RW was supported by Beijing Natural Science Foundation, China (No. 7222059), National Natural Science Foundation of China (No. 82002130), XZ was supported by the CAMS Innovation Fund for Medical Sciences (No. 2019-I2M-5-026).

The study was approved by the Ethics Committee of Beijing Children&#39;s Hospital, Capital Medical University (Approval Number: 2020-k-85). Informed consent of human subjects was waived as only residual samples after clinical testing were used in this study. Two labs are involved in this study. The transferring lab is where the standardized method was developed using one flow cytometer. The cytometer in this lab is hereinafter referred to as cytometer A. The test method lab is the laboratory that receives methods using another flow cytometer, and the cytometer in this lab is hereinafter referred to as cytometer B.
1. Peripheral blood sample collection and cell preparation
<ol>
	<li>Collect peripheral blood samples (2 mL) from JE-vaccinated children and unvaccinated children in EDTA-K2-anticoagulated tubes by standard venipuncture.</li>
	<li>Mix the whole blood sample by turning the tubes upside down 10x. Add 100 &#181;L of whole blood to a 12 mm x 75 mm tube. Make each sample in duplicate.</li>
	<li>Add 10 &#181;L of brilliant stain buffer (BV buffer) to a 12 mm x 75 mm tube. Add 5 &#181;L of each antibody (CD45, CD3, CD4, CD8, CD127, CD27, CD19, IgD; dilution factor: 1:20) and 20 &#181;L of antibody (CD25, CD45RA; dilution factor: 1:5) to the BV buffer. Vortex gently. 
	NOTE: The volumes and information of the antibody reagents are shown in Table 1.</li>
	<li>Add the antibody cocktail into the tube with the whole blood sample. Vortex gently and incubate at room temperature for 15 min in the dark.</li>
	<li>Dilute the 10x lysing solution 1:10 with distilled water to prepare 1x lysing solution. Lyse the blood samples by adding 2 mL of 1x lysing solution. Vortex gently and incubate for 10 min in the dark at room temperature.</li>
	<li>Centrifuge at 300 &#215; g for 5 min and decant the supernatant.</li>
	<li>Resuspend the pellet in 2 mL of 1x PBS, centrifuge at 300 &#215; g for 5 min, and decant the supernatant.</li>
	<li>Resuspend the pellet in 0.5 mL of 1x PBS and mix thoroughly. Store at 2 &#176;C to 8 &#176;C. Send the samples to the two labs for flow cytometric analysis. 
	&#8203;NOTE: The negative control sample and cell single-stained control must be processed simultaneously.</li>
</ol>
2. Preparing compensation beads and single-stained control
<ol>
	<li>Label V500-anti-CD45 single-stained, APC-H7-anti-CD3 single-stained, FITC-anti-CD4 single-stained, R718-anti-CD8 single-stained, BV605-anti-CD27 single-stained, APC-anti-CD45RA single-stained, PE-anti-CD25 single-stained, BV421-anti-CD127 single-stained, BB700-anti-CD19 single-stained, and PE-CY7-anti-IgD single-stained tubes.</li>
	<li>Add 100 &#181;L of 1x Dulbecco&#39;s phosphate-buffered saline (DPBS) buffer containing 1% fetal bovine serum (FBS) to a 5 mL round-bottom polystyrene test tube.</li>
	<li>Add 50 &#181;L of the negative beads and 50 &#181;L of the anti-mouse Ig, &#954; beads to each tube and vortex.</li>
	<li>Add 2 &#181;L of each labeled antibody (CD45, CD3, CD4, CD8, CD25, CD127, CD45RA, CD27, CD19, IgD) to a single-stained tube. Vortex the mixture gently and incubate for 15 min in the dark at room temperature (20 &#176;C to 25 &#176;C).</li>
	<li>Resuspend the beads in 2 mL of 1x PBS, centrifuge at 300 &#215; g for 5 min, and decant the supernatant.</li>
	<li>Resuspend the beads in 0.5 mL of 1x PBS and mix thoroughly. Store at 2 &#176;C to 8 &#176;C.</li>
</ol>
3. Using identical configuration names on the different cytometers in two labs
<ol>
	<li>Create a new configuration in the software of cytometer A. Click the Cytometer button and choose view Configurations to display the configuration window.</li>
	<li>In the configuration list, right-click the base configurations folder, choose New Folder, and rename it.</li>
	<li>Right-click the base configuration and choose copy.</li>
	<li>Right-click the new folder and paste the base configuration to create a new configuration. Rename the new configuration &#34;Standardized Method Transfer&#34;.</li>
	<li>Drag the parameter name, such as FITC, from the Parameters list onto the appropriate detector (530/30).</li>
	<li>Edit additional parameters (PE, BB700, PE-CY7, APC, R718, APC-H7, BV421, V500, and BV605) to the new configuration.</li>
	<li>Follow this method to create a new configuration on a different flow cytometer model using the same name &#34;Standardized Method Transfer&#34;. Ensure that the configuration includes the same parameters for each detector. 
	NOTE: To successfully identify the experiment template on the two different flow cytometer models, make sure that the name is consistent.</li>
