Salivary and serum beta 2-microglobulin in the diagnosis of primary Sjögren's syndrome.

beta 2-microglobulin (beta 2m) serum and salivary levels and total protein salivary levels were determined in 15 patients with primary Sjögren's syndrome (pSS), 14 patients with sicca syndrome and 11 healthy subjects. beta 2m serum and salivary levels were higher (p < 0.005) in the patients with pSS than in the healthy subjects and in the patients with sicca syndrome. The bioptic focus scores of minor salivary glands were correlated to beta 2m salivary levels with a high significance (p < 0.001) but were not correlated to beta 2m serum levels. The assessment of beta 2m serum and salivary levels is a non-invasive clinical investigation, which may be easily repeated. It is a very sensitive and highly specific test for the diagnosis of pSS. It may be therefore a useful mean to follow the natural course of pSS and to evaluate the effects of therapy.