T-cell surface glycoprotein CD8 (CD8) (CD8)

T-cell surface glycoprotein CD8 (CD8) is a transmembrane glycoprotein that functions as a co-receptor for the T-cell receptor (TCR) on cytotoxic T lymphocytes. It primarily exists as a heterodimer composed of an alpha and a beta chain, which specifically recognizes and binds to the alpha-3 domain of Major Histocompatibility Complex (MHC) class I molecules [UniProt: P01732]. This binding event is crucial for stabilizing the interaction between the TCR and the antigen-presenting cell, effectively lowering the threshold for T-cell activation [PubMed: 25033455]. Upon binding, CD8 recruits the intracellular tyrosine kinase Lck to the TCR-CD3 complex, initiating the phosphorylation of ITAMs and subsequent signaling pathways required for the release of cytotoxic granules like perforin and granzymes [StatPearls: NBK557634]. In clinical oncology, the presence and density of CD8+ T cells within the tumor microenvironment are used as significant prognostic indicators and predictors of response to immune checkpoint inhibitors [PubMed: 28491287]. Therapeutic interventions targeting or utilizing CD8 include the development of chimeric antigen receptor (CAR) T-cells and bispecific T-cell engagers (BiTEs) designed to harness the potent killing capacity of these cells against pathogens and tumors [PubMed: 30612353]. Additionally, CD8-specific imaging agents are being developed to non-invasively monitor immune responses during immunotherapy [PubMed: 29437149].

Other names

CD8 antigenT8Leu2Cluster of Differentiation 8Ly-2Lyt-2

CD8 acts as a co-receptor for the T-cell receptor (TCR), binding to MHC class I molecules to stabilize the TCR-pMHC complex and recruiting the Src-family tyrosine kinase Lck to initiate downstream signaling cascades [PubMed: 25033455].