurs during the development of T cells in the thymus and B cells in the bone marrow, where self-reactive cells are identified and removed from the repertoire.
  2. The process of clonal deletion is initiated when self-reactive lymphocytes encounter their cognate self-antigen with high affinity, triggering signaling cascades that lead to their apoptosis.
  3. Clonal deletion is a crucial mechanism for maintaining central tolerance, preventing the development of autoimmune diseases by eliminating self-reactive lymphocytes before they can mature and enter the periphery.
  4. Defects in the clonal deletion process can lead to the survival and activation of self-reactive lymphocytes, contributing to the development of various autoimmune disorders.
  5. The efficiency of clonal deletion is influenced by factors such as the expression of self-antigens in the thymus and bone marrow, the avidity of the T cell receptor or B cell receptor for self-antigens, and the signaling thresholds that trigger apoptosis.

Review Questions

  • Explain the role of clonal deletion in the maintenance of self-tolerance and the prevention of autoimmune disorders.
    • Clonal deletion is a crucial mechanism for maintaining self-tolerance and preventing autoimmune disorders. During the development of T cells and B cells in the primary lymphoid organs, self-reactive lymphocytes that recognize the body\'s own antigens with high affinity are identified and eliminated through the process of apoptosis. This process of clonal deletion ensures that self-reactive cells are removed from the repertoire before they can mature and enter the periphery, where they could potentially attack the body\'s healthy tissues and trigger autoimmune responses.
  • Describe the relationship between clonal deletion and the establishment of central tolerance.
    • Clonal deletion is a key component of the process of central tolerance, which is the establishment of self-tolerance in the primary lymphoid organs. During central tolerance, self-reactive lymphocytes are identified and eliminated through the process of clonal deletion, preventing them from maturing and entering the peripheral immune system. This ensures that the immune system does not mount an autoimmune response against the body\'s own healthy tissues. The efficiency and effectiveness of clonal deletion in the thymus and bone marrow are crucial for the maintenance of central tolerance and the prevention of autoimmune disorders.
  • Analyze the potential consequences of defects in the clonal deletion process and their contribution to the development of autoimmune diseases.
    • Defects in the clonal deletion process can have serious consequences for the maintenance of self-tolerance and the prevention of autoimmune disorders. If self-reactive lymphocytes are not effectively eliminated during their development in the thymus or bone marrow, they can survive and mature, entering the peripheral immune system. These self-reactive cells can then be activated and trigger autoimmune responses, leading to the development of various autoimmune diseases. Factors that can contribute to defects in clonal deletion include the improper expression of self-antigens in the primary lymphoid organs, alterations in the signaling thresholds that trigger apoptosis, and genetic or environmental factors that disrupt the mechanisms underlying clonal deletion. Understanding the role of clonal deletion in maintaining self-tolerance is crucial for identifying potential targets for therapeutic interventions in autoimmune disorders.

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