CD8+

Definition

CD8+ refers to a subtype of T cells that express the CD8 glycoprotein on their surface, primarily functioning as cytotoxic T lymphocytes (CTLs). These cells play a crucial role in the adaptive immune response by identifying and destroying infected or cancerous cells, thus helping to maintain the body's defense against pathogens and tumors. CD8+ T cells are essential for the recognition of antigens presented by Major Histocompatibility Complex (MHC) class I molecules, which are found on nearly all nucleated cells.

5 Must Know Facts For Your Next Test

1. CD8+ T cells are derived from progenitor cells in the bone marrow and mature in the thymus, where they undergo selection processes to ensure proper functionality.
2. These cells are essential for the immune response against intracellular pathogens, particularly viruses, as they can recognize and eliminate infected host cells.
3. Once activated by recognizing a specific antigen presented by MHC class I molecules, CD8+ T cells proliferate and differentiate into effector and memory T cells.
4. Memory CD8+ T cells remain in the body long after an infection has resolved, providing a faster and more robust response upon re-exposure to the same pathogen.
5. The dysfunction or depletion of CD8+ T cells can lead to increased susceptibility to infections and malignancies, highlighting their importance in immune surveillance.

Review Questions

• How do CD8+ T cells recognize and respond to infected or cancerous cells?
  • CD8+ T cells recognize infected or cancerous cells through their interaction with MHC class I molecules displaying specific antigen fragments. When a CD8+ T cell encounters an infected cell presenting an antigen it recognizes, it binds to this complex and is activated. This activation leads to the proliferation of CD8+ T cells, which then differentiate into effector cells that can directly kill the targeted infected or tumor cells.
• Discuss the significance of memory CD8+ T cells in the adaptive immune response.
  • Memory CD8+ T cells play a vital role in enhancing the adaptive immune response by ensuring that the body can respond more effectively to previously encountered pathogens. After an initial infection, some activated CD8+ T cells differentiate into memory cells, which persist long-term in the body. Upon re-exposure to the same pathogen, these memory CD8+ T cells can quickly proliferate and mount a rapid response, often neutralizing threats before they can cause significant harm.
• Evaluate how the dysfunction of CD8+ T cells impacts overall immunity and disease susceptibility.
  • The dysfunction of CD8+ T cells significantly compromises the body's immune system, leading to increased susceptibility to infections and cancers. For instance, in diseases like HIV/AIDS, CD8+ T cell function is impaired, allowing opportunistic infections and malignancies to thrive. Furthermore, understanding this dysfunction opens pathways for immunotherapy approaches aimed at enhancing CD8+ T cell responses in cancer treatment or developing vaccines that boost their effectiveness against infectious diseases.

Related terms

Cytotoxic T Lymphocytes: A subset of T cells that directly kill cancerous or infected cells, primarily recognized as CD8+ T cells.

Helper T Cells: A type of T cell that helps activate other immune cells, typically identified as CD4+ T cells.

Major Histocompatibility Complex (MHC): A set of molecules displayed on cell surfaces that present antigen fragments to T cells, critical for immune recognition.