Alpha E : No More Rejection?

Integrin αEβ7 (CD103) has been an enigmatic and tantalizing molecule (1). The history of experiments on its functional significance is a record of promise and disappointment in equal measure. CD103 has been considered to have a role mainly or exclusively in the mucosal immune system, but this supposition now needs to be reappraised. The molecule is expressed at high levels by mucosal T cells, especially the CD8⁺ population in the epithelium of the gut, but is found on small subsets of T cells elsewhere. It is also present on mucosal mast cells and mucosal dendritic APCs. This eccentric pattern of expression has recently been extended to include splenic CD4⁺ CD25⁺ Treg cells, ∼30% of which are CD103⁺ (2). A plausible explanation for the expression profile is that the αE subunit is transcriptionally regulated by transforming growth factor...