Salivary Immunoglobulins in Sjögren's Syndrome

Abstract

Using a new electro-immunodiffusion assay, serum and salivary immunoglobulin levels were measured in patients with SjÖgren’s syndrome (SS) and in normal control subjects. Salivary IgG levels were generally higher in the patients (mean 17.3 mg%, SEM 1.7) compared to normals (mean 12.1 mg%, SEM 1.3), the higher values usually correlating with elevated serum IgG levels. Salivary IgA levels were similar in both groups – a mean of 10.3 mg%, SEM 2.5 in normals and 8.9 mg%, SEM 2.0 in the patients. In the latter group much of the salivary IgA was secretory IgA; absolute levels of secretory IgA ranged from 2.5 to 6.4 mg% (mean 4.4). No measurable levels of IgM were detected in the salivas of patients or normal subjects, although IgM was demonstrated by immunofluorescence in labial gland biopsies from two patients. Four patients had serum anti-salivary duct antibodies, but none had this autoantibody in their saliva. Thus, patients with SS retain competence of the salivary immune system even in the advanced stages of their disease.