	<li>Under the cytometer configurations, use cytometer setup and tracking (CST) beads to define the cytometer baseline and track cytometer performance. Click on the Cytometer button and choose CST to display the cytometer setup and tracking workspace.</li>
	<li>Add three drops (150 &#181;L) of setup beads to 0.5 mL of 1x PBS in a 5 mL round-bottom polystyrene test tube. Place the beads tube on the cytometer.</li>
	<li>In the Setup Control window, choose Define Baseline, and click Run.</li>
</ol>
4. Standardizing experiment using cytometer A in the transferring lab
<ol>
	<li>Run a performance check using the cytometer setup and tracking beads to verify that the cytometer is performing well.</li>
	<li>In the software browser window, right-click the cytometer settings and choose Application Settings to create a worksheet.</li>
	<li>Using an unstained sample, adjust the photomultiplier tube (PMT) voltages of FSC, SSC, and all fluorescence parameters. FSC: 260; SSC: 460; FITC: 490; PE: 575; BB700: 620; PE-CY7: 640; APC: 600; R718: 620; APC-H7: 620; BV421: 466; V500: 420; and BV605: 505.</li>
	<li>Right-click the experiment cytometer settings and choose application settings to save it.</li>
	<li>Click on the experiment button and choose compensation setup menu. Then, choose Create compensation controls to automatically add compensation controls.</li>
	<li>Record data for all compensation control beads.</li>
	<li>Click on the experiment and choose compensation setup. Then, calculate the compensation automatically.</li>
	<li>Record data for cell single-stained controls.</li>
	<li>Use CD45RA APC to modify the compensation value of R718 to 15% APC. Use CD19 BB700 to modify the compensation value of APC-H7 to 14% BB700. Use CD8 R718 to modify the compensation value of APC-H7 to 60% R718.</li>
	<li>Record data for the CST beads.</li>
	<li>Create a global worksheet of the target value template for the CST bright beads.</li>
	<li>Using an FSC/SSC plot, draw the polygon gate for the CST bright beads. Obtain histogram plots of 10 fluorescence channels for the CST bright beads: FITC, PE, BB700, PE-Cy7, APC, R718, APC-H7, BV421, V500, and BV605. Create interval gates in the histogram plots. Create the statistics view by showing the median of the interval gates.</li>
	<li>Run the samples on the flow cytometer; collect a total of 25,000 lymphocytes.</li>
	<li>Create a global worksheet of the analysis template for the samples.</li>
	<li>Use the following sample gating strategy:
	<ol>
		<li>Using a CD45/side scatter-area (SSC-A) dot plot, draw the polygon gate to identify the intact lymphocyte population while excluding debris.</li>
		<li>Using a CD3/CD19 dot plot, draw a rectangular gate to select CD3+ T cells and CD19+ B cells.</li>
		<li>Using a CD4/CD8 dot plot, draw a quad gate to select CD4+ or CD8+ T cells (cells with a high fluorescence for these markers, respectively).</li>
		<li>Using a CD45RA/CD27 dot plot, draw a quad gate to subdivide CD8+ or CD4+ T cells into na&#239;ve (CD27+CD45RA+), TCM (CD27+ CD45RA-), TEM (CD27-CD45RA-), and TEMRA (CD27-CD45RA+) cells.</li>
		<li>Using a CD25/CD127 dot plot, draw a quad gate to subdivide CD4+ T cells into Treg cells (CD4+CD25++CD127low).</li>
		<li>Using a CD27/IgD dot plot, draw a quad gate to subdivide CD19+ B cells into na&#239;ve B cells (CD27-IgD+) and memory B cells (CD27+IgD-).</li>
	</ol>
	</li>
	<li>Save the experimental template on cytometer A.</li>
	<li>Use the CD-ROM to export the experimental template.</li>
</ol>
5. Transferring the experimental template to cytometer B in the test method lab
NOTE: The experimental template includes instrument settings, the analysis template, and the target value template of median fluorescence intensity (MFI).
<ol>
	<li>Conduct a performance check using CST beads to verify that the cytometer is performing well.</li>
	<li>Import the experimental template and create an experiment for cytometer B using the template.</li>
	<li>Use the same lot of CST beads to adjust the fluorescent parameter voltages for each fluorescence channel to match the previous MFI instrument. 
	NOTE: The MFI values vary within &#177;5% (the MFI of bright beads before and after transfer are shown in Table 2).</li>
	<li>Adjust the voltage for FSC using the unstained sample, if needed.</li>
	<li>Right-click on the experimental cytometer settings and choose application settings to save the application settings.</li>
	<li>Use CD45RA APC to modify the compensation value of R718 to 15% APC. Use CD19 BB700 to modify the compensation value of APC-H7 to 24% BB700. Use CD8 R718 to modify the compensation value of APC-H7 to 60% R718.</li>
	<li>Run the samples on the flow cytometer; collect a total of 25,000 lymphocytes.</li>
</ol>
6. Consistency between the experimental results obtained on the two cytometers
<ol>
	<li>Assess the differences in lymphocyte subsets between instruments using one-way ANOVA (p &#60; 0.05).</li>
</ol>

