Name: detection of polyfunctional t cells in children vaccinated with japanese encephalitis vaccine via the flow cytometry technique
Uploaded: 2022-09-23T15:00:00
Description: Watch this Scientific Journal Video about Detection of Polyfunctional T Cells in Children Vaccinated with Japanese Encephalitis Vaccine via the Flow Cytometry Technique at JoVE.com

R.W. was supported by National Natural Science Foundation of China (82002130), Beijing Natural Science Foundation of&#160;China (7222059). ZD.X. was supported by the CAMS Innovation Fund for Medical Sciences (2019-I2M-5-026).

Ethical approval for the present study was obtained by the Ethics Committee of Beijing Children&#39;s Hospital, Capital Medical University (Approval Number: 2020-k-85). Volunteers were recruited from Beijing Children&#39;s Hospital, Capital Medical University. Peripheral venous blood samples were obtained from apparently healthy children (2 years old) who had previously received a prime and boosted vaccination with live-attenuated JE SA14-14-2 vaccine for less than half a year (JE-vaccinated children, n = 5) and unvaccin...

<ol>
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This protocol represents a feasible flow cytometry-based detection method for TPF profiles in the PBMCs of children vaccinated with the JEV vaccine SA14-14-2. This study used the venous blood PBMCs of both vaccinated and unvaccinated children as research materials. With the stimulation of PBMCs with the JEV antigen, those amplified antigen-specific TPFs can be characterized by multicolor flow cytometry antibody staining. Compared with the conventional enzyme-linked immunospot assay method, flow cyto...

