T cell clones from a Sjögren's syndrome salivary gland biopsy produce high levels of IL‐10
Sjögren's syndrome (SS) is characterized by a focal periductal salivary gland infiltrate consisting mainly of T and B lymphocytes. Most of the T cells bear the memory of CD4+ Th‐1‐like phenotype and express high levels of class II, though CD8+ cells are also present. We have studied 17 labial salivary gland and 15 peripheral blood T cell clones from a patient with primary SS. The tissue clones were 71% CD8+ and 29% CD4+, and the peripheral blood‐derived clones were 60% CD8+ and 40% CD4+. The CD4+ T cell clones from both the salivary gland and autologous peripheral blood were of the Th1 phenotype, in that they produced interferon‐gamma (IFN‐γ) and IL‐2 but very little IL‐4 after 24 h stimulation with phorbol myristate acetate and anti‐CD3 antibody. The salivary gland‐derived CD4+ clones produced 15 times more IL‐10 (7.92 ng/ml) than peripheral blood‐derived CD4+ clones (0.52 ng/ml, P≤0.02). The tissue CD8+ clones produced 1.2 times (P<0.04) more IFN‐γ and CD4+ clones produced 3.5 times less IL‐2 (P<0.02) than the respective PBM‐derived clones. The accumulation of Th1‐type cells producing high levels of IL‐10 in the salivary gland suggests a specific immunoregulatory function at the site of inflammation in SS.