Cytotoxic T lymphocytes (CTLs)

Definition

Cytotoxic T lymphocytes (CTLs) are a type of white blood cell that directly kill infected or cancerous cells. They recognize their targets through specific antigens presented by MHC class I molecules on the surface of these cells.

5 Must Know Facts For Your Next Test

1. CTLs are also known as CD8+ T cells due to the presence of the CD8 glycoprotein on their surface.
2. CTL activation requires two signals: recognition of antigen-MHC class I complex and costimulatory signals from helper T cells.
3. Once activated, CTLs release perforin and granzymes to induce apoptosis in target cells.
4. CTLs play a crucial role in controlling viral infections and tumor surveillance.
5. Memory CTLs can quickly respond to previously encountered antigens, providing long-term immunity.

Review Questions

• What type of molecule must be present on the surface of target cells for CTLs to recognize them?
• What are the two main signals required for CTL activation?
• How do CTLs induce apoptosis in infected or cancerous cells?

Related terms

Helper T Cells: A type of T cell that assists other immune cells by releasing cytokines and providing necessary signals.

MHC Class I: Molecules found on almost all nucleated cells that present antigenic peptides to CD8+ T cells.

Apoptosis: The process of programmed cell death that eliminates damaged or infected cells without causing inflammation.