Name: dextran enhances the lentiviral transduction efficiency of murine and human primary nk cells
Uploaded: 2018-01-15T12:30:00
Description: Watch this Scientific Journal Video about Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells at JoVE.com

We thank Lucia Sammarco and her Lulu&#39;s Lemonade Stand for inspiration, motivation, and support. This work was supported in part by NIH R01 AI102893 and NCI R01 CA179363 (S.M.); NHLBI-HL087951 (S.R.); NIH-CA151893-K08 (M.J.R.); NCI 1R01CA164225 (L.W); the Alex Lemonade Stand Foundation (S.M.); the HRHM Program of the MACC Fund (S.M.; S.R.; M.S.T); the Nicholas Family Foundation (S.M.); the Gardetto Family (S.M.); the Hyundai Scholars Program (M.S.T.); Hyundai Hope on Wheels (S.R.); the MACC Fund (M.S.T. and S.M.); the Children&#39;s Research Institute, MCW (S.R.); and the Kathy Duffey Fogerty Award (M.J.R.).

All animal protocols followed the humane and ethical treatment of animals and were approved by the Institutional Animal Care and Use Committee (IACUC) within the Biomedical Research Center (BRC) of the Medical College of Wisconsin (MCW), Milwaukee, WI. The use of human peripheral blood mononuclear cells (PBMCs) was approved by the Institutional Review Board (IRB) of the Blood Research Institute of the Blood Center of Wisconsin, Milwaukee, WI.
1. Mice, cell lines, and vectors
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This study demonstrates that use of dextran as a cationic polymer agent enhances the lentiviral transduction efficiency of both murine and human primary NK cells. Additionally, other cationic agents, such as Pb or PS, have no discernible effect on the delivery of viral vectors into human primary NK cells. Previously, it has been demonstrated that Pb can augment gene transduction in human T cells17. These results, however, suggest that neither Pb nor PS have a similar efficiency on human primary NK...

Natural killer (NK) cells are the major lymphocytic population of the innate immune system1. NK cells function as the first-line defenders of the host immune response against tumors and infections2,3,4. NK cells also play a central role in the development of tolerance through the secretion of potent cytokines and chemokines5. Due to their potent ability to target and eliminate tumor cells, multiple clinical trials are being conducted to evaluate donor-derived human NK cells as an adoptive immunotherapy for cancer6,7. In contrast to T cells, the developmental biology of NK cells has yet to be well-characterized8. This lack of knowledge is partially due to the absence of efficient techniques that deliver genes of interest to mouse or human primary NK cells. For these reasons, most NK-cell studies have been conducted in cell lines, rather than in primary cells. Therefore, the need for a reliable and efficient protocol to transduce primary NK cells with genes of interest is crucial.
The overall goal of this study was to formulate a consistent and reliable method by which primary human or murine NK cells could be transduced with lenti- or retroviruses.
Earlier studies that attempted to address this problem have been performed, largely using the transient transformation of primary NK cells. This includes plasmid transfection9,10, Epstein-Barr Virus (EBV)/retroviral hybrid vector11, vaccinia vectors12,13, and Ad5/F35 chimeric adenoviral vectors14. Despite the modest efficiency of these techniques, the transient nature of transduction makes them unsuitable for the long-term utilization of the genetically modified NK cells. A few recent studies have used retroviral vectors to transduce NK cells, requiring multiple cycles of infection to achieve an acceptable level of gene expression11,15. In contrast to retroviral vectors, lentiviral vectors can use host-cell nuclear import machinery to translocate the viral pre-integration complex into the nucleus. This is a major limiting factor in the replication of the virus in non-dividing cells, which include primary NK cells.
Interactions between different cell-surface receptors and viral particles permit viral uptake into the cell. The initial engagements between the viral envelope proteins and their cognate host receptors could be limited because of the potential negative charges existing between these two. The rationale behind many transduction techniques is that the addition of cationic polymers, such as polybrene (Pb), protamine sulfate (PS), or dextran, could give a positive charge to the cell-surface receptors and thereby augment the binding of viral envelope proteins. This will increase the fusion efficiency and the uptake of the viral particles by the cells16. Although it has been reported that Pb or PS can improve gene transfer in T cells17, their application did not have any effect in the transduction efficiency of primary NK cells. Moreover, a comparative analysis between these reagents using primary NK cells has not been performed. In this study, the transduction efficiencies of the three cationic polymers were compared. The results show that, among these three cationic polymers, only dextran significantly enhances efficient viral transduction into both mouse and human primary NK cells.

