CD8+ cytotoxic T lymphocyte-mediated tumor cell killing (CTL-mediated tumor cell killing)

CD8+ cytotoxic T lymphocyte-mediated tumor cell killing is an immune effector process in which activated CD8+ T cells recognize tumor antigens presented by MHC class I on cancer cells and induce apoptosis of the targets via two principal mechanisms: release of cytotoxic granules (perforin and granzymes) and engagement of death receptors (Fas ligand–Fas), with additional indirect killing via cytokines such as TNF-α and IFN-γ[1][2][4]. Direct killing typically requires cell–cell contact and involves perforin-mediated pore formation that allows granzymes to enter tumor cells and trigger caspase-dependent apoptosis; Fas–FasL interactions can independently activate death domains and caspases to fragment target-cell DNA[1][2][4][5]. While classical models emphasize TCR recognition of peptide–MHC I, CD8+ T cells can also kill MHC I–negative tumor variants through an antigen-independent pathway mediated by NKG2D receptors engaging tumor NKG2D ligands, relying on prior T cell activation provided by antigen-presenting cells or neighboring MHC-replete tumor cells[3]. The magnitude and functionality of intratumoral CD8+ T cells correlate with improved antitumor effects and prognosis, and are enhanced by cytokines (e.g., IL-12, IL-2) and relieved from suppression by checkpoint blockade; however, tumor microenvironmental barriers (e.g., PD-L1, VEGF, TAMs, CAFs, fibrosis, metabolic stress) impede trafficking, survival, and cytolysis of CD8+ T cells[1][4].

Other names

CD8+ T cell-mediated cytotoxicityCytotoxic T lymphocyte (CTL) tumor cell killingCD8+ T cell anti-tumor cytotoxicityT cell-mediated cytotoxicity

Immune checkpoint blockade enhances CD8+ T cell activation and effector function by inhibiting PD-1/PD-L1 or CTLA-4 pathways, increasing cytotoxic killing of tumor cells[4]. - High-dose IL-2 supports expansion and cytolytic activity of CD8+ T cells, augmenting tumor cell killing[1]. - Adoptive transfer of tumor-infiltrating lymphocytes increases the number and function of CTLs at the tumor site, promoting direct cytolysis[1][4].