Monoclonal antibody detection of laminin in minor salivary glands of patients with Sjögren's syndrome.

The potential roles of the basement membrane proteins, laminin and fibronectin, and the cytoskeletal protein, tubulin, were assessed in the pathogenesis of Sjögren's Syndrome (SS) by comparing their expressions in SS with normal labial salivary gland (LSG) tissue. Laminin, fibronectin and tubulin expression were determined using well characterized monoclonal antibodies in the peroxidase anti-peroxidase technique on formalin-fixed LSG's from patients with SS and normal controls. Characteristic periductal staining for laminin occurred in the LSG's of 14/18 SS patients scored by one observer and 16/18 scored by the second observer. Staining of LSG's for laminin occurred in 2/35 control specimens consisting of 15 normal LSG's and 20 inflammatory lesions with attached normal LSG. The staining which occurred in the two controls was diffuse and 'non-specific' in one case, and indistinguishable from the characteristic periductal staining found in SS in the other case. Among the 20 controls containing inflammatory lesions, four showed diffuse staining for laminin within the actual lesion, but the adjacent LSG's did not stain. No statistically significant difference between SS and normal tissues stained by anti-fibronectin and anti-tubulin was observed. The study concluded that there was an increase in laminin or a laminin-like substance on salivary ductal epithelia of SS patients. This suggests a potential role for laminin in the pathologic mechanism and may indicate that increased laminin expression is a marker for SS.