Purification Of Natural Killer Cells Research Articles

Therapeutic Role of Carotenoids in Blood Cancer: Mechanistic Insights and Therapeutic Potential.

Blood cancers are characterized by pathological disorders causing uncontrolled hematological cell division. Various strategies were previously explored for the treatment of blood cancers, including chemotherapy, Car-T therapy, targeting chimeric antigen receptors, and platelets therapy. However, all these therapies pose serious challenges that limit their use in blood cancer therapy, such as poor metabolism. Furthermore, the solubility and stability of anticancer drugs limit efficacy and bio-distribution and cause toxicity. The isolation and purification of natural killer cells during Car-T cell therapy is a major challenge. To cope with these challenges, treatment strategies from phyto-medicine scaffolds have been evaluated for blood cancer treatments. Carotenoids represent a versatile class of phytochemical that offer therapeutic efficacy in the treatment of cancer, and specifically blood cancer. Carotenoids, through various signaling pathways and mechanisms, such as the activation of AMPK, expression of autophagy biochemical markers (p62/LC3-II), activation of Keap1-Nrf2/EpRE/ARE signaaling pathway, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), increased level of reactive oxygen species, cleaved poly (ADP-ribose) polymerase (c-PARP), c-caspase-3, -7, decreased level of Bcl-xL, cycle arrest at the G0/G1 phase, and decreasing STAT3 expression results in apoptosis induction and inhibition of cancer cell proliferation. This review article focuses the therapeutic potential of carotenoids in blood cancers, addressing various mechanisms and signaling pathways that mediate their therapeutic efficacy.

Human IL-15 Inhibits NK Cells Specific for Human NK-92 Cells

Recent studies have indicated that natural killer (NK) cells present in peripheral blood mononuclear cells (PBMCs) might be responsible for the somewhat poor outcome of clinical trials conducted with the NK cell line NK-92, as well as chimeric antigen receptor-modified NK-92 cells against leukemias and lymphomas. These NK cells and how their cytotoxic profiles can be altered by some common gamma chain receptor-dependent cytokines or by removal of CD4+ cells have been addressed herein. A time-resolved fluorometric assay using 2.2':6'.2"-terpyridine-6.6"-dicarboxylic acid-labeled NK-92 or K562 as target cells was used for measuring the cytotoxic activity of cytokine-treated PBMCs and purified NK cells. Pre-incubation with 25 ng/ml interleukin 12 (IL-12), IL-15 or IL-21 for 72 h increased NK cell activity against K562 cells by more than 90% (1:25 target:effector ratio), whereas the corresponding NK cell activity against NK-92 cells was reduced by 15.9±0.1% by IL-12 and 50.6±2.9% by IL-15 compared to cells treated with medium alone. IL-7, on the other hand, increased NK activity against K562 to a much smaller extent (10.4±0.4%) and inhibited NK-92 cell lysis by 15.2±0.3%. Interestingly, similar amounts of IL-2 potentiated NK cell activity against both K562 and NK-92 cells by 50.9±0.5% and 14.3±0.9%, respectively. Purification of NK cells with magnetic beads demonstrated that NK cells indeed were responsible for the observed cytotoxic activity against both NK-92 cells (58.5±9.10%, 1:100 target:effector ratio) and K562 cells (81.6±9.57%, 1:100 target:effector ratio). Elimination of CD4+ cells from PBMCs did not alter the NK activity profile. This study highlights a problem that might arise with immune-based NK-92 and chimeric antigen receptor-transduced NK-92 cell therapies and pinpoints the need for evaluating new NK-like cell lines.

Fully automated integrated process for depletion of T cells with or without subsequent purification of NK cells from apheresis using the CliniMACS Prodigy