<ol>
	<li>Cabanski, M., 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=Flow+cytometric+method+transfer:+Recommendations+for+best+practice.">Flow cytometric method transfer: Recommendations for best practice.</a> Cytometry Part B. Clinical Cytometry. 100 (1), 52-62 (2021).</li><li>Le Lann, 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=Standardization+procedure+for+flow+cytometry+data+harmonization+in+prospective+multicenter+studies.">Standardization procedure for flow cytometry data harmonization in prospective multicenter studies.</a> Scientific Reports. 10 (1), 11567 (2020).</li><li>Linskens, E., 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=Improved+standardization+of+flow+cytometry+diagnostic+screening+of+primary+immunodeficiency+by+software-based+automated+gating.">Improved standardization of flow cytometry diagnostic screening of primary immunodeficiency by software-based automated gating.</a> Frontiers in Immunology. 11, 584646 (2020).</li><li>Glier, H., 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=Standardization+of+8-color+flow+cytometry+across+different+flow+cytometer+instruments:+A+feasibility+study+in+clinical+laboratories+in+Switzerland.">Standardization of 8-color flow cytometry across different flow cytometer instruments: A feasibility study in clinical laboratories in Switzerland.</a> Journal of Immunological Methods. 475, 112348 (2019).</li><li>Wang, R., 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+epidemiology+and+disease+burden+of+children+hospitalized+for+viral+infections+within+the+family+Flaviviridae+in+China:+A+national+cross-sectional+study.">The epidemiology and disease burden of children hospitalized for viral infections within the family Flaviviridae in China: A national cross-sectional study.</a> PLOS Neglected Tropical Diseases. 16 (7), e0010562 (2022).</li><li>Ding, Y., 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=Reference+values+for+peripheral+blood+lymphocyte+subsets+of+healthy+children+in+China.">Reference values for peripheral blood lymphocyte subsets of healthy children in China.</a> The Journal of Allergy and Clinical Immunology. 142 (3), 970-973 (2018).</li><li>Zhang, 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=Detection+of+polyfunctional+T+cells+in+children+vaccinated+with+Japanese+encephalitis+vaccine+via+the+flow+cytometry+technique.">Detection of polyfunctional T cells in children vaccinated with Japanese encephalitis vaccine via the flow cytometry technique.</a> Journal of Visualized Experiments. (187), e64671 (2022).</li><li>Yu, N., 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=CD4(+)+CD25+(+)+CD127+(low/-)+T+cells:+a+more+specific+Treg+population+in+human+peripheral+blood.">CD4(+) CD25 (+) CD127 (low/-) T cells: a more specific Treg population in human peripheral blood.</a> Inflammation. 35 (6), 1773-1180 (2012).</li><li>Kalina, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reproducibility+of+flow+cytometry+through+standardization:+opportunities+and+challenges.">Reproducibility of flow cytometry through standardization: opportunities and challenges.</a> Cytometry Part A. 97 (2), 137-147 (2020).</li><li>Sommer, U., 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=Implementation+of+highly+sophisticated+flow+cytometry+assays+in+multicenter+clinical+studies:+considerations+and+guidance.">Implementation of highly sophisticated flow cytometry assays in multicenter clinical studies: considerations and guidance.</a> Bioanalysis. 7 (10), 1299-1311 (2015).</li><li>Glier, H., 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=Comments+on+EuroFlow+standard+operating+procedures+for+instrument+setup+and+compensation+for+BD+FACS+Canto+II,+Navios+and+BD+FACS+Lyric+instruments.">Comments on EuroFlow standard operating procedures for instrument setup and compensation for BD FACS Canto II, Navios and BD FACS Lyric instruments.</a> Journal of Immunological Methods. 475, 112680 (2019).</li></ol>

The authors declare no conflicts of interest.

Immunophenotyping of peripheral blood lymphocyte subsets can help understand the changes in cell-mediated adaptive immunity after vaccination in children. In clinical applications, unexpected situations occur, such as a failure to detect samples in a timely manner or the replacement of a flow cytometer; therefore, rapid standardized methods that facilitate transfers between flow cytometers in different labs are needed9,10,11. He...

