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Patients with Sjogren's syndrome may have a dysfunctional parasympathetic nervous system, which might explain why the disease causes decreased saliva and tear production. Sjogren's syndrome is characterized mostly by dry eyes and dry mouth.

The human T-cell lymphotropic virus type I (HTLV-I) may be associated with some cases of rheumatoid arthritis and Sjogren's syndrome. Sjogren's syndrome is an autoimmune disease characterized by inflammatory changes in salivary and other glands. Studies in Japan, where HTLV-I infection is widespread, show that people who tested positive for HTLV-I were more likely to have rheumatoid arthritis. People with Sjogren's syndrome were also more likely to test positive and they had antibodies against HTLV-I in their saliva. Viral DNA has also been found in the synovial fluid of joints in people with rheumatoid arthritis.

Epstein-Barr virus (EBV) causes infectious mononucleosis, a disease characterized by enlargement of the lymph nodes and spleen, and increased numbers of abnormal mononuclear leukocytes (white blood cells with a single nucleus). The virus infects the immune B cells and multiplies in the salivary glands and surface tissues of the nasal and throat passages. After the initial infection, the virus remains dormant in the host's body, that is, exists without being infective. EBV can stimulate the production of autoantibodies, which are abnormal immune proteins directed against the body's own tissues and cells. Various lines of evidence suggest that EBV may be involved in the development of two autoimmune disorders, rheumatoid arthritis and Sjogren's syndrome. Rheumatoid arthritis is an inflammatory joint disease characterized by the production of antibodies directed against the cell nucleus. Sjogren's syndrome is characterized by the accumulation of lymphocytes (immune cells), destruction of secretory cells in the salivary gland, and abnormal immune function. The role of EBV infection in rheumatoid arthritis and Sjogren's syndrome was assessed by measuring the levels of antibodies directed against specific EBV antigens, or elements of the virus that trigger an immune response. These viral antigens were components of the EBV nucleus and included Epstein-Barr nuclear antigens (EBNA)-1,-2,-3,-4, and -6. The type of antibody measured was immunoglobulin G (IgG). Increased levels of IgG antibodies to EBNAs were detected in patients with Sjogren's syndrome, but not in patients with rheumatoid arthritis. The relation between EBV infection and Sjogren's syndrome requires further investigation. (Consumer Summary produced by Reliance Medical Information, Inc.)