This work was supported in part by the NIH (N01 HHSN272201100019C, U19 AI 089992, and the NCRR/GCRC Program M01-RR00125). The authors declare no competing financial interests and thank Dr. Mark Shlomchik, director of the Yale Cell Sorter Core Facility.

1. Isolation and Stimulation of Immune Cells
<ol>
	<li>Obtain 10-50 ml heparinized blood from healthy volunteers after written informed consent under the guidelines of the local Institutional Review Board. For studies of aging or disease pathogenesis, exclusion and inclusion criteria for each volunteer or patient must be explicitly determined.</li>
	<li>Isolate human peripheral blood mononuclear cells (PBMCs) using CPT tubes or Ficoll-Paque Plus according to the manufacturer's instructions (GE Healthcare, NJ) and conduct experiments on the day of isolation7 (Reagents, Table 1).</li>
	<li>Incubate PBMCs (3 x 106/tube) in 1.5 ml tubes in 0.6 ml medium alone or stimulated with TLR ligands or other activating agents, e.g. the TLR7/8 ligand R848 (0.6 ml medium plus 0.6 &mu;l of 10 mM TLR7/8 ligand R848, final concentration 10 &mu;M) at 37 &deg;C for 10-60 min (InvivoGen, CA)9.</li>
</ol>
2. Labeling of Cells
<ol>
	<li>Label cell lineage and other surface markers on live cell suspensions using fluorescently-conjugated antibodies. Label 3 x 106 PBMCs for 20 min at 4 &deg;C in 100 &mu;l of PBS/2% FBS in a 1.5 ml Eppendorf tube with a cocktail of surface antibodies specific for monocyte or DC lineages (Table 2). Optimal antibody dilutions can be determined in preliminary experiments and samples should be processed in batches to minimize lot-to-lot variation. For vendor antibody stock of 0.1 mg/ml use 5 &mu;l of antibody (1:20 dilution). Use a separate tube of cells labeled with only one single color conjugate to set up the fluorescent channels on the instrument.</li>
	<li>After surface labeling, fix cells in 4% PFA/PBS for 10 min at RT. For storage until time of analysis, centrifuge cells at 500 x g and resuspend cells in freezing buffer (90% FBS containing 10% DMSO) at -80 &deg;C until the day of assay.</li>
	<li>For assessment, process batches of untreated and stimulated cells from a group of donors together to minimize variability. On the day of analysis, thaw cells quickly in 37 &deg;C water bath, centrifuge at 500x g to remove freezing buffer.</li>
	<li>To permeabilize cells for detection of intracellular cytokines or other markers, resuspend cell suspensions in 100 &mu;l BD Perm/Wash buffer (BD Biosciences, NJ). Label for intracellular signaling components with e.g., 1:20 dilution of rabbit anti-NF-&kappa;B (p65) antibody (final concentration 10 &mu;g/ml, SantaCruz Biotechnology, CA) for 20 min at RT, centrifuge at 500 x g, aspirate supernatant and resuspend cells in 100 &mu;l BD Perm/Wash buffer containing 1:250 dilution of goat anti-rabbit IgG-Alexa647 (Invitrogen, CA) and incubate for 20 min at RT.</li>
	<li>Immediately prior to imaging, counterstain nuclei with DAPI (0.2 &mu;g/ml, Invitrogen, CA) or propidium iodide (PI; 20 ng/ml, Invitrogen, CA).</li>
</ol>
3. ImageStream Analysis
<ol>
	<li>Conduct imaging by ImageStream on batched samples to reduce variability between human samples. Instrument settings for power of the lasers were as follows: 200 mW for 488 nm, 10 mW for 658 nm and 250 mW for 405 nm.</li>
	<li>To analyze data files (Fig. 1), first, gate on events with normal PI intensity and high PI aspect ratio (width:height ratio) to distinguish single cells (R1) from debris (low PI intensity) or multi-cellular events (high PI intensity and low aspect ratio). Monocytes are within a gate for CD14 positive cells. mDCs are within a gate for cells that are high for CD11c and low for CD4 (R2) and also low for Lin-1 markers (R3).</li>
	<li>Use IDEAS software (Amnis, WA) to provide an effective quantitative measure of the degree of activation of each cell. Determine similarity (or co-localization) of the cytoplasmic transcription factor NF-&kappa;B with nuclear dye PI to indicate translocation into the nucleus (R4). A high correlation of NF-&kappa;B/PI localization is reflected in a high similarity score and indicates the degree of activation10.</li>
	<li>Compare the similarity ratios between different treatment groups or patient populations to indicate relative functional efficiency of the cells. Quantify data between samples through statistical comparison of absolute values or fold differences. Use IDEAS software to display images of cells from key segments of population histograms (Fig. 2).</li>
</ol>
4. Representative Results
We have quantified signaling pathways in response to a model viral ligand by stimulating PBMCs with the TLR7/8 ligand, R848 (Fig. 1). We collected both cellular localization images and population statistics in our sample groups (Fig. 2). ImageStream allows us to gate cell subsets directly from PBMCs and image cell responses from gated, but unsorted cell populations. Here we quantified the effect of TLR signaling on nuclear localization of NF-&kappa;B (p65) in Lin1-, CD4 dim, CD11c+ myeloid DCs (mDCs). At baseline, we observed a high percentage of unstimulated cells with the transcription factor NF-&kappa;B (p65) in the cytoplasm. After stimulation, treated cells have a significantly higher similarity score of NF-B (p65) with nuclear stain PI, indicating that NF-&kappa;B (p65) translocated into the nucleus after stimulation (median similarity scores are 1.52 and 3.01, respectively, Fig. 2). Similar results are noted in TLR5-stimulated monocytes9.
<img alt="Figure 1" src="/files/ftp_upload/3741/3741fig1.jpg" /> 
Figure 1. Staining and Gating Strategy to quantify effects of stimulation on human mDCs. The NF-&kappa;B transcription factor regulates expression of numerous immune system genes. This study measures the nuclear localization of NF-&kappa;B (p65) in mDCs from one representative subject after TLR7/8 ligand stimulation. In-focus single cells were identified by gating on PI positive events with high nuclear aspect ratios (R1). mDCs (Lin1-, CD4dim, CD11c+) were gated in R3. Nuclear localization of NF-&kappa;B (p65) is plotted in R4. <a href="https://www.jove.com/files/ftp_upload/3741/3741fig1large.jpg" target="_blank">Click here to view larger figure</a>.
<img alt="Figure 2" src="/files/ftp_upload/3741/3741fig2.jpg" /> 
Figure 2. Translocation of NF-&kappa;B in mDCs after stimulation. The translocation of NF-&kappa;B (p65) into the nucleus after stimulation (R4) is depicted in populations of untreated and stimulated mDCs; the median similarity score is 1.52 in the untreated sample and 3.01 in the stimulated sample (A). Digital images collected simultaneously of the untreated or R848-stimulated cell populations show representative cells and the intensity of NF-B translocated into the cell nucleus (B). <a href="https://www.jove.com/files/ftp_upload/3741/3741fig2large.jpg" target="_blank">Click here to view larger figure</a>.