The standardization of flow cytometry is useful for the comparability of results obtained from different cytometers across different laboratories and study centers, and conducive to the mutual recognition of results to improve work efficiency. An increasing number of scenarios require standardization. During the drug development process, flow cytometry standardization is important, as a developed and validated assay will support the whole drug development process from preclinical to clinical analysis. Flow cytometric methods are frequently transferred between the pharmaceutical industry and collaborating laboratories1. Moreover, it is essential to obtain comparable data from multicentric clinical studies. For example, a standardization workflow was developed in the Systemic Autoimmune Diseases Multicenter Clinical Research Project to obtain comparable data from multicentric flow cytometry2.
The standardization of flow cytometry methods is challenging. The challenges experienced across labs are attributed to the lack of standardized materials, software compatibility issues, inconsistencies in instrument setup, and the use of different configurations among different flow cytometers and divergent gating strategies between the centers3,4. Therefore, it is important to conduct a gap analysis between laboratories. Sample access, quality systems, personnel qualifications, and instrument configuration must be reviewed to ensure that the requirements are met.
At present, children vaccinated with the Japanese encephalitis (JE) vaccine have a significantly reduced incidence of JE5. Monitoring peripheral blood immune cells can help understand the changes in cell-mediated adaptive immunity after vaccination, and the correlation between the changes in peripheral blood lymphocyte subsets and the effects of vaccination. Due to the limited stability of whole blood samples, evaluations of vaccine efficacy are often performed in multiple centers. For this analysis, we defined na&#239;ve CD8+ or CD4+ T cells as CD27+ CD45RA+, central memory T cells (TCM) as CD27+ CD45RA-, effector memory T cells (TEM) as CD27- CD45RA-,&#160;and terminally differentiated effector memory T cells (TEMRA) as CD27- CD45RA+. CD19+ B cells can be separated into populations that express CD27 versus IgD6,7, na&#239;ve B cells express CD27n memory B cells (mBCs) can be identified based on the expression of IgD6, and regulatory T cells (Tregs) can be identified as CD4+CD25++CD127low 8. To establish a standardized flow cytometry experiment to achieve the consistency and comparability of experimental results in multiple centers, a rapid and feasible standardization method was established to facilitate the transfer of protocols across different flow cytometers for the detection of lymphocytes in the whole blood of JE-vaccinated children. Six healthy children (2 years old) were recruited from Beijing Children&#39;s Hospital, Capital Medical University. After receiving a prime and boost vaccination with a live-attenuated JE SA14-14-2 vaccine less than 6 months prior, peripheral blood samples were collected from the volunteers. Highly comparable data were obtained from different instruments following standardized procedures, which is helpful for multicenter assessments.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>BD CompBeads Anti-Mouse Ig, &#954;/Negative Control Compensation Particles Set</td>
			<td>BD</td>
			<td>552843</td>
			<td>compensation</td>
		</tr>
		<tr>
			<td>BD FACSCanto</td>
			<td>BD</td>
			<td>FACSCanto</td>
			<td>flow Cytometry A in the transferring lab</td>
		</tr>
		<tr>
			<td>BD FACSDiva CS&#38;T Research Beads</td>
			<td>BD</td>
			<td>655051</td>
			<td>define flow cytometer baseline and track cytometer performance</td>
		</tr>
		<tr>
			<td>BD Horizon BV421 Mouse Anti-Human CD127</td>
			<td>BD</td>
			<td>562436</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Horizon BV605 Mouse Anti-Human CD27</td>
			<td>BD</td>
			<td>562656</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Horizon V500 Mouse Anti-Human CD45</td>
			<td>BD</td>
			<td>560777</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD LSRFortessa</td>
			<td>BD</td>
			<td>LSRFortessa</td>
			<td>flow Cytometry B in the test method lab</td>
		</tr>
		<tr>
			<td>BD OptiBuild BB700 Mouse Anti-Human CD19</td>
			<td>BD</td>
			<td>745907</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD OptiBuild R718 Mouse Anti-Human CD8</td>
			<td>BD</td>
			<td>751953</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Pharmingen APC Mouse Anti-Human CD45RA</td>
			<td>BD</td>
			<td>550855</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Pharmingen APC-H7 Mouse Anti-Human CD3</td>
			<td>BD</td>
			<td>560176</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Pharmingen FITC Mouse Anti-Human CD4</td>
			<td>BD</td>
			<td>566320</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Pharmingen PE Mouse Anti-Human CD25</td>
			<td>BD</td>
			<td>555432</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BD Pharmingen PE-Cy7 Mouse Anti-Human IgD</td>
			<td>BD</td>
			<td>561314</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>Brilliant Staining Buffer Plus</td>
			<td>BD</td>
			<td>566385</td>
			<td>Staining Buffer</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5810</td>
			<td>Cell centrifugation</td>
		</tr>
		<tr>
			<td>Centrifuge Tube</td>
			<td>BD Falcon</td>
			<td>BD-35209715</td>
			<td>15 mL centrifuge tube</td>
		</tr>
		<tr>
			<td>CS&#38;T IVD Beads</td>
			<td>BD</td>
			<td>662414</td>
			<td>standard beads to setup cytometer settings in different flow cytometer</td>
		</tr>
		<tr>
			<td>Lysing Solution 10x Concentrate</td>
			<td>BD</td>
			<td>349202</td>
			<td>lysing red blood cells</td>
		</tr>
		<tr>
			<td>Phosphate-buffered Saline (PBS)</td>
			<td>Gibco</td>
			<td>10010-023</td>
			<td>PBS</td>
		</tr>
		<tr>
			<td>Round-bottom test tube</td>
			<td>BD Falcon</td>
			<td>352235</td>
			<td>5 mL test tube</td>
		</tr>
	</tbody>
</table>

