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Updated: May 8, 2026
Characterization of Human Monocyte Subsets by Whole Blood Flow Cytometry Analysis
Published on: October 17, 2018
Phenotypic and functional heterogeneity of bovine blood monocytes
Jamal Hussen1, Anna Düvel, Olivier Sandra
1Immunology Unit, University of Veterinary Medicine, Hannover, Germany.
Insights
Bovine monocytes exhibit three distinct subsets: classical, intermediate, and nonclassical. Nonclassical monocytes show reduced inflammatory responses, unlike their human counterparts.
Area of Science:
- Immunology
- Veterinary Science
- Cell Biology
Background:
- Peripheral blood monocytes are heterogeneous in humans and mice.
- Understanding bovine monocyte heterogeneity is crucial for comparative immunology.
Purpose of the Study:
- To analyze the heterogeneity, phenotype, and function of bovine blood monocytes.
- To identify distinct bovine monocyte subsets and compare them to human and murine counterparts.
Main Methods:
- Flow cytometry was used to identify monocyte subsets based on CD14 and CD16 expression.
- Phenotypic markers (CD172a, MHC class II, CD163) and functional assays (phagocytosis, reactive oxygen species generation, cytokine expression) were analyzed.
- Inflammasome activation and response to Interferon-gamma (IFNγ) were assessed.
Main Results:
- Three bovine monocyte subsets were identified: classical (cM, 89%), intermediate (intM), and nonclassical (ncM).
- Distinct expression patterns of CD172a, MHC class II, and CD163 were observed across subsets.
- ncM exhibited reduced phagocytosis, reactive oxygen species generation, and inflammatory cytokine mRNA expression (CXCL8, CXCL1, IL-1β) post-LPS stimulation.
- Inflammasome activation occurred in cM and intM but not ncM.
- IFNγ induced CD16 expression on cM and promoted a cM to intM shift in vitro.
Conclusions:
- Bovine CD172a-positive mononuclear cells comprise three distinct monocyte subsets with unique phenotypes and functions.
- Bovine cM and intM share similarities with human monocyte subsets.
- Bovine ncM appear to be non-inflammatory, differing from human nonclassical monocytes.
Abstract:
Murine and human peripheral blood monocytes are heterogeneous in size, granularity, nuclear morphology, phenotype and function. Whether and how bovine blood monocytes follow this pattern was analyzed in this study. Flow cytometrically, classical monocytes (cM) CD14⁺CD16⁻, intermediate monocytes (intM) CD14⁺ CD16⁺ and nonclassical monocytes (ncM) CD14⁺ CD16⁺ were identified, with cM being the predominant subset (89%). cM showed a significant lower expression of CD172a, intM expressed the highest level of MHC class II molecules, and ncM were low positive for CD163. Compared to cM and intM, ncM showed a significantly reduced phagocytosis capacity, a significantly reduced generation of reactive oxygen species, and reduced mRNA expression of CXCL8, CXCL1 and IL-1β after LPS stimulation. Based on IL-1β secretion after LPS/ATP stimulation, the inflammasome could be activated in cM and intM, but not in ncM. IFNγ increased the expression of CD16 selectively on cM and induced a shift from cM into intM in vitro. In summary, bovine CD172a-positive mononuclear cells define three monocyte subsets with distinct phenotypic and functional differences. Bovine cM and intM share homologies with their human counterparts, whereas bovine ncM are not inflammatory monocytes.