<table>
	<tbody>
		<tr>
			<td>Dextran</td>
			<td>Sigma-Aldrich</td>
			<td>90-64-91-9</td>
			<td></td>
		</tr>
		<tr>
			<td>polybrene (Pb)</td>
			<td>Sigma-Aldrich</td>
			<td>TR-1003</td>
			<td></td>
		</tr>
		<tr>
			<td>protamine sulfate (PS)</td>
			<td>Sigma-Aldrich</td>
			<td>p3369</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Corning</td>
			<td>25-052-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI1640</td>
			<td>Corning</td>
			<td>10-040-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>ATALANTA</td>
			<td>S11150</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin</td>
			<td>Corning</td>
			<td>30-001-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>B-mercaptoethanol</td>
			<td>SIGMA</td>
			<td>M3148</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium pyruvate</td>
			<td>Corning</td>
			<td>MT25000CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Interferon gamma (IFN-&#947; )</td>
			<td>eBioscience</td>
			<td>14-7311-85</td>
			<td></td>
		</tr>
		<tr>
			<td>Propidium lodding staining solution</td>
			<td>BD</td>
			<td>51-66211E</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipofectamine 3000</td>
			<td>Thermo Fisher</td>
			<td>L3000015</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>PHOENIX</td>
			<td>NDC 57319-559-05</td>
			<td></td>
		</tr>
		<tr>
			<td>NK cell negative selection kit</td>
			<td>Stem Cell</td>
			<td>19855</td>
			<td></td>
		</tr>
		<tr>
			<td>Yac-1</td>
			<td>ATCC</td>
			<td>TIB-160</td>
			<td></td>
		</tr>
		<tr>
			<td>K562</td>
			<td>ATCC</td>
			<td>CCL-243</td>
			<td></td>
		</tr>
		<tr>
			<td>Mice</td>
			<td>Jakson</td>
			<td>664</td>
			<td></td>
		</tr>
		<tr>
			<td>293T cells</td>
			<td>ATCC</td>
			<td>CRL-3216</td>
			<td></td>
		</tr>
		<tr>
			<td>T75 flasks</td>
			<td>Cornnig</td>
			<td>430641U</td>
			<td></td>
		</tr>
		<tr>
			<td>antibody-based negative selection kits</td>
			<td>Stem Cell</td>
			<td>19055</td>
			<td></td>
		</tr>
		<tr>
			<td>51Chromium (Cr)-release assays</td>
			<td>perkin elmer&#39;s</td>
			<td>NEZ030</td>
			<td></td>
		</tr>
		<tr>
			<td>ELISA kits</td>
			<td>Ebioscience</td>
			<td>00-4201-56</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Butyrate</td>
			<td>Sigma</td>
			<td>5887-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Linear polyethylenimine</td>
			<td>polysciences</td>
			<td>23966-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Ficoll</td>
			<td>GE Life Science</td>
			<td>17-1440-03</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS</td>
			<td>Corning</td>
			<td>21-022-CV</td>
			<td></td>
		</tr>
	</tbody>
</table>

dextran enhances the lentiviral transduction efficiency of murine and human primary nk cells

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining the role of the gene of interest in the development, differentiation, and function of NK cells. Recent advances related to chimeric antigen receptors (CARs) in cancer immunotherapy accentuate the need for an efficient method to deliver exogenous genes to effector lymphocytes. The efficiencies of lentiviral-mediated gene transductions into primary human or mouse NK cells remain significantly low, which is a major limiting factor. Recent advances using cationic polymers, such as polybrene, show an improved gene transduction efficiency in T cells. However, these products failed to improve the transduction efficiencies of NK cells. This work shows that dextran, a branched glucan polysaccharide, significantly improves the transduction efficiency of human and mouse primary NK cells. This highly reproducible transduction methodology provides a competent tool for transducing human primary NK cells, which can vastly improve clinical gene delivery applications and thus NK cell-based cancer immunotherapy.

