我们要感谢吉尔纳西索，加州大学洛杉矶分校免疫遗传学中心，她求助与手稿的准备。

Samples were collected according to the ethical guidelines established by the UCLA Human Research Protection Program and IRB approved.
1. Preparation of reagents
NOTE: Unless otherwise stated, all reagents should be allowed to equilibrate at room temperature prior to use. All reagents must remain sterile.
<ol>
	<li>Prepare a 2x working solution of Tween-20 (i.e., 0.2%) by adding 10&#160;&#181;L of Tween-20 solution to 5 mL of phosphate-buffered saline (PBS) without calcium and magnesium with a p20 pipette.
	<ol>
		<li>Given the high viscosity of Tween-20, take the following steps to ensure accuracy: collect slowly to avoid bubble formation, do not submerge the entire tip to avoid carry-over, and pipette up and down several times in PBS to wash out all Tween-20 from the tip.</li>
	</ol>
	</li>
	<li>Add 2 &#181;L of IL-2 stock solution (2.1E6 IU/mL) to 198 &#181;L of complete media (i.e., 1:100 dilution), which is RPMI with 1% penicillin-streptomycin and 10% fetal bovine serum (FBS), then proceed to an additional 1:100 dilution by adding 2 &#181;L of IL-2 intermediate solution to 198 &#181;L of complete media to prepare a 7x working solution (210 IU/mL).</li>
	<li>Add 2 &#181;L of CFSE stock solution (5 mM) to 500 &#181;L of plain media (RPMI). Vortex, spin down to remove drops from the cap, then proceed with an additional 1:20 dilution by adding 50 &#181;L of the CFSE intermediate solution to 950 &#181;L of plain RPMI to obtain a 2x working solution of 1 &#181;M. Vortex well and keep protected from light.</li>
</ol>
2. Isolation of PBMCs as effector cells
NOTE: This assay has been validated for effective use with total PBMCs from healthy controls. However, it is recommended that NK cell content be verified with each PBMC preparation (Figure 1). Also, the volume of whole blood for collection is based on the frequency of NK cells in peripheral whole blood and this may vary from person to person, particularly between healthy donors and patients.
<ol>
	<li>Collect a minimum of 4 mL of human whole blood in sodium or lithium heparinized blood collection tubes. Store blood samples at room temperature upon collection and use within 30 h of collection.</li>
	<li>Dilute whole blood with 4 mL of PBS (i.e. equal volume of PBS to whole blood).</li>
	<li>Add 4 mL of density gradient solution (see table of materials) to a 15-mL conical tube. Carefully overlay diluted whole blood over the density gradient solution by tilting the tube.</li>
	<li>Centrifuge at 650 x g for 24 min with the brake off.</li>
	<li>Carefully collect the layer of mononuclear cells, which is the thin white layer below the top layer of plasma and platelets, into a new 15-mL conical tube. Bring the volume to 15 mL with PBS.</li>
	<li>Centrifuge at 450 x g for 10 min with the brake on. Aspirate the supernatant and resuspend cells in 0.5 mL of complete media.</li>
	<li>Use an automated cell counter or hemocytometer to count the cells, and adjust the PBMC&#160;concentration to 5x106 cells/mL with complete media.</li>
	<li>Check the NK cell content by flow cytometry (see step 4).</li>
	<li>Start the assay within 30 min. Keep cells at room temperature for up to 10 min, or place in a humidified 5% CO2 incubator at 37 &#176;C until ready for use.</li>
</ol>
3. Isolation of NK cells as effector cells
NOTE: This portion of the protocol is an alternative to using total PBMCs as effector cells. The typical yield from 4 mL of whole blood from a healthy individual is approximately 4x105 NK cells, or approximately 5-15% of PBMCs, though this frequency varies between donors 21. It is recommended that a purity check be performed after the isolation.
<ol>
	<li>Collect a minimum of 4 mL of human whole blood in sodium or lithium heparinized blood collection tubes. Take 50 &#181;L of whole blood to stain as a pre-enrichment sample.</li>
	<li>Add the enrichment cocktail to blood samples at 50 &#181;L/mL (see table of materials). Mix well and incubate for 10 min at room temperature.</li>
	<li>Add an equal volume of PBS + 2% FBS to dilute the sample and gently mix well.</li>
	<li>Add 4 mL of density gradient solution to a 15-mL conical tube. Carefully overlay the diluted sample on top of the density gradient medium.</li>
	<li>Centrifuge at 1,200 x g for 10 min with the brake off.</li>
	<li>Carefully collect the layer of enriched cells into a new 15-mL conical tube. Wash the cells by bringing the volume up to 50 mL with PBS + 2% FBS.</li>
	<li>Centrifuge at 300 x g for 10 min. Discard the supernatant and repeat the wash.</li>
	<li>Aspirate the supernatant and resuspend cells in 0.5 mL of complete media.</li>
	<li>Using an automated cell counter or hemocytometer, count the cells and adjust the concentration to 5x105 cells/mL. Take 50 &#181;L of purified cell suspension to stain as a post-enrichment sample.</li>
	<li>Keep cells at room temperature for up to 10 min, or place in a humidified 5% CO2 incubator at 37 &#176;C until ready for use.</li>
</ol>
4. Immunophenotyping for assessment of NK cell content
<ol>
	<li>Using 50 &#181;L total isolated PBMCs, pre-enrichment whole blood, or purified NK cells, stain with anti-CD56 fluorochrome-conjugated antibody as an NK cell marker. Markers for other cell types and lineages (i.e. CD3+ T cells, CD19+ B cells) may also be included to assess the origin of contamination, if any.</li>
	<li>Incubate for 20 min at 4 &#176;C, and wash by adding 2 mL of PBS + 2% FBS.</li>
	<li>Centrifuge at 450 x g for 5 min.</li>
	<li>For PBMCs or NK cells, aspirate supernatant and resuspend cells in 100 &#181;L of PBS + 2% FBS.</li>
	<li>For whole blood samples, perform red blood cell (RBC) lysis:
	<ol>
		<li>After centrifugation, aspirate the supernatant and resuspend in 2 mL red blood cell lysis buffer (31.75 g of ammonium chloride + 4.16 g of Tris base + 6.65 g of EDTA, dissolved in 5000 mL of deionized water).</li>
		<li>Incubate for 10 min at room temperature.</li>
		<li>Repeat wash twice, aspirate the supernatant, and resuspend lysed sample in 100 &#181;L of PBS + 2% FBS. 
		NOTE: RBC lysis may also be performed prior to staining.</li>
		<li>Proceed with flow cytometric analysis.</li>
	</ol>
	</li>
</ol>
5. Thawing, culturing, and harvesting of K562 target cells
<ol>
	<li>Aliquot 10 mL of complete media into a 15-mL conical tube and allow to warm in a 37 &#176;C water bath. For the thawing and culturing of K562 cells, use only media pre-warmed to 37 &#176;C for all steps.</li>
