Accumulation of macrophages with dendritic cell characteristics in the pulmonary response to Listeria.
Pulmonary immunity reflects a balance between proinflammatory and immunosuppressive factors in the lung. To determine the immune activities of exudate macrophages in the pulmonary immune response, Lewis rats were injected intratracheally with heat-killed Listeria (HKL), labeled ex vivo with the lipophilic dye PKH-26. At 24 h, macrophages from bronchoalveolar lavage fluid were purified on the basis of their surface membrane expression of RMA, a macrophage-specific antigen, which is brightly expressed by resident alveolar macrophages but dimly expressed by monocytes. Pulmonary macrophages were analyzed for uptake of PKH-26-HKL, and RMA(bright/dim) macrophages sorted by FACS were compared for cytokine expression, nitric oxide (NO) release, and APC activities. RMA(bright) macrophages were OX-62(-), B7(-), and factor XIIIa(-); they were the dominant mediators of phagocytosis when low doses of HKL were administered intratracheally but did not support the proliferation of T lymphocytes. RMA(dim) exudate macrophages were OX-62(+), B7(+), and factor XIIIa(+). They expressed more IL-1 and TNF, but less nitric oxide, than did RMA(bright) macrophages; they were excellent APCs for T cell responses. We conclude that a subset of RMA(dim) exudate macrophages shows phenotypic and functional evidence of dendritic cell differentiation.
Kradin
R L
RL
Departments of Pathology and Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA. rkradin@partners.org
Sakamoto
H
H
Preffer
F I
FI
Dombkowski
D
D
Springer
K M
KM
Leary
C P
CP
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D018836:Inflammation Mediators / Q000378:metabolism; D008088:Listeriosis / Q000276:immunology*; D008168:Lung / Q000276:immunology; D016676:Macrophages, Alveolar / Q000276:immunology*; D009569:Nitric Oxide / Q000378:metabolism; D018410:Pneumonia, Bacterial / Q000276:immunology*; D051381:Rats; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000276:immunology
D018836:Inflammation Mediators; D009569:Nitric Oxide