Dextran induces the efficient gene transfer of lentiviral vector in primary human and murine NK cells
Human NK cells were isolated and purified from PBMC (with a purity of more than 85%) and incubated overnight with rIL-2 300 U/mL. These primary NK cells were then transduced with GFP lentivirus at varied multiplicities of infection (MOI; 3, 10, and 20 IU per cell) in 24-well plates in the presence of 8 &#181;g/mL Pb, PS, or dextran...

Watch this Scientific Journal Video about Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells at JoVE.com

Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells

The goal of this study was to formulate technologies that allow for successful gene transduction in primary natural killer (NK) cells. The dextran-mediated lentiviral transduction of human or mouse primary NK cells results in higher gene expression efficiencies. This method of gene transduction will vastly improve NK cell genetic manipulation.

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining ...

The overall goal of this protocol is to formulate technologies that allow successful gene transduction in primary natural killer cells. This method can help answer key questions in the Immunotherapy field, like the effect of genetic modification on effector lymphocytes, such as natural killer, or NK cells. The main advantage of this technique is the efficient expression of a gene of interest in primary mouse or human NK cells.After preparing and titrating Lentiviral vectors according to the text protocol, purifying murine primary NK cells by passing single cell spleen suspensions through a nylon wool columns to deplete the adherent populations consisting of B-cells and macrophages. Use 1, 000 units per milliliter of Interleukin-2 in RPMI1640 complete medium to culture the non-adherent population that contains NK cells. On day four of culture, replace the medium using 20 milliliters of RPMI1640 complete medium, and 1, 000 units per milliliter of IL-2 to remove the non-adherent T and NKT cells.On day seven, use MK cell-specific markers to check the purity of the murine NK cells by flow cytometry using preparations with a greater than 95%CD3 negative and NK1.1 positive population. To isolate peripheral blood mononuclear cells, or PBMCs, carefully layer 35 milliliters of half diluted cells over a 15 milliliter density gradient in a 50 milliliter conical tube. Centrifuge the gradient in a swinging-bucket rotor at 400 times G and 20 degrees Celsius for 30 minutes without a break.After purifying human primary NK cells according to the text protocol, determine the purity of the cells by adding two micrograms per milliliter of anti-CD3, and two micrograms per milliliter of anti-CD56 antibodies. Incubate the cells at four degrees Celsius for 20 minutes. Use PBS to wash the cells twice.Then, analyze the cells by flow cytometry. The NK cell population will be positive for CD56 on the cell's surface, and negative for CD3. Suspend mouse or human primary NK cells in the wells of a 24-well plate at 0.5 times to the 5th per milliliter of medium with GFP Lentivirus supernatant, at an NLY of five, 10, and 20.Then in the presence of polybrene, protamine sulfate, or dextran. centrifuge the plates at 1, 000 times G for 60 minutes. Then, without decanting the supernatant, culture the cells in a 37 degree Celsius incubator infused with 5.2%carbon dioxide overnight.After the cells have been washed with 10 milliliters of PBS, use two milliliters of RPMI1640 medium with IL-2 to re-suspend the cells. The day before harvesting the cells, coat 96-well highly protein absorbent polystyrene plates with 2.5 micrograms per milliliter of anti-MKG2D monoclonal antibodies. and incubate the plates at room temperature or in the fridge overnight.The following day, use 100 microliters of PBS to wash each well three times. Harvest the transduced NK cells by first gently tapping the plates, then add 100 microliters of the cells to each well of the 96-well plates. 16 to 18 hours post-activation, use a multi-channel pipette to collect the supernatants.Then using the recombinant cytokine from an ELISA kit, generate a standard curve and quantify the cytokines, such as Interferon Gamma in the supernatant. To test the NK cell viability, four days after transduction, wash the cells with 10 milliliters of cold PBS two times. Then, harvest the cells and use an XM5 7-aminoactinomycin D to stain them.Use flow cytometry to determine the percent of necrotic cells among the transformed NK cells, and analyze the data according to the text protocol. This figure shows that human NK cells incubated with recombinant IL-2 and then transduced with GFP Lentivirus achieved a greater transduction efficiency and increased the viral titer when dextran was added to the culture, as compared to the addition of polybrene or protamine sulfate. As seen here, similar results were demonstrated in murine NK cells, where dextran augmented the efficiency of Lentiviral vectors, compared to polybrene or protamine sulfate.In this experiment, the cytotoxic capacity of transduced primary NK cells was examined by a CR-release assay against K562 and YAC-1 as target cells. The transduction of NK cells by dextran does not negatively alter the killing potential of transformed NK cells compared to non-transduced NK cells. Here, transduced human primary NK cells were co-cultured with K562 for 24 hours, and the supernatants were collected to measure Interferon Gamma.The results indicate that dextran has no impact on the ability of transduced NK cells to produce cytokines. In addition, an independent validation showed that dextran-treated NK cells activated with plate-bound anti-NKG2DA10 monoclonal antibodies were still able to produce the cytokine Interferon Gamma. While attempting this procedure, it's important to remember to spin the transduced cells.Following this procedure, other methods like transfection, can be profound in order to answer additional questions, like how to improve gene delivery. After its development, this technique paved the way of researchers in the field of Immunology, for explore gene manipulation in NK cells. After watching this video, you should have a good understanding of how to transduce NK cells.

