Related Experiment Video
Updated: May 11, 2026
Simultaneous Study of the Recruitment of Monocyte Subpopulations Under Flow In Vitro
Published on: November 26, 2018
Comparative analysis of monocyte subsets in the pig
Lynsey Fairbairn1, Ronan Kapetanovic, Dario Beraldi
1The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United Kingdom.
Abstract:
Human and mouse monocyte can be divided into two different subpopulations based on surface marker expression: CD14/16 and Ly6C/CX3CR1, respectively. Monocyte subpopulations in the pig were identified based on reciprocal expression of CD14 and the scavenger receptor CD163. The two populations, CD14(hi)-CD163(low) and CD14(low)-CD163(hi), show approximately equal abundance in the steady-state. Culture of pig PBMCs in CSF1 indicates that the two populations are a maturation series controlled by this growth factor. Gene expression in pig monocyte subpopulations was profiled using the newly developed and annotated pig whole genome snowball microarray. Previous studies have suggested a functional equivalence between human and mouse subsets, but certain genes such as CD36, CLEC4E, or TREM-1 showed human-specific expression. The same genes were expressed selectively in pig monocyte subsets. However, the profiles suggest that the pig CD14(low)-CD163(high) cells are actually equivalent to intermediate human monocytes, and there is no CD14(-) CD16(+) "nonclassical" population. The results are discussed in terms of the relevance of the pig as a model for understanding human monocyte function.
Insights
Pig monocytes, identified by CD14 and CD163 markers, represent a maturation series regulated by CSF1. Pig monocyte subsets show distinct gene expression, with CD14(low)-CD163(high) cells resembling intermediate human monocytes.
Area of Science:
- Immunology
- Comparative genomics
- Cell biology
Background:
- Monocytes are key immune cells with distinct subpopulations in humans and mice, defined by surface markers like CD14/16 and Ly6C/CX3CR1.
- Understanding monocyte heterogeneity is crucial for immunology and disease research.
- Previous research suggested functional equivalence of monocyte subsets across species, but species-specific gene expression patterns have been noted.
Purpose of the Study:
- To identify and characterize monocyte subpopulations in pigs.
- To compare pig monocyte subsets with those in humans and mice.
- To investigate the role of CSF1 in pig monocyte differentiation and gene expression.
Main Methods:
- Isolation and analysis of pig peripheral blood mononuclear cells (PBMCs).
- Flow cytometry for identifying monocyte subpopulations based on CD14 and CD163 expression.
- Cell culture with CSF1 to study differentiation.
- Gene expression profiling using a pig whole genome microarray.
Main Results:
- Two distinct pig monocyte populations, CD14(hi)-CD163(low) and CD14(low)-CD163(hi), were identified with equal abundance.
- CSF1 stimulation induced a maturation series in pig monocytes.
- Gene expression analysis revealed species-specific patterns for certain monocyte-associated genes.
- Pig CD14(low)-CD163(high) monocytes appear functionally equivalent to intermediate human monocytes, lacking a direct counterpart to the human "nonclassical" CD14(-) CD16(+) subset.
Conclusions:
- Pig monocytes can be classified into two main subsets based on CD14 and CD163 expression.
- CSF1 is a key regulator of pig monocyte maturation.
- The pig may not fully recapitulate human monocyte heterogeneity, particularly the nonclassical subset.
- These findings impact the utility of pigs as a model for studying human monocyte biology and diseases.