Japanese encephalitis virus (JEV) is an important mosquito-borne virus belonging to the genus Flavivirus within the Flaviviridae&#160;family1. Many Asia-Pacific countries have long faced enormous public health challenges due to the huge disease burden caused by Japanese encephalitis (JE), but this has improved dramatically with the increasing availability of various types of vaccinations2. Adaptive protective immune responses evoked by natural infection or vaccination contribute to the prevention and antiviral regulation. Humoral immunity and cell-mediated immunity are classified as adaptive immunity, and the induction of the former has always been regarded as a key strategy in vaccine design, albeit with relatively limited understanding in the past3. However, the role of T cell-mediated immunity in limiting flavivirus dissemination and virus clearance has been increasingly focused on and extensively studied4. Furthermore, T cell immunity is not only indispensable in JEV-specific antiviral responses but also plays a prominent role in cross-protection from secondary infection with heterologous flaviviruses, which has been demonstrated in previous studies5. It is speculated that this effect may bypass potential antibody-mediated enhancement effects in infection5. Of note, such cross-reactive T cell immunity is important, especially in the absence of vaccines and antiviral drugs against flaviviruses. Although many studies have been performed to determine the contribution of T cells in JEV infection with respect to CD4+ and CD8+ T cells6,7, the respective lineages secreting cytokines and their functional diversification remain undetermined, which means the elucidation of the exact functions of helper and killer T cells is hindered.
The scale of their antiviral defenses determines the quality of T cell responses. CD4+ or CD8+ T cells that can compatibly confer two or more functions, including cytokine secretion and degranulation, are characterized as polyfunctional T cells&#160;(TPFs)&#160;upon specific stimulation at the single-cell level8. CD4+ T cells that produce single or multiple cytokines may have various effects and immune memories. For example, IL-2+ IFN-&#947;+ CD4+ T cells are more likely to form a long-term effective protective response than IL-2+ CD4+ T cells9, which can be used as an important parameter in evaluating the vaccination effect. The frequency of IL-2+ IFN-&#947;+ CD4+ T cells is increased in patients with long-term non-progression of acquired immune deficiency syndrome (AIDS), while CD4+ T cells in patients with AIDS progression are more inclined to produce IFN-&#947; alone due to the promoting effect of IL-2 on T cell proliferation10. Furthermore, a subset of IL-2+ IFN-&#947;+ TNF-&#945;+ was shown to survive long-term in vivo and synergistically promote the killing function11. Although CD8+ T cells are more likely to exhibit cytotoxic activity, some CD4+ T cells are also equipped with cytotoxic activity as an indirectly detected expression of surface CD107a molecules12. In addition, certain T cell subsets express the chemokine MIP-1&#945;, which is often secreted by monocytes to participate in T cell-mediated neutrophil recruitment13. Similarly, CD8+ TPFs can also be used to characterize the versatility of the above markers. Studies have shown that the prime-boost strategy can effectively induce a prolonged period of TPF protective effects13, which can enhance the protection elicited by vaccination. A central feature in examining the immune system is the ability of memory T cells to facilitate stronger, faster, and more effective responses to secondary viral challenges than na&#239;ve T cells. Effector memory T cells (TEM) and central memory T cells (TCM) are important T cell subsets that are often differentiated by the composite expression of CD27/CD45RO or CCR7/CD45RA14. TCM (CD27+ CD45RO+ or CCR7+ CD45RA-) tends to localize in secondary lymphoid tissues, while TEM (CD27- CD45RO+ or CCR7- CD45RA-) localizes in lymphoid and peripheral tissues15,16. TEM provides immediate but not sustained defense, whereas TCM sustains the response by proliferating in the secondary lymphoid organs and generating new effectors17. Thus, given that memory cells can mediate specific and efficient recall responses to viruses, questions arise about the contribution of this subset of polyfunctions.