dextran-enhances-lentiviral-transduction-efficiency-murine-human

Research

JoVE Journal

Immunology and Infection

Expansion, Purification, and Functional Assessment of Human Peripheral Blood NK Cells

Natural killer (NK) cells play an important role in immune surveillance against a variety of infectious microorganisms and tumors. Limited availability of NK cells and ability to expand in vitro has restricted development of NK cell immunotherapy. Here we describe a method to efficiently expand vast quantities of functional NK cells ex vivo using K562 cells expressing membrane-bound IL21, as an artificial antigen-presenting cell (aAPC).
NK cell adoptive therapies to date have utilized a cell product obtained by steady-state leukapheresis of the donor followed by depletion of T cells or positive selection of NK cells. The product is usually activated in IL-2 overnight and then administered the following day 1. Because of the low frequency of NK cells in peripheral blood, relatively small numbers of NK cells have been delivered in clinical trials.
The inability to propagate NK cells in vitro has been the limiting factor for generating sufficient cell numbers for optimal clinical outcome. Some expansion of NK cells (5-10 fold over 1-2 weeks) has be achieved through high-dose IL-2 alone 2. Activation of autologous T cells can mediate NK cell expansion, presumably also through release of local cytokine 3. Support with mesenchymal stroma or artificial antigen presenting cells (aAPCs) can support the expansion of NK cells from both peripheral blood and cord blood 4. Combined NKp46 and CD2 activation by antibody-coated beads is currently marketed for NK cell expansion (Miltenyi Biotec, Auburn CA), resulting in approximately 100-fold expansion in 21 days.
Clinical trials using aAPC-expanded or -activated NK cells are underway, one using leukemic cell line CTV-1 to prime and activate NK cells5 without significant expansion. A second trial utilizes EBV-LCL for NK cell expansion, achieving a mean 490-fold expansion in 21 days6. The third utilizes a K562-based aAPC transduced with 4-1BBL (CD137L) and membrane-bound IL-15 (mIL-15)7, which achieved a mean NK expansion 277-fold in 21 days. Although, the NK cells expanded using K562-41BBL-mIL15 aAPC are highly cytotoxic in vitro and in vivo compared to unexpanded NK cells, and participate in ADCC, their proliferation is limited by senescence attributed to telomere shortening8. More recently a 350-fold expansion of NK cells was reported using K562 expressing MICA, 4-1BBL and IL159.
Our method of NK cell expansion described herein produces rapid proliferation of NK cells without senescence achieving a median 21,000-fold expansion in 21 days.

Here we describe a method to efficiently expand and purify large numbers of human NK cells and assess their function.

Natural killer (NK) cells play an important role in immune surveillance against a variety of infectious microorganisms and tumors. Limited availability of ...

Generation of Induced Regulatory T Cells from Primary Human Na&iuml;ve and Memory T Cells

