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Updated: Jan 29, 2026
Flow Cytometry-based Assay for the Monitoring of NK Cell Functions
Published on: October 30, 2016
NK Cells Require Cell-Extrinsic and -Intrinsic TYK2 for Full Functionality in Tumor Surveillance and Antibacterial
Natalija Simonović1, Agnieszka Witalisz-Siepracka1,2, Katrin Meissl1
1Department of Biomedical Science, Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
Abstract:
Tyrosine kinase 2 (TYK2) is a widely expressed receptor-associated kinase that is involved in signaling by a variety of cytokines with important immune regulatory activities. Absence of TYK2 in mice results in impaired NK cell maturation and antitumor activity, although underlying mechanisms are largely unknown. Using conditional ablation of TYK2 in NK cells we show that TYK2 is required for IFN-γ production by NK cells in response to IL-12 and for an efficient immune defense against Listeria monocytogenes Deletion of TYK2 in NK cells did not impact NK cell maturation and IFN-γ production upon NK cell activating receptor (actR) stimulation. Similarly, NK cell-mediated tumor surveillance was unimpaired upon deletion of TYK2 in NK cells only. In line with the previously reported maturation-associated Ifng promoter demethylation, the less mature phenotype of Tyk2 NK cells correlated with an increased CpG methylation at the Ifng locus. Treatment with the DNA hypomethylating agent 5-aza-2-deoxycytidine restored the ability of Tyk2 NK cells to produce IFN-γ upon actR but not upon IL-12 stimulation. NK cell maturation was dependent on the presence of TYK2 in dendritic cells and could be rescued in Tyk2-deficient mice by treatment with exogenous IL-15/IL-15Rα complexes. IL-15 treatment also rescued the in vitro cytotoxicity defect and the impaired actR-induced IFN-γ production of Tyk2 NK cells. Collectively, our findings provide the first evidence, to our knowledge, for a key role of TYK2 in the host environment in promoting NK cell maturation and antitumor activity.
Insights
Tyrosine kinase 2 (TYK2) is crucial for natural killer (NK) cell maturation and immune defense. Its absence impairs NK cell function, but TYK2 in the host environment, not NK cells, is key for maturation and anti-tumor activity.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Tyrosine kinase 2 (TYK2) is a receptor-associated kinase involved in cytokine signaling and immune regulation.
- Absence of TYK2 in mice leads to impaired natural killer (NK) cell maturation and antitumor activity, with unclear mechanisms.
- NK cells are vital for innate immunity, cytokine production (like IFN-γ), and tumor surveillance.
Purpose of the Study:
- To elucidate the role of TYK2 in NK cell maturation, function, and antitumor activity.
- To investigate the specific cell types (NK cells vs. dendritic cells) requiring TYK2 for these processes.
- To understand the molecular mechanisms, including epigenetic regulation, underlying TYK2's impact on NK cell function.
Main Methods:
- Conditional ablation of TYK2 in NK cells and dendritic cells in mice.
- Analysis of NK cell maturation, IFN-γ production, and cytotoxicity.
- Assessment of immune defense against *Listeria monocytogenes* infection.
- Investigation of epigenetic modifications (CpG methylation) at the *Ifng* locus.
- Treatment with DNA hypomethylating agents and cytokine complexes (IL-15/IL-15Rα).
Main Results:
- TYK2 is essential for NK cell IFN-γ production in response to IL-12 and for effective *Listeria monocytogenes* defense.
- TYK2 deletion in NK cells alone did not affect NK cell maturation or IFN-γ production upon activating receptor stimulation.
- NK cell maturation and antitumor activity were dependent on TYK2 in dendritic cells, not NK cells.
- Reduced TYK2 expression correlated with increased CpG methylation at the *Ifng* locus, impairing IFN-γ production.
- IL-15 treatment rescued NK cell cytotoxicity and IFN-γ production defects in *Tyk2*-deficient NK cells.
Conclusions:
- TYK2 plays a critical role in the host environment, particularly in dendritic cells, for promoting NK cell maturation and antitumor immunity.
- Epigenetic regulation at the *Ifng* locus is a key mechanism affected by TYK2 deficiency.
- Targeting TYK2 in the host environment, rather than solely in NK cells, may be a strategy to enhance immune responses.
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