With the development of flow cytometry technology, it has become common to simultaneously detect markers of more than 10 clusters, phenotypes, and differentiation antigens, which is beneficial to more abundantly annotate the functional immunological features on individual T cells to reduce misinterpretation and difficulties in understanding of T cell phenotypes. This study used ex vivo stimulation and flow cytometry to analyze TPF profiles in peripheral blood mononuclear cells (PBMCs) within JEV-vaccinated children. Applying this approach, the understanding of short- and long-term JEV-specific and even cross-reactive T cell immunity induced by vaccination will be expanded.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>anti-human CD28</td>
			<td>Biolegend</td>
			<td>302934</td>
			<td>Antibody</td>
		</tr>
		<tr>
			<td>anti-human CD49d</td>
			<td>Biolegend</td>
			<td>304339</td>
			<td>Antibody</td>
		</tr>
		<tr>
			<td>APC anti-human MIP-1&#945;</td>
			<td>BD</td>
			<td>551533</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>Automated cell counter</td>
			<td>BIO RAD</td>
			<td>TC20</td>
			<td>Cell count</td>
		</tr>
		<tr>
			<td>BD FACSymphony A5</td>
			<td>BD</td>
			<td>A5</td>
			<td>flow Cytometry</td>
		</tr>
		<tr>
			<td>BUV395 anti-human CD4</td>
			<td>BD</td>
			<td>563550</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BUV737 anti-human CCR7</td>
			<td>BD</td>
			<td>741786</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BUV737 anti-human CD27</td>
			<td>BD</td>
			<td>612829</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BV421 anti-human CD8</td>
			<td>Biolegend</td>
			<td>344748</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BV480 anti-human CD45RA</td>
			<td>BD</td>
			<td>566114</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BV480 anti-human CD45RO</td>
			<td>BD</td>
			<td>566143</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BV605 anti-human CD107a</td>
			<td>Biolegend</td>
			<td>328634</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BV650 anti-human CD3</td>
			<td>BD</td>
			<td>563999</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>BV785 anti-human IL-2</td>
			<td>Biolegend</td>
			<td>500348</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>Centrifuge Tube</td>
			<td>BD Falcon</td>
			<td>BD-35209715</td>
			<td>15 mL centrifuge tube</td>
		</tr>
		<tr>
			<td>Cytofix/Cytoperm Fixation/Permeabilization Solution Kit</td>
			<td>BD</td>
			<td>554714</td>
			<td>Cell fixation and permeabilization</td>
		</tr>
		<tr>
			<td>Density gradient medium</td>
			<td>Dakewe</td>
			<td>DKW-KLSH-0100</td>
			<td>Ficoll-Paque, human lymphocyte separation medium</td>
		</tr>
		<tr>
			<td>FITC anti-human IFN-&#947;</td>
			<td>Biolegend</td>
			<td>502506</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>Gibco Fetal Bovine Serum</td>
			<td>Thermo Fisher Scientific</td>
			<td>16000-044</td>
			<td>Fetal Bovine Serum</td>
		</tr>
		<tr>
			<td>Gibco RPMI-1640 medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>22400089</td>
			<td>cell culture medium</td>
		</tr>
		<tr>
			<td>High-speed&#160;centrifuge</td>
			<td>Sigma</td>
			<td>&#160;3K15</td>
			<td>Cell centrifugation for 15 mL centrifuge tube</td>
		</tr>
		<tr>
			<td>High-speed&#160;centrifuge</td>
			<td>Eppendorf</td>
			<td>5424R</td>
			<td>Cell centrifugation for 1.5 mL Eppendorf (EP) tube</td>
		</tr>
		<tr>
			<td>Microcentrifuge tubes</td>
			<td>Axygen</td>
			<td>MCT-150-C</td>
			<td>1.5 mL microcentrifuge tube</td>
		</tr>
		<tr>
			<td>PE anti-human TNF-&#945;</td>
			<td>Biolegend</td>
			<td>502909</td>
			<td>Fluorescent antibody&#160;</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>BI</td>
			<td>02-024-1ACS</td>
			<td>PBS</td>
		</tr>
		<tr>
			<td>Protein Transport Inhibitor (Containing Brefeldin A, GolgiPlug)</td>
			<td>BD</td>
			<td>555029</td>
			<td>blocks intracellular protein transport processes</td>
		</tr>
		<tr>
			<td>Protein Transport Inhibitor (Containing Monensin)</td>
			<td>BD</td>
			<td>554724</td>
			<td>blocks intracellular protein transport processes</td>
		</tr>
		<tr>
			<td>Round-bottom test tube</td>
			<td>BD Falcon</td>
			<td>352235</td>
			<td>5 mL test tube</td>
		</tr>
		<tr>
			<td>Trypan Blue Staining Cell Viability Assay Kit</td>
			<td>Beyotime</td>
			<td>C0011</td>
			<td>Trypan Blue Staining</td>
		</tr>
		<tr>
			<td>Zombie NIR Fixable Viability Dye</td>
			<td>Biolegend</td>
			<td>423106</td>
			<td>Dead cell stain</td>
		</tr>
	</tbody>
</table>

