CD103, also known as integrin αEβ7, is a transmembrane heterodimeric receptor primarily expressed on the surface of certain immune cells, including intraepithelial lymphocytes （IELs）, tissue-resident memory T cells, and dendritic cells. It plays a crucial role in cell adhesion and migration by binding to E-cadherin, a protein abundant in epithelial cells, thereby facilitating immune cell retention within mucosal tissues such as the skin, lung, and gastrointestinal tract. In cancer immunology, CD103 is associated with immune checkpoint pathways and has been identified as a potential biomarker for predicting responses to immunotherapies, such as anti-PD-1 treatments. Additionally, CD103+ dendritic cells are known for their ability to cross-present antigens to CD8+ T cells, enhancing adaptive immune responses.