This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2100-68003-30395 from the USDA National Institute of Food and Agriculture.

NOTE: All blood collection procedures were conducted in accordance with the guidelines set forth by the Appalachian State University (ASU) Institutional Review Board (IRB).
1. Whole Blood Collection
<ol>
	<li>Have a certified phlebotomist draw blood according to World Health Organization&#39;s guidelines.</li>
	<li>Draw blood into one 4 ml blood collection tube containing Di-Potassium Ethylenediaminetetraacetic acid (K2EDTA). Invert blood collection tube according to the manufactu...

<ol>
	<li>Cerwenka, A., Lanier, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+killer+cells,+viruses+and+cancer.">Natural killer cells, viruses and cancer.</a> Nat Rev Immunol. 1 (1), 41-49 (2001).</li><li>Nieman, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exercise,+infection,+and+immunity.">Exercise, infection, and immunity.</a> Int J Sports Med. 15, 131-141 (1994).</li><li>Romeo, J., Warnberg, J., Pozo, T., Marcos, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+activity,+immunity+and+infection.">Physical activity, immunity and infection.</a> Proc Nutr Soc. 69 (3), 390-399 (2010).</li><li>Nieman, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Marathon+training+and+immune+function.">Marathon training and immune function.</a> Sports Med. 37 (4-5), 412-415 (2007).</li><li>Simpson, R. J., Kunz, H., Agha, N., Graff, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exercise+and+the+Regulation+of+Immune+Functions.">Exercise and the Regulation of Immune Functions.</a> Prog Mol Biol Transl Sci. 135, 355-380 (2015).</li><li>Walsh, N. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Position+statement.+Part+one:+Immune+function+and+exercise.">Position statement. Part one: Immune function and exercise.</a> Exerc Immunol Rev. 17, 6-63 (2011).</li><li>Timmons, B. W., Cieslak, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+natural+killer+cell+subsets+and+acute+exercise:+a+brief+review.">Human natural killer cell subsets and acute exercise: a brief review.</a> Exerc Immunol Rev. 14, 8-23 (2008).</li><li>Westermann, J., Pabst, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+of+lymphocyte+subsets+and+natural+killer+cells+in+the+human+body.">Distribution of lymphocyte subsets and natural killer cells in the human body.</a> Clin Investig. 70 (7), 539-544 (1992).</li><li>Boyum, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+leucocytes+from+human+blood.+Further+observations.+Methylcellulose,+dextran,+and+ficoll+as+erythrocyteaggregating+agents.">Isolation of leucocytes from human blood. Further observations. Methylcellulose, dextran, and ficoll as erythrocyteaggregating agents.</a> Scand J Clin Lab Invest Suppl. 97, 31-50 (1968).</li><li>McMillan, R., Scott, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leukocyte+labeling+with+51-Chromium.+I.+Technic+and+results+in+normal+subjects.">Leukocyte labeling with 51-Chromium. I. Technic and results in normal subjects.</a> Blood. 32 (5), 738-754 (1968).</li><li>Berk, L. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+long+endurance+running+on+natural+killer+cells+in+marathoners.">The effect of long endurance running on natural killer cells in marathoners.</a> Med Sci Sports Exerc. 22 (2), 207-212 (1990).</li><li>McAnulty, L. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+blueberry+ingestion+on+natural+killer+cell+counts,+oxidative+stress,+and+inflammation+prior+to+and+after+2.5+h+of+running.">Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running.</a> Appl Physiol Nutr Metab. 36 (6), 976-984 (2011).</li><li>Millard, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brief+Exercise+Increases+Peripheral+Blood+NK+Cell+Counts+without+Immediate+Functional+Changes,+but+Impairs+their+Responses+to+ex+vivo+Stimulation.">Brief Exercise Increases Peripheral Blood NK Cell Counts without Immediate Functional Changes, but Impairs their Responses to ex vivo Stimulation.</a> Front Immunol. 4, 125 (2013).</li><li>Janeway, C. A., Travers, P., Walport, M., Shlomchik, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Immunobiology: The Immune System in Health and Disease. 5th edn. , (2001).</li></ol>

The method described in this study directly measures the specific activity of an individual&#39;s NK cells in response to stimuli (in this particular case, prolonged exercise). Typically, NK cells are isolated from one&#39;s blood using density gradients or cell sorting by using a combination of markers. While these methods are widely used, they have many drawbacks: they are time consuming, involve multiple manipulations, and are heavily user dependent. As a result, undue stress is placed on the isolated NK cells, which ...