The development and maintenance of immunosuppressive CD4+ regulatory T cells (Tregs) contribute to the peripheral tolerance needed to remain in immunologic homeostasis with the vast amount of self and commensal antigens in and on the human body. Perturbations in the balance between Tregs and inflammatory conventional T cells can result in immunopathology or cancer. Although therapeutic injection of Tregs has been shown to be efficacious in murine models of colitis1 , type I diabetes2 , rheumatoid arthritis and graft versus host disease,4 several fundamental differences in human versus mouse Treg biology5 has thus far precluded clinical use. The lack of sufficient number, purity, stability and homing specificity of therapeutic Tregs necessitated a dynamic platform of human Treg development on which to optimize conditions for their ex vivo expansion6.
Here we describe a method for the differentiation of induced Tregs (iTregs) from a single human peripheral blood donor which can be broken down into four stages: isolation of peripheral blood mononuclear cells, magnetic selection of CD4+ T cells, in vitro cell culture and fluorescence activated cell sorting (FACS) of T cell subsets. Since the Treg signature transcription factor forkhead box P3 (FoxP3) is an activation-induced transcription factor in humans7 and no other unique marker exists, a combinatorial panel of markers must be used to identify T cells with suppressor activity. After six days in culture, cells in our system can be demarcated into na&iuml;ve T cells, memory T cells or iTregs based on their relative expression of CD25 and CD45RA. As memory and na&iuml;ve T cells have different reported polarization requirements and plasticities8 , pre-sorting of the initial T cell population into CD45RA+ and CD45RO+ subsets can be used to examine these discrepancies. Consistent with others, our CD25HiCD45RA- iTregs express high levels of FoxP39 , GITR and CTLA-411 and low levels of CD12712 . Following FACS of each population, resultant cells can be used in a suppressor assay which evaluates the relative ability to retard the proliferation of carboxyfluorescein succinimidyl ester (CFSE)-labeled autologous T cells.

Generation of Induced Regulatory T Cells from Primary Human Na&amp;#239;ve and Memory T Cells

We describe a method for generating regulatory, memory and na&#239;ve T cells from a single human blood donor. Polarized Tregs can be then compared to other subsets in a variety of genetic and functional applications with genetic homogeneity, including a suppression assay also detailed here.

The development and maintenance of immunosuppressive CD4+ regulatory T cells (Tregs) contribute to the peripheral tolerance needed to remain in ...

piggyBac Transposon System Modification of Primary Human T Cells

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most commonly utilizing two plasmids with one expressing the piggyBac transposase enzyme and a transposon plasmid harboring the gene(s) of interest between inverted repeat elements which are required for gene transfer activity. PiggyBac mediates gene transfer through a "cut and paste" mechanism whereby the transposase integrates the transposon segment into the genome of the target cell(s) of interest. PiggyBac has demonstrated efficient gene delivery activity in a wide variety of insect1,2, mammalian3-5, and human cells6 including primary human T cells7,8. Recently, a hyperactive piggyBac transposase was generated improving gene transfer efficiency9,10.
Human T lymphocytes are of clinical interest for adoptive immunotherapy of cancer11. Of note, the first clinical trial involving transposon modification of human T cells using the Sleeping beauty transposon system has been approved12. We have previously evaluated the utility of piggyBac as a non-viral methodology for genetic modification of human T cells. We found piggyBac to be efficient in genetic modification of human T cells with a reporter gene and a non-immunogenic inducible suicide gene7. Analysis of genomic integration sites revealed a lack of preference for integration into or near known proto-oncogenes13. We used piggyBac to gene-modify cytotoxic T lymphocytes to carry a chimeric antigen receptor directed against the tumor antigen HER2, and found that gene-modified T cells mediated targeted killing of HER2-positive tumor cells in vitro and in vivo in an orthotopic mouse model14. We have also used piggyBac to generate human T cells resistant to rapamycin, which should be useful in cancer therapies where rapamycin is utilized15.
Herein, we describe a method for using piggyBac to genetically modify primary human T cells. This includes isolation of peripheral blood mononuclear cells (PBMCs) from human blood followed by culture, gene modification, and activation of T cells. For the purpose of this report, T cells were modified with a reporter gene (eGFP) for analysis and quantification of gene expression by flow cytometry.
PiggyBac can be used to modify human T cells with a variety of genes of interest. Although we have used piggyBac to direct T cells to tumor antigens14, we have also used piggyBac to add an inducible safety switch in order to eliminate gene modified cells if needed7. The large cargo capacity of piggyBac has also enabled gene transfer of a large rapamycin resistant mTOR molecule (15 kb)15. Therefore, we present a non-viral methodology for stable gene-modification of primary human T cells for a wide variety of purposes.

piggyBac Transposon System Modification of Primary Human T Cells

We describe a method to genetically modify primary human T cells with a transgene using the non-viral piggyBac transposon system. T cells modified to using the piggyBac transposon system exhibit stable transgene expression.