detection of polyfunctional t cells in children vaccinated with japanese encephalitis vaccine via the flow cytometry technique

T cell-mediated immunity plays an important role in controlling flavivirus infection, either after vaccination or after natural infection. The "quality" of a T cell needs to be assessed by function, and higher function is associated with more powerful immune protection. T cells that can simultaneously produce two or more cytokines or chemokines at the single-cell level are called polyfunctional T cells (TPFs), which mediate immune responses through a variety of molecular mechanisms to express degranulation markers (CD107a) and secrete interferon (IFN)-&#947;, tumor necrosis factor (TNF)-&#945;, interleukin (IL)-2, or macrophage inflammatory protein (MIP)-1&#945;. There is increasing evidence that TPFs are closely related to the maintenance of long-term immune memory and protection and that their increased proportion is an important marker of protective immunity and is important in the effective control of viral infection and reactivation. This evaluation applies not only to specific immune responses but also to the assessment of cross-reactive immune responses. Here, taking the Japanese encephalitis virus (JEV) as an example, the detection method and flow cytometry color scheme of JEV-specific TPFs produced by peripheral blood mononuclear cells of children vaccinated against Japanese encephalitis were tested to provide a reference for similar studies.

Figure 1 shows&#160;the gating strategy used to divide the TCM or TEM of&#160;CD8+ or CD4+ T cells from a representative JEV stimulation group of JE-vaccinated children. The FSC-A/SSC-A dot plot is used to identify lymphocytes, and the FSC-A/FSC-W dot plot is used to identify single cells. Viable cells are selected on the live/dead/SSC-A dot plot. The CD3/SSC-A dot plot is used to identify the CD3+ T cells. The CD4/CD8 dot plot is used t...

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Detection of Polyfunctional T Cells in Children Vaccinated with Japanese Encephalitis Vaccine via the Flow Cytometry Technique

The present protocol combines ex vivo stimulation and flow cytometry to analyze polyfunctional T cell (TPF)&#160;profiles in peripheral blood mononuclear cells (PBMCs) within Japanese encephalitis virus (JEV)-vaccinated children. The detection method and flow cytometry color scheme of JEV-specific TPFs were tested to provide a reference for similar studies.

Detection of Polyfunctional T Cells in Children Vaccinated with Japanese Encephalitis Vaccine via the Flow Cytometry Technique

T cell-mediated immunity plays an important role in controlling flavivirus infection, either after vaccination or after natural infection. The "quality" ...

The detection method and the flow cytometry color scheme of Japanese encephalitis virus-specific TPFS were tested to provide a reference for similar studies. Demonstrating the procedure will be performed by Linlin Zhang and Meng Zhang, two students from our laboratory. To begin, stimulate the PBMCs of the JEV stimulation group with concentrated inactivated JEV particles for 16 hours at 37 degrees Celsius in the presence of monoclonal antibodies, CD28 and CD49d, CD107a, GolgiPlug, and monensin.Then, stimulate the PBMCs of the control group without concentrated virus particles for 16 hours at 37 degrees Celsius in the presence of monoclonal antibodies, CD28 and CD49d, CD 107a, GolgiPlug and monensin. Collect the cell suspension from each group in a 1.5 milliliter microcentrifuge tube. Centrifuge at 500 g for five minutes at room temperature, and remove the supernatant with a pipette.Resuspend the cells in 1 milliliter of PBS. Add fixable viability dye to the cell suspension and incubate for 10 minutes at room temperature in the dark. Centrifuge at 500 g at room temperature for five minutes, and remove the supernatant.After resuspending the cells in 1 milliliter of PBS, again, centrifuge at 500 g at room temperature for five minutes and discard the supernatant as demonstrated previously. To perform cell surface marker staining, resuspend the cells in 100 microliters of PBS, and add two microliters of each surface marker antibody to the cell suspension in each tube. Incubate the tubes for 30 minutes at room temperature while protecting them from light.Centrifuge at 500 g for five minutes and remove the supernatant as demonstrated previously. Again, resuspend the cells in one milliliter of PBS. Centrifuge at 500 g for five minutes at room temperature and discard the supernatant carefully.To perform fixation and membrane breaking, resuspend the cells with 500 microliters of membrane-breaking fixative solution and fix the cells for 20 minutes in the dark at room temperature. Then centrifuge at 500 g for five minutes and remove the supernatant. After resuspending the cells in one milliliter of PBS, centrifuge for five minutes at 500 g at room temperature and remove the supernatant carefully, as demonstrated previously.Then, resuspend the cells in 100 microliters of PBS and add two microliters of each cytokine antibody to the cell suspension in each tube for intracellular cytokine staining. Incubate the tubes for 30 minutes at room temperature in the dark. Again, centrifuge at 500 g for five minutes, and remove the supernatant as demonstrated previously.Once again, resuspend the cells in one milliliter of PBS. Centrifuge at 500 g for five minutes at room temperature and remove the supernatant carefully as demonstrated previously. Then, add 500 microliters of PBS to resuspend the cells.After isolating the PBMC sample alone, as demonstrated previously, divide the cell suspension into 12 equal parts in 1.5 milliliter microcentrifuge tubes described in the manuscript. Similarly, after adding the cell surface markers and intracellular cytokine antibody, as demonstrated previously, add 500 microliters of PBS to resuspend the cells and vortex with low velocity. Using an unstained sample, adjust the forward scatter, side scatter and different fluorescent dye voltages, while adjust the flow cytometry compensation to eliminate the contamination signals between the different fluorophores, using the single staining samples.Draw a polygon gate through the forward scatter area, side scatter area dot plot to select the intact lymphocyte population, while excluding the debris, and a rectangular gate through the forward scatter area, forward scatter width dot plot to select the single cells. Next, draw a rectangular gate through the live, dead side scatter area dot plot to select the live cells, and a rectangular gate through the CD3 side scatter area dot plot to identify the CD three positive T-cells. Then, draw a quad gate through the CD4, CD8 dot plot to identify the CD4 positive or CD8 positive T-cells and through the CD45RO, CD27 dot plot to subdivide the CD4 positive or CD8 positive T-cells into TCM and TEM.After drawing the gates of CD107a, interferon gamma, tumor necrosis factor alpha, interleukin 2 and microphage inflammatory protein one alpha from the TCM or TEM of the CD8 positive or CD4 positive T-cells to determine the frequency of different response patterns respectively. Load the samples onto the cytometry sequentially. The gating strategy was employed to identify the TCM or TEM of CD8 positive or CD4 positive T-cells and their subsets using the forward scatter area width, then side scatter area dot plot.The poly functional characterization of CD4 positive and CD8 positive T-cell responses to JEV indicated that increased levels of CD107a, interferon gamma, tumor necrosis factor alpha and interleukin 2 were detected in the CD8 positive TCM cells of the vaccinated children after JEV stimulation compared to those in unvaccinated children. However, the level of macrophage inflammatory protein one alpha did not differ between the two groups. Higher levels of CD107a, and interferon gamma were detected in the CD8 positive TEM cells of the vaccinated group under JEV stimulation compared with the unvaccinated group.Whereas tumor necrosis factor alpha, interleukin 2 and macrophage inflammatory protein one alpha, were not significantly elevated in those positive cells. The JEV antigen successfully induced higher levels of CD107a, interferon gamma, tumor necrosis factor alpha, and macrophage inflammatory protein one alpha in the CD4 positive TCM cells of the vaccinated group compared with the unvaccinated group. However, the proportion of interleukin 2 positive cells did not differ between the two groups under JEV stimulation.The proportion of CD107a positive, interferon gamma positive and tumor necrosis factor alpha positive subsets, sub CD4 positive TEM cells in the vaccinated group was higher in the presence of JEV, than in the unvaccinated group. The T-cell immunogenicity of the stimuli and the compatible color matching strategies are critical steps in this protocol.

