T-cell receptor and CD8 co-receptor complex (TCR/CD8 complex)

The T-cell receptor and CD8 co-receptor complex is composed of the T-cell receptor (TCR), a heterodimer (usually αβ), and the CD8 molecule (typically a CD8αβ heterodimer or less commonly, CD8αα homodimer). This complex is found on the surface of cytotoxic T lymphocytes (CD8+ T cells). The TCR recognizes peptide antigens presented by the major histocompatibility complex (MHC) class I molecules on the surface of target cells, while CD8 acts as a co-receptor that binds to the α3 domain of MHC class I, stabilizing the TCR–peptide–MHC interaction and recruiting Lck kinase to promote intracellular signaling cascades essential for T cell activation, cytotoxicity, and immune responses. The TCR/CD8 complex is central to immune surveillance and is a key target in immuno-oncology, transplantation, and infectious disease research and therapy.

Other names

T-cell receptor–CD8 complexTCR–CD8TCR/CD8TCR-CD8

Blockade or depletion of CD8+ T cells (anti-CD8 mAbs); Engagement or redirection of TCR (TCR bispecific molecules in immunotherapy); Modulation of antigen-specific T cell responses (immunotherapy CAR-T or TCR therapies)