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Updated: Jan 5, 2026
Isolation and Characterization of Neutrophils with Anti-Tumor Properties
Published on: June 19, 2015
Bacterial Killing Activity of Polymorphonuclear Myeloid-Derived Suppressor Cells Isolated From Tumor-Bearing Dogs
Sabina I Hlavaty1, Yu-Mei Chang2, Rachel P Orth3
1Garden Immune Regulation Laboratory, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States.
Abstract:
Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are implicated in the progression and outcome of a variety of pathological states, from cancer to infection. Our previous work has identified three antimicrobial peptides differentially expressed by PMN-MDSCs compared to conventional neutrophils isolated from dogs, mice, and human patients with cancer. We therefore hypothesized that PMN-MDSCs in dogs with cancer possess antimicrobial activity. In the current work, we observed that exposure of PMN-MDSCs to Gram-negative bacteria (Escherichia coli) increased the expression of reactive oxygen species by the PMN-MDSCs, indicating that they are capable of initiating an anti-microbial response. Electron microscopy revealed that the PMN-MDSCs phagocytosed Gram-negative and Gram-positive (Staphylococcus aureus) bacterial species. Lysis of bacteria within some of the PMN-MDSCs suggested bactericidal activity, which was confirmed by the recovery of significantly lower numbers of bacteria of both species following exposure to PMN-MDSCs isolated from tumor-bearing dogs. Our data therefore indicate that PMN-MDSCs isolated from dogs with cancer, in common with PMNs, have phagocytic and bactericidal activity. This nexus of immunosuppressive and antimicrobial activity reveals a hitherto unrecognized function of MDSCs.
Insights
Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in dogs with cancer exhibit antimicrobial properties. These cells can phagocytose and kill bacteria, revealing a dual role in immunity.
Area of Science:
- Immunology
- Veterinary Medicine
- Cell Biology
Background:
- Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are known to play a role in various diseases, including cancer.
- Previous research identified antimicrobial peptides expressed by PMN-MDSCs in dogs, mice, and humans with cancer.
Purpose of the Study:
- To investigate the antimicrobial activity of PMN-MDSCs in dogs with cancer.
- To determine if PMN-MDSCs can combat bacterial infections.
Main Methods:
- Exposure of PMN-MDSCs to Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria.
- Measurement of reactive oxygen species production.
- Electron microscopy to observe phagocytosis.
- Bacterial viability assays to assess bactericidal activity.
Main Results:
- PMN-MDSCs exposed to E. coli increased reactive oxygen species production, indicating an antimicrobial response.
- Electron microscopy confirmed that PMN-MDSCs phagocytosed both Gram-negative and Gram-positive bacteria.
- Significant reduction in bacterial numbers after exposure to PMN-MDSCs from tumor-bearing dogs, demonstrating bactericidal activity.
Conclusions:
- PMN-MDSCs from dogs with cancer possess both phagocytic and bactericidal capabilities, similar to conventional neutrophils.
- This study uncovers a previously unrecognized dual function of PMN-MDSCs, combining immunosuppressive and antimicrobial activities.
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