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Active specific chemoimmunotherapy of lymph-node metastasis from a poorly immunogenic murine fibrosarcoma
Abstract:
The fibrosarcoma MCA-SP, which was recently induced with methylcholanthrene (MCA) in C3H/HeJ mice, displays poor immunogenicity in in vivo prophylaxis. A cell variant MCA-SPN1, which bears a tumor-specific transplantation antigen (TSTA) cross-reactive with the parental line MCA-SP, was selected because of its proclivity for axillary lymph-node metastases. Although these lymph-node metastases were resistant to sinecomitant (post-excisional) immunity, they were susceptible to combined active and passive specific chemoimmunotherapy, using tumor-specific, 1-butanol-extracted, preparative isoelectric focusing-purified, TSTA (1 microgram weekly sc injections), cyclophosphamide (CY, a single intraperitoneal 20 mg/kg dose), and adoptive transfer of immune splenic T lymphocytes, which had been re-stimulated in vitro with extracted TSTA and interleukin-2. This triple regimen both reduced the incidence of spontaneous lymph-node metastases, and prolonged the survival of tumor-bearing, as well as tumor-resected hosts. The results from local adoptive transfer assay using T-lymphocyte subpopulations of spleen and lymph nodes in these treated hosts suggested that Lyt 2+ cytotoxic T-lymphocytes (CTL) mediated in vivo tumor-neutralization. Thus TSTA/CY/CTL therapy activates tumoricidal host responses effective against the poorly immunogenic MCA-SP tumor and its lymph-node metastases.
Insights
This study shows that a combination of tumor-specific transplantation antigen (TSTA), cyclophosphamide (CY), and cytotoxic T-lymphocytes (CTL) therapy can effectively combat poorly immunogenic fibrosarcoma. This triple regimen reduces metastases and improves survival in mice.
Area of Science:
- Immunology
- Oncology
- Cancer Research
Background:
- Fibrosarcoma MCA-SP in C3H/HeJ mice exhibits poor immunogenicity, hindering effective in vivo prophylaxis.
- A variant, MCA-SPN1, was identified for its metastatic potential and cross-reactivity with a tumor-specific transplantation antigen (TSTA).
Purpose of the Study:
- To evaluate the efficacy of a combined chemoimmunotherapy regimen against a poorly immunogenic fibrosarcoma and its metastases.
- To investigate the role of cytotoxic T-lymphocytes (CTL) in mediating anti-tumor responses.
Main Methods:
- Administered a triple regimen: purified TSTA, cyclophosphamide (CY), and adoptive transfer of interleukin-2-stimulated splenic T lymphocytes.
- Assessed the incidence of lymph-node metastases and host survival.
- Utilized local adoptive transfer assays with T-lymphocyte subpopulations to identify effector cells.
Main Results:
- The TSTA/CY/CTL triple regimen significantly reduced spontaneous lymph-node metastases.
- This therapy prolonged survival in both tumor-bearing and tumor-resected hosts.
- Lyt 2+ cytotoxic T-lymphocytes (CTL) were identified as the primary mediators of in vivo tumor neutralization.
Conclusions:
- The combined TSTA/CY/CTL therapy effectively activates tumoricidal host responses against the poorly immunogenic MCA-SP fibrosarcoma.
- This approach demonstrates potential for treating established tumors and preventing metastasis.