Variations in the Phagosomal Environment of Human Neutrophils and Mononuclear Phagocyte Subsets

The phagosome microenvironment maintains enzyme activity and function. Here we compared the phagosomal pH of human neutrophils, monocytes, dendritic cells (DC), and monocyte-derived cells. An unexpected observation was the striking difference in phagosomal environment between the three monocytes sub...

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Bibliographic Details
Published in:Frontiers in immunology 2019-03, Vol.10, p.188-188
Main Authors: Foote, Juliet R, Patel, Amit A, Yona, Simon, Segal, Anthony W
Format: Article
Language:English
Subjects:
Biomarkers
Cellular Microenvironment - immunology
dendritic cell
Dendritic Cells - immunology
Dendritic Cells - metabolism
Humans
Hydrogen-Ion Concentration
Immunology
Immunophenotyping
Lysosomes - metabolism
macrophage
monocyte
Monocytes - immunology
Monocytes - metabolism
NADPH Oxidases - metabolism
neutrophil
Neutrophils - immunology
Neutrophils - metabolism
Oxidation-Reduction
Phagocytes - immunology
Phagocytes - metabolism
Phagocytosis
Phagosomes - metabolism
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Summary:The phagosome microenvironment maintains enzyme activity and function. Here we compared the phagosomal pH of human neutrophils, monocytes, dendritic cells (DC), and monocyte-derived cells. An unexpected observation was the striking difference in phagosomal environment between the three monocytes subsets. Classical monocytes and neutrophils exhibited alkaline phagosomes, yet non-classical monocytes had more acidic phagosomes, while intermediate monocytes had a phenotype in-between. We next investigated the differences between primary naïve DC vs. monocyte-derived DC (MoDC) and established that both these cells had acidic phagosomal environments. Across all phagocytes, alkalinization was dependent upon the activity of the NADPH oxidase activity, demonstrated by the absence of NADPH oxidase from a patient with chronic granulomatous disease (CGD) or the use of a pharmacological inhibitor, diphenylene iodonium (DPI). Interestingly, MoDC stimulated with bacterial lipopolysaccharide had increased phagosomal pH. Overall, the increase in alkalinity within the phagosome was associated with increased oxidase activity. These data highlight the heterogeneous nature and potential function of phagocytic vacuoles within the family of mononuclear phagocytes.
ISSN:1664-3224
1664-3224
DOI:10.3389/fimmu.2019.00188