CD8伪 is a crucial immune glycoprotein that plays a key role in coordinating immune responses against both external and internal threats. It serves as a co-receptor for the MHC class I-peptide complex, facilitating the recognition of antigens derived from cytosolic proteins by T cells. CD8伪 can form either a homodimer (CD8伪伪) or a heterodimer with CD8尾 (CD8伪尾), both of which interact with the T cell receptor (TCR) and MHC class I molecules to recruit the LCK kinase and initiate multiple signaling pathways. This interaction is essential for the activation of cytotoxic T lymphocytes (CTLs), which are critical for eliminating infected or abnormal cells. Additionally, CD8伪 is involved in the development and function of intraepithelial lymphocytes (IELs) in the gut, contributing to the maintenance of mucosal barriers.