Cytotoxic t cells

Definition

Cytotoxic T cells, also known as cytotoxic T lymphocytes (CTLs), are a type of immune cell that play a crucial role in the body's defense against infectious diseases and cancer. These cells are responsible for directly killing infected or cancerous cells, recognizing them through specific antigens presented on the surface of these cells. By identifying and destroying compromised cells, cytotoxic T cells help maintain the integrity of the immune system and prevent the spread of infections.

5 Must Know Facts For Your Next Test

1. Cytotoxic T cells primarily recognize and kill cells infected by viruses, as well as tumor cells, by detecting specific antigens on their surfaces.
2. They are activated by helper T cells, which provide necessary signals and cytokines to enhance their function during an immune response.
3. Cytotoxic T cells use perforin and granzymes to induce apoptosis (programmed cell death) in their target cells, effectively eliminating them.
4. Once activated, cytotoxic T cells can proliferate rapidly, forming memory T cells that remain in the body to provide faster responses to future infections by the same pathogen.
5. Dysfunction or depletion of cytotoxic T cells can lead to increased susceptibility to infections and malignancies, highlighting their importance in maintaining immune health.

Review Questions

• How do cytotoxic T cells recognize and target infected or cancerous cells in the body?
  • Cytotoxic T cells recognize infected or cancerous cells by identifying specific antigens presented on these cells through major histocompatibility complex (MHC) molecules. The process begins when antigen-presenting cells (APCs) process and display these antigens, allowing cytotoxic T cells to bind to them via their unique receptors. This recognition triggers the cytotoxic T cell to initiate an immune response aimed at destroying the compromised cell.
• Discuss the role of helper T cells in the activation and function of cytotoxic T cells during an immune response.
  • Helper T cells play a critical role in activating cytotoxic T cells by providing necessary signals such as cytokines. Once a helper T cell recognizes an antigen presented by an APC, it becomes activated and secretes cytokines that stimulate the proliferation and differentiation of cytotoxic T cells. This collaboration enhances the effectiveness of the immune response, ensuring that cytotoxic T cells can effectively target and eliminate infected or cancerous cells.
• Evaluate the significance of memory cytotoxic T cells in providing long-term immunity against specific pathogens.
  • Memory cytotoxic T cells are significant because they provide long-term immunity by remaining in the body after an initial infection has been cleared. When a pathogen re-enters the body, these memory T cells can quickly recognize it due to their prior exposure, leading to a rapid and robust immune response. This quick action is essential for controlling infections before they can spread and cause more severe disease, illustrating the importance of cytotoxic T cells in adaptive immunity.

Related terms

T lymphocytes: A category of white blood cells that play a central role in the adaptive immune response, including helper T cells and cytotoxic T cells.

Antigen presenting cells (APCs): Cells that process and present antigens to T cells, enabling them to recognize and respond to pathogens or abnormal cells.

Major histocompatibility complex (MHC): Molecules found on cell surfaces that present peptide fragments (antigens) to T cells, playing a vital role in the immune response.