Objective: To characterize the initiation and progress of localized autoimmune damage in Sjögren's syndrome (SS), an autoimmune disease that is also considered to be a lymphoaggressive disorder, by examining the pattern of cytokine production at the site of autoimmune damage.
Methods: Using a polymerase chain reaction-based method, cytokine messenger RNA (mRNA) expression in the labial salivary glands of 15 patients with SS was investigated. In addition, the infiltrating lymphocytes in the labial salivary glands were examined immunohistochemically.
Results: Messenger RNAs of Th1 cytokines, such as interleukin-2 (IL-2) and interferon-gamma, were consistently detected in all patients, while Th2 cytokine mRNAs, such as IL-4 and IL-5, were detected in some cases, in association with strong B cell accumulation in the labial salivary glands. Other cytokine mRNAs produced by a variety of cell types, including IL-10, IL-6, and transforming growth factor beta (TGF beta), were also consistently detected in all patients, while IL-12 mRNA was detected in some of the patients.
Conclusion: These results suggest that Th1 cytokines, as well as IL-10, IL-6, and TGF beta, are essential in the induction and/or maintenance of SS, while Th2 cytokines are involved in the progression of the disease process, especially local B cell activation.