CD8伪 is a crucial subunit of the CD8 co-receptor complex found on the surface of cytotoxic T lymphocytes (CTLs) and some natural killer (NK) cells. It is a 32 kDa glycoprotein that can form either an 伪/尾 heterodimer or an 伪/伪 homodimer with CD8尾. CD8伪 plays a vital role in immune responses by binding to MHC class I molecules on antigen-presenting cells (APCs), facilitating the recognition and destruction of infected or abnormal cells. This interaction helps activate the T cell receptor (TCR) complex, recruiting the LCK kinase and initiating multiple signaling pathways. Additionally, CD8伪伪 homodimers are found on intraepithelial lymphocytes (IELs), which protect mucosal surfaces like the intestinal barrier.