The authors would like to thank other members of the Tigno-Aranjuez Lab including Madelyn H. Miller, Omar Cardona, Andjie Jeudy, and Roopin Singh for their help in laboratory upkeep and mouse colony maintenance. Support for this research was provided by grant R00 HL122365 and Start-up funds to J.T.T-A.

<ol>
	<li>Winterbourn, C. C., Kettle, A. J., Hampton, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactive+Oxygen+Species+and+Neutrophil+Function.">Reactive Oxygen Species and Neutrophil Function.</a> Annual Review of Biochemistry. 85, 765-792 (2016).</li><li>Schieber, M., Chandel, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ROS+function+in+redox+signaling+and+oxidative+stress.">ROS function in redox signaling and oxidative stress.</a> Current Biology. 24 (10), R453-R462 (2014).</li><li>Robinson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactive+oxygen+species+in+phagocytic+leukocytes.">Reactive oxygen species in phagocytic leukocytes.</a> Histochemistry and Cell Biology. 130 (2), 281-297 (2008).</li><li>Thomas, 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=The+phagocyte+respiratory+burst:+Historical+perspectives+and+recent+advances.">The phagocyte respiratory burst: Historical perspectives and recent advances.</a> Immunology Letters. 192, 88-96 (2017).</li><li>Fang, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+actions+of+reactive+oxygen+species.">Antimicrobial actions of reactive oxygen species.</a> MBio. 2 (5), (2011).</li><li>Iles, K. E., Forman, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+signaling+and+respiratory+burst.">Macrophage signaling and respiratory burst.</a> Immunologic Research. 26 (1-3), 95-105 (2002).</li><li>Curnutte, J. T., Whitten, D. M., Babior, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defective+superoxide+production+by+granulocytes+from+patients+with+chronic+granulomatous+disease.">Defective superoxide production by granulocytes from patients with chronic granulomatous disease.</a> New England Journal of Medicine. 290 (11), 593-597 (1974).</li><li>Good, R. A., 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=Fatal+(chronic)+granulomatous+disease+of+childhood:+a+hereditary+defect+of+leukocyte+function.">Fatal (chronic) granulomatous disease of childhood: a hereditary defect of leukocyte function.</a> Seminars in Hematology. 5 (3), 215-254 (1968).</li><li>Holmes, B., Page, A. R., Good, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+of+the+metabolic+activity+of+leukocytes+from+patients+with+a+genetic+abnormality+of+phagocytic+function.">Studies of the metabolic activity of leukocytes from patients with a genetic abnormality of phagocytic function.</a> Journal of Clinical Investigation. 46 (9), 1422-1432 (1967).</li><li>Windhorst, D. B., Page, A. R., Holmes, B., Quie, P. G., Good, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pattern+of+genetic+transmission+of+the+leukocyte+defect+in+fatal+granulomatous+disease+of+childhood.">The pattern of genetic transmission of the leukocyte defect in fatal granulomatous disease of childhood.</a> Journal of Clinical Investigation. 47 (5), 1026-1034 (1968).</li><li>Dikalov, S. I., Harrison, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+detection+of+mitochondrial+and+cellular+reactive+oxygen+species.">Methods for detection of mitochondrial and cellular reactive oxygen species.</a> Antioxidants &amp; Redox Signaling. 20 (2), 372-382 (2014).</li><li>Held, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Introduction+to+Reactive+Oxygen+Species:+Measurement+of+ROS+in+cells.">An Introduction to Reactive Oxygen Species: Measurement of ROS in cells.</a> White Paper. , (2015).</li><li>Woolley, J. F., Stanicka, J., Cotter, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+reactive+oxygen+species+measurement+in+biological+systems.">Recent advances in reactive oxygen species measurement in biological systems.</a> Trends in Biochemical Sciences. 38 (11), 556-565 (2013).</li><li>Chen, X., Zhong, Z., Xu, Z., Chen, L., Wang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2',7'-Dichlorodihydrofluorescein+as+a+fluorescent+probe+for+reactive+oxygen+species+measurement:+Forty+years+of+application+and+controversy.">2',7'-Dichlorodihydrofluorescein as a fluorescent probe for reactive oxygen species measurement: Forty years of application and controversy.</a> Free Radical Research. 44 (6), 587-604 (2010).</li><li>Zielonka, J., Kalyanaraman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydroethidine-+and+MitoSOX-derived+red+fluorescence+is+not+a+reliable+indicator+of+intracellular+superoxide+formation:+another+inconvenient+truth.">Hydroethidine- and MitoSOX-derived red fluorescence is not a reliable indicator of intracellular superoxide formation: another inconvenient truth.</a> Free Radical Biology and Medicine. 48 (8), 983-1001 (2010).</li><li>Swamydas, M., Lionakis, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+purification+and+labeling+of+mouse+bone+marrow+neutrophils+for+functional+studies+and+adoptive+transfer+experiments.">Isolation, purification and labeling of mouse bone marrow neutrophils for functional studies and adoptive transfer experiments.</a> Journal of Visualized Experiments. (77), e50586 (2013).</li></ol>

