Cluster of Differentiation 8 Alpha Chain (None)

The CD8α co-receptor is a transmembrane glycoprotein that plays a central role in the immune system, particularly in T cell-mediated responses. It is most commonly found on the surface of cytotoxic T lymphocytes (CD8+ T cells), where it functions as a co-receptor alongside the T-cell receptor (TCR) to recognize antigens presented by major histocompatibility complex class I (MHC-I) molecules. It enhances antigen recognition by binding to non-polymorphic regions of MHC-I molecules, specifically the α3 domain, distinct from where TCR binds, and facilitates signaling through association with Lck kinase via its cytoplasmic tail, promoting phosphorylation events necessary for full T cell activation. CD8 exists as either a homodimer of two alpha chains (CD8αα) or a heterodimer of one alpha and one beta chain (CD8αβ). Targeting CD8 with monoclonal antibodies has research applications in immune modulation. Features from its structure are used in engineering chimeric antigen receptors for immunotherapy applications against cancer or infectious diseases due to its role in enhancing specificity/activation thresholds for engineered immune effector cells.

Modulation of T cell activation and cytotoxicity