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Rescue of the tumor-specific immune response of aged mice in vitro
Abstract:
In contrast to young mice, old mice fail to reject a transplanted challenge of the highly immunogenic, ultraviolet light-induced tumor 1591-RE. Old mice also fail to mount a cytolytic tumor-specific immune response in vivo, and spleen cells of old mice are defective in their ability to generate tumor-specific T cells in vitro. In the present study we report the results of cell culture mixing experiments that show that this deficiency is due to a decreased responsiveness of the Lyt-2+ tumor-specific cytolytic T cell precursors of the old animals. We also demonstrate with limiting dilution analysis that the defective responsiveness is not due to a clonal exhaustion of the precursors. In fact, the responsiveness could be restored in vitro by culturing the spleen cells of old animals at high density or by the addition of excess Lyt-1-/Lyt-2-/2000-rad-resistant spleen cells from young or old mice. Our results suggest that the rescue of tumor immunity in old individuals may be possible, perhaps by educating effector cells in vitro for adoptive immunotherapy.
Insights
Old mice exhibit impaired tumor immunity due to defective T cell precursors. Their immune response can be restored in vitro, suggesting potential for adoptive immunotherapy in aged individuals.
Area of Science:
- Immunology
- Aging Research
- Cancer Immunology
Background:
- Aging impairs the immune system's ability to reject tumors.
- Old mice fail to reject transplanted tumors and mount effective anti-tumor immune responses.
- Spleen cells from old mice show defects in generating tumor-specific T cells.
Purpose of the Study:
- Investigate the cause of defective T cell generation in old mice.
- Identify mechanisms underlying the age-related decline in anti-tumor immunity.
- Explore strategies for restoring tumor immunity in aged individuals.
Main Methods:
- Cell culture mixing experiments using spleen cells from young and old mice.
- Limiting dilution analysis to assess T cell precursor responsiveness.
- In vitro culture of spleen cells at varying densities and with added accessory cells.
Main Results:
- Defective anti-tumor immunity in old mice is linked to decreased responsiveness of Lyt-2+ cytolytic T cell precursors.
- This defect is not due to clonal exhaustion of precursors.
- Immune responsiveness was restored in vitro by high-density culture or addition of accessory spleen cells.
Conclusions:
- Age-related immune deficiency in tumor rejection stems from impaired T cell precursor function.
- Restoring T cell precursor responsiveness in vitro offers a potential therapeutic avenue.
- Educating effector cells in vitro may enable adoptive immunotherapy for enhancing tumor immunity in the elderly.