The authors have no conflicts of interest to disclose.

DCFH2-DA and DHE-based detection of ROS is a widely-used technique14,15. Ease of use and the adaptability of these ROS probes for kinetic microplate formats, fluorescence microscopy or flow cytometric analysis has contributed to their popularity. However, in our studies of Fc&#947;R-mediated macrophage functions, there did not seem to be a standard protocol for performing this assay for flow cytometric analysis of Fc&#947;R cross-linked cells. Given th...

Reactive oxygen species (ROS) are reactive molecules or free radicals that are by-products of aerobic respiration (reviewed in 1). These include the superoxide anion, peroxide, hydrogen peroxide, hydroxyl radical, and hydroxyl ions, among others. Under normal physiologic conditions, ROS are produced mainly by the mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and are rapidly detoxified by various enzymes and proteins such as superoxide dismutase and glutathione. An exaggerated production of ROS or a defect in the ability to remove ROS can result in oxidative stress, whereby reactive oxygen species promote the damage of proteins, lipids, and DNA leading to cellular stress or death and pathological disease states. However, it is currently appreciated that ROS can also act as signaling molecules (redox signaling), and ROS-mediated modification of various molecules and pathway intermediates can influence cellular metabolism, proliferation, survival, inflammatory signaling, and aging2. In phagocytic cells, ROS plays an essential role in providing antimicrobial activity during the so-called &#8220;respiratory burst&#8221;1,3,4,5,6. During the response of phagocytes to external stimuli, components of the NADPH oxidase complex (p40phox, p47phox, p67phox) translocate from the cytosol to the phagosomal membrane containing the gp91phox and p22phox subunits, and together with the actions of Rac1/2, form a fully functional NADPH oxidase enzyme complex. The assembled NADPH oxidase then utilizes NADPH to reduce oxygen to superoxide within the phagosomal vacuole. Superoxide anions can directly cause damage or be dismutated into hydrogen peroxide. Both superoxide and hydrogen peroxide can react with other molecules to generate highly reactive hydroxyl radicals. Damage is mediated by reaction of these ROS with iron-sulfur clusters on proteins or by causing base oxidation of DNA, ultimately leading to restricted microbial metabolism or death of the microbe5. The importance of the NADPH oxidase enzyme complex and ROS produced during the respiratory burst is illustrated clinically in patients with Chronic Granulomatous Disease (CGD)7,8,9,10. Individuals with CGD possess mutations in gp91phox, resulting in a lack of ROS production and susceptibility to recurrent infections with bacteria and fungi which are not usually a concern with immunocompetent individuals. Therefore, whether studying oxidative stress, redox signaling, or host defense, being able to measure ROS production in real-time is a useful endeavor.
Multiple assays have been utilized to measure ROS production or the results of oxidative stress11,12,13. Among these, one of the most widely used is the fluorescent probe 2&#8217;,7&#8217; dichlorodihydrofluorescein diacetate (DCFH2-DA)14. This molecule is colorless and lipophilic. Diffusion of DCFH2-DA across the cell membrane allows it to be acted upon by intracellular esterases, which deacetylates it into DCFH2, rendering it cell impermeable. The actions of multiple types of ROS (hydrogen peroxide, peroxynitrite, hydroxyl radicals, nitric oxide, and peroxy radicals) on DCFH2 oxidize it into DCF which is fluorescent (reported Ex/Em: 485-500 nm/515-530 nm) and can be detected using a flow cytometer equipped with a standard filter set for fluorescein (FL1 channel). Superoxide does not strongly react with DCFH2 but can react with another probe dihydroethidium (DHE) to yield the fluorescent product 2-hydroxyethidium (as well as other fluorescent superoxide-independent oxidation products)15. The fluorescent products of DHE oxidation can be detected using an excitation wavelength of 518 nm and an emission wavelength of 605 nm (FL2 channel). Although relatively simple to use, utilization of these probes for detection of ROS requires knowledge of their limitations and careful incorporation of staining procedures and controls into the specific assay being performed in order to have valid experimental results and conclusions. The following protocol demonstrates the use of a commercially available kit employing these 2 probes designed to measure ROS by flow cytometry. We stain primed bone marrow-derived macrophages with these probes and induce ROS production through Fc&#947;R cross-linking. We present representative data obtained using this protocol and stress appropriate precautions that must be undertaken for successful experimentation.

