Cytotoxic T lymphocyte (CD8 T cell) (CTL)

Cytotoxic T lymphocytes are CD8+ T cells that recognize antigenic peptides presented by MHC class I and kill infected or malignant cells with high specificity. Killing mechanisms include release of cytotoxic granules containing perforin and granzymes, which induce apoptosis in target cells, and Fas ligand engagement of Fas on targets to trigger apoptosis. CTLs also produce cytokines such as IFN-γ and TNF-α that contribute to antiviral, antitumor, and immunoregulatory effects. CTL activity underpins many successful cancer immunotherapies and is central to antiviral defense, though dysregulated CTL responses can contribute to tissue injury.

Other names

Cytotoxic T cellCytotoxic T lymphocyteKiller T cellT-killer cellCytolytic T cellCD8+ T cell

For checkpoint inhibitors: blockade of inhibitory receptors/ligands (PD-1/PD-L1, CTLA-4) to restore/enhance CTL activation and cytotoxic function against tumors. For CAR-T: engineered T-cell receptors redirect CTL cytotoxicity toward specific antigens on tumor cells. For cytokine support (e.g., IL-2): augment proliferation and effector function of CTLs.