Abstract

alpha E beta 7 is a member of the integrin family and is expressed almost exclusively by cells of the T lymphocyte lineage in mucosal tissues. Expression is induced by transforming growth factor beta in the mucosal microenvironment. Genetic elements that control transcription are under investigation and may prove valuable for directing the expression of transgenes in mucosal T cells. The only known ligand for alpha E beta 7 is E-cadherin, which is expressed on epithelial cells. In this article, molecular aspects of ligand recognition by alpha E beta 7 in relation to recent structural data on cadherin domains are reviewed. Expression of alpha E beta 7 is often increased in inflammatory diseases, particularly where T cells infiltrate epithelial tissues. The function of alpha E beta 7 is not yet fully understood, but it is likely to be important in retention of T cells in mucosal tissues and may also have a role in cell signalling and communication between lymphocytes and epithelial surfaces.