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most ...

Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow.
Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%&#177; 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%&#177; 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection. 
This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

Here we present a protocol that generates large amounts of murine monocytes from heterogeneous bone marrow for translational applications. In comparison to others, this new method helps reduce the number of sacrificed animals and lowers costs by avoiding expensive methods such as high gradient magnetic cell separation (MACS).

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of ...

Retroviral Transduction of Helper T Cells as a Genetic Approach to Study Mechanisms Controlling their Differentiation and Function

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents autoimmunity. Many approaches involving different model organisms have been utilized to understand the mechanisms controlling helper T cell development and function. However, studies using mouse models have proven to be highly informative due to the availability of genetic, cellular, and biochemical systems. One genetic approach in mice used by many labs involves retroviral transduction of primary helper T cells. This is a powerful approach due to its relative ease, making it accessible to almost any laboratory with basic skills in molecular biology and immunology. Therefore, multiple genes in wild type or mutant forms can readily be tested for function in helper T cells to understand their importance and mechanisms of action. We have optimized this approach and describe here the protocols for production of high titer retroviruses, isolation of primary murine helper T cells, and their transduction by retroviruses and differentiation toward the different helper subsets. Finally, the use of this approach is described in uncovering mechanisms utilized by microRNAs (miRNAs) to regulate pathways controlling helper T cell development and function.

Many experimental systems have been utilized to understand the mechanisms regulating T cell development and function in an immune response. Here a genetic approach using retroviral transduction is described, which is economic, time efficient, and most importantly, highly informative in identifying regulatory pathways.

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents ...

A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity

Within the innate immune system, effector lymphocytes known as natural killer (NK) cells play an essential role in host defense against aberrant cells, specifically eliminating tumoral and virally infected cells. Approximately 30 known monogenic defects, together with a host of other pathological conditions, cause either functional or classic NK cell deficiency, manifesting in reduced or absent cytotoxic activity. Historically, cytotoxicity has been investigated with radioactive methods, which are cumbersome, expensive and potentially hazardous. This article describes a streamlined, clinically applicable flow cytometry-based method to quantify NK cell cytotoxic activity. In this assay, peripheral blood mononuclear cells (PBMCs) or purified NK cell preparations are co-incubated at different ratios with a target tumor cell line known to be sensitive to NK cell-mediated cytotoxicity (NKCC). The target cells are pre-labeled with a fluorescent dye to allow their discrimination from the effector cells (NK cells). After the incubation period, killed target cells are identified by a nucleic acid stain, which specifically permeates dead cells. This method is amenable to both diagnostic and research applications and, thanks to the multi-parameter capabilities of flow cytometry, has the added advantage of potentially enabling a deeper analysis of NK cell phenotype and function.

A flow cytometry-based method to quantitatively determine the cytotoxic activity of human natural killer cells is shown here.

Within the innate immune system, effector lymphocytes known as natural killer (NK) cells play an essential role in host defense against aberrant cells, ...

Assessment of the Synaptic Interface of Primary Human T Cells from Peripheral Blood and Lymphoid Tissue

The current understanding of the dynamics and structural features of T-cell synaptic interfaces has been largely determined through the use of glass-supported planar bilayers and in vitro-derived T-cell clones or lines1,2,3,4. How these findings apply to the primary human T cells isolated from blood or lymphoid tissues is not known, partly due to significant difficulties in obtaining a sufficient number of cells for analysis5. Here we address this through the development of a technique exploiting multichannel flow slides to build planar lipid bilayers containing activating and adhesion molecules. The low height of the flow slides promotes rapid cell sedimentation in order to synchronize cell:bilayer attachment, thereby allowing researchers to study the dynamic of the synaptic interface formation and the kinetics of the granules release. We apply this approach to analyze the synaptic interface of as few as 104 to 105 primary cryopreserved T cells isolated from lymph nodes (LN) and peripheral blood (PB). The results reveal that the novel planar lipid bilayer technique enables the study of the biophysical properties of primary human T cells derived from blood and tissues in the context of health and disease.

The protocol describes a technique to study the ability of primary polyclonal human T cells to form synaptic interfaces using planar lipid bilayers. We use this technique to show the differential synapse formation capability of human primary T cells derived from lymph nodes and peripheral blood.

