CD8 cell, a T lymphocyte that recognizes antigens presented by major histocompatibility complex (MHC) class I molecules present on infected or cancer cells. Binding of the T cell receptor with the MHC-I/antigen complex induces killing of the infected or cancer cell by the CD8 T cell. Antigen-presenting cells and CD4 T cells are essential for initial CD8 T cell activation. Activated CD8 T cells can secrete large amounts of gamma-interferon, a cytokine involved in the body’s defense against viruses. Also called cytotoxic T cell. See also cell-mediated cytotoxicity.