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JoVE Journal

Immunology and Infection

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.

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 ...

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 ...

The Use of Flow Cytometry to Assess the State of Chromatin in T Cells

During a proper immune response, quiescent T cells become activated upon antigen presentation to their antigen-specific T cell receptor. This leads to clonal proliferation of only those T cells that bear a receptor that recognizes the antigen. Chromatin decondensation is a hallmark of T cell activation and is required for T cells to acquire the ability to proliferate after antigen engagement. This change in chromatin condensation can be detected using antibodies raised against histone proteins. These antibodies cannot bind to their epitopes in na&#239;ve T cells as well as they can in activated T cells. We describe how to simultaneously stain T cell-specific surface markers, track viability with a fixable dead cell stain, and measure chromatin status via intracellular staining of Histone H3 proteins. Stained cells are analyzed by flow cytometry and chromatin condensation status is measured as the mean fluorescence intensity (MFI) of the Histone H3 stain. Chromatin decondensation during T cell activation is demonstrated as an increase in the MFI

Flow cytometry can be utilized to assess the state of chromatin within T cells. This protocol allows scientists to interpret evidence of chromatin decondensation during T cell activation demonstrated by an increase in the mean florescence intensity (MFI) of fluorescent Histone H3 antibodies

During a proper immune response, quiescent T cells become activated upon antigen presentation to their antigen-specific T cell receptor. This leads to ...

