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Updated: Jun 29, 2026
06:08
A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity
Published on: August 9, 2017
Olive Leaf Extract Enhances Natural Killer Cell-Mediated Cytotoxicity against Colorectal Cancer Cells
Gulnihal Sisman1, Ayfer Sendul2, Abdurrahim Kocyigit3
1Bezmialem Vakıf University, Health Sciences Instute, Department of Medical Biochemistry, Istanbul, Turkey.
Iranian Journal of Immunology : IJI
|June 28, 2026
Summary
Olive Leaf Extract (OLE) enhances Natural Killer (NK) cell activity against colorectal cancer (CRC) cells. This study shows OLE boosts NK-cell cytotoxicity at physiologically achievable doses, offering a promising CRC therapeutic strategy.
Area of Science:
- Immunology
- Oncology
- Natural Products Chemistry
Background:
- Natural Killer (NK) cells are crucial for eliminating malignant cells through cytotoxicity.
- Olive Leaf Extract (OLE), rich in oleuropein and hydroxytyrosol, has shown direct anticancer effects.
- OLE's therapeutic potential is limited by poor bioavailability, necessitating high concentrations for direct action.
Purpose of the Study:
- To investigate the potential of Olive Leaf Extract (OLE) to enhance NK-92 cell-mediated cytotoxicity against HT-29 colorectal cancer cells.
- To evaluate the immunomodulatory effects of OLE on NK cells in a co-culture system.
Main Methods:
- Olive leaves were extracted using 70% methanol.
- Cell viability was assessed using MTT and ATP assays.
- NK-92 cell cytotoxicity against HT-29 cells was measured in co-culture, with Granzyme B and perforin levels quantified via ELISA.
Main Results:
- OLE inhibited HT-29 cell proliferation in a dose-dependent manner (IC₅₀ = 548 µg/mL).
- Low OLE concentrations (100-200 µg/mL) promoted NK-92 cell proliferation, while higher concentrations were cytotoxic.
- OLE significantly enhanced NK-92-mediated cytotoxicity against HT-29 cells at non-toxic concentrations, correlating with increased Granzyme B and perforin levels.
Conclusions:
- OLE demonstrates potential as an immunomodulatory agent to enhance innate antitumor immunity.
- OLE can elicit potent anticancer responses via NK cells at lower, physiologically achievable doses.
- This suggests a promising therapeutic strategy for colorectal cancer leveraging OLE's effects on NK-cell function.
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