[Oral immune system and oral immune disorder.].

Oral immune system is maintained by various lymphoid tissues in head and neck region and efficient function of oral mucosa and saliva. A variety of oral immune disorders such as infection, allergic disease and autoimmune disease are induced by dysfunction of oral immune system. Sjogren's syndrome is an autoimmune disease that affects exocrine glands, including salivary glands, causing dry mouth symptoms. Because the pathogenesis of Sjogren's syndrome is complex, the study with multiple approaches using many models has been developed to understand the precise mechanism of the disease onset.