The current understanding of the dynamics and structural features of T-cell synaptic interfaces has been largely determined through the use of ...

Generation of Knock-out Primary and Expanded Human NK Cells Using Cas9 Ribonucleoproteins

CRISPR/Cas9 technology is accelerating genome engineering in many cell types, but so far, gene delivery and stable gene modification have been challenging in primary NK cells. For example, transgene delivery using lentiviral or retroviral transduction resulted in a limited yield of genetically-engineered NK cells due to substantial procedure-associated NK cell apoptosis. We describe here a DNA-free method for genome editing of human primary and expanded NK cells using Cas9 ribonucleoprotein complexes (Cas9/RNPs). This method allowed efficient knockout of the TGFBR2 and HPRT1 genes in NK cells. RT-PCR data showed a significant decrease in gene expression level, and a cytotoxicity assay of a representative cell product suggested that the RNP-modified NK cells became less sensitive to TGF&#946;. Genetically modified cells could be expanded post-electroporation by stimulation with irradiated mbIL21-expressing feeder cells.

Here, we present a protocol to genetically modify primary or expanded human natural killer (NK) cells using Cas9 Ribonucleoproteins (Cas9/RNPs). By using this protocol, we generated human NK cells deficient for transforming growth factor&#8211;b receptor 2 (TGFBR2) and hypoxanthine phosphoribosyltransferase 1 (HPRT1).

CRISPR/Cas9 technology is accelerating genome engineering in many cell types, but so far, gene delivery and stable gene modification have been challenging ...

High-throughput Measurement of Plasma Membrane Resealing Efficiency in Mammalian Cells

In their physiological environment, mammalian cells are often subjected to mechanical and biochemical stresses that result in plasma membrane damage. In response to these damages, complex molecular machineries rapidly reseal the plasma membrane to restore its barrier function and maintain cell survival. Despite 60 years of research in this field, we still lack a thorough understanding of the cell resealing machinery. With the goal of identifying cellular components that control plasma membrane resealing or drugs that can improve resealing, we have developed a fluorescence-based high-throughput assay that measures the plasma membrane resealing efficiency in mammalian cells cultured in microplates. As a model system for plasma membrane damage, cells are exposed to the bacterial pore-forming toxin listeriolysin O (LLO), which forms large 30-50 nm diameter proteinaceous pores in cholesterol-containing membranes. The use of a temperature-controlled multi-mode microplate reader allows for rapid and sensitive spectrofluorometric measurements in combination with brightfield and fluorescence microscopy imaging of living cells. Kinetic analysis of the fluorescence intensity emitted by a membrane impermeant nucleic acid-binding fluorochrome reflects the extent of membrane wounding and resealing at the cell population level, allowing for the calculation of the cell resealing efficiency. Fluorescence microscopy imaging allows for the enumeration of cells, which constitutively express a fluorescent chimera of the nuclear protein histone 2B, in each well of the microplate to account for potential variations in their number and allows for eventual identification of distinct cell populations. This high-throughput assay is a powerful tool expected to expand our understanding of membrane repair mechanisms via screening for host genes or exogenously added compounds that control plasma membrane resealing.

Here we describe a high-throughput fluorescence-based assay that measures the plasma membrane resealing efficiency through fluorometric and imaging analyses in living cells. This assay can be used for screening drugs or target genes that regulate plasma membrane resealing in mammalian cells.

In their physiological environment, mammalian cells are often subjected to mechanical and biochemical stresses that result in plasma membrane damage. In ...

Quantification of Antibody-dependent Enhancement of the Zika Virus in Primary Human Cells

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barr&#233; syndrome and microcephaly in infants, has brought serious public safety concerns. Among the risk factors, antibody-dependent enhancement (ADE) poses the most significant threat, as the recent re-emergence of the Zika virus (ZIKV) is primarily in areas where the population has been exposed and is in a state of pre-immunity to other closely related flaviviruses, especially dengue virus (DENV). Here, we describe a protocol for quantifying the effect of human serum antibodies against DENV on ZIKV infection in primary human cells or cell lines.

We describe a method to evaluate the effect of pre-existing immunity against dengue virus on the Zika virus infection by using human serum, primary human cells, and infection quantification by quantitative real-time polymerase chain reaction.

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barr&#233; syndrome and microcephaly in infants, has brought ...