PHENOTYPIC CHARACTERIZATION OF MONONUCLEAR INFLAMMATORY CELLS IN SALIVARY-GLANDS OF BIOBREEDING RATS

The purpose of this study was to assess whether mononuclear cell abnor malities exist in salivary glands from autoimmune Bio-Breeding (BB) ra ts. Frozen sections of gland tissues were prepared from five diabetes- resistant BB rats (BB-DR), from five BB rats with diabetes (BB-DP) and from five Wistar rats. A panel of six monoclonal antibodies was used to identify membrane antigens associated primarily with monocytes (ED1 ), mature tissue macrophages (ED2), lymphoid macrophages (ED3), MHC cl ass II (Ia) antigen (OX6), CD5+ T lymphocytes (OX19), and rat B lympho cytes (OX33). Normal submandibular, sublingual and parotid glands cont ained few ED1-positive cells, usually two or fewer per field. Tissue m acrophages identified by clone ED2 comprised a major mononuclear cell subset in both Wistar and BB rats. However, the number of ED2-positive mononuclear cells was significantly depressed in the submandibular an d parotid glands from BE-DR and BB-DP animals, being present in quanti ties 25-50% of those observed in glands from normal Wistar rats (p < 0 .001). In contrast, 25- to 30-fold greater numbers of ED3-positive mac rophages were observed in submandibular glands from BE rats (p < 0.001 ). MHC class II (Ia) antigen expression also was 4- to 6-fold greater in BE rat submandibular glands, compared to Wistar rats (p < 0.001). C D5+ T-lymphocytes were rare or entirely absent in BE sublingual glands (0 to 1 cell per 0.87 mm(2) field), compared to 47 cells per field fr om Wistar sublingual glands. No B lymphocytes were identified with ant ibody OX33 in any of the rat strains. These findings indicate that BB rat salivary glands differ significantly from Wistar salivary glands. In BB rats there is a rich population of EDS-positive macrophages and T lymphocytes in submandibular gland, low quantities of T lymphocytes in sublingual gland, and fewer ED2-positive macrophages in all three m ajor salivary glands. These differences in mononuclear cell subpopulat ions may also influence salivary gland function in mucosal immunity. ( C) 1997 Elsevier Science Ltd.