title: Primary type II alveolar epithelial cells present microbial antigens to antigen-specific CD4+ T cells.
abstract: Type II alveolar epithelial cells (AEC) can produce various antimicrobial and proinflammatory effector molecules. This, together with their abundance and strategic location, suggests a role in host defense against pulmonary pathogens. We report that murine type II AEC, like their human counterparts, express class II major histocompatibility complex (MHC). Using a murine model of pulmonary tuberculosis, we find that type II AEC become activated and have increased cell surface expression of class II MHC, CD54, and CD95 following infection. Type II AEC use the class II MHC pathway to process and present mycobacterial antigens to immune CD4+ T cells isolated from mice infected with Mycobacterium tuberculosis. Therefore, not only can type II AEC contribute to the pulmonary immunity by secreting chemokines that recruit inflammatory cells to the lung, but they can also serve as antigen-presenting cells. Although type II AEC are unlikely to prime naïve T cells, their ability to present antigens to T cells demonstrates that they can participate in the effector phase of the immune response. This represents a novel role for type II AEC in the immunological response to pulmonary pathogens.
authors.affiliation: Division of Rheumatology, Brigham and Women's Hospital, Smith Bldg., Rm. 516, 1 Jimmy Fund Way, Boston, MA 02115, USA.
authors.forename: Hajer
authors.initials: H
authors.lastname: Debbabi
authors.forename: Shamik
authors.initials: S
authors.lastname: Ghosh
authors.forename: Arati B
authors.initials: AB
authors.lastname: Kamath
authors.forename: Jennifer
authors.initials: J
authors.lastname: Alt
authors.forename: Daphne E
authors.initials: DE
authors.lastname: Demello
authors.forename: Sarah
authors.initials: S
authors.lastname: Dunsmore
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Behar
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D004847:Epithelial Cells / Q000276:immunology; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000276:immunology; D011650:Pulmonary Alveoli / Q000276:immunology*; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D000949:Histocompatibility Antigens Class II; D019014:fas Receptor; D018799:Intercellular Adhesion Molecule-1