Activation-induced cell death of peripheral blood T lymphocytes in patients with primary Sjögren’s syndrome

Abstract

Activation-induced cell death (AICD) in T lymphocytes is important for the maintenance of peripheral tolerance. We studied AICD of peripheral blood T cells from patients with primary Sj6gren's syndrome (SS). AICD was induced in mitogen-activated T cells in vitro using mAb to CD3 or Fas (CD95). Cell death and proliferation, Fas and Fas ligand (FasL) expression, and soluble Fas and soluble FasL production were measured. Surface phenotypes and cytokine production of AICDsurviving cells and effects of cytokines on AICD were examined. Anti-CD3 mAb induced cell death in SS and normal T cells in the presence of exogenous interleukin (IL)-2. In the absence of IL-2 anti-CD3 mAb induced cell proliferation in SS and normal T cells. There was no significant difference in Fas/FasL expression and sFas/sFasL production between SS patients and normals. AICD-surviving cells consisted of more CD4 + T cells and less CD8 + T cells in SS compared to normals. AICDsurviving cells produced abundant interferon-y and little IL-4. There was no significant difference in the effects of cytokines on AICD between SS patients and normals. These findings suggest that IL-2 is a critical factor for AICD. AICD works almost normally in SS T cells when sufficient IL-2 is present prior to T cell receptor re-stimulation.