	<li>Place one vial of frozen K562 cells in the 37 &#176;C water bath until most of it is thawed.</li>
	<li>Transfer the semi-thawed K562 cells to the complete media, pre-warmed to 37 &#176;C, in the 15-mL conical tube. Wash the inside of the cryogenic vial with some pre-warmed media, and add the wash to the 15-mL tube.</li>
	<li>Centrifuge at 140 x g for 7 min with the brake on. Remove the supernatant and resuspend the pellet in 1 mL of complete media.</li>
	<li>Aliquot an appropriate amount of cell suspension to count cells using an automated cell counter or hemocytometer.</li>
	<li>Adjust the concentration to 1x105-2x105 cells/mL&#160;and culture in a humidified 5% CO2 incubator at 37 &#176;C for at least 2 days before use. Maintain the culture at this density range for no longer than 3 months, then thaw a new aliquot.&#160;Never exceed a cell concentration of 1x106 cells/mL in culture.</li>
	<li>For use in the assay, mix the K562 cell culture well with a 10-mL serological pipette and remove an aliquot to count and assess cell viability using an automated cell counter or hemocytometer and Trypan Blue staining.
	<ol>
		<li>If the viability is less than 85%, proceed with the following dead cell removal steps.
		<ol>
			<li>Add 15 mL of density gradient solution to 50-mL conical tubes, as needed. Collect all cells from culture and slowly overlay the cell suspension over the density gradient solution by tilting the tube.</li>
			<li>Centrifuge at 650 x gfor 24 min with brake off. Carefully collect the layer of live cells into a new 15-mL conical tube. Bring the volume to 50 mL with PBS.</li>
			<li>Centrifuge at 450 x g for 10 min with the brake on. Remove the supernatant and resuspend the pellet in 1 mL of complete media. Count the cells and check cell viability (as in 5.7).</li>
			<li>Culture in a humidified 5% CO2 incubator at 37 &#176;C for at least 2 days before use.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Collect 5x105 K562 target cells and centrifuge at 140 x g for 7 min. Aspirate the supernatant and resuspend the cell pellet in 500 &#181;L in media with 1% FBS.</li>
</ol>
6. Labeling of K562 target cells
NOTE: Make sure the K562 cells are well resuspended before adding the CFSE working solution.
<ol>
	<li>Pipette 500 &#181;L of the CFSE working solution to the 500 &#181;L of K562 cells for a final concentration of 0.5 &#181;M. Using the same 1000-1250 &#181;L tip, mix immediately by gently pipetting up and down 3-5 times.</li>
	<li>Incubate in the 37 &#176;C water bath or in a humidified 5% CO2 incubator at 37 &#176;C for 10 min in the dark. 
	NOTE: Since the temperature equilibration lag time is longer in the incubator compared to the water bath, incubation time might need to be adjusted especially for volumes &#62; 1 mL.</li>
	<li>Quench the labeling reaction with 10 mL of complete media for 10 min in the dark at room temperature.</li>
	<li>Centrifuge the labeled K562 cells at 140 x g for 7 min. Remove the supernatant and resuspend in 1 mL of complete media.</li>
	<li>Count the cells using an automated cell counter or hemocytometer and bring the concentration to 1x105 cells/mL in complete media.</li>
	<li>Place cells in a humidified 5% CO2 incubator at 37 &#176;C until ready for use. Cells can be kept at room temperature for up to 10 min, or in in a humidified CO2 incubator at 37 &#176;C until ready for use. Do not refrigerate.</li>
</ol>
7. Plating
NOTE: If NK cells are limiting, the concentration of both K562 and NK cells can be halved, so that half of the cells are plated in the assay. The assay yields comparable results with half the amount of cells (as long as the ratios are kept consistent).
<ol>
	<li>If using total PBMCs, label a 96-well, U-bottom, tissue culture-treated plate for the following conditions per well: (1) Effector (E) : Target (T) = 50 : 1 + IL-2 - positive control for NK cell cytotoxicity; (2) E : T = 50 : 1; (3) E : T = 25 : 1; (4) E : T = 12.5 : 1; (5) E : T = 6.25 : 1; (6) T - target cells only - negative control for K562 death; (7) E - effector cells only; (8) T + Tween - Positive control for K562 death</li>
	<li>If using purified NK cells, label a 96-well, U-bottom, tissue culture treated plate for the following conditions per well: (1) Effector (E) : Target (T) = 5: 1&#160;+ IL-2 - positive control for NK cell cytotoxicity; (2) E : T = 5 : 1; (3) E : T = 2.5 : 1; (4) E : T = 1.25 : 1; (5) E : T = 0.625: 1; (6) T - target cells only - negative control for K562 death; (7) E - effector cells only; (8) T + Tween - positive control for K562 death</li>
	<li>Add 100 &#181;L of complete media to conditions 3, 4, 5, 6, 7. For this and all subsequent steps, (recommended) use a multichannel pipette.</li>
	<li>Add 100 &#181;L of effector cells (PBMCs at 5x106 cells/mL or purified NK cells at 5x105 cells/mL) to conditions 1, 2, 3. Add effector cells for conditions 4-7 by serial dilution. Do not change tips from condition to condition.
	<ol>
		<li>Mix condition 3, take 100 &#181;L, and transfer to condition 4.</li>
		<li>Mix condition 4, take 100 &#181;L, and transfer to condition 5.</li>
		<li>Mix condition 5, take 100 &#181;L, and transfer to condition 7; Condition 6 does not have effector cells.</li>
	</ol>
	</li>
	<li>Add 100 &#181;L of prepared 2x 0.2% Tween working solution to condition 8 (final concentration: 0.1% Tween-20); condition 8 does not have effector cells.</li>
	<li>Add 30 &#181;L of IL-2 working solution to condition 1. IL-2 should be added to the effector cell suspension prior to the addition of target cell suspension (final concentration: 27 IU/mL).</li>
	<li>Add 100 &#181;L of target cells (labeled K562 cells at 1x105 cells/mL) to conditions 1, 2, 3, 4, 5, 6, 8. Condition 7 does not have target cells.</li>
	<li>Mix all wells with a multichannel pipette and centrifuge the plate at 120 x g for 2 min.</li>
	<li>Incubate in a humidified CO2 incubator at 37 &#176;C for 4 h. At the end of the incubation, place the plate on ice and proceed to viability staining within 30 min.</li>
</ol>
8. Staining for viability and acquisition
<ol>
	<li>Prepare dead cell stain (see table of materials) by adding 3 &#181;L of the 5 &#181;M stock solution to 600 &#181;L of PBS.</li>
	<li>Add 50 &#181;L of diluted dead cell stain to each well for a final volume of 250 &#181;L and a final concentration of 0.005 &#181;M. Mix well with a multichannel pipette.</li>
	<li>Proceed with flow cytometric analysis. Using a flow cytometer, collect at least 1,000 events in the target cell gate (Figure 2) for statistically meaningful results.</li>
</ol>