Fluorescence-activated Cell Sorting for Purification of Plasmacytoid Dendritic Cells from the Mouse Bone Marrow

Fluorescence-activated cell sorting (FACS) is a technique to purify specific cell populations based on phenotypes detected by flow cytometry. This method enables researchers to better understand the characteristics of a single cell population without the influence of other cells. Compared to other methods of cell enrichment, such as magnetic-activated cell sorting (MCS), FACS is more flexible and accurate for cell separation due to the ability of phenotype detection by flow cytometry. In addition, FACS is usually capable of separating multiple cell populations simultaneously, which improves the efficiency and diversity of experiments. Although FACS has some limitations, it has been broadly used to purify cells for functional studies in both in vitro and in vivo settings. Here we report a protocol using fluorescence-activated cell sorting to isolate a very rare population of immune cells, plasmacytoid dendritic cells (pDC), with high purity from the bone marrow of lupus-prone mice for in vitro functional studies of pDC.

We report a protocol using fluorescence-activated cell sorting to isolate plasmacytoid dendritic cells (pDC) with high purity from the bone marrow of lupus-prone mice for functional studies of pDC.

Fluorescence-activated cell sorting (FACS) is a technique to purify specific cell populations based on phenotypes detected by flow cytometry. This method ...

Measurement of T Cell Alloreactivity Using Imaging Flow Cytometry

The measurement of immunological reactivity to donor antigens in transplant recipients is likely to be crucial for the successful reduction or withdrawal of immunosuppression. The mixed leukocyte reaction (MLR), limiting dilution assays, and trans-vivo delayed-type hypersensitivity (DTH) assay have all been applied to this question, but these methods have limited predictive ability and/or significant practical limitations that reduce their usefulness. Imaging flow cytometry is a technique that combines the multiparametric quantitative powers of flow cytometry with the imaging capabilities of fluorescent microscopy. We recently made use of an imaging flow cytometry approach to define the proportion of recipient T cells capable of forming mature immune synapses with donor antigen-presenting cells (APCs). Using a well-characterized mouse heart transplant model, we have shown that the frequency of in vitro immune synapses among T-APC membrane contact events strongly predicted allograft outcome in rejection, tolerance, and a situation where transplant survival depends on induced regulatory T cells. The frequency of T-APC contacts increased with T cells from mice during acute rejection and decreased with T cells from mice rendered unresponsive to alloantigen. The addition of regulatory T cells to the in vitro system reduced prolonged T-APC contacts. Critically, this effect was also seen with human polyclonally expanded, naturally occurring regulatory T cells, which are known to control the rejection of human tissues in humanized mouse models. Further development of this approach may allow for a deeper characterization of the alloreactive T-cell compartment in transplant recipients. In the future, further development and evaluation of this method using human cells may form the basis for assays used to select patients for immunosuppression minimization, and it can be used to measure the impact of tolerogenic therapies in the clinic.

This paper describes a method for measuring alloreactivity in a mixed population of T cells using imaging flow cytometry.

The measurement of immunological reactivity to donor antigens in transplant recipients is likely to be crucial for the successful reduction or withdrawal ...

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and their important role in lung development and function, as well as their lung-localized responses to infection and inflammation. To date, no unified method for identification, isolation, and handling of alveolar macrophages from humans and mice exists. Such a method is needed for studies on these important innate immune cells in various experimental settings. The method described here, which can be easily adopted by any laboratory, is a simplified approach to harvesting alveolar macrophages from bronchoalveolar lavage fluid or from lung tissue and maintaining them in vitro. Because alveolar macrophages primarily occur as adherent cells in the alveoli, the focus of this method is on dislodging them prior to harvest and identification. The lung is a highly vascularized organ, and various cell types of myeloid and lymphoid origin inhabit, interact, and are influenced by the lung microenvironment. By using the set of surface markers described here, researchers can easily and unambiguously distinguish alveolar macrophages from other leukocytes, and purify them for downstream applications. The culture method developed herein supports both human and mouse alveolar macrophages for in vitro growth, and is compatible with cellular and molecular studies.