Background & Aim Donor-derived natural killer (NK) cells mediate graft-versus-leukemia effects low risk in inducing alloreactive graft-versus-host-disease and are used as component of T cell-depleted donor lymphocyte infusion (DLI) or purified. As clinical grade purification of NK cells requires two semi-automated separation procedures, including multiple manual hands-on steps, we developed an integrated fully automated process enabling either preparation of T cell-depleted DLI or clinical grade purification of NK cells within a single automated process on the CliniMACS Prodigy. Methods, Results & Conclusion The novel integrated CliniMACS Prodigy LP-3-56 System uses the CliniMACS Prodigy Tubing Set 320 for an fully automated procedure with integrated labeling and washing steps for both, CD3 and CD56 separation enabled through an integrated lytic rinsing sequence allowing subsequent CD56 enrichment in the same tubing set. By users choice the depletion of CD3+ cells will be performed with or without subsequent enrichment of CD56+ cells. For both strategies target cells are prepared with user-chosen formulation solution (e. g. sodium chloride or NK MACS medium). The new application software effectively depletes 9.6 × 109 CD3+ cells, and enriches 4.5 × 109 CD56+ cells from up to 40 × 109 total white blood cells. Inhouse evaluation runs with leukapheresis products (n= 29 in total, n=17 with CD3 depletion, n=12 with CD3 depletion and CD56 enrichment) were performed. After CD3 depletion, mean log depletion of T cells was 4.0. The mean recovery of NK cells was 89% with an average NK:T ratio-increase of 9509 fold. After CD3 depletion and CD56 enrichment, mean log depletion of T and B cells was 4.2 and 2.7, respectively. Purity of NK cells was 90.7% on average with a mean recovery of 49%. The majority of non-NK cells after the process were monocytes with a mean frequency of 5.9%. Functionality of purified NK cells was proven by their ability to lyse AML cells, to secrete cytokines after co-culture, and to perform antibody dependent cell-mediated cytotoxicity (ADCC) against Raji cells, using human CD20 antibody. In summary, the integrated fully automated CliniMACS Prodigy LP-3-56 System is capable of efficiently deplete CD3+ cells with or without subsequent CD56 enrichment to purify functional NK cells from leukapheresis products and provides target cells in formulation solution. The performance verification and submission to an European notified body for CE mark are the important next steps.

GMP-compliant, automated process for generation of CAR NK cells in a closed system for clinical use

Background & Aim Major advances have been made in harnessing natural killer (NK) cells in cancer immunotherapy in recent years. Regulated by their germ-line encoded activating and inhibitory receptors, NK cells can recognize and eliminate tumor cells rapidly without prior sensitization. Clinical evidence has shown that donor-derived NK cells have low risk in inducing graft-versus-host-disease (GvHD) as well as a reduced risk of life-threatening cytokine storms during therapy. Both properties make NK cells ideal for allogeneic application. To enhance the anti-tumor specificity and efficiency, NK cells can be further modified by chimeric antigen receptors (CARs). Promising clinical outcome of CAR-engineered NK cells has been recently reported for patients with relapsed or refractory B cell malignancies. Methods, Results & Conclusion In this study purified NK cells were cultivated with a feeder cell-free protocol including cytokines in NK MACS GMP Medium. For generation of CAR NK cells we used a Baboon endogenous virus (BaEV)-pseudotyped lentiviral vector system to efficiently transduce NK cells with various CARs and routinely obtained transduction efficiencies between 30-70%. To facilitate the clinical application of CAR NK cells, we implemented this protocol into a highly efficient, automated process to generate CAR NK cells under good manufacturing practice (GMP)-compliant conditions in a closed system by using CliniMACS Prodigy device. The process covers the complete procedure of NK cell manufacturing, including separation, activation, gene modification, and expansion/cultivation. High purity of NK cells (mean 94%) could be achieved by CD3 depletion followed by subsequent CD56 enrichment, resulting in a mean log depletion of T cells of 4.3. Inhouse evaluation runs with leukapheresis products (n=11) achieved a mean transduction efficiency of 52.0% CAR+ cells, resulting in 5.2 – 17.9 x 108 (mean 7.17 x 108) CAR+ NK cells after 14 days of culture. In summary, we developed a novel process for automated NK cell purification, transduction, and cultivation in a closed GMP-compatible system. The high level of automation enables standardized, consistent, and operator independent genetic engineering of NK cells for therapeutic applications.