<table><tbody><tr><td>Anti-BSA IgG1</td><td>Innovative Research</td><td>IBSA9E2C2</td><td></td></tr><tr><td>Alexa Fluor 647 Rat IgG2b, &amp;kappa; Isotype Ctrl Antibody</td><td>BioLegend</td><td>400626</td><td></td></tr><tr><td>Anti-mouse CD16/32</td><td>BioLegend</td><td>101302</td><td></td></tr><tr><td>Anti-mouse F4/80 antibody conjugated to Alexa Fluor 647</td><td>BD Biosciences</td><td>565853</td><td></td></tr><tr><td>Anti-mouse F4/80 antibody conjugated to FITC</td><td>BioLegend</td><td>123108</td><td></td></tr><tr><td>Anti-mouse/human CD11b antibodyconjugated to Alexa Fluor 647&amp;nbsp;</td><td>BioLegend</td><td>101218</td><td></td></tr><tr><td>beta-mercaptoethanol (BME)</td><td>Sigma</td><td>M3148-100ml</td><td></td></tr><tr><td>Bovine Serum Albumin (BSA) FractionV</td><td>Fisher</td><td>BP1600-100</td><td></td></tr><tr><td>C57BL/6J&amp;nbsp;</td><td>Jackson labs</td><td>Stock No.000664</td><td></td></tr><tr><td>CM-H2DCFDA</td><td>Molecular Probes</td><td>C6827</td><td>Can be a substitute for oxidative stress detection reagent in the Enzo kit</td></tr><tr><td>Dihydroethidium (DHE)</td><td>Molecular Probes</td><td>D11347</td><td>Can be a substitute for superoxide detection reagent in the Enzo kit</td></tr><tr><td>DMEM 1x</td><td>Corning</td><td>10-013-CV</td><td></td></tr><tr><td>DMEM no phenol red</td><td>Gibco</td><td>31053-028</td><td></td></tr><tr><td>DMF Anhydrous&amp;nbsp;</td><td>Acros Organics</td><td>61094-1000</td><td></td></tr><tr><td>Fetal Bovine Serum (FBS)</td><td>VWR</td><td>97068-085</td><td></td></tr><tr><td>FITC Rat IgG2a, &amp;kappa; Isotype Ctrl Antibody</td><td>BioLegend</td><td>400506</td><td></td></tr><tr><td>HEPES (1M)</td><td>Gibco</td><td>15630-080</td><td></td></tr><tr><td>L glutamine</td><td>Gibco</td><td>25030-081</td><td></td></tr><tr><td>LADMAC cells</td><td>ATCC</td><td>CRL-2420</td><td></td></tr><tr><td>MEM</td><td>Corning</td><td>10-010-CV</td><td></td></tr><tr><td>mouse IFN-g</td><td>GoldBio</td><td>1360-06-100</td><td></td></tr><tr><td>N-Acetyl-L-cysteine</td><td>EMD Milipore</td><td>106425</td><td>Can be a substitute for ROS inhibitor/scavenger in the Enzo kit</td></tr><tr><td>Novocyte flow cytometer with autosampler</td><td>Acea</td><td>2060R</td><td></td></tr><tr><td>Pyocyanin (ROS inducer)</td><td>Cayman chemical</td><td>10009594</td><td>Can be a substitute for inducer in the Enzo kit</td></tr><tr><td>ROS-ID total ROS/superoxide detection kit</td><td>ENZO</td><td>ENZ-51010</td><td></td></tr><tr><td>Sodium pyruvate (100mM)</td><td>Gibco</td><td>11360-070</td><td></td></tr><tr><td>Trypsin-EDTA (0.25%)</td><td>Gibco</td><td>25200-056</td><td></td></tr></tbody></table>

flow cytometric measurement of ros production in macrophages in response to fc&#947;r cross-linking

