Sjogren's Syndrome Antigen...Getting at theCause

Antigens are substances that can stimulate the immune system to develop a response resulting in the production of an antibody. Antibodies are proteins that can bind antigens in the normal immune response. When antigen comes from the body's own tissues (such as a certain tissue protein) it is referred to as an autoantigen. The antibody that acts against it is referred to as an autoantibody. When a disease is characterized by the production of autoantibodies, it is called an autoimmune disease.

Sjogren's syndrome is an autoimmune disease, characterized by the abnormal production of extra antibodies in the blood that are directed against various tissues of the body. This particular autoimmune illness is caused by inflammation in the glands of the body. Inflammation of the glands that produce tears (lacrimal glands) lead to decreased water production for tears and eye dryness. Inflammation of the glands that produce the saliva in the mouth (salivary glands, including the parotid glands) leads to mouth dryness.

Sjogren's syndrome classically combines dry eyes, dry mouth, and another disease of the connective tissues, most commonly rheumatoid arthritis. This syndrome is named after the Swedish ophthalmologist who first described it over 70 years ago.

Sjogren's syndrome that only involves the gland inflammation (only dryness of the eyes and mouth), is referred to as primary Sjogren's syndrome. Secondary Sjogren's syndrome involves not only gland inflammation, but is associated with a connective tissue disease, such as

• rheumatoid arthritis,
• systemic lupus erythematosus, or
• scleroderma.

Research scientists at the University of Tokushima in Japan identified a specific protein that was purified from the salivary glands of a mouse species that has the equivalent of Sjogren's syndrome. Dr. Norio Haneji and associates reported their data in SCIENCE (276: 604-606, 1997),which demonstrated that this protein may be an autoantigen which plays a critical role in stimulating the development of Sjogren's syndrome.

The identification of this protein autoantigen (named alpha-fodrin) could lead to new breakthroughs in treatment and/or prevention of Sjogren's syndrome and other autoimmune diseases.