CD8α is a crucial immune glycoprotein that serves as a co-receptor for the MHC I-peptide complex, facilitating the recognition of antigens presented by APCs （antigen-presenting cells） to T cells. It is a key component of the CD8 receptor complex, which is predominantly found on cytotoxic T lymphocytes （CTLs）. CD8α can form either an α/β heterodimer with CD8β or an α/α homodimer, both of which play essential roles in CTL activation and function. By interacting with the TCR （T cell receptor） and MHC I molecules, CD8α helps recruit the LCK kinase, initiating multiple signaling pathways that drive the CTL-mediated immune response.