The oxidative or respiratory burst is used to describe the rapid consumption of oxygen and generation of reactive oxygen species (ROS) by phagocytes in response to various immune stimuli. ROS generated during immune activation exerts potent antimicrobial activity primarily through the ability of ROS to damage DNA and proteins, causing death of microorganisms. Being able to measure ROS production reproducibly and with ease is necessary in order to assess the contribution of various pathways and molecules to this mechanism of host defense. In this paper, we demonstrate the use of fluorescent probes and flow cytometry to detect ROS production. Although widely used, fluorescent measurement of ROS is notoriously problematic, especially with regards to measurement of ROS induced by specific and not mitogenic stimuli. We present a detailed methodology to detect ROS generated as a result of specific Fc&#947;R stimulation beginning with macrophage generation, priming, staining, Fc&#947;R cross-linking, and ending with flow cytometric analysis.

Using the protocol outlined within, we present representative data demonstrating flow cytometric detection of ROS production resulting from stimulation of WT C57BL/6J BMDMs through the Fc&#947;R. As expected, we observe minimal changes in FL1 or FL2 fluorescence above background levels in unstimulated cells (Figure 3A, compare &#8220;stained, unstimulated&#8221; vs &#8220;unstained, unstimulated&#8221; dot plots). We observe a marked increase in FL1 and FL2 fluorescence when cells are stimul...

Watch this Scientific Journal Video about Flow Cytometric Measurement Of ROS Production In Macrophages In Response To FcÎ³R Cross-linking at JoVE.com

Flow Cytometric Measurement Of ROS Production In Macrophages In Response To Fc&#947;R Cross-linking

This study demonstrates the use of flow cytometry to detect reactive oxygen species (ROS) production resulting from activation of the Fc&#947;R. This method can be used to assess changes in the antimicrobial and redox signaling function of phagocytes in response to immune complexes, opsonized microorganisms, or direct Fc&#947;R cross-linking.

The oxidative or respiratory burst is used to describe the rapid consumption of oxygen and generation of reactive oxygen species (ROS) by phagocytes in ...

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15.6K Views.  University of Central Florida. This study demonstrates the use of flow cytometry to detect reactive oxygen species (ROS) production resulting from activation of the FcγR. This method can be used to assess changes in the antimicrobial and redox signaling function of phagocytes in response to immune complexes, opsonized microorganisms, or direct FcγR cross-linking.

Video: Flow Cytometric Measurement Of ROS Production In Macrophages In Response To FcγR Cross-linking

Multicolor Flow Cytometry Analyses of Cellular Immune Response in Rhesus Macaques

The rhesus macaque model is currently the best available model for HIV-AIDS with respect to understanding the pathogenesis as well as for the development of vaccines and therapeutics1,2,3. Here, we describe a method for the detailed phenotypic and functional analyses of cellular immune responses, specifically intracellular cytokine production by CD4+ and CD8+ T cells as well as the individual memory subsets. We obtained precise quantitative and qualitative measures for the production of interferon gamma (INF-) and interleukin (IL) -2 in both CD4+ and CD8+ T cells from the rhesus macaque PBMC stimulated with PMA plus ionomycin (PMA+I). The cytokine profiles were different in the different subsets of memory cells. Furthermore, this protocol provided us the sensitivity to demonstrate even minor fractions of antigen specific CD4+ and CD8+ T cell subsets within the PBMC samples from rhesus macaques immunized with an HIV envelope peptide cocktail vaccine developed in our laboratory. The multicolor flow cytometry technique is a powerful tool to precisely identify different populations of T cells 4,5 with cytokine-producing capability6 following non-specific or antigen-specific stimulation 5,7.

