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Updated: May 17, 2026
Orthotopic Implantation and Peripheral Immune Cell Monitoring in the II-45 Syngeneic Rat Mesothelioma Model
Published on: October 2, 2015
Incomplete tumour control following DNA vaccination against rat gliomas expressing a model antigen
Christian Ginzkey1, Sven Eicker, Matthias Marget
1Department of Neurosurgery, University of Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Background:
Vaccination against tumour-associated antigens is one approach to elicit anti-tumour responses. We investigated the effect of polynucleotide (DNA) vaccination using a model antigen (E. coli lacZ) in a syngeneic gliosarcoma model (9L).
Methods:
Fisher 344 rats were vaccinated thrice by intramuscular injection of a lacZ-encoding or a control plasmid in weekly intervals. One week after the last vaccination, lacZ-expressing 9L cells were implanted into the striatum.
Results:
After 3 weeks, in lacZ-vaccinated animals the tumours were significantly smaller than in control-vaccinated animals. In cytotoxic T cell assays lysis rates of >50 % could only be observed in a few of the lacZ-vaccinated animals. This response was directed against lacZ-expressing and parental 9L cells but not against syngeneic MADB 106 adenocarcinoma cells. In Elispot assays interferon-γ production was observed upon stimulation with 9LlacZ and 9L wild-type but not MADB 106 cells. This response was higher for lacZ-immunized animals. All animals revealed dense infiltrates with CD8+ lymphocytes and, to a lesser extent, with NK cells. CD25-staining indicated cells possibly associated with the maintenance of peripheral tolerance to self-antigens. All tumours were densely infiltrated by microglia consisting mostly of ramified cells. Only focal accumulation of macrophage-like cells expressing ED1, a marker for phagocytic activity, was observed.
Conclusion:
Prophylactic DNA vaccination resulted in effective but incomplete suppression of brain tumour formation. Mechanisms other than cytotoxic T cell responses as measured in the generally used in vitro assays appear to play a role in tumour suppression.
Insights
Prophylactic DNA vaccination using a model antigen significantly suppressed brain tumour growth in rats. Immune responses, including cytotoxic T cells and interferon-gamma production, were observed, suggesting complex mechanisms beyond direct T cell killing.
Area of Science:
- Immunology
- Oncology
- Neuroscience
Background:
- Tumour-associated antigen vaccination is a strategy to induce anti-tumour immune responses.
- This study utilized a syngeneic gliosarcoma model (9L) in Fisher 344 rats to investigate DNA vaccination.
Purpose of the Study:
- To evaluate the efficacy of polynucleotide (DNA) vaccination against a model antigen (E. coli lacZ) in suppressing gliosarcoma formation.
- To investigate the immune mechanisms underlying tumour suppression induced by DNA vaccination.
Main Methods:
- Rats received three intramuscular DNA plasmid injections (lacZ-encoding or control) weekly.
- Following vaccination, lacZ-expressing 9L gliosarcoma cells were implanted intracranially.
- Tumour size, cytotoxic T cell activity, interferon-gamma production, and immune cell infiltrates were assessed.
Main Results:
- DNA vaccination significantly reduced tumour size compared to controls.
- Cytotoxic T cell assays showed limited lysis, but interferon-gamma production was elevated in vaccinated animals upon stimulation with tumour cells.
- Tumours showed infiltrates of CD8+ lymphocytes, NK cells, and microglia; limited macrophage activity was noted.
Conclusions:
- Prophylactic DNA vaccination effectively suppressed brain tumour formation, although not completely.
- Mechanisms beyond standard in vitro cytotoxic T cell assays likely contribute to tumour suppression.
