Cluster Of Differentiation 8b (CD8b)

The T-cell differentiation antigen CD8 is a glycoprotein present at the surface of thymocytes and T lymphocytes that recognizes antigenic peptides in the context of the class I major histocompatibility complex (MHC) molecules. In the human, the CD8 antigen is a heterodimeric product of the association of an alpha (CD8A) and a beta chain (CD8B).CD8 is a T-cell glycoprotein expressed only in cytotoxic T cells that recognize antigen in context with class I major histocompatibility antigens. Antibodies against CD8 can block the killing activity of these cells, the inhibition occurring at the level of target cell adhesion. Mouse CD8 consists of 2 distinct chains, Ly-2 (Cd8a) and Ly-3 (Cd8b1); rat CD8, called Ox-8, also has 2 chains. Human CD8 was thought to be made up of only 1 chain in mature T cells.