The overall goal of this study is to investigate the potential use of salivary protein electrophoresis in the diagnosis of Sjogren's syndrome (SS). SS is an autoimmune disease that predominantly affects salivary, lacrimal and other exocrine glands. It is frequently associated with a connective tissue disease or autoimmune disease such as rheumatoid arthritis,, systemic lupus-erythematosus, progressive systemic sclerosis, vasculitis, primary biliary cirrhosis and cryoglobulinemia. The etiology of SS is not clearly understood. The diagnosis of SS is based on cumulative clinical and laboratory findings in which a salivary gland biopsy is essential to establish the diagnosis. However, the sensitivity, specificity, and reliability of methods employed for evaluation of the glandular and extra-glandular signs and symptoms are not uniform. Studies from independent laboratories have indicated that saliva of patients with SS and rheumatoid arthritis exhibit additional anionic proteins (SS-P) on gel electrophoresis. This finding has a potential of providing a convenient non-invasive diagnostic criteria and eliminate the need for a salivary gland biopsy. In addition, characterization of the origin and nature of SS-P may be a key to understand the mechanism of SS development. The origin of SS-P is unknown and no definite correlation between the appearance of these protein bands and SS has been established. In this study we propose to employ our current knowledge of normal saliva and salivary proteins to investigate changes in salivary proteins in patients suffering from SS. Parotid saliva will be subjected to different systems of gel electrophoresis. Salivary proteins will be characterized based on their molecular weight, charge and immunological reactivity. The electrophoretic profile of salivary proteins of patients with SS will be compared with that of sex/age and ethnic matched controls. The origin of SS-P will be examined based on its (their) immunological reactivity with anti-human saliva and anti-human whole serum. In addition, SS-P band will be excised from the gel and antisera will be raised against it. The reactivity of this antisera with other salivary and serum proteins will be examined. Results of this study may provide a simple and fairly inexpensive tool for the diagnosis of SS, thereby, reducing the extensive laboratory testing currently used for the diagnosis of the disease.