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Establishment of Cytotoxic and Non-cytotoxic NK-92 Cell Clones - Evaluation of Their Function as Target Cells
Hans Bergman1, Elinda Hermanson1, Christer Lindqvist2
1Cell Biology, Biosciences, Faculty of Sciences and Engineering, Åbo Akademi University, Turku, Finland.
Background/Aim:
Previous studies have demonstrated that NK cells present in PBMCs might explain why clinical trials conducted with NK-92 as well as CAR modified NK-92 cells have to a large extent failed. Two NK-92 clones with different NK target cell properties have been established and are described here.
Materials And Methods:
Two NK-92 cell clones, NK-92 clone 1 and clone 2, were established using the limiting dilution technique. A time-resolved fluorometric assay (TDA-labeled NK-92 clone 1, 2 or K562 as target cells) was used for measuring their sensitivities to NK cell-mediated cytolysis and their NKG2D expression was identified with immunoblotting.
Results:
A striking difference between the NK-92 clones in their cytotoxic capacity against K562 cells was observed. A clear correlation was noticed between these NK-92 clones when used as target cells and their ability to kill K562 cells. A 50:1 effector:target ratio (PBMCs:NK-92 clone 1) gave 6.50±5.44% lysis whereas the corresponding value was 39.9±10.0% with NK-92 clone 2 as target cells. Interestingly, incubating PBMCs in medium for longer times slightly potentiated their NK activity also against the NK-92 clone 1 (E:T ratio 50:1), from 2.5±0.88% lysis (24 h pre-incubation time) to 13.7±9.04% (48 h) and 13.8±6.89% (72 h). Immunoblotting with anti-NKG2D antibodies stained an approximately 34 kDa protein band in lysates prepared from NK-92 clone 1 cells, which corresponds to the NKG2D antigen. A very faint band of the same size was observed in lysates prepared from NK-92 clone 2 cells.
Conclusion:
The NK-92 clones 1 and 2, established and described here, might turn out to be very useful for finding possible solutions for using NK-92 and CAR NK-92 cells in future treatments of human malignant diseases.
Insights
Two novel NK-92 cell clones were established, exhibiting distinct cytotoxic properties. These clones, particularly NK-92 clone 2, demonstrate enhanced killing of K562 target cells, offering potential for improved cancer immunotherapies.
Area of Science:
- Immunology
- Cell Biology
- Cancer Research
Background:
- Previous NK-92 cell clinical trials faced challenges, potentially due to peripheral blood mononuclear cell (PBMC) interactions.
- Understanding NK-92 cell properties is crucial for optimizing their therapeutic application.
Purpose of the Study:
- To establish and characterize two distinct NK-92 cell clones with varying target cell interaction capabilities.
- To investigate the cytotoxic potential and NKG2D expression of these new NK-92 clones.
Main Methods:
- NK-92 cell clones were generated using the limiting dilution technique.
- Cytolytic activity was assessed using a time-resolved fluorometric assay with K562 target cells.
- NKG2D expression was analyzed via immunoblotting.
Main Results:
- Significant differences in cytotoxic capacity against K562 cells were observed between the two NK-92 clones.
- NK-92 clone 2 exhibited markedly higher lysis of K562 cells compared to clone 1.
- NKG2D expression was detected in NK-92 clone 1, with minimal expression in clone 2.
Conclusions:
- The established NK-92 clones possess distinct characteristics relevant for NK cell-based therapies.
- These clones may serve as valuable tools for developing strategies to overcome limitations in current NK-92 and CAR NK-92 cell treatments.
- Further research with these clones could advance the use of NK cells in treating human malignancies.
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