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.