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作者宣称没有的财务上的利益冲突。

这里介绍的方法提供了一个简单和具有成本效益的替代传统51铬释放检测评估 NK 细胞杀伤活性。此方法是灵敏、 重现性好，比以前的标准方法，像 cra 法案，耗时少，可以用于临床和研究应用程序。
同时测定工程与总外周血和浓缩的 NK 细胞，而无需使用外周血净化细胞群体的选项是极大的好处与小卷收集的血或少或质量差细胞来自病人的样本打交道时。这种测定方法利用只有 CFSE 和死细胞排除可行性污点。看着这两个参数仅用于诊断目的，与不需要进一步在流式细胞术分析补偿的额外好处提供简洁和足够的信息。
此方法还可以用于研究基本 NK 细胞生物学和测试新 NK 细胞靶向疗法。在这方面，流式细胞仪的不断扩展功能的多功能性，这种测定方法，允许多参数分析的 NK 细胞和他们的活动不像 CRA 的检测方法与以前可能引入宝贵。跟踪的替代细胞活力染料，荧光在其他渠道，并可应付调查人员的需要。
本议定书是为使用而优化与原型的 NK 细胞靶细胞 K562 细胞株。然而，它可以适应不同程度的敏感性对 NK 细胞毒性、 HL 60、 达乌迪、 U937 和 Raji 等替代悬浮目标细胞系。在这方面，它是重要的是请注意浓度的荧光染料和血清用于在目标单元格贴标过程中可能需要为每个目标单元格的行，优化作为不同的细胞株可能会占用荧光标签，以不同的方式，并为每个流式细胞仪。虽然它通常建议避免使用血清在贴标过程中，我们选择轻微淬火与 0.5%胎牛血清的原因有两个。首先，它有助于减少目标细胞应力，因此背景染色;第二，它带来我们流式细胞仪检测适当范围 CFSE 信号无需日常的设置调整，从而帮助测定的重现性。附加议定书 》 的变化可能包括测试不同 E:T 比率和孵育时间，以适应不同的活化条件对测定。共同文化效应与靶细胞 NK 细胞毒性测试的持续时间从历史上看已从 4-16 个小时，虽然长时间往往会导致增加自发释放9，16。在我们的方法，较长的潜伏期可能也导致丢失的荧光标记的靶细胞因杀害或扩散，由于这些荧光染料稀释后细胞分裂。因此，孵化时间窗口下端是首选，他们不应超过一夜孵化6，，1622。
它是重要的是注意到其中变量可以潜在地影响这种测定方法的结果。K562 细胞靶细胞在我们的经验，对温度变化特别敏感。因此，K562 细胞应该不是冷藏而是室温保存或放在湿润的 CO2培养箱，在其使用前 37 ° C。为同样的原因，所有试剂都应至适当的温度下议定书 》 所示。影响这些细胞的另一个参数是离心速度，应该降低细胞的压力减至最低。此外，限制效应/靶制备工艺和共同孵化到少于 30 分钟的开始之间的滞后时间是必须确保最大的杀伤活性和含量测定的重现性。同样，因为 CFSE 信号是一般鲁棒，准确滴管，适当搅拌的细胞和精确的孵化时间标签和淬火时确保染色的一致性的关键。最后，NK 细胞的杀伤能力是高度可变的即使在健康的个体，受很多因素，包括发育阶段、 性别、 年龄和体重23，24，25。此外，起到 30%的健康对照大幅度减少或完全丧失细胞毒能力如果显示测试超过 24 小时后血画。因此，它被建议使用新鲜纯化外周血或 NK 细胞只要有可能。

An erratum was issued for: <a href="https://www-jove-com.remotexs.ntu.edu.sg/video/56191/a-flow-cytometry-based-cytotoxicity-assay-for-assessment-human-nk">A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity</a>. Figure 4 has been corrected to show background-corrected data.
Figure 4 was updated from:
<img alt="Figure 4" src="/files/ftp_upload/56191/56191fig4v1.jpg" />
to:
<img alt="Figure 4" src="/files/ftp_upload/56191/56191fig4v2.jpg" />

An erratum was issued for: <a href="https://www-jove-com.remotexs.ntu.edu.sg/video/56191/a-flow-cytometry-based-cytotoxicity-assay-for-assessment-human-nk">A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity</a>. Figure 4 has been corrected to show background-corrected data.

