Preferential localization of CD8⁺ α(E)β₇⁺ T cells around acinar epithelial cells with apoptosis in patients with Sjogren's syndrome

The T lymphocytes that infiltrate the exocrine glands in Sjogren's syndrome (SS) play a key role in damaging glandular epithelial cells, but the mechanisms of tiffs damage by T lymphocytes are not fully understood. To determine the cellular basis of this phenomenon, we focused our attention on the T lymphocytes around acinar epithelial cells in SS. We showed that CD8⁺ but not CD4⁺ T lymphocytes were located around the acinar epithelial cells and that a majority of these CD8⁺ T lymphocytes possess an unique integrin, α(E)β₇ (CD103). The acinar epithelial cell adherent with α(E)β₇ (CD103)+ CD8⁺ T lymphocytes was apoptotic. Both the perforin/granzyme B and Fas/Fas ligand pathways were implicated in the process of programmed cell death in lacrimal glands. These results suggested that α(E)β₇ integrin, by interacting with E-cadherin, mediates the adhesion between CD8⁺ T lymphocytes and acinar epithelial cells in SS and participates in inducing epithelial cell apoptosis, leading to secretory dysfunction of exocrine glands, a hallmark of SS.