We demonstrate the utility of multicolor flow cytometry for detailed phenotypic and functional characterization of total as well as memory subsets of CD4+ and CD8+ T cells in rhesus macaques, the ideal model for HIV/AIDS vaccine studies.

The rhesus macaque model is currently the best available model for HIV-AIDS with respect to understanding the pathogenesis as well as for the development ...

High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization

The goal of fluorometric analysis is to serve as an efficient, cost effective, high throughput method of analyzing phagocytosis and other cellular processes. This technique can be used on a variety of cell types, both adherent and non-adherent, to examine a variety of cellular properties. When studying phagocytosis, fluorometric technique utilizes phagocytic cell types such as macrophages, and fluorescently labeled opsonized particles whose fluorescence can be extinguished in the presence of trypan blue. Following plating of adherent macrophages in 96-well plates, fluorescent particles (green or red) are administered and cells are allowed to phagocytose for varied amounts of time. Following internalization of fluorescent particles, cells are washed with trypan blue, which facilitates extinction of fluorescent signal from bacteria which are not internalized, or are merely adhering to the cell surface. Following the trypan wash, cells are washed with PBS, fixed, and stained with DAPI (nuclear blue fluorescent label), which serves to label nuclei of cells. By a simple fluorometric quantification through plate reading of nuclear (blue) or particle (red/green) fluorescence we can examine the ratio of relative fluorescence units of green:blue and determine a phagocytic index indicative of amount of fluorescent bacteria internalized per cell. The duration of assay using a 96-well method and multichannel pipettes for washing, from end of phagocytosis to end of data acquisition, is less than 45 min. Flow cytometry could be used in a similar manner but the advantage of fluorometry is its high throughput, rapid method of assessment with minimal manipulation of samples and quick quantification of fluorescent intensity per cell. Similar strategies can be applied to non adherent cells, live labeled bacteria, actin polymerization, and essentially any process utilizing fluorescence. Therefore, fluorometry is a promising method for its low cost, high throughput capabilities in the study of cellular processes.

Here we present a protocol to quantify phagocytosis of fluorescent particles by adherent macrophage cell line using a fluorometric method. This method facilitates a high throughput quantification of particle internalization as well as the resulting actin polymerization.

The goal of fluorometric analysis is to serve as an efficient, cost effective, high throughput method of analyzing phagocytosis and other cellular ...

IP-FCM:  Immunoprecipitation Detected by Flow Cytometry

Immunoprecipitation detected by flow cytometry (IP-FCM) is an efficient method for detecting and quantifying protein-protein interactions. The basic principle extends that of sandwich ELISA, wherein the captured primary analyte can be detected together with other molecules physically associated within multiprotein complexes. The procedure involves covalent coupling of polystyrene latex microbeads with immunoprecipitating monoclonal antibodies (mAb) specific for a protein of interest, incubating these beads with cell lysates, probing captured protein complexes with fluorochrome-conjugated probes, and analyzing bead-associated fluorescence by flow cytometry. IP-FCM is extremely sensitive, allows analysis of proteins in their native (non-denatured) state, and is amenable to either semi-quantitative or quantitative analysis. As additional advantages, IP-FCM requires no genetic engineering or specialized equipment, other than a flow cytometer, and it can be readily adapted for high-throughput applications.

The IP-FCM method is presented, which allows a sensitive, robust, biochemical assessment of native protein-protein interactions, without requiring genetic engineering or large sample sizes.

Immunoprecipitation detected by flow cytometry (IP-FCM) is an efficient method for detecting and quantifying protein-protein interactions. The basic ...

