[Study of apoptosis in Sjögren's syndrome]

To clarify the role of apoptosis in the pathogenesis of Sjögren's syndrome (SS), we investigated apoptosis and apoptosis-related molecules in peripheral blood lymphocytes (PBL) and salivary glands (SG) from SS patients and normal controls. In PBL, SS T lymphocytes showed accelerated in vitro apoptosis, and CD4+ T cells showed increased Fas expression compared to those in normal controls. Interestingly, SS T cells also showed increased Bcl-2 expression. The acinar epithelial cells in SS were Fas+ and FasL+, and these cells died by apoptosis. The majority of infiltrating lymphocytes in SS were Fas+ and Bcl-2+, while few lymphocytes expressed FasL. In situ detection of apoptosis showed minimal cell death among lymphocytes, particularly in dense periductal foci. Bax seemed to be expressed in apoptotic acinar cells. In conclusion, blocked apoptosis of SG infiltrating lymphocytes as well as enhanced apoptosis of peripheral T cells may be characteristics of SS. SS acinar cells may die by apoptosis, and this may ultimately lead to SG destruction in SS patients.