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

自然杀伤 (NK) 细胞是人类先天淋巴细胞批判地参与消除病毒感染的细胞，转化的细胞和其他致病性威胁1，2的复杂的子集。NK 细胞裂解颗粒房子像穿孔素和 granzymes 细胞毒性蛋白质。激活后，NK 细胞形成复杂的互动关系，与他们的目标称为免疫突触，藉以本地释放这些细胞毒性分子，造成的直接目标细胞裂解和细胞凋亡与细胞因子和趋化因子的释放，并最终在诱导炎症状态1，，34。
NK 细胞活化涉及复杂的字符串的激活和抑制相互作用 NK 细胞受体与配体形成严格监管的系统的靶细胞表面表达。NK 细胞活化的研究最机制之一是"缺少自我"。事实上，缺乏检测类我主要组织相容性复合物 (MHC) 上或人类白细胞抗原 (HLA) 分子的感染或转化细胞触发器 NK 细胞毒性。肿瘤和病毒感染的细胞普遍下调这些抗原逃避 T 细胞介导的免疫功能，从而成为初级 NK 细胞目标1，，34。
NK 细胞功能的评估主要分为肥大或细胞毒性检测方法。然而，脱颗粒含量测定，如 CD107a，肥大关联标记流流式细胞术检测仅仅是功能的指示性的 NK 细胞活化而不是功能的其最终，直接杀死目标细胞5，，67，8的。因此，这种限制已经提请调查人员细胞毒性试验作为一种更生动、 更直接的替代。
长期的"金本位"评估细胞介导的细胞毒活性的 T 和 NK 细胞是铬释放检测 (CRA)。CRA 涉及放射性标记的靶细胞与51Cr 和效应器细胞共同孵育他们。这种测定方法被沉浸在那细胞裂解结果中释放的蛋白质绑定51Cr 到上清液，可以通过伽玛计数测量的原理。这种测定方法，同时有效，是有问题的各种原因: 材料成本高、 处理和处置放射性51Cr、 51Cr，自发释放和困难标准化-使它完全不切实际9，10。
大量的非放射性检测，涉及荧光标记、 酶释放和甚至生物发光，已经得到发展，作为 CRA 11，，1213，14的替代品。在这里，我们可以描述流测量的 NK 细胞杀伤活性对 k562 细胞的靶细胞，是简单、 灵敏，基于流式细胞仪的方法。K562 细胞是人类 erythroleukemic 细胞线与 HLA 类表达减少第一和配体的活化 NK 受体，这使得它们特别容易受到 NK 细胞介导的细胞毒性15高度的表达。在这种测定方法，K562 细胞前带有羧基荧光素二乙酸琥珀酰亚胺酯 (CFSE) 和共培养在各种比率与任一外周血单个核细胞 （外周血） 或纯化 NK 细胞1。CFSE 是稳定、 蛋白结合的荧光染料，允许歧视的靶细胞效应器 NK 细胞16，17日。共同孵育后, 核酸染色，具体渗透膜的死细胞，用于标识被杀死的靶细胞 （见材料表）。样品上流式细胞仪来确定死 （即，染色 +） 的百分比，得出 CFSE + 靶细胞。
这种测定方法可以用作常规的诊断筛查，为单基因缺陷影响 NK 细胞隔间，其中有大约 30 已知的缺陷导致功能或经典 NK 细胞缺乏症，并为原发性或继发性噬血细胞综合征。它也是用于调查患者反复发作，严重的疱疹病毒感染，评价免疫重建造血细胞移植或邮政免疫调节治疗18，，1920后, 为基本研究应用程序宿主 NK 细胞活性。

<table>
	<tbody>
		<tr>
			<td>Phosphate-buffered Saline (1x, w/o Ca2+ and Mg2+)</td>
			<td>Corning (Cellgro)</td>
			<td>21-040-CM</td>
			<td></td>
		</tr>
		<tr>
			<td>Ficoll-Paque PLUS</td>
			<td>GE Healthcare</td>
			<td>17-1440-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Sigma</td>
			<td>BP337-100</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI 1640 Media</td>
			<td>Corning (Cellgro)</td>
			<td>10-040-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Heat-inactivated Fetal Bovine Serum</td>
			<td>Omega Scientific</td>
			<td>FB-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin Streptomycin</td>
			<td>Life Technologies</td>
			<td>15140-163</td>
			<td>Stock solution at 10,000 U/mL</td>
		</tr>
		<tr>
			<td>IL-2</td>
			<td>R&#38;D Systems</td>
			<td>202-IL-050</td>
			<td>Lyophilized from a 0.2 &#956;m filtered solution in Acetonitrile and TFA with BSA as a carrier protein. Reconstitute with 500 ul at 100 &#956;g/mL in sterile 100 mM Acetic Acid containing at least 0.1% bovine serum albumin (2.1x10E6 IU/ml)</td>
		</tr>
		<tr>
			<td>K562 Cells</td>
			<td>ATCC</td>
			<td>CCL-243</td>
			<td>Cancer cell line&#160;</td>
		</tr>
		<tr>
			<td>T-75 cell culture flasks</td>
			<td>Corning</td>
			<td>431464</td>
			<td></td>
		</tr>
		<tr>
			<td>CFSE cell proliferation kit</td>
			<td>Life Technologies (CellTrace)</td>
			<td>C34554</td>
			<td>Reconstitute I vial with 18 ul DMSO to prepare a 5mM stock solution. Do not freeze/thaw.</td>
		</tr>
		<tr>
			<td>Sytox Red</td>
			<td>Life Technologies</td>
			<td>S34859</td>
			<td>Stock solution is provided at 5 &#956;M in 1 mL DMSO. The DMSO solution may be subjected to multiple freeze-thaw cycles without reagent degradation.</td>
		</tr>
		<tr>
			<td>Sodium/lithium heparin blood collection tubes</td>
			<td>BD</td>
			<td>02-687-95</td>
			<td></td>
		</tr>
		<tr>
			<td>U-bottom 96-well plate</td>
			<td>Corning</td>
			<td>CLS3897</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipettes</td>
			<td>BD Falcon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Polystyrene round-bottom tubes (5mL)</td>
			<td>BD Falcon</td>
			<td>14959-5</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL polypropylene conical tube</td>
			<td>BD Falcon</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL polypropylene conical tube</td>
			<td>BD Falcon</td>
			<td>352097</td>
			<td></td>
		</tr>
		<tr>
			<td>Reagent reservoir</td>
			<td>USA Scientific</td>
			<td>2321-2230</td>
			<td></td>
		</tr>
		<tr>
			<td>Human NK cell enrichment cocktail</td>
			<td>StemCell Technologies (RosetteSep)</td>
			<td>15065</td>
			<td></td>
		</tr>
	</tbody>
</table>