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

This communication describes methodologies for isolation and culture of alveolar macrophages from humans and murine models for experimental purposes.

Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and ...

Multicolor Flow Cytometry-based Quantification of Mitochondria and Lysosomes in T Cells

T cells utilize different metabolic programs to match their functional needs during differentiation and proliferation. Mitochondria are crucial cellular components responsible for supplying cell energy; however, excess mitochondria also produce reactive oxygen species (ROS) that could cause cell death. Therefore, the number of mitochondria must constantly be adjusted to fit the needs of the cells. This dynamic regulation is achieved in part through the function of lysosomes that remove surplus/damaged organelles and macromolecules. Hence, cellular mitochondrial and lysosomal contents are key indicators to evaluate the metabolic adjustment of cells. With the development of probes for organelles, well-characterized lysosome or mitochondria-specific dyes have become available in various formats to label cellular lysosomes and mitochondria. Multicolor flow cytometry is a common tool to profile cell phenotypes, and has the capability to be integrated with other assays. Here, we present a detailed protocol of how to combine organelle-specific dyes with surface markers staining to measure the amount of lysosomes and mitochondria in different T cell populations on a flow cytometer.

This article illustrates a powerful method to quantify mitochondria or lysosomes in living cells. The combination of lysosome- or mitochondria-specific dyes with fluorescently conjugated antibodies against surface markers allows the quantification of these organelles in mixed cell populations, like primary cells harvested from tissue samples, by using multicolor flow cytometry.

T cells utilize different metabolic programs to match their functional needs during differentiation and proliferation. Mitochondria are crucial cellular ...

Isolation of Mouse Kidney-Resident CD8+ T cells for Flow Cytometry Analysis

Tissue-resident memory T cell (TRM) is a rapidly expanding field of immunology research. Isolating T cells from various non-lymphoid tissues is one of the key steps to investigate TRMs. There are slight variations in lymphocyte isolation protocols for different organs. Kidney is an essential non-lymphoid organ with numerous immune cell infiltration especially after pathogen exposure or autoimmune activation. In recent years, multiple labs including our own have started characterizing kidney resident CD8+ T cells in various physiological and pathological settings in both mouse and human. Due to the abundance of T lymphocytes, kidney represents an attractive model organ to study TRMs in non-mucosal or non-barrier tissues. Here, we will describe a protocol commonly used in TRM-focused labs to isolate CD8+ T cells from mouse kidneys following systemic viral infection. Briefly, using an acute lymphocytic choriomeningitis virus (LCMV) infection model in C57BL/6 mice, we demonstrate intravascular CD8+ T cell labeling, enzymatic digestion, and density gradient centrifugation to isolate and enrich lymphocytes from mouse kidneys to make samples ready for the subsequent flow cytometry analysis.

Isolation of Mouse Kidney-Resident CD8+ T cells for Flow Cytometry Analysis

Following viral infection, kidney harbors a relatively large number of CD8+ T cells and offers an opportunity to study non-mucosal TRM cells. Here, we describe a protocol to isolate mouse kidney lymphocytes for flow cytometry analysis.

Tissue-resident memory T cell (TRM) is a rapidly expanding field of immunology research. Isolating T cells from various non-lymphoid tissues is one of the ...

A DNA/Ki67-Based Flow Cytometry Assay for Cell Cycle Analysis of Antigen-Specific CD8 T Cells in Vaccinated Mice

