T lymphocyte: immune cell that carries the "cluster of differentiation 8" (CD8) marker. CD8 T cells may be cytotoxic T lymphocytes or suppressor T cells. (See also cytotoxic T lymphocyte (CTL); T cell.)
White blood cells are composed primarily of neutrophils, monocytes and lymphocytes. Lymphocytes are either T-cells or B-cells. T-cells (CD3 cells) are divided into T-helper (CD4 cells) and T-suppressor/cytotoxic (CD8 cells) cells.
The cell surface protein CD8 is important for recognition by the T-cell receptor of antigenic peptides bound to MHC class I molecules. It acts as a co-receptor by binding to the lateral face of MHC class I molecules.
CD8 (cluster of differentiation 8) is a glycoprotein which serves as a co-receptor that is expressed on the surface of cytotoxic T cells. CD8 consists of an Î± and a ÃŸ chain, which both resemble an immunoglobulin-like domain that is connected to the membrane by a thin stalk. It is attracted to the Î±3 portion of the Class I MHC molecule.