Subcellular distribution of aquaporin 5 in salivary glands in primary Sjögren's syndrome.

Secretions from salivary and lacrimal glands are reduced in patients with primary Sjögren's syndrome (PSS). Since aquaporin 5 is involved in transport of water and is present in salivary and lacrimal glands, this protein was thought to have a major role in the pathogenesis of PSS. We used indirect immunofluorescence and an immunoperoxidase technique to assess expression and subcellular localisation of aquaporin 5 in patients and controls. Our results suggest that the distribution and density of aquaporin 5 in salivary glands does not differ between patients with PSS and those without. Thus, the role of aquaporin 5 in the pathogenesis of PSS needs to be reassessed and alternative pathogenetic mechanisms investigated.