a flow cytometry-based cytotoxicity assay for the assessment of human nk cell activity

先天免疫系统内效应器淋巴细胞称为自然杀伤 (NK) 细胞在宿主防御对异常细胞，专门消除肿瘤和病毒感染细胞发挥了重要的作用。大约 30 已知的单基因缺陷，一大批其他的病理状况，导致功能或经典 NK 细胞缺陷，表现在减少或缺失细胞毒活性。历史上，还用放射性方法，它是繁琐、 昂贵和有潜在危险的方法研究了细胞毒性。这篇文章描述了一个精简、 临床适用流流式细胞仪基于方法量化 NK 细胞杀伤活性。这种测定方法，外周血单个核细胞 （外周血） 或纯化的 NK 细胞制剂在不同比例共同孵育与已知为 NK 细胞介导的细胞毒性 (NKCC) 对敏感目标肿瘤细胞系。靶细胞是预先标记荧光的荧光染料，使他们从效应器细胞 （NK 细胞） 的歧视。后潜伏期，杀死的靶细胞核酸染色，具体地渗透到死细胞由标识。此方法是服从既诊断研究和应用，得益于多参数流式细胞的能力，有好处，有可能使 NK 细胞表型和功能的更深入的分析。

在设置前检测，强烈建议 NK 细胞内容会在选择的效应器人口评估。图 1显示了典型 CD56 沾色 （浅蓝色） 之前和之后 （红色） NK 细胞富集。NK 细胞组成达 15%的外周血和浓缩后应至少 80%的纯。
流式细胞术分析这种测定方法中的涉及的两个参数的检测: CFSE，检出相同的通道作为 FITC;和死细胞染色，在相同的通道作为 APC （图 2A、 B） 检测。后数据采集，在图 2中的浇注策略用于分析数据。死者 （即，死细胞染色 +） 细胞株 K562 目标细胞闸 CFSE + 人口，提供死亡细胞内目标人口的 %。
控制条件是确保检测的有效性本身和其单独的组件的关键。为了使检测才被视为有效，以下应在控制条件下 (6-8): 靶的细胞只有 (条件6) 应最终导致细胞死亡 &#60; 15%(图 3A)。应检测到没有 CFSE 信号，为免疫效应细胞只有 (条件7)，和细胞死亡应该是 &#60; 5%(图 3B)。对于补间介导靶细胞 (条件8) 杀害，细胞死亡应该是 &#62; 85%(图 3)。
NK 细胞功能缺陷的患者预计有最减少杀伤活性或所有比率都测试与一个健康的个体。健康献血者和病人的细胞，在图 4 中的并行显示目标细胞死亡随效应器目标细胞比减小微分的显着减少。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56191/56191fig1.jpg"> 
图 1: NK 细胞内的内容效应器人口评估。代表直方图后染色共外周血 （浅蓝色） 或净化 CD56 NK 细胞 （红色）。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56191/56191fig1large.jpg" target="_blank">请点击这里查看此图的大版本。</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56191/56191fig2.jpg"> 
图 2: 浇注的靶细胞的检测策略。A)在 FITC A SSC 的情节中设置初始的门。K562 细胞闸作为 CFSE + 事件。B)死 K562 细胞 （即为死细胞阳性染色） 封闭入 CFSE + 目标细胞群体内随后的 APC A SSC 的情节。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56191/56191fig2large.jpg" target="_blank">请点击这里查看此图的大版本。</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56191/56191fig3.jpg"> 
图 3: 控制条件的代表数据。 A) 百分比的死细胞染色 + K562 细胞内 （浇注策略如图 2 所示） 的门 CFSE + 条件6 （只有靶细胞）-阴性对照的 K562 细胞死亡。B) CFSE 与死细胞染色检测条件7 （免疫效应细胞只有-总外周血）。C)百分比的死细胞染色 + K562 细胞内 （浇注策略如图 2 所示） 的门 CFSE + 条件8 （靶细胞 + 补间）-阳性对照的 K562 细胞死亡。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56191/56191fig3large.jpg" target="_blank">请点击这里查看此图的大版本。</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56191/56191fig4.jpg"> 
图 4: 各种效应目标细胞比率的稀释效应的代表数据。测试的效应: 目标细胞比率如下: 50: 1、 25: 1;12.5: 1;6.25:1.数据是背景 （条件 #6）-删除。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56191/56191fig4large.jpg" target="_blank">请点击这里查看此图的大版本。</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>示例</td>
			<td>条件</td>
			<td>效应器 (E): 目标 (T)</td>
		</tr>
		<tr>
			<td rowspan="8">外周血</td>
			<td>1-阳性对照为 NK 细胞毒性的</td>
			<td>50:1 + 白细胞介素-2</td>
		</tr>
		<tr>
			<td>2</td>
			<td>50:1</td>
		</tr>
		<tr>
			<td>3</td>
			<td>25:1</td>
		</tr>
		<tr>
			<td>4</td>
			<td>12.5: 1</td>
		</tr>
		<tr>
			<td>5</td>
			<td>6.25: 1</td>
		</tr>
		<tr>
			<td>6</td>
			<td>只有 T</td>
		</tr>
		<tr>
			<td>7-阴性对照的 k562 细胞死亡</td>
			<td>E 只</td>
		</tr>
		<tr>
			<td>8-阳性对照的 k562 细胞死亡</td>
			<td>T + 补间</td>
		</tr>
		<tr>
			<td rowspan="8">NK 细胞 （纯）</td>
			<td>1-阳性对照为 NK 细胞毒性的</td>
			<td>5:1 + 白细胞介素-2</td>
		</tr>
		<tr>
			<td>2</td>
			<td>5:1</td>
		</tr>
		<tr>
			<td>3</td>
			<td>2.5: 1</td>
		</tr>
		<tr>
			<td>4</td>
			<td>1.25: 1</td>
		</tr>
		<tr>
			<td>5</td>
			<td>0.625: 1</td>
		</tr>
		<tr>
			<td>6</td>
			<td>只有 T</td>
		</tr>
		<tr>
			<td>7-阴性对照的 k562 细胞死亡</td>
			<td>E 只</td>
		</tr>
		<tr>
			<td>8-阳性对照的 k562 细胞死亡</td>
			<td>T + 补间</td>
		</tr>
	</tbody>
</table>
表 1