Natural killer cells are an essential element of the innate immune system. While they are very regulated, they have the capability to recognize and eliminate abnormal cells through cell-to-cell contact and without prior activation1. As such, they form a quick line of defense against infections. Exercise, especially intense, has been shown to transiently depress the immune system2,3,4,5. NK cells are particularly prone to this effect4,6,7, effectively creating a window of enhanced sensitivity to disease. Hence, the study of interventions before, during or after intense exercise with the goal of reducing its impact on NK cell function is of particular interest for the well-being of athletes post-competitions.
However, the study of such interventions is complicated by numerous factors: 1)&#160;NK cells are sparse8, at about 1% of the white blood cell compartment; 2)&#160;NK cells are very sensitive to stress and rely on constant exposure to physiological conditions to remain viable and stable during experimentation; and 3)&#160;standard assays to determine NK cell cytotoxicity, such as Ficoll gradients9 and release assays10, are unreliable and inconsistent. The inherent variability of human samples only compound these issues. Fresh human samples collected during interventions are fairly regulated and difficult to procure, at least when compared to animal samples or immortalized cell lines. This reduces opportunities to repeat experiments or add participants to the study cohort to reach significant statistical thresholds. Collectively, these issues support the need for a streamlined protocol that allows for both high-throughput and a high-reliability analysis of NK cell lytic activity in human samples.
We established a workflow that shortens the time necessary to identify, isolate and test NK cells from human whole blood while minimizing exposure to extraneous factors. The method optimizes the use of two instruments, a magnetic-based cell sorter and an imaging flow cytometer, and an assay-specific, optimized T:E ratio to allow the detection of decreases or increases of NK cell cytotoxicity.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">K-562 lymphoblasts</td>
			<td style="width:183px;">ATCC</td>
			<td style="width:136px;">CCL-243</td>
			<td style="width:585px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Iscove&#39;s Modified Dulbecco&#39;s Media</td>
			<td style="width:183px;">ATCC</td>
			<td style="width:136px;">30-2005</td>
			<td>High glucose, with L-Glutamine, with HEPES, Sterile-filtered</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Alpha Minimum Essential medium</td>
			<td style="width:183px;">ATCC</td>
			<td style="width:136px;">CRL-2407</td>
			<td style="width:585px;">Without ribonucleosides and deoxyribonucleosides but with 2 mM L-glutamine and 1.5 g/L sodium bicarbonate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">Trypan Blue Solution 0.4%</td>
			<td style="width:183px;">Amresco</td>
			<td style="width:136px;">K940-100ML</td>
			<td>Tissue culture grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">Propridium Iodide Staining Solution</td>
			<td style="width:183px;">BD Pharmingen</td>
			<td style="width:136px;">51-66211E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">Vybranto DiO cell-labeling solution</td>
			<td style="width:183px;">Vybranto</td>
			<td style="width:136px;">V-22886</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">autoMACS Pro Separator</td>
			<td style="width:183px;">Miltenyi Biotec</td>
			<td style="width:136px;">130-092-545</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">autoMACS Running Buffer</td>
			<td style="width:183px;">Miltenyi Biotec</td>
			<td style="width:136px;">130-091-221</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">autoMACS Washing Buffer</td>
			<td style="width:183px;">Miltenyi Biotec</td>
			<td style="width:136px;">130-092-987</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">autoMACS Columns</td>
			<td style="width:183px;">Miltenyi Biotec</td>
			<td style="width:136px;">130-021-101</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Whole Blood CD56 MicroBeads, human</td>
			<td style="width:183px;">Miltenyi Biotec</td>
			<td style="width:136px;">130-090-875</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ImageStream X Mark II Imaging Flow Cytometer</td>
			<td style="width:183px;">EMD Millipore</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Speedbeads</td>
			<td style="width:183px;">Amnis Corporation</td>
			<td style="width:136px;">400030</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.4-0.7% Hypochlorite (Sterilizer)</td>
			<td style="width:183px;">VWR</td>
			<td>JT9416-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Coulter Clenz</td>
			<td style="width:183px;">Beckman Coulter</td>
			<td>8546929</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">70% Isopropanol (Debubbler)</td>
			<td style="width:183px;">EMD Millipore</td>
			<td style="width:136px;">1.3704</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">D-PBS (Sheath fluid)</td>
			<td style="width:183px;">EMD Millipore</td>
			<td style="width:136px;">BSS-1006-B (1X)</td>
			<td>No calcium or magnesium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">INSPIRE Software</td>
			<td style="width:183px;">EMD Millipore</td>
			<td style="width:136px;"></td>
			<td>Version Mark II, September 2013</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ideas Application Software</td>
			<td style="width:183px;">EMD Millipore</td>
			<td style="width:136px;"></td>
			<td>Version 6.1, July 2014</td>
		</tr>
	</tbody>
</table>

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.

Determination of NK cell count 
The effect of heavy running on NK cell count in whole blood was measured, using the exercise protocol described in Figure 2. Blood samples were drawn before exercise, immediately after exercise, 1.5 h after exercise, and finally 24 and 48 h after the initial blood draw. The concentration of NK cells per milliliter of whole blood was measured for each runner (Figure 3A) and on average (Figure 3B) for ea...

Watch this Scientific Journal Video about Flow Cytometric Analysis of Natural Killer Cell Lytic Activity in Human Whole Blood at JoVE.com

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

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.