The cell cycle of antigen-specific T cells in vivo has been examined by using a few methods, all of which possess some limitations. Bromodeoxyuridine (BrdU) marks cells that are in or recently completed S-phase, and carboxyfluorescein succinimidyl ester (CFSE) detects daughter cells after division. However, these dyes do not allow identification of the cell cycle phase at the time of analysis. An alternative approach is to exploit Ki67, a marker that is highly expressed by cells in all phases of the cell cycle except the quiescent phase G0. Unfortunately, Ki67 does not allow further differentiation as it does not separate cells in S-phase that are committed to mitosis from those in G1 that can remain in this phase, proceed into cycling, or move into G0.
Here, we describe a flow cytometric method for capturing a &#34;snapshot&#34; of T cells in different cell cycle phases in mouse secondary lymphoid organs. The method combines Ki67 and DNA staining with major histocompatibility complex (MHC)-peptide-multimer staining and an innovative gating strategy, allowing us to successfully differentiate between antigen-specific CD8 T cells in G0, in G1 and in S-G2/M phases of the cell cycle in the spleen&#160;and draining lymph nodes of mice after vaccination with viral vectors carrying the model antigen gag of human immunodeficiency virus (HIV)-1.
Critical steps of the method were the choice of the DNA dye and the gating strategy to increase the assay sensitivity and to include highly activated/proliferating antigen-specific T cells that would have been missed by current criteria of analysis. The DNA dye, Hoechst 33342, enabled us to obtain a high-quality discrimination&#160;of the G0/G1 and G2/M DNA peaks, while preserving membrane and intracellular staining. The method has great potential to increase knowledge about T cell response in vivo and to improve immuno-monitoring analysis.

Clonal expansion is a key feature of antigen-specific T cell response. However, the cell cycle of antigen-responding T cells has been poorly investigated, partly because of technical limitations. We describe a flow cytometric method to analyze clonally expanding antigen-specific CD8 T cells in spleen and lymph nodes of vaccinated mice.

The cell cycle of antigen-specific T cells in vivo has been examined by using a few methods, all of which possess some limitations. Bromodeoxyuridine ...

Analysis of SAMHD1 Restriction by Flow Cytometry in Human Myeloid U937 Cells

Sterile &#945;-motif/histidine-aspartate domain-containing protein 1 (SAMHD1) inhibits replication of HIV-1 in quiescent myeloid cells. U937 cells are widely used as a convenient cell system for analyzing SAMHD1 activity due to a low level of SAMHD1 RNA expression, leading to undetectable endogenous protein expression. Based on similar assays developed in the Stoye laboratory to characterize other retroviral restriction factors, the Bishop lab developed a two-color restriction assay to analyze SAMHD1 in U937 cells. Murine Leukaemia Virus-like particles expressing SAMHD1, alongside YFP expressed from an IRES, are used to transduce U937 cells. Cells are then treated with phorbol myristate acetate to induce differentiation to a quiescent phenotype. Following differentiation, cells are infected with HIV-1 virus-like particles expressing a fluorescent reporter. After 48 h, cells are harvested and analyzed by flow cytometry. The proportion of HIV-infected cells in the SAMHD1-expressing population is compared to that in internal control cells lacking SAMHD1. This comparison reveals a restriction ratio. SAMHD1 expression leads to a five-fold reduction in HIV infection, corresponding to a restriction ratio of 0.2. Our recent substitution of RFP for the original GFP as the reporter gene for HIV infection has facilitated flow cytometry analysis.
This assay has been successfully used to characterize the effect of amino acid substitutions on SAMHD1 restriction by transducing with viruses encoding altered SAMHD1 proteins, derived from site-directed mutagenesis of the expression vector. For example, the catalytic site substitutions HD206-7AA show a restriction phenotype of 1, indicating a loss of restriction activity. Equally, the susceptibility of different tester viruses can be determined. The assay can be further adapted to incorporate the effect of differentiation status, metabolic status, and SAMHD1 modifiers to better understand the relationship between SAMHD1, cell metabolic state, and viral restriction.

Described here is an established method to determine the extent of HIV-1 restriction by the cellular inhibitory protein SAMHD1. Human myeloid lineage U937 cells are transduced with a SAMHD1 expression vector co-expressing YFP, differentiated and then challenged with HIV-RFP. The level of restriction is determined by flow cytometry analysis.

Sterile &#945;-motif/histidine-aspartate domain-containing protein 1 (SAMHD1) inhibits replication of HIV-1 in quiescent myeloid cells. U937 cells are ...