CD8

Definition

CD8 is a glycoprotein found on the surface of certain immune cells, primarily cytotoxic T cells, which play a crucial role in the adaptive immune response. This marker helps distinguish CD8+ T cells from other T cell populations, such as CD4+ helper T cells, and is essential for their function in recognizing and destroying infected or cancerous cells by binding to MHC class I molecules.

5 Must Know Facts For Your Next Test

1. CD8+ T cells are vital for targeting and eliminating cells infected with viruses, as well as cancerous cells, making them crucial for immune surveillance.
2. The interaction between CD8 and MHC class I is essential for the activation and proliferation of cytotoxic T cells, enabling them to mount an effective immune response.
3. During T cell development in the thymus, CD8+ T cells undergo positive and negative selection to ensure self-tolerance and functional competency.
4. The presence of CD8 helps distinguish between different T cell subsets, facilitating targeted immune responses based on the type of threat.
5. CD8+ T cells can develop memory functions after an initial exposure to antigens, allowing for a quicker and more efficient response upon re-exposure.

Review Questions

• How does the presence of CD8 influence the function and development of cytotoxic T cells during their maturation process?
  • CD8 plays a crucial role during the maturation of cytotoxic T cells in the thymus. It assists in their positive selection by enabling these T cells to recognize and interact with MHC class I molecules. This interaction is vital for their survival and further development into functional CD8+ T cells. Additionally, CD8+ T cells that strongly recognize self-antigens are eliminated during negative selection, ensuring they do not attack the body's own tissues.
• Discuss the importance of CD8 in distinguishing between different types of T cells and its role in adaptive immunity.
  • CD8 is critical for distinguishing cytotoxic T cells from helper T cells (which express CD4). This distinction is important because each type has unique functions within the adaptive immune response. CD8+ cytotoxic T cells are primarily responsible for directly killing infected or malignant cells, while CD4+ helper T cells assist in orchestrating the immune response by activating other immune components. Therefore, understanding CD8 helps clarify how different T cell populations contribute to overall immunity.
• Evaluate how the interaction between CD8+ T cells and MHC class I molecules impacts the outcomes of viral infections and cancer treatments.
  • The interaction between CD8+ T cells and MHC class I molecules is pivotal in controlling viral infections and targeting tumor cells. When a virus infects a host cell, it presents viral peptides on MHC class I, which are recognized by CD8+ T cells, leading to cell death and viral clearance. In cancer treatment, therapies aimed at enhancing this interaction can improve anti-tumor responses, as well-activated CD8+ T cells can effectively identify and destroy cancerous cells. Thus, strategies that amplify this recognition are critical in developing successful immunotherapies.

Related terms

Cytotoxic T Cells: A subtype of T cells that are directly involved in killing virus-infected cells and tumor cells, characterized by the expression of CD8.

MHC Class I:

Major Histocompatibility Complex class I molecules present peptides from intracellular proteins on the surface of all nucleated cells, allowing CD8+ T cells to recognize and eliminate infected or abnormal cells.

T Cell Receptor (TCR): A molecule found on T cells that recognizes specific antigens presented by MHC molecules, playing a key role in the activation and function of T cells.