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Reversal of multiple-site tumor cell-induced immunosuppression by specific cytokines and pharmacological agents
C C Ting1, J Wang, M E Hargrove
1Division of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract:
The present study explores a model for tumor cell-induced immunosuppression and reversal of suppression by cytokines and other pharmacological agents. To simulate tumor-cell-induced suppression, a panel of suppressor agents which included CsA (cyclosporin A), SSP (staurosporine), BSO (L-buthionine-[S,R]-sulfoximine) and PMA, and a panel of anti-suppressor agents which included IL-2, IL-4, GSH (glutathione) and amiloride, were tested. These suppressor/anti-suppressor agents acted differently on four specific sites of the immune arm that affected the alpha CD3-induced T cell proliferative and cytotoxic responses. They included (1) IL-2 production, (2) PKC-regulated cytolytic granule production, (3) GSH-regulated maturation of functional granules, and (4) granule exocytosis. When a single suppressor agent was used, all the suppressor agents tested in this study inhibited the generation of alpha CD3-induced activated killer cells (CD3-AK), whereas alpha CD3-induced proliferation was inhibited by CsA, BSO, and EL-4 tumor cells. Except for EL-4, suppression induced by a single suppressor agent could be corrected by an appropriate single anti-suppressor agent. Multiple suppressor agents induced profound suppression of CD3-AK response. In most cases, multiple anti-suppressor agents were required to correct the immune defects induced by multiple suppressor agents. Finally, EL-4 tumor-cell-induced immunosuppression could not be corrected by any single anti-suppressor agent tested, but a combination of IL-4, GSH and amiloride fully restored the CD3-AK response. These results suggest that tumor cells may induce multiple immune defects that require multiple anti-suppressor agents for correcting the defects to restore the host immunocompetence.
Insights
This study models how tumor cells suppress the immune system. It found that multiple immune defects caused by tumors require multiple agents to restore immune function.
Area of Science:
- Immunology
- Cancer Biology
- Pharmacology
Background:
- Tumor cells can induce immunosuppression, hindering anti-tumor immune responses.
- Understanding the mechanisms of tumor-induced immunosuppression is crucial for developing effective cancer therapies.
Purpose of the Study:
- To explore a model of tumor cell-induced immunosuppression.
- To investigate the reversal of this suppression using cytokines and pharmacological agents.
- To identify specific immune defects targeted by suppressor and anti-suppressor agents.
Main Methods:
- Tested suppressor agents (cyclosporin A, staurosporine, L-buthionine-[S,R]-sulfoximine, PMA) and anti-suppressor agents (IL-2, IL-4, glutathione, amiloride).
- Assessed effects on alpha CD3-induced T cell proliferation and cytotoxic responses, focusing on IL-2 production, PKC-regulated granule production, GSH-regulated granule maturation, and granule exocytosis.
- Evaluated single and multiple agent combinations for their ability to reverse suppression.
Main Results:
- All tested suppressor agents inhibited alpha CD3-induced activated killer cells (CD3-AK).
- Single suppressor agents, except for EL-4 tumor cells, could be reversed by single anti-suppressor agents.
- Multiple suppressor agents caused profound suppression, often requiring multiple anti-suppressor agents for correction.
- EL-4 tumor cell-induced immunosuppression required a combination of IL-4, glutathione, and amiloride for full restoration of CD3-AK response.
Conclusions:
- Tumor cells can induce multiple, complex immune defects.
- Restoring immunocompetence in the presence of tumor-induced immunosuppression often necessitates a multi-agent therapeutic approach.
- Targeting multiple pathways is key to overcoming tumor-mediated immune evasion.