Sjögren's syndrome: a condition with features of chronic graft-versus-host disease: does duct cell adhesion or permeability play a role in pathogenesis?

Primary and Secondary Sjögren's syndrome are disease complexes characterized by periductal inflammatory cell infiltration of the salivary and lacrimal glands and manifest as dry mouth and dry eyes. Secondary Sjögren's syndrome may be associated with a connective tissue disorder. Additional extraglandular features in Sjögren's syndrome include a generalized inflammatory exocrinopathy that might be associated with abnormalities of both humoral and cellular mediated immunity. Similar inflammatory changes and extraglandular features, including an altered immune response, have been reported in patients developing graft-versus-host disease after bone-marrow transplantation and in patients with primary biliary cirrhosis. The periductal nature of the inflammatory response involving minor salivary and other glands raises the possibility of altered duct cell adhesion or permeability in playing a role in the aetiopathogenesis of Sjögren's syndrome. The paper pulls together evidence that could be interpreted in this light. Evidence for bacterial or viral factor(s) altering the antigenicity of the histocompartibility (HC) complex on ductal cells in Sjögren's syndrome patients is also described. A hypothesis is proposed for Sjögren's syndrome in which the principal feature is an alteration in salivary gland duct cell adhesion or permeability. A re-evaluation of current knowledge of these two conditions from a clinical and experimental context are interpreted in this light.