CD8

Definition

CD8 is a glycoprotein expressed on the surface of a subset of T lymphocytes, known as cytotoxic T cells. It plays a crucial role in cellular immunity by recognizing and destroying infected or cancerous cells.

5 Must Know Facts For Your Next Test

1. CD8 acts as a co-receptor, binding to MHC class I molecules on the surface of target cells, which enhances the interaction between the T cell receptor and the presented antigen.
2. CD8+ T cells, also known as cytotoxic T cells, are responsible for directly killing infected or cancerous cells through the release of cytotoxic granules and the activation of apoptotic pathways.
3. The binding of CD8 to MHC class I molecules triggers a signaling cascade that activates the cytotoxic T cell, leading to the release of cytotoxic granules containing perforin and granzymes.
4. CD8+ T cells play a crucial role in the immune response against viral infections, as they can recognize and destroy cells that have been infected by viruses and are expressing viral antigens.
5. Impairment or dysfunction of CD8+ T cells can lead to increased susceptibility to viral infections, as well as the development of certain types of cancer, as the immune system is unable to effectively eliminate transformed cells.

Review Questions

• Explain the role of CD8 in the function of cytotoxic T cells and their involvement in cellular immunity.
  • CD8 is a glycoprotein expressed on the surface of cytotoxic T cells, a subset of T lymphocytes responsible for directly killing infected or cancerous cells. The binding of CD8 to MHC class I molecules on the target cell enhances the interaction between the T cell receptor and the presented antigen, triggering a signaling cascade that activates the cytotoxic T cell. This activation leads to the release of cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell, effectively eliminating the threat. CD8+ T cells play a crucial role in the immune response against viral infections and in the surveillance and destruction of transformed cells, making them a key component of cellular immunity.
• Describe how the dysfunction or impairment of CD8+ T cells can impact the immune system's ability to respond to viral infections and cancer development.
  • Impairment or dysfunction of CD8+ T cells can have significant consequences for the immune system's ability to effectively respond to viral infections and the development of certain types of cancer. Without the proper functioning of CD8+ cytotoxic T cells, the immune system is unable to efficiently recognize and eliminate cells that have been infected by viruses or have undergone cancerous transformation. This can lead to increased susceptibility to viral infections, as the immune system is unable to effectively clear the infected cells. Additionally, the inability of the immune system to detect and destroy transformed cells can contribute to the development and progression of certain types of cancer, as the immune system fails to effectively eliminate these threats. The critical role of CD8+ T cells in cellular immunity highlights the importance of maintaining their proper function for the overall health and protection of the body.
• Analyze the significance of the binding between CD8 and MHC class I molecules in the activation and function of cytotoxic T cells, and explain how this interaction is crucial for the immune system's ability to recognize and respond to infected or transformed cells.
  • The binding of CD8 to MHC class I molecules on the surface of target cells is a crucial step in the activation and function of cytotoxic T cells, and is essential for the immune system's ability to recognize and respond to infected or transformed cells. The CD8 co-receptor enhances the interaction between the T cell receptor and the presented antigen, amplifying the signal and triggering a signaling cascade that activates the cytotoxic T cell. This activation leads to the release of cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell. Without this CD8-MHC class I interaction, the cytotoxic T cell would be unable to effectively recognize and respond to the infected or transformed cell, compromising the immune system's ability to eliminate these threats. The significance of this interaction highlights the critical role of CD8+ T cells in cellular immunity and the surveillance and destruction of cells that pose a danger to the body's health and well-being.

Related terms

T Lymphocytes:

A type of white blood cell that plays a central role in cell-mediated immunity, responsible for recognizing and destroying infected or abnormal cells.

Cytotoxic T Cells:

A subtype of T lymphocytes that directly kill infected or cancerous cells through the release of cytotoxic granules and the activation of apoptotic pathways.

MHC Class I: A type of major histocompatibility complex molecule that presents peptide fragments from the cell's own proteins to CD8+ T cells, allowing them to detect and respond to infected or transformed cells.