CD103
CD103 is the alpha chain of the integrin alphaEbeta7, encoded by the ITGAE gene and paired exclusively with the beta7 subunit. The receptor recognizes E-cadherin on epithelial cells, anchoring lymphocytes within epithelial layers. CD103 defines intraepithelial lymphocytes in the gut and marks the mucosal dendritic cell population that metabolizes retinal to retinoic acid and imprints gut-homing receptors on responding T cells. It is also a defining surface feature of tissue-resident memory T cells and of a major regulatory T cell fraction in tumors. Consequently CD103 is a central marker in mucosal immunology and in studies of tumor-infiltrating lymphocytes.