Watch this Scientific Journal Video about A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity at JoVE.com

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

示了流基于流式细胞仪的方法定量地确定人类自然杀手细胞的细胞毒活性。

人外周血 NK 细胞活性评估流基于流式细胞仪检测细胞毒性检测

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

a-flow-cytometry-based-cytotoxicity-assay-for-assessment-human-nk

Nanyang Technological University

Research

JoVE Journal

Immunology and Infection

23.6K 次观看.  University of California, Los Angeles. 示了流基于流式细胞仪的方法定量地确定人类自然杀手细胞的细胞毒活性。

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

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.

人外周血NK细胞的扩展，纯化和功能评估

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

科研

免疫与感染

Human In Vitro Suppression as Screening Tool for the Recognition of an Early State of Immune Imbalance

Regulatory T cells (Tregs) are critical mediators of immune tolerance to self-antigens. In addition, they are crucial regulators of the immune response following an infection. Despite efforts to identify unique surface marker on Tregs, the only unique feature is their ability to suppress the proliferation and function of effector T cells. While it is clear that only in vitro assays can be used in assessing human Treg function, this becomes problematic when assessing the results from cross-sectional studies where healthy cells and cells isolated from subjects with autoimmune diseases (like Type 1 Diabetes-T1D) need to be compared. There is a great variability among laboratories in the number and type of responder T cells, nature and strength of stimulation, Treg:responder ratios and the number and type of antigen-presenting cells (APC) used in human in vitro suppression assays. This variability makes comparison between studies measuring Treg function difficult. The Treg field needs a standardized suppression assay that will work well with both healthy subjects and those with autoimmune diseases. We have developed an in vitro suppression assay that shows very little intra-assay variability in the stimulation of T cells isolated from healthy volunteers compared to subjects with underlying autoimmune destruction of pancreatic &beta;-cells. The main goal of this piece is to describe an in vitro human suppression assay that allows comparison between different subject groups. Additionally, this assay has the potential to delineate a small loss in nTreg function and anticipate further loss in the future, thus identifying subjects who could benefit from preventive immunomodulatory therapy1. Below, we provide thorough description of the steps involved in this procedure. We hope to contribute to the standardization of the in vitro suppression assay used to measure Treg function. In addition, we offer this assay as a tool to recognize an early state of immune imbalance and a potential functional biomarker for T1D.

Human In Vitro Suppression as Screening Tool for the Recognition of an Early State of Immune Imbalance

Tregs are potent suppressors of the immune system. There is a lack of unique surface markers to define them, hence, definitions of Tregs are primarily functional. Here we describe an optimized in vitro assay capable of identifying immune imbalance in subjects at risk to develop T1D.

人类<em在体外承认免疫失衡的早期国家禁止作为筛检工具

Regulatory T cells (Tregs) are critical mediators of immune tolerance to self-antigens. In addition, they are crucial regulators of the immune response ...

Quantitative High-throughput Single-cell Cytotoxicity Assay For T Cells

Cancer immunotherapy can harness the specificity of immune response to target and eliminate tumors. Adoptive cell therapy (ACT) based on the adoptive transfer of T cells genetically modified to express a chimeric antigen receptor (CAR) has shown considerable promise in clinical trials1-4. There are several advantages to using CAR+ T cells for the treatment of cancers including the ability to target non-MHC restricted antigens and to functionalize the T cells for optimal survival, homing and persistence within the host; and finally to induce apoptosis of CAR+ T cells in the event of host toxicity5.
Delineating the optimal functions of CAR+ T cells associated with clinical benefit is essential for designing the next generation of clinical trials. Recent advances in live animal imaging like multiphoton microscopy have revolutionized the study of immune cell function in vivo6,7. While these studies have advanced our understanding of T-cell functions in vivo, T-cell based ACT in clinical trials requires the need to link molecular and functional features of T-cell preparations pre-infusion with clinical efficacy post-infusion, by utilizing in vitro assays monitoring T-cell functions like, cytotoxicity and cytokine secretion. Standard flow-cytometry based assays have been developed that determine the overall functioning of populations of T cells at the single-cell level but these are not suitable for monitoring conjugate formation and lifetimes or the ability of the same cell to kill multiple targets8.
Microfabricated arrays designed in biocompatible polymers like polydimethylsiloxane (PDMS) are a particularly attractive method to spatially confine effectors and targets in small volumes9. In combination with automated time-lapse fluorescence microscopy, thousands of effector-target interactions can be monitored simultaneously by imaging individual wells of a nanowell array. We present here a high-throughput methodology for monitoring T-cell mediated cytotoxicity at the single-cell level that can be broadly applied to studying the cytolytic functionality of T cells.