Biology

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

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

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

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

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

Use of a Monocyte Monolayer Assay to Evaluate Fc&#947; Receptor-mediated Phagocytosis

Although originally developed for predicting transfusion outcomes of serologically incompatible blood, the monocyte monolayer assay (MMA) is a highly versatile in vitro assay that can be modified to examine different aspects of antibody and Fc&#947; receptor (Fc&#947;R)-mediated phagocytosis in both research and clinical settings. The assay utilizes adherent monocytes from peripheral blood mononuclear cells isolated from mammalian whole blood. MMA has been described for use in both human and murine investigations. These monocytes express Fc&#947;Rs (e.g., Fc&#947;RI, Fc&#947;RIIA, Fc&#947;RIIB, and Fc&#947;RIIIA) that are involved in immune responses. The MMA exploits the mechanism of Fc&#947;R-mediated interactions, phagocytosis in particular, where antibody-sensitized red blood cells (RBCs) adhere to and/or activate Fc&#947;Rs and are subsequently phagocytosed by the monocytes. In vivo, primarily tissue macrophages found in the spleen and liver carry out Fc&#947;R-mediated phagocytosis of antibody-opsonized RBCs, causing extravascular hemolysis. By evaluating the level of phagocytosis using the MMA, different aspects of the in vivo Fc&#947;R-mediated process can be investigated. Some applications of the MMA include predicting the clinical relevance of allo- or autoantibodies in a transfusion setting, assessing candidate drugs that promote or inhibit phagocytosis, and combining the assay with fluorescent microscopy or traditional Western immunoblotting to investigate the downstream signaling effects of Fc&#947;R-engaging drugs or antibodies. Some limitations include the laboriousness of this technique, which takes a full day from start to finish, and the requirement of research ethics approval in order to work with mammalian blood. However, with diligence and adequate training, the MMA results can be obtained within a 24-h turnover time.

The monocyte monolayer assay (MMA) is an in vitro assay that utilizes isolated primary monocytes obtained from mammalian peripheral whole blood to evaluate Fc&#947; receptor (Fc&#947;R)-mediated phagocytosis.

Although originally developed for predicting transfusion outcomes of serologically incompatible blood, the monocyte monolayer assay (MMA) is a highly ...

Visualization of Vascular Ca2+ Signaling Triggered by Paracrine Derived ROS

Oxidative stress has been implicated in a number of pathologic conditions including ischemia/reperfusion damage and sepsis. The concept of oxidative stress refers to the aberrant formation of ROS (reactive oxygen species), which include O2&bull;-, H2O2, and hydroxyl radicals. Reactive oxygen species influences a multitude of cellular processes including signal transduction, cell proliferation and cell death1-6. ROS have the potential to damage vascular and organ cells directly, and can initiate secondary chemical reactions and genetic alterations that ultimately result in an amplification of the initial ROS-mediated tissue damage. A key component of the amplification cascade that exacerbates irreversible tissue damage is the recruitment and activation of circulating inflammatory cells. During inflammation, inflammatory cells produce cytokines such as tumor necrosis factor-&alpha; (TNF&alpha;) and IL-1 that activate endothelial cells (EC) and epithelial cells and further augment the inflammatory response7. Vascular endothelial dysfunction is an established feature of acute inflammation. Macrophages contribute to endothelial dysfunction during inflammation by mechanisms that remain unclear. Activation of macrophages results in the extracellular release of O2&bull;- and various pro-inflammatory cytokines, which triggers pathologic signaling in adjacent cells8. NADPH oxidases are the major and primary source of ROS in most of the cell types. Recently, it is shown by us and others9,10 that ROS produced by NADPH oxidases induce the mitochondrial ROS production during many pathophysiological conditions. Hence measuring the mitochondrial ROS production is equally important in addition to measuring cytosolic ROS. Macrophages produce ROS by the flavoprotein enzyme NADPH oxidase which plays a primary role in inflammation. Once activated, phagocytic NADPH oxidase produces copious amounts of O2&bull;- that are important in the host defense mechanism11,12. Although paracrine-derived O2&bull;- plays an important role in the pathogenesis of vascular diseases, visualization of paracrine ROS-induced intracellular signaling including Ca2+ mobilization is still hypothesis. We have developed a model in which activated macrophages are used as a source of O2&bull;- to transduce a signal to adjacent endothelial cells. Using this model we demonstrate that macrophage-derived O2&bull;- lead to calcium signaling in adjacent endothelial cells.

Visualization of Vascular Ca2+ Signaling Triggered by Paracrine Derived ROS

An efficient method to gain insights into visualizing the paracrine-derived ROS induction of endothelial Ca2+ signaling is described. This method takes advantage of measuring paracrine derived ROS triggered Ca2+ mobilization in vascular endothelial cells in a co-culture model.