<ol>
	<li>Linton, P. J., Dorshkind, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-related+changes+in+lymphocyte+development+and+function.">Age-related changes in lymphocyte development and function.</a> Nat. Immunol. 5, 133-139 (2004).</li><li>Shaw, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dysregulation+of+Human+Toll-like+Receptor+Function+in+Aging.">Dysregulation of Human Toll-like Receptor Function in Aging.</a> Ageing Research Reviews. 10, 346-353 (2011).</li><li>Medzhitov, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toll-like+receptors+and+innate+immunity.">Toll-like receptors and innate immunity.</a> Nature Rev. Immunol. 1, 135-145 (2001).</li><li>van Duin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-associated+Defect+in+Human+TLR1+Function+and+Expression.">Age-associated Defect in Human TLR1 Function and Expression.</a> J. Immunol. 178, 970-975 (2007).</li><li>Panda, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-associated+decrease+in+TLR+function+in+primary+human+dendritic+cells+predicts+influenza+vaccine+response.">Age-associated decrease in TLR function in primary human dendritic cells predicts influenza vaccine response.</a> J. Immunol. 184, 2518-2527 (2010).</li><li>Kong, K. -. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dysregulation+of+TLR3+impairs+the+innate+immune+response+to+West+Nile+virus+in+the+elderly.">Dysregulation of TLR3 impairs the innate immune response to West Nile virus in the elderly.</a> J. Virol. 82, 7613-7623 (2008).</li><li>Qian, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+interferon+signaling+in+dendritic+cells+from+older+donors+infected+in+vitro+with+West+Nile+virus.">Impaired interferon signaling in dendritic cells from older donors infected in vitro with West Nile virus.</a> J. Infect. Dis. 203, 1415-1424 (2011).</li><li>Hayden, M. S., Ghosh, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NF-kappaB+in+immunobiology.">NF-kappaB in immunobiology.</a> Cell research. 21, 223-244 (2011).</li><li>Qian, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-associated+elevation+in+TLR5+leads+to+increased+inflammatory+responses+in+the+elderly.">Age-associated elevation in TLR5 leads to increased inflammatory responses in the elderly.</a> Aging Cell. 11, 104-110 (2011).</li><li>George, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+measurement+of+nuclear+translocation+events+using+similarity+analysis+of+multispectral+cellular+images+obtained+in+flow.">Quantitative measurement of nuclear translocation events using similarity analysis of multispectral cellular images obtained in flow.</a> Journal of immunological. 311, 117-129 (2006).</li></ol>

