title: MHC class II antigen-bearing dendritic cells in pulmonary tissues of the rat. Regulation of antigen presentation activity by endogenous macrophage populations.
abstract: Collagenase digestion of tissue slices from perfused, lavaged SPF rat lung released approximately 10(8) viable mononuclear cells per gram tissue, which comprised 35% T lymphocytes and up to 26% macrophages. A subset of these cells that were Ia+, surface Ig-, nonadherent, FcR- and of ultra low density (putative dendritic cells [DC]), presented protein antigen to immune T cells in vitro, and this function was inhibited by the presence of low numbers of endogenous adherent, FcR+ cells (putative macrophages). APCs were also identified in digests from tracheal epithelium, and were shown to bind antigen in immunogenic form as a result of natural (inhalation) exposure in vivo. Immunoperoxidase staining of frozen sections revealed populations of strongly Ia+ cells with prominent DC-like morphology within the alveolar septal walls and the tracheal epithelium; in both areas, they were closely associated with pleiomorphic cells that expressed macrophage surface markers. We accordingly postulate that interactions between Ia+ antigen-presenting DCs and endogenous tissue macrophages play an important role in regulating T cell activity in the respiratory tract.
authors.affiliation: Clinical Immunology Research Unit, Princess Margaret Hospital, Subiaco, Western Australia.
authors.forename: P G
authors.initials: PG
authors.lastname: Holt
authors.forename: M A
authors.initials: MA
authors.lastname: Schon-Hegrad
authors.forename: J
authors.initials: J
authors.lastname: Oliver
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D003713:Dendritic Cells / Q000145:classification* / Q000276:immunology; D004847:Epithelial Cells; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007150:Immunohistochemistry; D008264:Macrophages / Q000145:classification* / Q000276:immunology; D010047:Ovalbumin / Q000276:immunology; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000276:immunology; D051381:Rats; D011919:Rats, Inbred Strains; D014132:Trachea / Q000166:cytology
chemical_list: D000949:Histocompatibility Antigens Class II; D010047:Ovalbumin