Cobalamin-Binding Proteins in Serum and Saliva from Patients with Sjögren's Syndrome

Cobalamin-binding proteins in saliva and in serum were determined in 28 patients with primary Sjögren's syndrome (primary SS), 8 patients with secondary SS and 20 matched healthy controls. The unsaturated transcobalamin II level in serum was significantly increased in patients with secondary SS. The unsaturated cobalamin binding capacity in saliva was increased in patients with primary SS. Considerable interindividual variations were found between patients and in the control group. The local production of cobalamin-binding proteins in SS was sufficient to achieve concentrations in saliva comparable to the control group. The cobalamin-binding capacity in saliva was significantly correlated to the albumin concentration in both primary and secondary SS patients, suggesting a defect in the aqueous phase.