It has been found that the pattern of cytokine mRNA expression was closely associated with the initiation and the progression of the disease process. The cytokine mRNA expression in the labial glands of patients with Sjögren's syndrome was examined by a PCR-based method. Th1 cytokines, such as IL-2 and IFN-gamma, were consistently detected in all patients examined, while Th2 cytokines, such as IL-4 and IL-5, were detected in some cases with strong B cell accumulation in the labial glands. These results suggest that Th1 cytokines are essential in the induction and/or maintenance of the disease, while Th2 cytokines are involved in the progression of the disease process. Other studies were also reviewed and a role of cytokines, produced by T cells and the target organ, was discussed.