No conflicts of interest declared.

The critical steps in use of ImageStream for translational studies are the selection of relevant comparison groups and optimization and validation of antibody specificity. Differences between subject groups in the labeled target will be readily apparent through histograms and cell images. In combination with a thorough analysis of changes in relevant receptors and signaling pathways, these data will provide valuable insight into mechanisms that underlie immune dysregulation in specialized cohorts. The technique will b...

<table border="1">
 <tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 </tr>
 <tr>
 <td>Ficoll-Paque Plus</td>
 <td>GE Healthcare </td>
 <td>17-1440-03</td>
 </tr>
 <tr>
 <td>R848</td>
 <td>Invivogen</td>
 <td>tlrl-r848</td>
 </tr>
 <tr>
 <td>Paraformaldehyde (16%) </td>
 <td>Electron Microscopy Sciences </td>
 <td>15710</td>
 </tr>
 <tr>
 <td>BD Perm/Wash</td>
 <td>BD Biosciences</td>
 <td>554723</td>
 </tr>
 <tr>
 <td>CD14-PE</td>
 <td>eBioscience</td>
 <td>12-0149-41</td>
 </tr>
 <tr>
 <td>CD4-PacBlue</td>
 <td>BD Pharmingen</td>
 <td>68436</td>
 </tr>
 <tr>
 <td>Lineage cocktail 1 (lin 1)-FITC</td>
 <td>BD Biosciences</td>
 <td>340546</td>
 </tr>
 <tr>
 <td>CD11c-PE</td>
 <td>BD Biosciences</td>
 <td>347637</td>
 </tr>
 <tr>
 <td>CD123-PE</td>
 <td>BD Biosciences</td>
 <td>340545</td>
 </tr>
 <tr>
 <td>rabbit anti-NF-&kappa;B (p65) </td>
 <td>SantaCruz </td>
 <td>SC-372 </td>
 </tr>
 <tr>
 <td>Alexa647 F(ab')2 goat anti-rabbit IgG </td>
 <td>Invitrogen </td>
 <td>A21246</td>
 </tr>
 <tr>
 <td>DAPI </td>
 <td>Invitrogen </td>
 <td>D21490</td>
 </tr>
 <tr>
 <td>ImageStream X</td>
 <td>Amnis</td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
</table>
Table 1. Specific reagents and equipment.
<table border="1">
 <tbody>
 <tr>
 <td>Cell type</td>
 <td>FITC</td>
 <td>PE</td>
 <td>Alexa 647</td>
 <td>PacBlue</td>
 </tr>
 <tr>
 <td>Monocyte</td>
 <td>&nbsp;</td>
 <td>CD14</td>
 <td>NF-&kappa;B (p65)</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>mDC</td>
 <td>Lin1</td>
 <td>CD11c</td>
 <td>NF-&kappa;B (p65)</td>
 <td>CD4</td>
 </tr>
 <tr>
 <td>pDC</td>
 <td>Lin1</td>
 <td>CD123</td>
 <td>NF-&kappa;B (p65)</td>
 <td>CD4</td>
 </tr>
 </tbody>
</table>
Table 2. Antibody panel for cell lineage staining of signaling pathways
Monocyte: CD14+ mDC: Lin1-, CD4dim, CD11c+ pDC: Lin1-, CD4dim, CD123+ Lin1 (lineage) marker includes CD3, CD14, CD19, CD20, CD56 markers for monocytes, NK cells, T &amp; B cells.

quantitative imaging of lineage-specific toll-like receptor-mediated signaling in monocytes and dendritic cells from small samples of human blood

