Cytotoxic T Lymphocytes

Definition

Cytotoxic T lymphocytes, also known as CD8+ T cells, are a type of T cell that play a crucial role in the body's cellular immune response. They are specialized in recognizing and destroying cells that have been infected by pathogens or have become cancerous.

5 Must Know Facts For Your Next Test

1. Cytotoxic T lymphocytes recognize and bind to MHC class I molecules on the surface of target cells, which can be infected or cancerous cells.
2. Upon activation, cytotoxic T lymphocytes release cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell.
3. Cytotoxic T lymphocytes play a crucial role in the body's defense against viral infections, as they can recognize and destroy cells infected with viruses.
4. Cytotoxic T lymphocytes are also important in the body's immune response against certain types of cancer, as they can identify and eliminate cancerous cells.
5. The development and differentiation of cytotoxic T lymphocytes is regulated by various transcription factors, such as T-bet and Eomesodermin.

Review Questions

• Explain the mechanism by which cytotoxic T lymphocytes recognize and destroy their target cells.
  • Cytotoxic T lymphocytes recognize their target cells through the interaction between the T cell receptor (TCR) on the surface of the cytotoxic T cell and the MHC class I molecules expressed on the target cell. This recognition triggers the activation of the cytotoxic T cell, which then releases cytotoxic granules containing perforin and granzymes. Perforin creates pores in the target cell's membrane, allowing the granzymes to enter and induce apoptosis (programmed cell death) in the target cell.
• Describe the role of cytotoxic T lymphocytes in the body's immune response against viral infections and cancer.
  • Cytotoxic T lymphocytes play a crucial role in the body's defense against viral infections and certain types of cancer. During a viral infection, cytotoxic T lymphocytes can recognize and bind to MHC class I molecules on the surface of cells infected with the virus. This triggers the cytotoxic T cell to release cytotoxic granules, which induce apoptosis in the infected cell, preventing the virus from replicating and spreading. Similarly, cytotoxic T lymphocytes can identify and eliminate cancerous cells that express abnormal MHC class I molecules, making them an important component of the body's immune response against cancer.
• Analyze the significance of the development and differentiation of cytotoxic T lymphocytes in the context of the adaptive immune system.
  • The development and differentiation of cytotoxic T lymphocytes is a crucial process in the adaptive immune system. Cytotoxic T lymphocytes originate from T cell precursors in the bone marrow and undergo maturation in the thymus gland, where they undergo positive and negative selection to ensure they can recognize MHC class I molecules but not self-antigens. The expression of specific transcription factors, such as T-bet and Eomesodermin, regulates the differentiation of cytotoxic T lymphocytes and their acquisition of cytotoxic effector functions. This precise regulation of cytotoxic T lymphocyte development and differentiation is essential for the adaptive immune system to mount an effective response against pathogens and cancer cells, while maintaining self-tolerance and avoiding autoimmune reactions.

Related terms

T Cells:

T cells are a type of lymphocyte that originate in the bone marrow and mature in the thymus gland. They are responsible for cell-mediated immunity and play a central role in the adaptive immune response.

CD8 Receptor: The CD8 receptor is a glycoprotein expressed on the surface of cytotoxic T lymphocytes. It binds to the major histocompatibility complex (MHC) class I molecules, helping the T cell to recognize and interact with its target cells.

Perforin and Granzymes: Perforin and granzymes are cytotoxic proteins produced by cytotoxic T lymphocytes. Perforin creates pores in the target cell's membrane, allowing granzymes to enter and induce apoptosis (programmed cell death).