A simple method for in vitro preparation of natural killer cells from cord blood

BackgroundCord Blood (CB) has been considered a promising source of natural killer (NK) cells for cellular immunotherapy. However, it is difficult to expand the large numbers of highly pure NK cells from CB without cell sorting and feeder cells/multiple cytokines. In this study, we try to develop a simple, safe and economical method for ex vivo expansion and purification of NK cells from CB without cell sorting and feeder cells/multiple cytokines.ResultsThe large numbers (mean: 1.59 × 1010) of highly pure (≥90%) NK cells from CB could be obtained through interleukin-2, group A streptococcus and zoledronate stimulation of mononuclear cells using the 21-day culture approach. When compared to resting NK cells, expanded NK cells were a higher expression of activating receptors CD16, NKG2D, NKp30, NKp44, NKp46 and activating markers CD62L and CD69, while the inhibitory receptors, CD158a and CD158b remained largely unchanged. In addition, these cells showed a higher concentration of IFN-γ, TNF-α and GM-CSF secretion and cytotoxicity to K562 cells and acute myeloid leukemia targets than resting NK cells.ConclusionWe develop a simple, safe and economical method to obtain high yield, purity, and functionality NK cells from CB without cell sorting and feeder cells/multiple cytokines.

An improved method to quantify human NK cell-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) per IgG FcR-positive NK cell without purification of NK cells

Natural killer (NK) lymphocyte ADCC supports anti-viral protection and monoclonal antibody (mAb) anti-tumor therapies. To predict in vivo ADCC therapeutic responses of different individuals, measurement of both ADCC cellular lytic capacity and their NK cellular receptor recognition of antibodies on ‘target’ cells are needed, using clinically available amounts of blood. Twenty ml of blood provides sufficient peripheral blood mononuclear cells (PBMCs) for the new assay for lytic capacity described here and for an antibody EC50 assay for Fc-receptor recognition. For the lytic capacity assay, we employed flow cytometry to quantify the CD16A IgG Fc-receptor positive NK effector cells from PBMCs to avoid loss of NKs during isolation. Targets were 51Cr-labeled Daudi B cells pretreated with excess obinutuzumab type 2 anti-CD20 mAb and washed; remaining free mAb was insufficient to convert B cells in the PBMCs into ‘targets’. We calculated: the percentage Daudis killed at a 1:1 ratio of CD16A-positive NK cells to Daudis (CX1:1); lytic slopes; and ADCC50 lytic units. Among 27 donors, we detected wide ranges in CX1:1 (16–73% targets killed) and in lytic slopes. Slope variations prevented application of lytic units. We recommend CX1:1 to compare individuals' ADCC capacity. CX1:1 was similar for purified NK cells vs. PBMCs and independent of CD16A V & F genotypes and antibody EC50s. With high mAb bound onto targets and the high affinity of obinutuzumab Fc for CD16A, CX1:1 measurements discern ADCC lytic capacity rather than antibody recognition. This assay allows ADCC to be quantified without NK cell isolation and avoids distortion associated with lytic units.

Evaluation of purified natural killer cell functions in familial hemophagocytic lymphohistiocytosis

Background: Familial hemophagocytic lymphohistiocytosis (FHL) is a rare, genetic, immune dysregulation disorder of aberrant hyperactivation of lymphocytes causing inflammation and hemophagocytosis. We report on a 3-month old male who was evaluated for the possibility of FHL because of a positive family history. The patient was asymptomatic; however, levels of the soluble interleukin 2 (IL-2) receptor were elevated and the quantity and function of the natural killer (NK) cells were severely decreased. Methods: Purification of NK cells and evaluation of the cytotoxicity and IFNγ/TNFα secretion of NK cells after IL-2 activation relative to the patient's family members. Results: The patient's NK specific lysis was enhanced compared with his mother, and it was slightly higher than his sister. The IFNγ and TNFα secretion by the patient's NK cells after challenge with target 721 cells or anti-natural cytotoxicity receptors (NKp30 and NKp44) antibodies showed levels that are close to the mother's and sister's NK secretion levels. Owing to a low yield of NK cells from the patient's father the results for his NK cells are incomplete. The patient did not undergo HSCT and continued to be followed. He is now 7 years old and thriving without signs of FHL. His last examination was in August 2012 for functionality of isolated NK cells. The results showed normal cytotoxicity, cytokine secretion, and CD107a up-regulation to the NK cell surface. Conclusion: We propose that NK function assessment in patients with presumed FHL should be performed on isolated NK cell populations. This practice may reduce the number of false-negative results in NK function assays. Statement of novelty: In this case report we show that functional assessment of unpurified NK cells could lead to a false-negative assessment in 1 of the parameters in FHL. Assessment of NK function without NK purification may lead to an erroneous diagnosis of poor NK function.

