title: Dendritic Cells and Monocytes with Distinct Inflammatory Responses Reside in Lung Mucosa of Healthy Humans.
abstract: Every breath we take contains potentially harmful pathogens or allergens. Dendritic cells (DCs), monocytes, and macrophages are essential in maintaining a delicate balance of initiating immunity without causing collateral damage to the lungs because of an exaggerated inflammatory response. To document the diversity of lung mononuclear phagocytes at steady-state, we performed bronchoscopies on 20 healthy subjects, sampling the proximal and distal airways (bronchial wash and bronchoalveolar lavage, respectively), as well as mucosal tissue (endobronchial biopsies). In addition to a substantial population of alveolar macrophages, we identified subpopulations of monocytes, myeloid DCs (MDCs), and plasmacytoid DCs in the lung mucosa. Intermediate monocytes and MDCs were highly frequent in the airways compared with peripheral blood. Strikingly, the density of mononuclear phagocytes increased upon descending the airways. Monocytes from blood and airways produced 10-fold more proinflammatory cytokines than MDCs upon ex vivo stimulation. However, airway monocytes were less inflammatory than blood monocytes, suggesting a more tolerant nature. The findings of this study establish how to identify human lung mononuclear phagocytes and how they function in normal conditions, so that dysregulations in patients with respiratory diseases can be detected to elucidate their contribution to immunity or pathogenesis.
authors.affiliation: Immunology and Allergy Unit, Department of Medicine, Solna, Karolinska Institutet, 171 76 Stockholm, Sweden;
authors.forename: Faezzah
authors.identifier: 0000-0003-4513-3600
authors.initials: F
authors.lastname: Baharom
authors.affiliation: Immunology and Allergy Unit, Department of Medicine, Solna, Karolinska Institutet, 171 76 Stockholm, Sweden;
authors.forename: Saskia
authors.initials: S
authors.lastname: Thomas
authors.affiliation: Division of Medicine, Department of Public Health and Clinical Medicine, Umeå University, 901 85 Umeå, Sweden; and.
authors.forename: Gregory
authors.identifier: 0000-0002-8753-830X
authors.initials: G
authors.lastname: Rankin
authors.affiliation: Immunology and Allergy Unit, Department of Medicine, Solna, Karolinska Institutet, 171 76 Stockholm, Sweden;
authors.forename: Rico
authors.initials: R
authors.lastname: Lepzien
authors.affiliation: Division of Medicine, Department of Public Health and Clinical Medicine, Umeå University, 901 85 Umeå, Sweden; and.
authors.forename: Jamshid
authors.identifier: 0000-0003-0041-4644
authors.initials: J
authors.lastname: Pourazar
authors.affiliation: Division of Medicine, Department of Public Health and Clinical Medicine, Umeå University, 901 85 Umeå, Sweden; and.
authors.forename: Annelie F
authors.identifier: 0000-0002-1533-9002
authors.initials: AF
authors.lastname: Behndig
authors.affiliation: Department of Clinical Microbiology, Infectious Diseases, Umeå University, 901 85 Umeå, Sweden.
authors.forename: Clas
authors.identifier: 0000-0003-2018-8592
authors.initials: C
authors.lastname: Ahlm
authors.affiliation: Division of Medicine, Department of Public Health and Clinical Medicine, Umeå University, 901 85 Umeå, Sweden; and.
authors.forename: Anders
authors.identifier: 0000-0002-2452-7347
authors.initials: A
authors.lastname: Blomberg
authors.affiliation: Immunology and Allergy Unit, Department of Medicine, Solna, Karolinska Institutet, 171 76 Stockholm, Sweden; anna.smed.sorensen@ki.se.
authors.forename: Anna
authors.initials: A
authors.lastname: Smed-Sörensen
mesh_terms: D000293:Adolescent; D000328:Adult; D003713:Dendritic Cells / Q000276:immunology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007249:Inflammation / Q000276:immunology*; D008297:Male; D009000:Monocytes / Q000276:immunology*; D020545:Respiratory Mucosa / Q000276:immunology*; D055815:Young Adult