Fibrinolysis-resistant fibrin deposits in minor labial salivary glands of patients with Sjögren's syndrome.

Minor labial salivary glands obtained at biopsy from 12 patients with Sjögren's syndrome were investigated by immunomorphological methods for the presence of fibrinolysis-resistant fibrin deposition. Fibrin could be found in extracellular localization between individual inflammatory cells infiltrating minor salivary glands. In the areas surrounding mononuclear infiltrations the labeling for fibrin showed an essentially fibrillar pattern. Staining for factor XIII A was observed over fibrin deposits and in large, stellate cells not showing reaction for fibrin. Here it is demonstrated that factor XIII A+ tissue macrophages are in an intimate relationship with fibrin deposits. The authors suggest that tissue macrophages may play a regulatory role in fibrin accumulation in association with autoimmune inflammation and consequently in demarcation of the inflamed tissue.