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 α and a ß chain, which both resemble an immunoglobulin-like domain that is connected to the membrane by a thin stalk. It is attracted to the α₃ portion of the Class I MHC molecule. This affinity keeps the T cell receptor of the cytotoxic T cell and the target cell bound closely together during antigen-specific activation. Cytotoxic T cells with CD8 surface protein are called CD8+ T cells.

Clusters of differentiation

CD8-Rezeptor | CD8 | CD8