Clinical Grade Purification and Expansion of NK Cell Products for an Optimized Manufacturing Protocol

Allogeneic natural killer (NK) cells are used for adoptive immunotherapy after stem cell transplantation. In order to overcome technical limitations in NK cell purification and activation, the following study investigates the impact of different variables on NK cell recovery, cytotoxicity, and T-cell depletion during good manufacturing practice (GMP)-grade NK cell selection. Forty NK cell products were derived from 54 unstimulated donor leukaphereses using immunomagnetic CD3 T-cell depletion, followed by a CD56 cell enrichment step. For T-cell depletion, either the depletion 2.1 program in single or double procedure (D2.11depl, n = 18; D2.12depl, n = 13) or the faster depletion 3.1 (D3.1, n = 9) was used on the CliniMACS instrument. Seventeen purified NK cell products were activated in vitro by IL-2 for 12 days. The whole process resulted in a median number of 7.59 × 108 CD56+CD3− cells with both purity and viability of 94%, respectively. The T-cell depletion was significantly better using D2.11depl/2depl compared to D3.1 (log 4.6/log 4.9 vs. log 3.7; p < 0.01) and double procedure in two stages led always to residual T cells below 0.1%. In contrast D3.1 was superior to D2.11depl/2depl with regard to recovery of CD56+CD3− NK cells (68% vs. 41%/38%). Concomitant monocytes and especially IL-2 activation led to increased NK cell activity against malignant target cells compared to unstimulated NK cells, which correlated with both up-regulation of natural cytotoxicity receptors and intracellular signaling. Overall, wide variations in the NK cell expansion rate and the distribution of NK cell subpopulations were found. In conclusion, our results indicate that GMP-grade purification of NK cells might be improved by a sequential processing of T-cell depletion program D2.1 and D3.1. In addition NK cell expansion protocols need to be further optimized.

Influence of NK cell magnetic bead isolation methods on phenotype and function of murine NK cells

Natural killer (NK) cells are a promising tool for cell therapy due to their capacity to lyse tumor cells without prior activation and their influence on the innate as well as the adaptive immunity. To characterize distinct NK cell populations, it is important to find a reliable isolation method. We investigated separation methods for NK cell isolation by magnetic bead labeling. There are three commonly used different MACS protocols to isolate NK cells from murine spleen: CD49b (DX5) MicroBeads, the NK Cell Isolation Kit and a separation method which is based on a positive selection for NKp46 expressing cells.Interestingly, we found a significant difference of NK cell purities depending on the mouse strains and the purification protocol used. We observed a significantly higher level of purity and yield of NK cells by preparations from Balb/c splenocytes. In this study, we modified the negative selection protocol and adapted it to C57Bl/6 mice to obtain equal purity, viability and yields of NK cells in the different mouse strains. Moreover, we optimized the NKp46 NK cell selection method by addition of a B cell depletion step. To our knowledge, this is the first report that has directly compared and essentially modified the different NK cell purification strategies in parallel, both in C57Bl/6 and Balb/c mouse strains. Altogether, these results are a basic prerequisite for the further development of NK cell therapy protocols in murine in vivo models.

Probiotics, dendritic cells and bladder cancer

What's known on the subject? and What does the study add? The suppressor effect of probiotics on superficial bladder cancer is an observed phenomenon but the specific mechanism is poorly understood. The evidence strongly suggests natural killer (NK) cells are the anti-tumour effector cells involved and NK cell activity correlates with the observed anti-tumour effect in mice. It is also known that dendritic cells (DC) cells are responsible for the recruitment and mobilization of NK cells so therefore it may be inferred that DC cells are most likely to be the interphase point at which probiotics act. In support of this, purification of NK cells was associated with a decrease in NK cells activity. The current use of intravesical bacille Calmette-Guérin in the management of superficial bladder cancer is based on the effect of a localised immune response. In the same way, understanding the mechanism of action of probiotics and the role of DC may potentially offer another avenue via which the immune system may be manipulated to resist bladder cancer. Probiotic foods have been available in the UK since 1996 with the arrival of the fermented milk drink (Yakult) from Japan. The presence of live bacterial ingredients (usually lactobacilli species) may confer health benefits when present in sufficient numbers. The role of probiotics in colo-rectal cancer may be related in part to the suppression of harmful colonic bacteria but other immune mechanisms are involved. Anti-cancer effects outside the colon were suggested by a Japanese report of altered rates of bladder tumour recurrence after ingestion of a particular probiotic. Dendritic cells play a central role to the general regulation of the immune response that may be modified by probiotics. The addition of probiotics to the diet may confer benefit by altering rates of bladder tumour recurrence and also alter the response to immune mechanisms involved with the application of intravesical treatments (bacille Calmette-Guérin).

