Cluster of differentiation 8 (CD8) co-receptor (CD8)

The Cluster of differentiation 8 (CD8) co-receptor is a cell surface glycoprotein expressed primarily on cytotoxic and suppressor T cells, where it functions as a co-receptor for the T cell receptor (TCR)[1][2]. CD8 exists as either a CD8αα homodimer or CD8αβ heterodimer, each with distinct functional properties[1][2]. Its major role is to bind to the membrane-proximal domain of major histocompatibility complex class I (MHC-I) molecules, stabilizing the interaction between the TCR and antigen-presenting cells, and thereby enhancing T cell activation and signaling[1][2]. CD8 is essential for the detection and elimination of cells infected by pathogens, cancerous cells, and those involved in autoimmune processes[1][2]. The molecule is structurally organized into several domains: ectodomain (antigen-binding), hinge (signaling relay and flexibility), transmembrane (membrane anchoring), and cytoplasmic tail (signaling and lipid raft localization)[1][2]. Post-translational modifications, such as O-linked glycosylation and palmitoylation, in the hinge and cytoplasmic tail influence CD8’s affinity for MHC-I and its signaling efficiency[1][2]. CD8 not only acts as a co-stimulator but can also serve as a co-repressor in certain immune contexts, and its function is modulated by interactions with both classical and non-classical MHC-I molecules[1][2]. It plays a critical role in thymic selection and the maturation of CD8+ T cells[1][2]. CD8 is a recognized therapeutic target in immunotherapy, with anti-CD8 monoclonal antibodies and CD8-derived chimeric antigen receptors being explored for modulating immune responses[1][2]. The hinge region’s glycosylation status, which varies between immature and mature T cells, is a potential biomarker for immune cell activation and a target for immunomodulation[1][2].

Other names

CD8 co-receptorCD8 antigenCD8 molecule

Anti-CD8 monoclonal antibodies – block CD8/MHC-I interaction to modulate immune response; Chimeric antigen receptors – utilize CD8 domains to enhance T cell signaling and targeting; Sialidase enzymes – modulate CD8 hinge glycosylation to alter immune cell activation