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Updated: Aug 9, 2026
Isolation and Flow Cytometric Analysis of Glioma-infiltrating Peripheral Blood Mononuclear Cells
Published on: November 28, 2015
Dexamethasone-induced abolition of the inflammatory response in an experimental glioma model: a flow cytometry study
B Badie1, J M Schartner, J Paul
1Department of Neurological Surgery, University of Wisconsin School of Medicine, Madison 53792-3232, USA. badie@neurosurg.wisc.edu
Insights
Dexamethasone, a steroid, significantly inhibits the infiltration of lymphocytes and microglia into brain tumors in a rat glioma model. This finding is crucial for evaluating immunotherapeutic strategies for brain tumors.
Area of Science:
- Neuro-oncology
- Immunology
- Pharmacology
Background:
- Steroids, like dexamethasone, are used to manage cerebral edema in brain tumors.
- Steroids possess immunosuppressive functions that can impact the central nervous system's response to tumors.
Purpose of the Study:
- To investigate the effects of dexamethasone on inflammatory cell infiltration in an immunogenic rat glioma model.
- To quantify the extent of microglia, macrophage, and lymphocyte infiltration into tumors and surrounding brain tissue.
Main Methods:
- Utilized flow cytometry to analyze inflammatory cell infiltration in C6 gliomas from dexamethasone-treated and untreated rats.
- Monoclonal antibodies were used to identify and quantify microglia, macrophages, and lymphocytes based on specific cell surface antigens.
- Assessed infiltration into the tumor, tumor periphery, and contralateral hemisphere.
Main Results:
- Microglia and lymphocytes were the predominant infiltrating cells in the glioma model.
- Low-dose dexamethasone (0.1 mg/kg/day) significantly inhibited microglia and lymphocyte infiltration into tumors (>50%).
- Higher dexamethasone doses further reduced lymphocyte infiltration but did not enhance microglia inhibition; macrophage infiltration remained unaffected.
Conclusions:
- Flow cytometry is effective for characterizing tumor-associated inflammatory cells in gliomas.
- Dexamethasone, even at low doses, significantly inhibits brain tumor infiltration by lymphocytes and microglia.
- These results are important for considering steroid effects in the context of experimental immunotherapies for brain tumors.
Object:
Commonly used for management of cerebral edema in patients with brain tumors, steroid medications also have immunosuppressive functions. To characterize the effects of steroids on the central nervous system's response to tumors more clearly, flow cytometry was used to quantify the extent of inflammatory cell infiltration in an immunogenic rat glioma model.
Methods:
Freshly prepared 11-day-old intracranial C6 tumors that had been excised from dexamethasone-treated and untreated rats were labeled ex vivo with monoclonal antibodies against CD 11b/c, CD45, and CD8a antigens. The extent of microglia (CD11b/c-highly positive, CD45-slightly positive cell), macrophage (CD11b/c-highly positive, CD45-highly positive cell), lymphocyte (CD11b/c-negative, CD45-highly positive cell), and cytotoxic T-cell (CD8a-positive cell) infiltration into each rat's tumor, tumor periphery, and contralateral tumor-free hemisphere was analyzed using flow cytometry. Microglia and lymphocytes constituted a significant component of infiltrating cells in this model, comprising 23 +/- 3% and 33 +/- 5% of viable cells, respectively. Macrophages, on the other hand, accounted for only 9 +/- 1% of infiltrating cells. Treatment of rats with a 7-day course of low-dose dexamethasone (0.1 mg/kg/day) resulted in a greater than 50% inhibition of microglia (p = 0.03) and lymphocyte (p = 0.001) infiltration into tumors. Increasing the dexamethasone dose to 1 mg/kg/day further abolished lymphocyte infiltration (89% inhibition, p = 0.001) but had no additional inhibitory effect on microglia invasion. Macrophage infiltration of tumors was not inhibited at the dexamethasone doses used in this study (p = 0.42).
Conclusions:
Flow cytometry is a valuable technique for characterizing tumor-associated inflammatory cells in gliomas. Even at low doses, dexamethasone was found to inhibit significantly the infiltration of brain tumors by lymphocytes and microglia. These findings should be considered when experimental immunotherapeutic strategies are evaluated for clinical application.