Individual variations in immune status determine responses to infection and contribute to disease severity and outcome. Aging is associated with an increased susceptibility to viral and bacterial infections and decreased responsiveness to vaccines with a well-documented decline in humoral as well as cell-mediated immune responses1,2. We have recently assessed the effects of aging on Toll-like receptors (TLRs), key components of the innate immune system that detect microbial infection and trigger antimicrobial host defense responses3. In a large cohort of healthy human donors, we showed that peripheral blood monocytes from the elderly have decreased expression and function of certain TLRs4 and similar reduced TLR levels and signaling responses in dendritic cells (DCs), antigen-presenting cells that are pivotal in the linkage between innate and adaptive immunity5. We have shown dysregulation of TLR3 in macrophages and lower production of IFN by DCs from elderly donors in response to infection with West Nile virus6,7. 
Paramount to our understanding of immunosenescence and to therapeutic intervention is a detailed understanding of specific cell types responding and the mechanism(s) of signal transduction. Traditional studies of immune responses through imaging of primary cells and surveying cell markers by FACS or immunoblot have advanced our understanding significantly, however, these studies are generally limited technically by the small sample volume available from patients and the inability to conduct complex laboratory techniques on multiple human samples. ImageStream combines quantitative flow cytometry with simultaneous high-resolution digital imaging and thus facilitates investigation in multiple cell populations contemporaneously for an efficient capture of patient susceptibility. Here we demonstrate the use of ImageStream in DCs to assess TLR7/8 activation-mediated increases in phosphorylation and nuclear translocation of a key transcription factor, NF-&kappa;B, which initiates transcription of numerous genes that are critical for immune responses8. Using this technology, we have also recently demonstrated a previously unrecognized alteration of TLR5 signaling and the NF-&kappa;B pathway in monocytes from older donors that may contribute to altered immune responsiveness in aging9.

Watch this Scientific Journal Video about Quantitative Imaging of Lineage-specific Toll-like Receptor-mediated Signaling in Monocytes and Dendritic Cells from Small Samples of Human Blood at JoVE.com

Quantitative Imaging of Lineage-specific Toll-like Receptor-mediated Signaling in Monocytes and Dendritic Cells from Small Samples of Human Blood

We describe use of ImageStream technology (<a href="http://www.amnis.com/" target="_blank">www.amnis.com</a>), which combines quantitative flow cytometry with simultaneous high-resolution digital imaging, to quantify cellular mechanisms of primary immune cells from well-defined patient cohorts. Our studies provide a blueprint for translational investigations to quantify lineage specific cellular responses in small samples from subject cohorts.

Individual variations in immune status determine responses to infection and contribute to disease severity and outcome.  Aging is associated with an ...

quantitative-imaging-lineage-specific-toll-like-receptor-mediated

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Immunology and Infection

35.0K Views.  Yale University School of Medicine. Descriviamo l'uso della tecnologia ImageStream ( Www.amnis.com), Che combina quantitative citometria di flusso con simultanea alta risoluzione digital imaging, per quantificare i meccanismi cellulari di cellule immunitarie primarie da ben definiti coorti di pazienti. I nostri studi forniscono un modello per le indagini traslazionali quantificare lignaggio risposte specifiche cellulari a piccoli campioni di coor...

Video: Quantitative Imaging of Lineage-specific Toll-like Receptor-mediated Signaling in Monocytes and Dendritic Cells from Small Samples of Human Blood

Detection of  Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation

Mammalian Toll-like receptors (TLRs) are a family of receptors that recognize pathogen-associated molecular patterns. Not only are TLRs crucial sensors of microbial (e.g., viruses, bacteria and parasite) infections, they also play an important role in the pathophysiology of infectious diseases, inflammatory diseases, and possibly in autoimmune diseases. Thus, the intensity and duration of TLR responses against infectious diseases must be tightly controlled. It follows that understanding the structural integrity of sensor receptors, their ligand interactions and signaling components is essential for subsequent immunological protection. It would also provide important opportunities for disease modification through sensor manipulation. Although the signaling pathways of TLR sensors are well characterized, the parameters controlling interactions between the sensors and their ligands still remain poorly defined. We have recently identified a novel mechanism of TLR activation by its natural ligand, which has not been previously observed 1,2. It suggests that ligand-induced TLR activation is tightly controlled by Neu1 sialidase activation. We have also reported that Neu1 tightly regulates neurotrophin receptors like TrkA and TrkB 3, which involve Neu1 and matrix metalloproteinase-9 (MMP-9) cross-talk in complex with the receptors 4. The sialidase assay has been initially use to find a novel ligand, thymoquinone, in the activation of Neu4 sialidase on the cell surface of macrophages, dendritic cells and fibroblast cells via GPCR G&alpha;i proteins and MMP-9 5. For TLR receptors, our data indicate that Neu1 sialidase is already in complex with TLR-2, -3 and -4 receptors, and is induced upon ligand binding to either receptor. Activated Neu1 sialidase hydrolyzes sialyl &alpha;-2,3-linked &beta;-galactosyl residues distant from ligand binding to remove steric hinderance to TLR-4 dimerization, MyD88/TLR4 complex recruitment, NFkB activation and pro-inflammatory cell responses. In a collaborative report, Neu1 sialidase has been shown to regulate phagocytosis in macrophage cells 6. Taken together, the sialidase assay has provided us with powerful insights to the molecular mechanisms of ligand-induced receptor activation. Although the precise relationship between Neu1 sialidase and the activation of TLR, Trk receptors has yet to be fully elucidated, it would represent a new or pioneering approach to cell regulation pathways.

