Document Type : Original Article
Authors
1
Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran
2
Cellular and Molecular Research Centre, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran
3
Department of Stem Cells and Developmental Biology, Cell Science Research Centre, Royan Institute for Stem Cells, ACECR, Tehran, Iran
4
Cancer Research Centre, Shahid Beheshti University of Medical Sciences, Tehran, Iran
5
Paediatric Cell and Gene Therapy Research Centre, Gene, Cell & Tissue Research Institute, Tehran University of Medical Sciences, Tehran, Iran
6
Department of Immunology, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran
7
Department of Regenerative Medicine, Cell Science Research Centre, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
8
Department of Clinical Biochemistry, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran
Abstract
Objective: There is interest in using cytotoxic T lymphocyte antigen-4 (CTLA-4) immunotherapy to treat blood cancers.
Unfortunately, patients with acute lymphoblastic leukaemia (ALL) frequently exhibit resistance to treatment and natural
killer (NK) cell exhaustion. This study aims to increase the cytotoxic potency of natural killer cells by using CTLA-4 to
block the Nalm-6 leukaemia cell line.
Materials and Methods: In this experimental study, NK cells were purified from the peripheral blood mononuclear cells
(PBMCs) of 10 healthy people and assessed by flow cytometry for purity and viability. The purified cells were activated
overnight at 37°C and 5% CO2 with interleukin-15 (IL-15, 10 ng/ml) followed by evaluation of expressions of CTLA-4,
activating and inhibitory receptors, and the release of interferon gamma (IFN-γ) and granzyme B (GZM B). CTLA-4
expression on NK cells from recurrent ALL patients was also evaluated. Finally, the cytotoxic activity of NK cells was
assessed after the CTLA-4 blockade.
Results: The purity of the isolated cells was 96.58 ± 2.57%. Isolated NK cells activated with IL-15 resulted in significantly
higher CTLA-4 expression (8.75%, P<0.05). Similarly, CTLA-4 expression on the surface of NK cells from patients
with ALL was higher (7.46%) compared to healthy individuals (1.46%, P<0.05). IL-15 reduced NKG2A expression
(P<0.01), and increased expressions of NKP30 (P<0.05) and NKP46 (P<0.01). The activated NK cells released more
IFN-γ (P<0.5) and GZM B (P<0.01) compared to unactivated NK cells. Blockade of CTLA-4 enhanced the NK cell
killing potential against Nalm-6 cells (56.3%, P<0.05); however, IFN-γ and GZM B levels were not statistically different
between the blocked and non-blocked groups.
Conclusion: Our findings suggest that CTLA-4 blockage of Nalm-6 cells causes an increase in antitumour activity of
NK cells against these cells. Our study also provides evidence for the potential of cancer immunotherapy treatment
using blocking anti-CTLA-4 mAbs.
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