Oxidative stress has been implicated in a number of pathologic conditions including ischemia/reperfusion damage and sepsis. The concept of oxidative ...

Production and Characterization of Human Macrophages from Pluripotent Stem Cells

Macrophages are present in most vertebrate tissues and comprise widely dispersed and heterogeneous cell populations with different functions. They are key players in health and disease, acting as phagocytes during immune defense and mediating trophic, maintenance, and repair functions. Although it has been possible to study some of the molecular processes involved in human macrophage function, it has proved difficult to apply genetic engineering techniques to primary human macrophages. This has significantly hampered our ability to interrogate the complex genetic pathways involved in macrophage biology and to generate models for specific disease states. An off-the-shelf source of human macrophages that is amenable to the vast arsenal of genetic manipulation techniques would, therefore, provide a valuable tool in this field. We present an optimized protocol that allows for the generation of macrophages from human induced pluripotent stem cells (iPSCs) in vitro. These iPSC-derived macrophages (iPSC-DMs) express human macrophage cell surface markers, including CD45, 25F9, CD163, and CD169, and our live-cell imaging functional assay demonstrates that they exhibit robust phagocytic activity. Cultured iPSC-DMs can be activated to different&#160;macrophage states that display altered gene expression and phagocytic activity by the addition of LPS and IFNg, IL4, or IL10. Thus, this system provides a platform to generate human macrophages carrying genetic alterations that model specific human disease and a source of cells for drug screening or cell therapy to treat these diseases.

This protocol describes the robust generation of macrophages from human induced pluripotent stem cells, and methods for their subsequent characterization. Cell surface marker expression, gene expression, and functional assays are used to assess the phenotype and function of these iPSC-derived macrophages.

Macrophages are present in most vertebrate tissues and comprise widely dispersed and heterogeneous cell populations with different functions. They are key ...

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Haemophilus influenzae (Hi) is a prevalent bacterium found in a range of respiratory conditions. A variety of different assays/techniques may be used to assess the respiratory immune/inflammatory response to this bacterium. Flow cytometry and confocal microscopy are fluorescence-based technologies that allow detailed characterization of biological responses.&#160;Different forms of Hi antigen can be used, including cell wall components, killed/inactivated preparations, and live bacteria. Hi is a fastidious bacterium that requires enriched media but is generally easy to grow in standard laboratory settings. Tissue samples for stimulation with Hi may be obtained from peripheral blood, bronchoscopy, or resected lung (e.g., in patients undergoing surgery for the treatment of lung cancer). Macrophage and neutrophil function may be comprehensively assessed using flow cytometry with a variety of parameters measured, including phagocytosis, reactive oxygen species, and intracellular cytokine production. Lymphocyte function (e.g., T cell and NK cell function) may be specifically assessed using flow cytometry, principally for intracellular cytokine production. Hi infection is a potent inducer of extracellular trap production, both by neutrophils (NETs) and macrophages (METs). Confocal microscopy is arguably the most optimal way to assess NET and MET expression, which may also be used to assess protease activity. Lung immunity to Haemophilus influenzae can be assessed using flow cytometry and confocal microscopy.

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Haemophilus influenzae induces inflammation in the respiratory tract. This article will focus on the use of flow cytometry and confocal microscopy to define immune responses by phagocytes and lymphocytes in response to this bacterium.

Haemophilus influenzae (Hi) is a prevalent bacterium found in a range of respiratory conditions. A variety of different assays/techniques may be used to ...

Flow Cytometry Approach to Characterize Phagocytic Properties of Acutely-Isolated Adult Microglia and Brain Macrophages In Vitro

