Cytotoxic t lymphocytes

Definition

Cytotoxic T lymphocytes (CTLs) are a subtype of T cells that play a crucial role in the immune response by directly killing infected or cancerous cells. They recognize specific antigens presented on major histocompatibility complex (MHC) class I molecules and are essential for eliminating cells that display abnormal proteins, such as tumor antigens. Their activity is a key aspect of immune surveillance, helping to maintain tissue health and preventing the growth of tumors.

5 Must Know Facts For Your Next Test

1. Cytotoxic T lymphocytes are activated by antigen-presenting cells, which display tumor antigens on MHC class I molecules.
2. Upon activation, CTLs release perforin and granzymes to induce apoptosis in target cells, effectively killing them.
3. These cells can also produce cytokines like interferon-gamma that enhance the immune response and recruit other immune cells to the site of infection or tumors.
4. CTLs undergo clonal expansion upon activation, resulting in a larger pool of effector cells that can respond quickly to antigens.
5. Memory CTLs are formed after an initial immune response, providing long-lasting immunity against previously encountered antigens.

Review Questions

• How do cytotoxic T lymphocytes identify and eliminate infected or cancerous cells?
  • Cytotoxic T lymphocytes identify infected or cancerous cells by recognizing specific antigens presented on MHC class I molecules. When CTLs encounter a target cell displaying these abnormal proteins, they bind to the antigen-MHC complex and become activated. This activation triggers the CTLs to release cytotoxic molecules such as perforin and granzymes, which lead to apoptosis in the target cell, effectively eliminating the threat.
• Discuss the importance of cytotoxic T lymphocytes in immune surveillance and how they contribute to tumor immunology.
  • Cytotoxic T lymphocytes play a vital role in immune surveillance by constantly monitoring tissues for signs of infection or malignancy. They recognize tumor antigens presented by MHC class I molecules on abnormal cells and initiate a targeted immune response. This process helps prevent tumor development by destroying cancerous cells before they can proliferate. In cancer immunotherapy, enhancing CTL activity is a key strategy for boosting the immune system's ability to combat tumors.
• Evaluate how understanding cytotoxic T lymphocytes can inform therapeutic strategies in cancer treatment.
  • Understanding cytotoxic T lymphocytes provides valuable insights for developing cancer immunotherapies that aim to harness and amplify the body's immune response against tumors. Strategies such as checkpoint inhibitors enhance CTL activity by removing inhibitory signals that prevent their function. Additionally, vaccines targeting specific tumor antigens can stimulate CTL responses, increasing their numbers and effectiveness against cancer cells. By leveraging CTLs' capabilities, researchers aim to create more effective treatments that can lead to durable responses in patients with cancer.

Related terms

T cells:

A type of white blood cell that plays a central role in the immune response, with subtypes including helper T cells and cytotoxic T lymphocytes.

MHC class I: Molecules found on nearly all nucleated cells that present peptide fragments from inside the cell to cytotoxic T lymphocytes, allowing them to recognize and eliminate infected or malignant cells.

tumor antigens: Specific proteins expressed on the surface of tumor cells that can trigger an immune response, making them recognizable to cytotoxic T lymphocytes.