NK cell IFNγ response to HLA-G: a role for myeloid DCs? (147.10)

Abstract Previous studies report that stimulation of freshly isolated Natural Killer (NK) cells with soluble (but not solid-phase) ligand to KIR2DL4 results in IFNγ production. We have found that stimulation of 13-day cultured, activated, KIR2DL4-expressing NK cells with solid-phase (but not soluble) ligand to KIR2DL4 also results in NK cell IFNγ production. Human Leukocyte Antigen-G (HLA-G) has been reported to be the ligand for KIR2DL4, but controversy persists due to the irreproducibility of interactions between HLA-G (in soluble or solid-phase form) and KIR2DL4. In this study, we took freshly isolated NK cells purified by two methods, stimulated with soluble recombinant HLA-G or control, and measured IFNγ response. We observed an IFNγ response only from RosetteSep purified NK cells, and not from Easysep purified cells. Antibody cocktail analysis predicted that dendritic cells would be removed by the Easysep method but not the RosetteSep method. We confirmed the presence of CD11c+ myeloid dendritic cells (mDCs) in the RosetteSep NK cell purification and showed that removal of mDCs by cell sorting negated the IFNγ response. We further found that addition of mDCs to 13-day cultured, activated, KIR2DL4-expressing NK cells enabled IFNγ production in response to soluble HLA-G. Lastly, we have observed HLA-G tetramers binding to mDCs but not NK cells. We therefore hypothesize that mDCs bind and subsequently present “soluble” HLA-G to NK cells in order to induce an IFNγ response.

Clinical‐grade purification of natural killer cells in haploidentical hematopoietic stem cell transplantation

Because of a high risk of graft-versus-host disease (GVHD), donor lymphocyte infusions with unmodified lymphapheresis products are not used after haploidentical hematopoietic stem cell transplantation. Natural killer (NK) cells have antitumor activity and may consolidate engraftment without inducing GVHD. Production of NK cells under good manufacturing practice (GMP) conditions in a sufficient number is difficult. Twenty-four apheresis procedures and subsequent NK-cell enrichment from 14 haploidentical donors were performed. NK-cell enrichment was performed using a GMP suitable immunomagnetic procedure. Factors influencing the NK-cell recovery, purity, and NK-cell dose were analyzed. A median number of 4.9 x 10(8) NK cells were obtained and median NK-cell recovery was 58 percent. Median T-cell depletion was 4.32 log. The absolute NK-cell number in the final product after processing significantly correlated with the preharvest NK-cell content of the peripheral blood (p = 0.002, r = 0.867). The NK-cell recovery was inversely correlated to the absolute NK-cell number in the apheresis product (p = 0.01, r = -0.51). The NK-cell dose per kg of body weight of the patient was inversely correlated to the weight of the patient (p = 0.007, r = -0.533). Donors with a high NK-cell count in peripheral blood are likely to provide NK-cell products with the highest cell number. However, maximal NK-cell dose is limited and high NK-cell doses may only be obtained for patients with a low body weight, making children and young adults the best candidates for NK-cell therapy.

Phenotype and function of human natural killer cells purified by using a clinical-scale immunomagnetic method.

