Cytotoxic T lymphocytes

Definition

Cytotoxic T lymphocytes (CTLs) are a subset of T cells that directly kill infected or cancerous cells. They recognize antigens presented by MHC class I molecules on target cells.

5 Must Know Facts For Your Next Test

1. CTLs express CD8 surface proteins which help them interact with MHC class I molecules.
2. They are essential for controlling intracellular pathogens like viruses.
3. Activation of CTLs requires both antigen recognition and co-stimulatory signals.
4. Once activated, CTLs release perforin and granzymes to induce apoptosis in target cells.
5. Memory CTLs can respond more rapidly upon re-exposure to the same antigen.

Review Questions

• What type of surface protein do Cytotoxic T lymphocytes express?
• How do Cytotoxic T lymphocytes kill their target cells?
• What is required for the activation of Cytotoxic T lymphocytes?

Related terms

Helper T Cells:

T cells that assist other white blood cells in immunologic processes, including maturation of B cells into plasma cells.

MHC Class I Molecules: Protein complexes found on all nucleated cells that present endogenous antigens to cytotoxic T lymphocytes.

Perforin:

A protein released by CTLs that forms pores in the membranes of target cells to facilitate entry of granzymes.