Increased frequency of cells secreting interleukin-6 and interleukin-10 in peripheral blood of patients with primary Sjögren's syndrome.

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Sjögren's syndrome (SS) is a chronic autoimmune disease of exocrine glands. There is increasing evidence that interferon-gamma (IFN-gamma) plays a role in the pathogenesis of SS. It has also been suggested that other type 1 cytokines, as well as interleukin-6 (IL-6), IL-10 and transforming growth factor-beta, are important in the induction and/or maintenance of SS. The aim of this study was to investigate the type 1/type 2 cytokine pattern in peripheral blood of primary SS patients. The enzyme-linked immunospot (ELISPOT) assay was performed to quantify the number of mononuclear cells (MNC) secreting IFN-gamma, IL-6 and IL-10 in peripheral blood samples from 33 patients with primary SS and 12 healthy controls. The mean number of cells secreting IFN-gamma was 9/105 MNC in the SS patient group, and 4/105 MNC in the control group (P = 0.73). Fifteen of the SS patients had anti-Ro 52 kDa antibodies in serum. In this patient group the mean number of cells secreting IFN-gamma was 4/105 MNC, while in the patient group without such antibodies the mean number of cells secreting IFN-gamma was 14/105 MNC (P = 0.04). The mean number of cells secreting IL-6 was 12 000/105 MNC in the SS patient group, and 5000/105 MNC in the control group (P = 0.01). The mean number of cells secreting IL-10 was 270/105 MNC in the SS patient group, and 180/105 MNC in the control group (P = 0.04). The SS patients had a significantly higher number of cells secreting IL-6 and IL-10 in peripheral blood than the healthy controls, which may facilitate B-cell activation and production of autoantibodies.