Diagnostic significance of salivary levels of beta 2-microglobulin in Sjögren's syndrome.

To evaluate the diagnostic significance of salivary beta 2m in Sjögren's syndrome we measured salivary beta 2m levels in 19 patients with primary sicca syndrome (PSS), 15 with secondary Sjögren's syndrome (SSS) and compared the results with 20 normal healthy persons. We showed that beta 2m is specifically excreted in the saliva, because in normal saliva the concentration of beta 2m was unrelated to IgA levels. Also in normals, there was no relationship between serum and saliva concentrations of beta 2m. The mean saliva levels of beta 2m were increased in PSS (1.13 +/- 0.58) and SSS (1.39 +/- 0.69) compared with the levels in normals (0.53 +/- 0.22). The determination of beta 2m in the saliva can therefore be used as a noninvasive measurement for the confirmation of the diagnosis Sjögren's syndrome.