We describe a single-cell high-throughput assay to measure cytotoxicity of T cells when incubated with tumor target cells. This method employs a dense, elastomeric array of sub-nanoliter wells (~100,000 wells/array) to spatially confine the T cells and target cells at defined ratios and is coupled to fluorescence microscopy to monitor effector-target conjugation and subsequent apoptosis.

定量高通量单细胞的细胞毒性T细胞的测定

Cancer immunotherapy can harness the specificity of  immune response to target and eliminate tumors. Adoptive cell therapy (ACT)  based on the adoptive ...

Cell-based Flow Cytometry Assay to Measure Cytotoxic Activity

Cytolytic activity of CD8+ T cells is rarely evaluated. We describe here a new cell-based assay to measure the capacity of antigen-specific CD8+ T cells to kill CD4+ T cells loaded with their cognate peptide. Target CD4+ T cells are divided into two populations, labeled with two different concentrations of CFSE. One population is pulsed with the peptide of interest (CFSE-low) while the other remains un-pulsed (CFSE-high). Pulsed and un-pulsed CD4+ T cells are mixed at an equal ratio and incubated with an increasing number of purified CD8+ T cells. The specific killing of autologous target CD4+ T cells is analyzed by flow cytometry after coculture with CD8+ T cells containing the antigen-specific effector CD8+ T cells detected by peptide/MHCI tetramer staining. The specific lysis of target CD4+ T cells measured at different effector versus target ratios, allows for the calculation of lytic units, LU30/106 cells. This simple and straightforward assay allows for the accurate measurement of the intrinsic capacity of CD8+ T cells to kill target CD4+ T cells.

This protocol describes a sensitive, cell-based cytotoxicity assay. By enumerating the decrease in frequency of live target CD4+ T cells in the presence of an increasing number of effector CD8+ T cells, this assay allows for the direct assessment of cytolytic activity of antigen-specific CD8+ T cells.

基于细胞的流式细胞仪检测，以测量细胞毒活性

Cytolytic activity of CD8+ T cells is rarely evaluated. We describe here a new cell-based assay to measure the capacity of antigen-specific CD8+ T cells ...

Fast and Specific Assessment of the Halogenating Peroxidase Activity in Leukocyte-enriched Blood Samples

In this paper a protocol for the quick and standardized enrichment of leukocytes from small whole blood samples is described. This procedure is based on the hypotonic lysis of erythrocytes and can be applied to human samples as well as to blood of non-human origin. The small initial sample volume of about 50 to 100 &#181;l makes this method applicable to recurrent blood sampling from small laboratory animals. Moreover, leukocyte enrichment is achieved within minutes and with low material efforts regarding chemicals and instrumentation, making this method applicable in multiple laboratory environments.
Standardized purification of leukocytes is combined with a highly selective staining method to evaluate halogenating peroxidase activity of the heme peroxidases, myeloperoxidase (MPO) and eosinophil peroxidase (EPO), i.e., the formation of hypochlorous and hypobromous acid (HOCl and HOBr). While MPO is strongly expressed in neutrophils, the most abundant immune cell type in human blood as well as in monocytes, the related enzyme EPO is exclusively expressed in eosinophils. The halogenating activity of these enzymes is addressed by using the almost HOCl- and HOBr-specific dye aminophenyl fluorescein (APF) and the primary peroxidase substrate hydrogen peroxide. Upon subsequent flow cytometry analysis all peroxidase-positive cells (neutrophils, monocytes, eosinophils) are distinguishable and their halogenating peroxidase activity can be quantified. Since APF staining may be combined with the application of cell surface markers, this protocol can be extended to specifically address leukocyte sub-fractions. The method is applicable to detect HOCl and HOBr production both in human and in rodent leukocytes.
Given the widely and diversely discussed immunological role of these enzymatic products in chronic inflammatory diseases, this protocol may contribute to a better understanding of the immunological relevance of leukocyte-derived heme peroxidases.

This protocol describes the quick enrichment of leukocytes from small blood samples for a subsequent specific determination of the halogenating peroxidase activity within the cells. The method can be applied to human and non-human material and may contribute to the evaluation of new inflammatory markers.

在富含白细胞的血液样本卤化过氧化物酶活性的快速，具体的评估

In this paper a protocol for the quick and standardized enrichment of leukocytes from small whole blood samples is described. This procedure is based on ...

Flow Cytometry-based Assay for the Monitoring of NK Cell Functions

Natural killer (NK) cells are an important part of the human tumor immune surveillance system. NK cells are able to distinguish between healthy and virus-infected or malignantly transformed cells due to a set of germline encoded inhibitory and activating receptors. Upon virus or tumor cell recognition a variety of different NK cell functions are initiated including cytotoxicity against the target cell as well as cytokine and chemokine production leading to the activation of other immune cells. It has been demonstrated that accurate NK cell functions are crucial for the treatment outcome of different virus infections and malignant diseases. Here a simple and reliable method is described to analyze different NK cell functions using a flow cytometry-based assay. NK cell functions can be evaluated not only for the whole NK cell population, but also for different NK cell subsets. This technique enables scientists to easily study NK cell functions in healthy donors or patients in order to reveal their impact on different malignancies and to further discover new therapeutic strategies.

