title: Immunophenotypic characterization and depletion of pulmonary intravascular macrophages of horses.
abstract: Pulmonary intravascular macrophages (PIMs) are present in horses and are believed to increase their sensitivity to endotoxin-induced cardio-pulmonary shock. However, owing to a lack of a marker for PIMs and the inability to isolate them, their precise contributions in the horse remain unknown. We designed this study to identify an immuno-phenotypic marker for PIMs and to develop a protocol for their transient depletion with gadolinium chloride (GC). GC is a lanthanide that has been used to deplete liver and lung macrophages. The horses (N = 15) were divided into control (n = 5) and GC-treated (n = 10) groups and the lung samples were examined by routine and immunocytochemical light and electron microscopy. GC-treated horses were euthanized at 48 h (n = 6) and 72 h (n = 4) post-treatment. The PIMs reacted with MAC-387 but not with ED-1 and CD-68 anti-macrophage antibodies. GC reduced the number of PIMs in horses at 48 and 72 h compared with the control (p < 0.05). There were increased intravascular TUNEL-positive cells in GC-treated horses and electron microscopy showed apoptotic PIMs in these horses. These data show that MAC-387 is a reliable marker for PIMs and GC is a safe tool to reduce the number of PIMs.
authors.affiliation: Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: Om P
authors.initials: OP
authors.lastname: Parbhakar
authors.forename: Tanya
authors.initials: T
authors.lastname: Duke
authors.forename: Hugh G G
authors.initials: HG
authors.lastname: Townsend
authors.forename: Baljit
authors.initials: B
authors.lastname: Singh
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015415:Biomarkers; D003287:Contrast Media / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology*; D006736:Horses / Q000276:immunology*; D007150:Immunohistochemistry / Q000662:veterinary; D016130:Immunophenotyping / Q000662:veterinary; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D008168:Lung / Q000166:cytology / Q000473:pathology / Q000648:ultrastructure; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods / Q000662:veterinary; D016253:Microscopy, Immunoelectron / Q000662:veterinary; D011897:Random Allocation
chemical_list: D000893:Anti-Inflammatory Agents; D015415:Biomarkers; D003287:Contrast Media; D005682:Gadolinium; C038958:gadolinium chloride