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CD8α is a crucial immune glycoprotein that plays a vital role in the immune system as a co-receptor for the T-cell receptor （TCR） on T cells. It is typically found in a heterodimer with CD8β or as a homodimer in certain cell types. CD8α binds to MHC class I molecules on antigen-presenting cells （APCs） to facilitate the recognition of intracellular pathogens, such as viruses and cancer cells, by cytotoxic T lymphocytes （CTLs）. This interaction is essential for T cell activation and the initiation of downstream signaling pathways, including the recruitment of LCK kinase. Additionally, CD8α is expressed on intraepithelial lymphocytes （IELs） in the gut, where it contributes to mucosal immunity and the maintenance of gut barrier integrity.