A discrete subpopulation of human monocytes expresses a neutrophil-like proinflammatory (P) phenotype.
We have demonstrated that a discrete and naturally occurring subpopulation of human monocytes expresses a neutrophil-like proinflammatory (P) phenotype. P monocytes constitute 20-30% of the circulating monocyte pool and are characterized by 1) avid adherence to extracellular matrix through high-level cell-surface expression of alpha 5-, beta 1-, and beta 2-integrins; 2) high capacity to produce reactive oxygen species; 3) high content of serine proteinases and alpha 1-proteinase inhibitor; and 4) proteolytic activity against a soluble peptide human leukocyte elastase substrate, [3H]elastin, and solid-phase fibronectin, even in the presence of proteinase inhibitors. However, P monocytes express little or no cell-surface HLA-DR antigen, suggesting that they are unable to participate in specific immune responses. In contrast, the remainder of circulating monocytes have a low proinflammatory potential but contain the population of monocytes with high-level expression of HLA-DR antigen. P monocytes can readily be separated from the remainder of monocytes on the basis of 1) their capacity to adhere to fibronectin; and 2) their absent expression of HLA-DR antigen when flow cytometry or immunomagnetic beads are used. Our data indicate that, when recruited to sites of inflammation, P monocytes can either promote resolution of inflammation or contribute to tissue injury.
Owen
C A
CA
Department of Medicine, University of Utah Health Sciences Center, Salt Lake City 84132.
Campbell
M A
MA
Boukedes
S S
SS
Stockley
R A
RA
Campbell
E J
EJ
D002469:Cell Separation; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D016023:Integrins / Q000032:analysis; D009000:Monocytes / Q000201:enzymology / Q000276:immunology / Q000502:physiology*; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology / Q000502:physiology*; D010641:Phenotype; D012697:Serine Endopeptidases / Q000032:analysis; D000515:alpha 1-Antitrypsin / Q000032:analysis
D006684:HLA-DR Antigens; D016023:Integrins; D000515:alpha 1-Antitrypsin; D012697:Serine Endopeptidases