The immunology of Sjögren's syndrome: emphasis on the role of salivary gland autoantigen

Primary Sjögren's syndrome (SS) in humans is an autoimmune disease characterized by diffuse lymphoid cell infiltrates in the salivary and lacrimal glands, resulting in symptoms of dry mouth and dry eye due to insufficient secretion. The spectrum of presentation of the disease is broad, ranging from the organ-localized dysfunction of exocrine gland to systemic complications such as liver, kidney and lung involvement. A significant proportion of the SS patients may develop malignant lymphoproliferative disorders such as B cell lymphoma and macroglobulinemia. Although it has been assumed that a combination of immunologic, genetic, and environmental factors may play a key role on the development of autoimmune lesion in the salivary and lacrimal gland, little is known about the pathogenesis of primary SS. The hypofunction of the salivary glands is associated with lymphocytic infiltration, in which autoreactive T cells recognize unknown self-antigen and play a central role in the pathobiology of SS. This disease is also characterized by systemic production of auto antibodies to ribonucleoprotein particles SS-A/Ro and SS-B/La, however, the specificity for this immunogenicity remains to be defined. The 120 kD α-fodrin is an important salivary gland autoantigen implicated in the development of SS in both animal model and SS patients. This article will review recent observations of the immunological aspects of autoimmune sialadenitis as it occurs in SS patients, and in murine model for SS, and particularly emphasize on the role of salivary gland autoantigen during development of auto immune lesions in SS.Biomedical Reviews 1998; 9: 131-141