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Updated: Jun 11, 2026
Artificial Antigen Presenting Cell (aAPC) Mediated Activation and Expansion of Natural Killer T Cells
Published on: December 29, 2012
Defective NKT cell activation by CD1d+ TRAMP prostate tumor cells is corrected by interleukin-12 with
Michael Nowak1, Mohammed S Arredouani, Adrian Tun-Kyi
1Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America. michael.nowak@ukb.uni-bonn.de
Abstract:
Numerical and functional defects of invariant natural killer T cells (iNKT) have been documented in human and mouse cancers, resulting in a defect in IFN production in several malignancies. iNKT cells recognize glycolipids presented on CD1d molecules by dendritic and related cells, leading to their activation and thereby regulating immune reactions. Activated iNKT cells cytokine secretion and cytotoxicity can inhibit existing and spontaneous tumor growth, progression, and metastasis. We have identified functional iNKT cell defects in the murine TRAMP prostate cancer model. We found that iNKT cells show the ability to migrate into TRAMP prostate tumors. This infiltration was mediated through CCL2: CCR5 chemokine: receptor interaction. Prostate tumor cells expressing CD1d partially activated iNKT cells, as appreciated by up-regulation of CD25, PD-1 and the IL-12R. However, despite inducing up-regulation of these activation markers and, hence, delivering positive signals, prostate tumor cells inhibited the IL-12-induced STAT4 phosphorylation in a cell-cell contact dependent but CD1d-independent manner. Consequently, tumor cells did not induce secretion of IFNgamma by iNKT cells. Blocking the inhibitory Ly49 receptor on iNKT cells in the presence of alpha-GalCer restored their IFNgamma production in vivo and in vitro. However, Ly49 blockade alone was not sufficient. Importantly, this defect could be also be reversed into vigorous secretion of IFNgamma by the addition of both IL-12 and the exogenous CD1d ligand alpha-galactosylceramide, but not by IL-12 alone, both in vivo and in vitro. These data underscore the potential to optimize iNKT-based therapeutic approaches.
Insights
Invariant natural killer T (iNKT) cells show defects in prostate cancer, inhibiting IFN-gamma production. Restoring iNKT cell function requires blocking inhibitory receptors and providing specific ligands and cytokines for therapeutic potential.
Area of Science:
- Immunology
- Oncology
- Cancer Research
Background:
- Invariant natural killer T (iNKT) cells play a crucial role in immune regulation and anti-tumor responses.
- Defects in iNKT cell function and number are observed in various cancers, impairing anti-tumor immunity.
- Prostate cancer models exhibit functional iNKT cell defects, impacting interferon-gamma (IFN-γ) production.
Purpose of the Study:
- To investigate the functional defects of iNKT cells in the TRAMP murine prostate cancer model.
- To elucidate the mechanisms underlying iNKT cell dysfunction in the tumor microenvironment.
- To explore strategies for restoring iNKT cell anti-tumor activity.
Main Methods:
- Analysis of iNKT cell infiltration and activation markers in TRAMP prostate tumors.
- Investigation of chemokine-receptor interactions (CCL2:CCR5) mediating iNKT cell migration.
- Assessment of prostate tumor cell interactions with iNKT cells, including CD1d presentation and inhibitory receptor signaling.
- Evaluation of therapeutic interventions, such as Ly49 receptor blockade, IL-12, and alpha-galactosylceramide (α-GalCer) administration.
Main Results:
- iNKT cells infiltrate TRAMP prostate tumors via CCL2:CCR5 interaction.
- Prostate tumor cells partially activate iNKT cells but inhibit IL-12-induced STAT4 phosphorylation in a CD1d-independent, cell-contact-dependent manner.
- Tumor cells suppressed IFN-γ secretion by iNKT cells.
- Blocking Ly49 receptors combined with α-GalCer restored IFN-γ production.
- Co-administration of IL-12 and α-GalCer effectively reversed iNKT cell dysfunction and induced vigorous IFN-γ secretion.
Conclusions:
- Prostate tumor cells induce functional iNKT cell defects through cell-contact-dependent inhibition, impairing anti-tumor immunity.
- Targeting inhibitory Ly49 receptors and providing exogenous CD1d ligands and cytokines can restore iNKT cell function.
- These findings highlight the potential for optimizing iNKT-based immunotherapies for prostate cancer.
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