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Updated: May 20, 2026
Isolation and Characterization of Neutrophil-derived Microparticles for Functional Studies
Published on: March 2, 2018
Human microparticles generated during sepsis in patients with critical illness are neutrophil-derived and modulate
Priya S Prakash1, Charles C Caldwell, Alex B Lentsch
1Division of Research, Department of Surgery University of Cincinnati, Cincinnati, Ohio, USA. priya.prakash09@gmail.com
Background:
Microparticles (MPs) are 0.3 μm to 1.0 μm vesicles generated after cell activation or apoptosis that may play a role in the pathophysiology of sepsis. We sought to elucidate the role of MPs in patients with critical illness and hypothesized that MPs are generated at the site of inflammation and can modulate the immune response.
Methods:
Surgical patients with critical illness with ongoing sepsis were enrolled from the intensive care unit of an urban, Level I trauma center from March to June 2011. Abdominal washings and bronchoalveolar lavage fluid were collected from sites of inflammation. MPs were isolated using differential centrifugation, then characterized by flow cytometry. Immunologic assays were conducted by incubating neutrophil-derived MPs (NDMPs) with a human monocytic cell line (THP-1). A p value ≤0.05 was considered significant.
Results:
MPs were absent in noninflamed foci in patients, whereas NDMPs were present in locations of inflammation. NDMPs were added to cultured THP-1 cells to quantify immunomodulatory effects. THP-1 cells were able to phagocytose NDMPs. Cells that ingested NDMPs demonstrated increased activation. In contrast, bystander THP-1 cells without ingested NDMPs demonstrated decreased activation.
Conclusion:
NDMPs are generated at the site of inflammation in patients with critical illness during sepsis. They have a divergent effect on the immune response by activating phagocytic cells and deactivating bystander cells. NDMPs may play an important role in regulating the inflammatory response to sepsis in patients with critical illness.
Insights
Neutrophil-derived microparticles (NDMPs) are generated at inflammation sites in critical illness sepsis. These NDMPs uniquely activate immune cells while deactivating bystander cells, suggesting a key role in sepsis regulation.
Area of Science:
- Immunology
- Critical Care Medicine
- Cell Biology
Background:
- Microparticles (MPs) are cell-derived vesicles implicated in sepsis pathophysiology.
- MPs are generated during cell activation or apoptosis.
- Their specific role in critical illness sepsis requires elucidation.
Purpose of the Study:
- To investigate the generation and function of MPs in critically ill patients with sepsis.
- To test the hypothesis that MPs originate at inflammatory sites and modulate immune responses.
Main Methods:
- Collected inflammatory site fluids (abdominal washings, bronchoalveolar lavage) from surgical sepsis patients.
- Isolated and characterized MPs using differential centrifugation and flow cytometry.
- Assessed immunomodulatory effects of neutrophil-derived MPs (NDMPs) on monocytic cells (THP-1).
Main Results:
- NDMPs were detected exclusively at sites of inflammation, not in non-inflamed areas.
- THP-1 cells phagocytosed NDMPs, leading to increased activation.
- Bystander THP-1 cells, not ingesting NDMPs, showed decreased activation.
Conclusions:
- NDMPs are produced at inflammatory loci in sepsis patients.
- NDMPs exert differential immune effects: activating phagocytes and suppressing bystander cells.
- NDMPs likely play a significant role in modulating the inflammatory response during critical illness sepsis.
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