standardization of transfer across labs between flow cytometers for detection of lymphocytes in japanese encephalitis vaccinated children

An increasing number of laboratories need to collect data from multiple flow cytometers, especially for research projects performed across multiple centers. The challenges of using two flow cytometers in different labs include the lack of standardized materials, software compatibility issues, inconsistencies in instrument setup, and the use of different configurations for different flow cytometers. To establish a standardized flow cytometry experiment to achieve the consistency and comparability of experimental results across multiple centers, a rapid and feasible standardization method was established to transfer parameters across different flow cytometers. 
The methods developed in this study allowed the transfer of experimental settings and analysis templates between two flow cytometers in different laboratories for the detection of lymphocytes in Japanese encephalitis (JE)-vaccinated children. A consistent fluorescence intensity was obtained between the two cytometers using fluorescence standard beads to establish the cytometer settings. Comparable results were obtained in two laboratories with different types of instruments. Using this method, we can standardize analysis for evaluating the immune function of JE-vaccinated children in different laboratories with different instruments, diminish the differences in data and results among flow cytometers in multiple centers, and provide a feasible approach for the mutual accreditation of laboratory results. The standardization method of flow cytometer experiments will ensure the effective performance of research projects across multiple centers.

Figure 1&#160;shows a global worksheet of the target value template for the CST bright beads. Using an FSC/SSC plot, a polygon gate is drawn to select the CST bright beads. Histogram plots of 10 fluorescence channels were obtained for the CST bright beads: FITC, PE, BB700, PE-Cy7, APC, R718, APC-H7, BV421, V500, and BV605. The target value for each parameter is displayed by showing the median within the histogram gates in Table 2. The screenshots of templates and parameter s...

Watch this Scientific Journal Video about Standardization of Transfer across Labs between Flow Cytometers for Detection of Lymphocytes in Japanese Encephalitis Vaccinated Children at JoVE.com

Standardization of Transfer across Labs between Flow Cytometers for Detection of Lymphocytes in Japanese Encephalitis Vaccinated Children

In this study, a method was developed to facilitate the transfer of experimental settings and analysis templates between two flow cytometers in two laboratories for the detection of lymphocytes in Japanese encephalitis-vaccinated children. The standardization method for the flow cytometer experiments will allow research projects to be effectively conducted in multiple centers.

An increasing number of laboratories need to collect data from multiple flow cytometers, especially for research projects performed across multiple ...

standardization-transfer-across-labs-between-flow-cytometers-for

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JoVE Journal

Immunology and Infection

882 Views.  Becton Dickinson Medical Devices (Shanghai) Co Ltd. In this study, a method was developed to facilitate the transfer of experimental settings and analysis templates between two flow cytometers in two laboratories for the detection of lymphocytes in Japanese encephalitis-vaccinated children. The standardization method for the flow cytometer experiments will allow research projects to be effectively conducted in multiple centers.

Video: Standardization of Transfer across Labs between Flow Cytometers for Detection of Lymphocytes in Japanese Encephalitis Vaccinated Children

Combination of Adhesive-tape-based Sampling and Fluorescence in situ Hybridization for Rapid Detection of Salmonella on Fresh Produce

