Sialochemical markers of salivary gland involvement with Sjogren's syndrome secondary to rheumatoid arthritis and primary biliary cirrhosis

Sjogren's syndrome is an autoimmune condition affecting the lacrimal and salivary glands and can be associated with rheumatoid arthritis and primary biliary cirrhosis. Parotid salivas collected from patients and normal controls were analysed for lactoferrin, IgA and beta(2)-microglobulin (measured by ELISA), and cystatin (measured by a enzyme inhibition assay). Output data provided less variable means, whilst expressing results as a proportion of the total protein provided greater specificity as markers for Sjogren's syndrome. Levels of specificity for IgA, lactoferrin and beta(2)-microglobulin were all high (100, 95 and 100%, respectively). Sensitivity levels of these markers (but not cystatin) tended to be similar for Sjogren's syndrome secondary to primary biliary cirrhosis (IgA, 25%; lactoferrin, 63%; and beta(2)-microglobulin, 50%), compared to Sjogren's syndrome secondary to connective tissue diseases such as rheumatoid arthritis (IgA, 50%; lactoferrin, 86%; and beta(2)-microglobulin; 38%).