Infection, disease relapse, graft failure, and graft-versus-host disease (GVHD) are significant adverse events associated with allogeneic bone marrow transplantation. Donor natural killer (NK) cells may be an ideal cell type for prevention or treatment of all these adverse events. Therefore, we investigated the phenotype and function of human NK cells purified by using a clinical-scale immunomagnetic method. We found that the NK cell purification procedures did not adversely affect the expression of killer cell immunoglobulin-like receptors, adhesion molecules, intracellular cytokines, perforin, and granzyme B. Purified NK cells had extensive proliferative capacity and potent antitumor activity when assessed using an immunodeficient mouse model. While all mice transplanted with unpurified mononuclear cells developed GVHD, none of the mice transplanted with purified NK cells did. NK cells were highly susceptible to lysis by antithymocyte globulin (ATG), whereas G-CSF had a minimal effect on their natural cytotoxicity. These results support future clinical investigation of the use of purified NK cells for adoptive immunotherapy in the absence of ATG.

Purification of human natural killer cells using a clinical-scale immunomagnetic method.

Infection, graft failure, disease relapse, and GvHD are significant adverse events associated with allogeneic BMT. Although donor leukocyte infusion has been used to prevent or to treat infection, graft failure, and relapse, the potential clinical benefits are often outweighed by the risk of T cell-mediated GvHD. Results from animal studies suggest that donor natural killer (NK) cells may be an ideal cell type for prevention or treatment of these adverse events. We have therefore sought to develop an automated, efficient, and clinical-scale human NK cell-purification method. Twelve leukopheresis products were purified for NK cells using a two-step immunomagnetic method. CD3(+) cells were first depleted from the apheresis products. CD56(+) cells were then enriched from the CD3(+) cell-depleted products. The median percentage of CD3(-)CD56(+) NK cells in the final products was 91.0%, and the median recovery was 48.7%. The median depletion for CD3(+)CD56(-) T cells was 5.3 log. Natural cytotoxicity of the purified cells was approximately five-fold higher than that of unpurified mononuclear cells, and it could be further increased by stimulation of the purified cell with IL2. We described a large-scale purification method for automated, efficient, and rapid isolation of human NK cells that yielded minimal contamination with T cells or B cells. These purified NK cells may be expedient for preclinical and clinical uses.

Effect of in vitrocadmium exposure on natural killer (NK) cells of catfish, Ictalurus melas

The effect of in vitrocadmium exposure on catfish natural killer (NK) cells was investigated. Purification of NK cells by nylon-wool columns and density gradient centrifugation indicated that they were a population of nylon-wool adherent cells. Subsequently NK cells were separated only by density gradient centrifugation, where these cells band at the 43 /45 ·5 % Percoll interface. In some cytotoxicity assays, catfish NK cells were exposed to 5, 10, 30 and 50 μ M cadmium (CdCl 2); 10 μ l of Cd solutions were added to NK cells simultaneously with the target cells.In vitro , 5μM Cd inhibited the ability of catfish NK cells to kill the human erythroleukemic cell line K-562. In the presence of 10 μM Cd, the antibody-independent cytotoxic activity was totally suppressed.

Inhibition of natural killer cell function by marijuana components.

The extent of modulation of host resistance mechanisms by marijuana components is not fully understood. Natural killer (NK) cells are a subpopulation of lymphoid cells and are important in host resistance mechanisms against malignant cells, virus-infected cells, and possibly pathogenic bacteria and fungi. We report that the marijuana component delta-9-tetrahydrocannabinol (THC) injected into mice results in a suppression of splenic NK activity. Furthermore, THC and the hydroxylated metabolite 11-hydroxy-delta-9-tetrahydrocannabinol (11-hydroxy-THC) suppress the NK activity of cultured murine splenocytes in a dose-dependent manner (range 1 X 10(-5) to 3.2 X 10(-5) M) without diminishing NK cell viability. The hydroxylated derivative appears to possess a more potent suppressive effect, in that it suppresses at lower concentrations than THC does and requires a shorter incubation time with the effector cells for its suppressive action. Purification of NK cells by Percoll density-gradient centrifugation suggests that both cannabinoids act directly on the natural killer cell population, resulting in suppression. Studies involving target binding analysis and calcium ionophore experiments suggest that cannabinoids do not suppress NK cell killing by the inhibition of effector/target binding or by disruption of calcium ion flux. These results suggest that two principal psychoactive cannabinoids can suppress natural killer cell function by interacting directly with the killer cells and disrupting cellular events postbinding and during the programming for lysis. Furthermore, the data suggest different modes of action for THC and the hydroxylated metabolite.