Cytotoxic T cells

Definition

Cytotoxic T cells, also known as CD8+ T cells, are a type of immune cell that plays a crucial role in the adaptive immune response by directly killing infected or cancerous cells. They recognize antigens presented by infected or abnormal cells through Major Histocompatibility Complex (MHC) class I molecules, leading to the activation of these cells and subsequent destruction of the target cells. This targeted response is vital for controlling infections and eliminating tumors, highlighting their importance in both cellular immunity and immunotherapy.

5 Must Know Facts For Your Next Test

1. Cytotoxic T cells develop from precursor cells in the bone marrow and mature in the thymus, where they undergo selection processes to ensure they can effectively recognize foreign antigens.
2. Upon activation, cytotoxic T cells proliferate and differentiate into effector T cells capable of killing target cells through mechanisms like releasing perforin and granzymes.
3. Cytotoxic T cells require signals from helper T cells for optimal activation, including cytokine signaling and co-stimulatory interactions.
4. These cells play a vital role in controlling viral infections and are also important in the rejection of transplanted tissues due to their ability to recognize non-self antigens.
5. Research is ongoing into harnessing cytotoxic T cells for cancer immunotherapy, with strategies aimed at enhancing their ability to target and destroy tumor cells.

Review Questions

• How do cytotoxic T cells recognize and target infected or cancerous cells?
  • Cytotoxic T cells recognize infected or cancerous cells through the binding of their T cell receptors (TCR) to specific antigens presented by Major Histocompatibility Complex (MHC) class I molecules on the surface of these target cells. This recognition is essential for their activation, which leads them to initiate a killing response. Once activated, cytotoxic T cells can directly kill these abnormal cells using proteins like perforin and granzymes.
• Discuss the role of helper T cells in the activation and function of cytotoxic T cells.
  • Helper T cells play an essential role in activating cytotoxic T cells by providing necessary signals through cytokines and co-stimulatory interactions. When antigen-presenting cells present antigens to helper T cells, these activated helper T cells release cytokines that promote the proliferation and differentiation of cytotoxic T cells. This cooperation enhances the overall adaptive immune response, ensuring that cytotoxic T cells effectively eliminate infected or cancerous targets.
• Evaluate the potential impact of targeting cytotoxic T cell responses in cancer immunotherapy.
  • Targeting cytotoxic T cell responses in cancer immunotherapy has shown promising results, as enhancing their ability to recognize and kill tumor cells can lead to more effective treatment outcomes. Techniques such as CAR-T cell therapy involve engineering patients' own T cells to express chimeric antigen receptors that specifically target tumor antigens. By boosting cytotoxic T cell activity against cancer, researchers aim to improve patient survival rates and reduce tumor recurrence, highlighting the importance of these immune cells in modern therapeutic approaches.

Related terms

Helper T cells: A subtype of T cells (CD4+ T cells) that assist other immune cells by releasing cytokines, enhancing the immune response.

Antigen-presenting cells: Cells that display foreign antigens on their surface to T cells, facilitating the activation of the adaptive immune response.

Cytokines:

Signaling molecules produced by immune cells that mediate and regulate immunity, inflammation, and hematopoiesis.