This protocol describes a simple approach for adhesive-tape-based sampling of tomato and other fresh produce surfaces, followed by on-tape fluorescence in situ hybridization (FISH) for rapid culture-independent detection of Salmonella spp. Cell-charged tapes can also be placed face-down on selective agar for solid-phase enrichment prior to detection. Alternatively, low-volume liquid enrichments (liquid surface miniculture) can be performed on the surface of the tape in non-selective broth, followed by FISH and analysis via flow cytometry. To begin, sterile adhesive tape is brought into contact with fresh produce, gentle pressure is applied, and the tape is removed, physically extracting microbes present on these surfaces. Tapes are mounted sticky-side up onto glass microscope slides and the sampled cells are fixed with 10% formalin (30 min) and dehydrated using a graded ethanol series (50, 80, and 95%; 3 min each concentration). Next, cell-charged tapes are spotted with buffer containing a Salmonella-targeted DNA probe cocktail and hybridized for 15 - 30 min at 55&deg;C, followed by a brief rinse in a washing buffer to remove unbound probe. Adherent, FISH-labeled cells are then counterstained with the DNA dye 4',6-diamidino-2-phenylindole (DAPI) and results are viewed using fluorescence microscopy. For solid-phase enrichment, cell-charged tapes are placed face-down on a suitable selective agar surface and incubated to allow in situ growth of Salmonella microcolonies, followed by FISH and microscopy as described above. For liquid surface miniculture, cell-charged tapes are placed sticky side up and a silicone perfusion chamber is applied so that the tape and microscope slide form the bottom of a water-tight chamber into which a small volume (&le; 500 &mu;L) of Trypticase Soy Broth (TSB) is introduced. The inlet ports are sealed and the chambers are incubated at 35 - 37&deg;C, allowing growth-based amplification of tape-extracted microbes. Following incubation, inlet ports are unsealed, cells are detached and mixed with vigorous back and forth pipetting, harvested via centrifugation and fixed in 10% neutral buffered formalin. Finally, samples are hybridized and examined via flow cytometry to reveal the presence of Salmonella spp. As described here, our "tape-FISH" approach can provide simple and rapid sampling and detection of Salmonella on tomato surfaces. We have also used this approach for sampling other types of fresh produce, including spinach and jalape&ntilde;o peppers.

Combination of Adhesive-tape-based Sampling and Fluorescence in situ Hybridization for Rapid Detection of Salmonella on Fresh Produce

This protocol describes a simple adhesive-tape-based approach for sampling of tomato and other fresh produce surfaces, followed by rapid whole cell detection of Salmonella using fluorescence in situ hybridization (FISH).

This protocol describes a simple approach for adhesive-tape-based sampling of tomato and other fresh produce surfaces, followed by on-tape fluorescence in ...

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.

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

Locked Nucleic Acid Flow Cytometry-fluorescence in situ Hybridization (LNA flow-FISH): a Method for Bacterial Small RNA Detection

Fluorescence in situ hybridization (FISH) is a powerful technique that is used to detect and localize specific nucleic acid sequences in the cellular environment. In order to increase throughput, FISH can be combined with flow cytometry (flow-FISH) to enable the detection of targeted nucleic acid sequences in thousands of individual cells. As a result, flow-FISH offers a distinct advantage over lysate/ensemble-based nucleic acid detection methods because each cell is treated as an independent observation, thereby permitting stronger statistical and variance analyses. These attributes have prompted the use of FISH and flow-FISH methods in a number of different applications and the utility of these methods has been successfully demonstrated in telomere length determination1,2, cellular identification and gene expression3,4, monitoring viral multiplication in infected cells5, and bacterial community analysis and enumeration6.
Traditionally, the specificity of FISH and flow-FISH methods has been imparted by DNA oligonucleotide probes. Recently however, the replacement of DNA oligonucleotide probes with nucleic acid analogs as FISH and flow-FISH probes has increased both the sensitivity and specificity of each technique due to the higher melting temperatures (Tm) of these analogs for natural nucleic acids7,8. Locked nucleic acid (LNA) probes are a type of nucleic acid analog that contain LNA nucleotides spiked throughout a DNA or RNA sequence9,10. When coupled with flow-FISH, LNA probes have previously been shown to outperform conventional DNA probes7,11 and have been successfully used to detect eukaryotic mRNA12 and viral RNA in mammalian cells5.
Here we expand this capability and describe a LNA flow-FISH method which permits the specific detection of RNA in bacterial cells (Figure 1). Specifically, we are interested in the detection of small non-coding regulatory RNA (sRNA) which have garnered considerable interest in the past few years as they have been found to serve as key regulatory elements in many critical cellular processes13. However, there are limited tools to study sRNAs and the challenges of detecting sRNA in bacterial cells is due in part to the relatively small size (typically 50-300 nucleotides in length) and low abundance of sRNA molecules as well as the general difficulty in working with smaller biological cells with varying cellular membranes. In this method, we describe fixation and permeabilzation conditions that preserve the structure of bacterial cells and permit the penetration of LNA probes as well as signal amplification steps which enable the specific detection of low abundance sRNA (Figure 2).

Locked Nucleic Acid Flow Cytometry-fluorescence in situ Hybridization LNA flow-FISH: a Method for Bacterial Small RNA Detection

A novel high-throughput method is described that enables the detection and relative quantitation of small RNA and mRNA expression from single bacterial cells using locked nucleic acid probes and flow cytometry-fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) is a powerful technique that is used to detect and localize specific nucleic acid sequences in the cellular ...

