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In Vitro and In Vivo Assessment of T, B and Myeloid Cells Suppressive Activity and Humoral Responses from Transplant Recipients
Published on: August 12, 2017
Bystander central memory but not effector memory CD8+ T cells suppress allograft rejection
1Center for Biomedical Research, University of Texas Health Center, Tyler, TX 75708, USA.
Bystander central memory (TCM) CD8+ T cells, not effector memory (TEM) cells, suppress immune responses and allograft rejection. These memory T cells migrate to lymph nodes, unlike TEM cells, to inhibit T cell activation and proliferation.
Area of Science:
- Immunology
- Cellular Immunology
- Transplantation Immunology
Background:
- Memory T cells are crucial for adaptive immunity, responding rapidly to antigens.
- The role of bystander memory T cells in immune responses to irrelevant antigens was previously unclear.
- It was generally accepted that bystander memory T cells remain neutral during immune responses.
Purpose of the Study:
- To investigate the behavior and function of bystander memory T cells (TCM and TEM) in the context of allograft rejection.
- To determine if bystander memory T cells can suppress immune responses and T cell proliferation.
- To elucidate the mechanisms and requirements for suppression mediated by bystander memory T cells.
Main Methods:
- Comparison of migration patterns and proliferation of bystander central memory (TCM), effector memory (TEM), and naive CD8+ T cells in recipient mice.
- Assessment of allograft rejection and T cell proliferation in draining lymph nodes (DLN).
- Investigation of the roles of IL-15 and TGF-beta1 in bystander TCM cell-mediated suppression.
Main Results:
- Bystander TCM cells, but not TEM cells, suppressed allograft rejection and T cell proliferation in DLN.
- TCM cells migrated to DLN and exhibited faster turnover, suggesting an advantage in suppression.
- TEM cells migrated to inflammatory graft sites but not DLN, failing to suppress immune responses.
- Suppression by bystander TCM cells was dependent on IL-15 and TGF-beta1.
Conclusions:
- Bystander central memory (TCM) CD8+ T cells are potent suppressors of immune responses, not neutral bystanders.
- Migration to lymph nodes is essential for bystander memory T cells to exert suppression.
- IL-15 and TGF-beta1 are critical mediators of TCM cell-driven suppression, impacting cellular immunology and potentially tolerance induction.
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