[Molecular mechanism on Sjögren's syndrome]

Sjögren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration into lachrymal and salivary glands leading to symptomatic dye eyes and mouth. Immunohistological studies have clarified that the majority of infiltrating lymphocytes around the lachrymal glands and labial salivary glands are CD4 positive alpha beta T cells. To analyze the nature of T cells in lachrymal glands and labial salivary glands, we examined TCR V beta genes of infiltrating T cells into both glands from SS patients, using PCR-SSCP and sequencing methods. The results showed the following two findings. 1) Some of T cells infiltrating in both glands expand clonally, suggesting that these cells proliferate by antigen-driven stimulation. 2) The common T cells accumulated in lachrymal and labial salivary glands. In conclusion, autoreactive T cells in lips and eyes should recognize the same epitopes of autoantigen in individual patients with SS. Further analysis on autoantigen using T cell lines from labial salivary glands supports the notion that Ro/SS-A 52 kD is a possible autoantigen recognized by autoreactive T cells.