Total Protein Extraction and 2-D Gel Electrophoresis Methods for Burkholderia Species

The investigation of the intracellular protein levels of bacterial species is of importance to understanding the pathogenic mechanisms of diseases caused by these organisms. Here we describe a procedure for protein extraction from Burkholderia species based on mechanical lysis using glass beads in the presence of ethylenediamine tetraacetic acid and phenylmethylsulfonyl fluoride in phosphate buffered saline. This method can be used for different Burkholderia species, for different growth conditions, and it is likely suitable for the use in proteomic studies of other bacteria. Following protein extraction, a two-dimensional (2-D) gel electrophoresis proteomic technique is described to study global changes in the proteomes of these organisms. This method consists of the separation of proteins according to their isoelectric point by isoelectric focusing in the first dimension, followed by separation on the basis of molecular weight by acrylamide gel electrophoresis in the second dimension. Visualization of separated proteins is carried out by silver staining.

Total Protein Extraction and 2-D Gel Electrophoresis Methods for Burkholderia Species

Members of the Burkholderia genus are pathogens of clinical importance. We describe a method for total bacterial protein extraction, using mechanical disruption, and 2-D gel electrophoresis for subsequent proteomic analysis.

The investigation of  the intracellular protein levels of bacterial species is of importance to  understanding the pathogenic mechanisms of diseases ...

Detection of Fluorescent Nanoparticle Interactions with Primary Immune Cell Subpopulations by Flow Cytometry

Engineered nanoparticles are endowed with very promising properties for therapeutic and diagnostic purposes. This work describes a fast and reliable method of analysis by flow cytometry to study nanoparticle interaction with immune cells. Primary immune cells can be easily purified from human or mouse tissues by antibody-mediated magnetic isolation. In the first instance, the different cell populations running in a flow cytometer can be distinguished by the forward-scattered light (FSC), which is proportional to cell size, and the side-scattered light (SSC), related to cell internal complexity. Furthermore, fluorescently labeled antibodies against specific cell surface receptors permit the identification of several subpopulations within the same sample. Often, all these features vary when cells are boosted by external stimuli that change their physiological and morphological state. Here, 50 nm FITC-SiO2 nanoparticles are used as a model to identify the internalization of nanostructured materials in human blood immune cells. The cell fluorescence and side-scattered light increase after incubation with nanoparticles allowed us to define time and concentration dependence of nanoparticle-cell interaction. Moreover, such protocol can be extended to investigate Rhodamine-SiO2 nanoparticle interaction with primary microglia, the central nervous system resident immune cells, isolated from mutant mice that specifically express the Green Fluorescent Protein (GFP) in the monocyte/macrophage lineage. Finally, flow cytometry data related to nanoparticle internalization into the cells have been confirmed by confocal microscopy.

Analysis of nanoparticle interaction with defined subpopulations of immune cells by flow cytometry.

Engineered nanoparticles are endowed with very promising properties for therapeutic and diagnostic purposes. This work describes a fast and reliable ...

A Simple and Rapid Protocol to Non-enzymatically Dissociate Fresh Human Tissues for the Analysis of Infiltrating Lymphocytes

The ability of malignant cells to evade the immune system, characterized by tumor escape from both innate and adaptive immune responses, is now accepted as an important hallmark of cancer. Our research on breast cancer focuses on the active role that tumor infiltrating lymphocytes play in tumor progression and patient outcome. Toward this goal, we developed a methodology for the rapid isolation of intact lymphoid cells from normal and abnormal tissues in an effort to evaluate them proximate to their native state. Homogenates prepared using a mechanical dissociator show both increased viability and cell recovery while preserving surface receptor expression compared to enzyme-digested tissues. Furthermore, enzymatic digestion of the remaining insoluble material did not recover additional CD45+ cells indicating that quantitative and qualitative measurements in the primary homogenate likely genuinely reflect infiltrating subpopulations in the tissue fragment. The lymphoid cells in these homogenates can be easily characterized using immunological (phenotype, proliferation, etc.) or molecular (DNA, RNA and/or protein) approaches. CD45+ cells can also be used for subpopulation purification, in vitro expansion or cryopreservation. An additional benefit of this approach is that the primary tissue supernatant from the homogenates can be used to characterize and compare cytokines, chemokines, immunoglobulins and antigens present in normal and malignant tissues. This protocol functions extremely well for human breast tissues and should be applicable to a wide variety of normal and abnormal tissues.

This protocol describes the rapid non-enzymatic dissociation of fresh human tissue fragments for qualitative and quantitative assessment of CD45+ cells (lymphocytes/leukocytes) present in various normal and malignant human tissues. Additionally, the supernatant obtained from the primary tissue homogenate can be collected and stored for further analysis or experimentation.

The ability of malignant cells to evade the immune system, characterized by tumor escape from both innate and adaptive immune responses, is now accepted ...

