T Lymphocytes: Cytotoxic


Cytotoxic T lymphocytes (CTLs) are T cells that have the ability to recognise and destroy other nucleated target cells that express ‘nonself’ or ‘foreign’ peptide (e.g. derived from viral proteins) in the context of major histocompatibility complex (MHC) class I or class II molecules on their surface. Most CTLs are MHC class I restricted CD8 T cells, but some CD4 T cells (besides their well‐known helper and regulatory functions) also have the capacity to recognise and kill infected cells. Cytotoxic T cells are of great importance in host defence against cytosolic pathogens in general.

Key Concepts:

  • Cytotoxic T‐cells (cytotoxic T lymphocytes, CTLs) are a subset of lymphocytes that participate in cellular immunity.

  • They originate from haematopoietic stem cells in the bone marrow but develop in the thymus.

  • Their main role is to combat intracellular infection.

  • They possess antigen‐specific receptors (T‐cell receptor, TCR) on their cell surface.

  • Most CTL are CD8+ and recognise antigen‐derived peptides presented by MHC class I molecules on the surface of the infected cell.

  • A minority of CTL are CD4+ and recognise peptides presented by MHC class II molecules.

  • In addition to destroying infected cells, CTL also play a role in antitumour and autoimmune responses.

  • They destroy infected cells by induction of apoptotic cell death in the target cell.

  • Apoptosis can be induced in the target cell using the granzyme/perforin, Fas/Fas ligand or tumour necrosis factor (TNF)/TNF receptor pathways.

Keywords: apoptosis; cytotoxic; T‐cell; infection; lymphocyte; CD8; perforin; Fas

Figure 1.

The T‐cell development maturation pathway. (TdT); cell‐surface glycoproteins (CD); 1,7,5,2,3,4 and 8; (TCR).

Figure 2.

Interactions between cytotoxic T lymphocytes and target cells. (CTL); T‐cell receptor (TCR); major histocompatibility complex (MHC); (LFA); (ICAM).



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Further Reading

Chowdhury D and Lieberman L (2008) Death by a thousand cuts: granzyme pathways of programmed cell death. Annual Review of Immunology 26: 389–420.

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How to Cite close
Gotch, Frances M(Oct 2012) T Lymphocytes: Cytotoxic. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0001223.pub3]