Mast cells in the labial salivary glands of patients with Sjögren's syndrome: a histochemical, immunohistochemical, and electron microscopical study.

Mast cells in labial salivary glands obtained from patients with xerostomia with or without focal sialadenitis/Sjögren's syndrome were studied. There was no significant correlation between the intensity of local lymphocyte infiltration and the morphometrically analysed number of mast cells staining positive with toluidine blue. Histamine staining with heterologous 11C antiserum showed significantly fewer positive cells than staining with toluidine blue (mean (SD) 62 (10) v 138 (30)). This suggests heterogeneity of the mast cell population. Furthermore, there was a correlation between the focus score and the number of mast cells containing histamine. This suggests that the proliferation of mast cells containing histamine may be locally regulated by the immune inflammation, possibly through mediators from macrophages and fibroblasts. In contrast, the number of mast cells staining positive with toluidine blue could not be used as a marker of the degree of local inflammation. Although transmission electron microscopic analysis did not disclose signs of 'en masse' mast cell degranulation, mast cells may have a role in the local disease process.