Microglia and central nervous system (CNS)-infiltrating macrophages, collectively called CNS mononuclear phagocytes (CNS-MPs), play central roles in neurological diseases including neurodegeneration and stroke. CNS-MPs are involved in phagocytic clearance of pathological proteins, debris and neuronal synapses, each with distinct underlying molecular pathways. Characterizing these phagocytic properties can provide a functional readout that compliments molecular profiling of microglia using traditional flow cytometry, transcriptomics and proteomics approaches. Phagocytic profiling of microglia has relied on microscopic visualization and in vitro cultures of mouse neonatal microglia. The former approach suffers from limited sampling while the latter approach is inherently poorly reflective of the true in vivo state of adult CNS-MPs. This paper describes optimized protocols to phenotype phagocytic properties of acutely-isolated mouse CNS-MPs by flow cytometry. CNS-MPs are acutely isolated from adult mouse brain using mechanical dissociation followed by density gradient centrifugation, incubated with fluorescent microspheres or fluorescent A&#946; fibrils, washed, and then labeled with panels of antibodies against surface markers (CD11b, CD45). Using this approach, it is possible to compare phagocytic properties of brain-resident microglia with CNS-infiltrating macrophages and then assess the effect of aging and disease pathology on these phagocytic phenotypes. This rapid method also holds potential to functionally phenotype acutely-isolated human CNS-MPs from post-mortem or surgical brain specimens. Additionally, specific mechanisms of phagocytosis by CNS-MP subsets can be investigated by inhibiting select phagocytic pathways.

Assessment of phagocytic properties of microglia and brain macrophages can provide a valuable functional dimension to molecular profiling studies. We describe a validated protocol that uses flow cytometry to rapidly and reliably quantify phagocytosis of fluorescent microspheres and amyloid beta fibrils by acutely-isolated microglia and brain macrophages from mouse models.

Microglia and central nervous system (CNS)-infiltrating macrophages, collectively called CNS mononuclear phagocytes (CNS-MPs), play central roles in ...

Neuroscience

Quantification of Reactive Oxygen Species Using 2&#8242;,7&#8242;-Dichlorofluorescein Diacetate Probe and Flow-Cytometry in M&#252;ller Glial Cells

The redox balance has an important role in maintaining cellular homeostasis. The increased generation of reactive oxygen species (ROS) promotes the modification of proteins, lipids, and DNA, which finally may lead to alteration in cellular function and cell death. Therefore, it is beneficial for cells to increase their antioxidant defense in response to detrimental insults, either by activating an antioxidant pathway like Keap1/Nrf2 or by improving redox scavengers (vitamins A, C, and E, &#946;-carotene, and polyphenols, among others). Inflammation and oxidative stress are involved in the pathogenesis and progression of retinopathies, such as diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Since M&#252;ller glial cells (MGCs) play a key role in the homeostasis of neural retinal tissue, they are considered an ideal model to study these cellular protective mechanisms. In this sense, quantifying ROS levels with a reproducible and simple method is essential to assess the contribution of pathways or molecules that participate in the antioxidant cell defense mechanism. In this article, we provide a complete description of the procedures required for the measurement of ROS with DCFH-DA probe and flow cytometry in MGCs. Key steps for flow cytometry data processing with the software are provided here, so the readers will be able to measure ROS levels (geometric means of FITC) and analyze fluorescence histograms. These tools are highly helpful to evaluate not only the increase in ROS after a cellular insult but also to study the antioxidant effect of certain molecules that can provide a protective effect on the cells.

Here, we propose a systematized, accessible, and reproducible protocol to detect cellular reactive oxygen species (ROS) using 2&#8242;,7&#8242;-dichlorofluorescein diacetate probe (DCFH-DA) in M&#252;ller glial cells (MGCs). This method quantifies total cellular ROS levels with a flow cytometer. This protocol is very easy to use, suitable, and reproducible.

The redox balance has an important role in maintaining cellular homeostasis. The increased generation of reactive oxygen species (ROS) promotes the ...

Flow Cytometric Measurement Of ROS Production In Macrophages In Response To FcγR Cross-linking

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Chapters in this video

Multicolor Flow Cytometry Analyses of Cellular Immune Response in Rhesus Macaques

High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization

IP-FCM: Immunoprecipitation Detected by Flow Cytometry

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

Use of a Monocyte Monolayer Assay to Evaluate Fcγ Receptor-mediated Phagocytosis

Visualization of Vascular Ca²⁺ Signaling Triggered by Paracrine Derived ROS

Production and Characterization of Human Macrophages from Pluripotent Stem Cells

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Flow Cytometry Approach to Characterize Phagocytic Properties of Acutely-Isolated Adult Microglia and Brain Macrophages In Vitro

Quantification of Reactive Oxygen Species Using 2′,7′-Dichlorofluorescein Diacetate Probe and Flow-Cytometry in Müller Glial Cells