An investigation of parotid gland function and histopathology in autoimmune disease-prone mice of different age groups.

This work aimed to characterize parotid gland function in autoimmune disease-prone murine strains (MRL/n, MRL/l and NZB/W) in relation to increasing age and to relate the extent of functional impairment to the intensity of histopathologic changes observed at the different ages. Pilocarpine-stimulated parotid saliva was collected to assess salivary flow rate and composition. Parotid tissue was then removed for histopathologic assessment. Parotid flow rates were not significantly reduced in autoimmune strains compared to controls but were reduced with age in NZB/W mice and in males of the C57 (control) strain. Age-related salivary compositional changes were present in MRL/l mice and in male NZB/W mice. Focal lymphocytic adenitis increased with age in prevalence and intensity in both sexes. The functional and histopathologic changes were not closely correlated. These results suggest that the parotid gland of autoimmune disease-prone mice provides only a poor replication of the salivary changes in human Sjögren's syndrome. Nevertheless, both the functional and histopathological changes developing in these strains, even though of limited extent, are significantly influenced by age.