A simple and reliable method is described here to analyze a set of NK cell functions such as degranulation, cytokine and chemokine production within different NK cell subsets.

流式细胞仪为基础的检测方法的NK细胞功能的监控

Natural killer (NK) cells are an important part of the human tumor immune surveillance system. NK cells are able to distinguish between healthy and ...

Assessing Retinal Microglial Phagocytic Function In Vivo Using a Flow Cytometry-based Assay

Microglia are the tissue resident macrophages of the central nervous system (CNS) and they perform a variety of functions that support CNS homeostasis, including phagocytosis of damaged synapses or cells, debris, and/or invading pathogens. Impaired phagocytic function has been implicated in the pathogenesis of diseases such as Alzheimer's and age-related macular degeneration, where amyloid-&#946; plaque and drusen accumulate, respectively. Despite its importance, microglial phagocytosis has been challenging to assess in vivo. Here, we describe a simple, yet robust, technique for precisely monitoring and quantifying the in vivo phagocytic potential of retinal microglia. Previous methods have relied on immunohistochemical staining and imaging techniques. Our method uses flow cytometry to measure microglial uptake of fluorescently labeled particles after intravitreal delivery to the eye in live rodents. This method replaces conventional practices that involve laborious tissue sectioning, immunostaining, and imaging, allowing for more precise quantification of microglia phagocytic function in just under six hours. This procedure can also be adapted to test how various compounds alter microglial phagocytosis in physiological settings. While this technique was developed in the eye, its use is not limited to vision research.

Assessing Retinal Microglial Phagocytic Function In Vivo Using a Flow Cytometry-based Assay

Microglial phagocytosis is critical for the maintenance of tissue homeostasis and inadequate phagocytic function has been implicated in pathology. However, assessing microglia function in vivo is technically challenging. We have developed a simple but robust technique for precisely monitoring and quantifying the phagocytic potential of microglia in a physiological setting.

评估视网膜小胶质细胞吞噬功能<em&gt;在体内</em&gt;使用基于流式细胞术流量测定

Microglia are the tissue resident macrophages of the central nervous system (CNS) and they perform a variety of functions that support CNS homeostasis, ...

Flow Cytometric Analysis of Particle-bound Bet v 1 Allergen in PM10

Flow cytometry is a method widely used to quantify suspended solids such as cells or bacteria in a size range from 0.5 to several tens of micrometers in diameter. In addition to a characterization of forward and sideward scatter properties, it enables the use of fluorescent labeled markers like antibodies to detect respective structures. Using indirect antibody staining, flow cytometry is employed here to quantify birch pollen allergen (precisely Bet v 1)-loaded particles of 0.5 to 10 &#181;m in diameter in inhalable particulate matter (PM10, particle size &#8804;10 &#181;m in diameter). PM10 particles may act as carriers of adsorbed allergens possibly transporting them to the lower respiratory tract, where they could trigger allergic reactions.
So far the allergen content of PM10 has been studied by means of enzyme linked immunosorbent assays (ELISAs) and scanning electron microscopy. ELISA measures the dissolved and not the particle-bound allergen. Compared to scanning electron microscopy, which can visualize allergen-loaded particles, flow cytometry may additionally quantify them. As allergen content of ambient air can deviate from birch pollen count, allergic symptoms might perhaps correlate better with allergen exposure than with pollen count. In conjunction with clinical data, the presented method offers the opportunity to test in future experiments whether allergic reactions to birch pollen antigens are associated with the Bet v 1 allergen content of PM10 particles &#62;0.5 &#181;m.

Here, we present a protocol to quantify allergen-loaded particles by flow cytometry. Ambient particulate matter particles may act as carriers of adsorbed allergens. We show here that flow cytometry, a method widely used to characterize suspended solids &#62;0.5 &#181;m in diameter, can be used to measure these allergen-loaded particles.

粒子结合Bet v 1的变应原PM10的流式细胞分析

Flow cytometry is a method widely used to quantify suspended solids such as cells or bacteria in a size range from 0.5 to several tens of micrometers in ...

Flow Cytometric Analysis of Natural Killer Cell Lytic Activity in Human Whole Blood

NK cell cytotoxicity is a widely used measure to determine the effect of outside intervention on NK cell function. However, the accuracy and reproducibility of this assay can be considered unstable, either because of user&#39;s errors or because of the sensitivity of NK cells to experimental manipulation. To eliminate these issues, a workflow that reduces them to a minimum was established and is presented here. To illustrate, we obtained blood samples, at various time points, from runners (n = 4) that were submitted to an intense bout of exercise. First, NK cells are simultaneously identified and isolated through CD56 tagging and magnetic-based sorting, directly from whole blood and from as little as one milliliter. The sorted NK cells are removed of any reagent or capping antibodies. They can be counted in order to establish an accurate NK cell count per milliliter of blood. Secondly, the sorted NK cells (effectors cells or E) can be mixed with 3,3&#39;-Diotadecyloxacarbocyanine Perchlorate (DiO) tagged K562 cells (target cells or T) at an assay-optimal 1:5 T:E ratio, and analyzed using an imaging flow-cytometer that allows for the visualization of each event and the elimination of any false positive or false negatives (such as doublets or effector cells). This workflow can be completed in about 4 h, and allows for very stable results even when working with human samples. When available, research teams can test several experimental interventions in human subjects, and compare measurements across several time points without compromising the data&#39;s integrity.

This work describes an advanced workflow for the accurate and fast determination of NK (Natural Killer) cell count and NK cell cytotoxicity in human blood samples.

人全血中NK细胞杀伤活性的流式细胞仪分析

NK cell cytotoxicity is a widely used measure to determine the effect of outside intervention on NK cell function. However, the accuracy and ...

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.

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.

葡聚糖增强小鼠和人原发性 NK 细胞的慢转导效率

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