CD8-positive T lymphocyte (CD8+ T cell)

CD8-positive T lymphocytes are a lineage of adaptive immune cells derived from hematopoietic stem cells, maturing in the thymus, which recognize antigens presented by MHC class I molecules via their T cell receptor (TCR). Upon activation by peptide antigens and costimulatory signals, naïve CD8+ T cells differentiate into effector cytotoxic T cells capable of directly killing infected, neoplastic, or otherwise abnormal cells—primarily through release of perforin and granzymes, or engagement of death receptors (Fas). They also secrete cytokines such as interferon gamma and tumor necrosis factor alpha that amplify immune responses. After antigen clearance, most effector CD8+ T cells undergo apoptosis, but a subset forms long-lived memory CD8+ T cells that provide rapid secondary immune responses. CD8+ T cell responses play essential roles in controlling intracellular infections, tumors, and in maintaining immune balance, but their dysfunction (such as exhaustion or autoreactivity) contributes to poor pathogen clearance, tumor persistence, and a variety of autoimmune and degenerative diseases. Interventions that enhance, suppress, or alter CD8+ T cell responses underpin modern immunotherapies.

Other names

cytotoxic T lymphocyte (CTL)CD8+ lymphocyteCD8-positive cytotoxic T cellCD8 T cell

Checkpoint blockade (relieves inhibition on CD8+ T cells to boost response); Cytokine stimulation (e.g., via IL-2, IL-15 to promote proliferation and function); Adoptive transfer (infusion of modified or expanded CD8+ T cells).