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

The overall goal of this experiment is to determine NK cell count and cytotoxic activation levels in a human whole blood sample in a fast, reliable and stable manner. This method can help answer questions in the immunological fields, such as, What are the effects of outside interventions on the bioactivity of NK cells? The main advantage of this technique is that it is fast and accurate, While still providing reproducible results across experiments.To isolate NK cells from human whole blood, first place 15 milliliter tubes labeled Whole blood sample, Negative Fraction and Positive Fraction into the appropriate positions in the cell separator tube rack. When all of the tubes are loaded, insert the separator rack onto the mini-sampler for auto labeling, and select Reagent on the menu, to highlight the position where the vial will be placed on the rack. Select Read Reagent to activate the 2D code reader and hold the appropriate reagent vial in front of the 2D code reader at an angle 0.5 to 2.5 centimeters from the code reader cover.Place the read vial into the appropriate separator rack position. Next, under the Separation tab, highlight the desired positions. Then open the Labeling submenu and select an auto-labeling program.Assign the cell separation reagent microbeads to rack positions 1, 2, 3 and 4. And select the Posselwb separaton program. Select the Rinse Wash program.Enter 1500 microliters for the Sample Volume under the Volume sub menu, and press Enter. Then click Run to begin the cell separation. Clicking okay to confirm that enough buffer is available for processing all of the samples.To prepare a Cytotoxicity Assay sample, first, label 1.5 milliliter tubes for each sample and/or participant as appropriate, and pipe out the desired ratio of NK cells and DIO labeled K562 cells into each tube. Collect the cells by centrifugation, and carefully remove the supernatant without disturbing the cell pellet. Next, resuspend the cell mixture in 500 microliters of incomplete NK cell medium, and label the cells in each tube with 5 microliters of propidium iodide.Collect the cells via another centrifugation, and incubate the cull culture at 37 degrees celsius for two hours. At the end of the incubation, centrifuge the cells under the same centrifuge conditions, and resuspend the pellet in 25 microliters of fresh incomplete NK cell culture medium. To analyze the cells by Flow Cytometry, first, click the start up button in the imaging flow cytometer software to flush the system.Next, click on the scatterplot button to create four scatterplots, and load the double positive control tube. Using the double positive control sample, determine the desired intensity for the 405 milliwatt laser, so that the detector is not overloaded, and set the imager to acquire the appropriate number of cell counts. Setting the 405 milliwatt laser at an intensity that is suitable for the detection of both DIO and PI will require experience with both dyes and the detection range of the flow cytometer.After the acquisition of the double positive control sample finishes, load the DIO only control sample, select the 40X objective, and turn off the 642 milliwatt laser and the Brightfield channel. Breed the appropriate number of cells and repeat the acquisition for the propidium iodide only sample. When all of the control samples have been run, turn the 405 milliwatt laser and Brightfield channel, back on, and click Set Intensity.Then, under the File Acquisition tab, enter a custom file name, and select a folder for saving the data files. Next, enter the number of cells to acquire. Load the first experimental sample tube and click the Acquire button.When all of the samples have been run, open the imaging flow cytometer analysis software application, and open a single experimental RIF file. Under the compensation tab, select Create New Matrix. The software will prompt for the selection of the single color files, and merge them to create a matrix file to be selected for applying the channel compensation.Use the Building Blocks function to set up the appropriate dot plots. Then click on the statistics function to access the cell numbers in each gate. In this representative experiment, blood samples were drawn as indicated and the concentration of NK cells per milliliter of whole blood was measured for each runner, and on average for each time point.Three out of four runners presented a similar slight increase in NK cell count after exercise. Immediately followed by a sharp decrease, before slowly returning to normal, 24 to 48 hours after the end of the event. On average the NK cell count decreased 1.5 hours after exercise, but returned to near normal levels after 24 hours.After calculating the cell count, the cytotoxic activity of the NK cells was immediately analyzed as just demonstrated, with an average decrease in NK cell cytotoxicity immediately, and 1.5 hours after the termination of the exercise event, that increased significantly by 24 hours post exercise. The NK cytotoxicity remained high compared to the pre-exercise levels, albeit nonsignificantly. Once mastered, this technique can be completed in about four hours when performed properly.After watching this video, you should have a good understanding of how to obtain and characterize NK cells count and cytotoxic activity from human blood samples in a reproducible hydropic manner.

flow-cytometric-analysis-natural-killer-cell-lytic-activity-human

Research

JoVE Journal

Immunology and Infection

12.2K vistas.  North Carolina A&T State University, North Carolina Research Campus. The overall goal of this experiment is to determine NK cell count and cytotoxic activation levels in a human whole blood sample in a fast, reliable and stable manner. This method can help answer questions in the immunological fields, such as, What are the effects of outside interventions on the bioactivity of NK cells? The main advantage of this technique is that it is fast and accurate, While still providing reproducible results across experiments.To isolate NK cells from human whole ...