Isolation and Flow Cytometric Characterization of Murine Small Intestinal Lymphocytes

The intestines &#8212; which contain the largest number of immune cells of any organ in the body &#8212; are constantly exposed to foreign antigens, both microbial and dietary. Given an increasing understanding that these luminal antigens help shape the immune response and that education of immune cells within the intestine is critical for a number of systemic diseases, there has been increased interest in characterizing the intestinal immune system. However, many published protocols are arduous and time-consuming. We present here a simplified protocol for the isolation of lymphocytes from the small-intestinal lamina propria, intraepithelial layer, and Peyer&#39;s patches that is rapid, reproducible, and does not require laborious Percoll gradients. Although the protocol focuses on the small intestine, it is also suitable for analysis of the colon. Moreover, we highlight some aspects that may need additional optimization depending on the specific scientific question. This approach results in the isolation of large numbers of viable lymphocytes that can subsequently be used for flow cytometric analysis or alternate means of characterization.

There is growing interest in the quantitative characterization of intestinal lymphocytes owing to increasing recognition that these cells play a critical role in a variety of intestinal and systemic diseases. In this protocol, we describe how to isolate single cell populations from different small-intestinal compartments for subsequent flow cytometric characterization.

The intestines &#8212; which contain the largest number of immune cells of any organ in the body &#8212; are constantly exposed to foreign antigens, both ...

Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the development and persistence of many health related infections. One of the most well described and studied biofilms in human disease occurs in chronic pulmonary infection of cystic fibrosis patients. When studying biofilms in the context of the host, many factors can impact biofilm formation and development. In order to identify how host factors may affect biofilm formation and development, we used a static chambered coverglass method to grow biofilms in the presence of host-derived factors in the form of sputum supernatants. Bacteria are seeded into chambers and exposed to sputum filtrates. Following 48 hr of growth, biofilms are stained with a commercial biofilm viability kit prior to confocal microscopy and analysis. Following image acquisition, biofilm properties can be assessed using different software platforms. This method allows us to visualize key properties of biofilm growth in presence of different substances including antibiotics.

This protocol describes the visualization of biofilm development following exposure to host-factors using a slide chamber model. This model allows for direct visualization of biofilm development as well as analysis of biofilm parameters using computer software programs.

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the ...

A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.

Fecal-oral transmission of acute gastroenteritis occurs from time to time, especially when people who handled food and water are infected by Salmonella spp./Shigella spp. The gold standard method for the detection of Salmonella spp./Shigella spp. is direct culture but this is labor-intensive and time-consuming. Here, we describe a high-throughput platform for Salmonella spp./Shigella spp. screening, using real-time polymerase chain reaction (PCR) combined with guided culture. There are two major stages: real-time PCR and the guided culture. For the first stage (real-time PCR), we explain each step of the method: sample collection, pre-enrichment, DNA extraction and real-time PCR. If the real-time PCR result is positive, then the second stage (guided culture) is performed: selective culture, biochemical identification and serological characterization. We also illustrate representative results generated from it. The protocol described here would be a valuable platform for the rapid, specific, sensitive and high-throughput screening of Salmonella spp./Shigella spp.

A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.

Salmonella spp./Shigella spp. are common pathogens attributed to diarrhea. Here, we describe a high-throughput platform for the screening of Salmonella spp./Shigella spp. using real-time PCR combined with guided culture.

Fecal-oral transmission of acute gastroenteritis occurs from time to time, especially when people who handled food and water are infected by Salmonella ...

Intravital Imaging of Intraepithelial Lymphocytes in Murine Small Intestine

Intraepithelial lymphocytes expressing &#947;&#948; T cell receptor (&#947;&#948; IEL) play a key role in immune surveillance of the intestinal epithelium. Due in part to the lack of a definitive ligand for the &#947;&#948; T cell receptor, our understanding of the regulation of &#947;&#948; IEL activation and their function in vivo remains limited. This necessitates the development of alternative strategies to interrogate signaling pathways involved in regulating &#947;&#948; IEL function and the responsiveness of these cells to the local microenvironment. Although &#947;&#948; IELs are widely understood to limit pathogen translocation, the use of intravital imaging has been critical to understanding the spatiotemporal dynamics of IEL/epithelial interactions at steady-state and in response to invasive pathogens. Herein, we present a protocol for visualizing IEL migratory behavior in the small intestinal mucosa of a GFP &#947;&#948; T cell reporter mouse using inverted spinning disk confocal laser microscopy. Although the maximum imaging depth of this approach is limited relative to the use of two-photon laser-scanning microscopy, spinning disk confocal laser microscopy provides the advantage of high speed image acquisition with reduced photobleaching and photodamage. Using 4D image analysis software, T cell surveillance behavior and their interactions with neighboring cells can be analyzed following experimental manipulation to provide additional insight into IEL activation and function within the intestinal mucosa.

We describe a method to visualize GFP-labeled &#947;&#948; IELs using intravital imaging of murine small intestine by inverted spinning disk confocal microscopy. This technique enables the tracking of live cells within the mucosa for up to 4 h and can be used to investigate a variety of intestinal immune-epithelial interactions. &#160;