The sialidase assay is a simple technical approach that will elucidate novel molecular mechanism(s) of TLR sensors of microbial infections and involvement in inflammatory diseases at the receptor level on the cell surface of live macrophages.

Mammalian Toll-like receptors (TLRs) are a family of receptors that recognize pathogen-associated molecular patterns. Not only are TLRs crucial sensors of ...

Isolation of Myeloid Dendritic Cells and Epithelial Cells from Human Thymus

In this protocol we provide a method to isolate dendritic cells (DC) and epithelial cells (TEC) from the human thymus. DC and TEC are the major antigen presenting cell (APC) types found in a normal thymus and it is well established that they play distinct roles during thymic selection. These cells are localized in distinct microenvironments in the thymus and each APC type makes up only a minor population of cells. To further understand the biology of these cell types, characterization of these cell populations is highly desirable but due to their low frequency, isolation of any of these cell types requires an efficient and reproducible procedure. This protocol details a method to obtain cells suitable for characterization of diverse cellular properties. Thymic tissue is mechanically disrupted and after different steps of enzymatic digestion, the resulting cell suspension is enriched using a Percoll density centrifugation step. For isolation of myeloid DC (CD11c+), cells from the low-density fraction (LDF) are immunoselected by magnetic cell sorting. Enrichment of TEC populations (mTEC, cTEC) is achieved by depletion of hematopoietic (CD45hi) cells from the low-density Percoll cell fraction allowing their subsequent isolation via fluorescence activated cell sorting (FACS) using specific cell markers. The isolated cells can be used for different downstream applications.

This protocol details a method to isolate antigen presenting cells from human thymus via different steps of enzymatic digestion of the tissue followed by density centrifugation of the single cell suspension and finally magnetic and/or FACS sorting of the cell populations of interest.

In this protocol we provide a method to isolate dendritic cells (DC) and epithelial cells (TEC) from the human thymus. DC and TEC are the major antigen ...

Generation of Human Alloantigen-specific T Cells from Peripheral Blood

The study of human T lymphocyte biology often involves examination of responses to activating ligands. T cells recognize and respond to processed peptide antigens presented by MHC (human ortholog HLA) molecules through the T cell receptor (TCR) in a highly sensitive and specific manner. While the primary function of T cells is to mediate protective immune responses to foreign antigens presented by self-MHC, T cells respond robustly to antigenic differences in allogeneic tissues. T cell responses to alloantigens can be described as either direct or indirect alloreactivity. In alloreactivity, the T cell responds through highly specific recognition of both the presented peptide and the MHC molecule. The robust oligoclonal response of T cells to allogeneic stimulation reflects the large number of potentially stimulatory alloantigens present in allogeneic tissues. While the breadth of alloreactive T cell responses is an important factor in initiating and mediating the pathology associated with biologically-relevant alloreactive responses such as graft versus host disease and allograft rejection, it can preclude analysis of T cell responses to allogeneic ligands. To this end, this protocol describes a method for generating alloreactive T cells from naive human peripheral blood leukocytes (PBL) that respond to known peptide-MHC (pMHC) alloantigens. The protocol applies pMHC multimer labeling, magnetic bead enrichment and flow cytometry to single cell in vitro culture methods for the generation of alloantigen-specific T cell clones. This enables studies of the biochemistry and function of T cells responding to allogeneic stimulation.

This article describes a method for the generation and propagation of human T cell clones that specifically respond to a defined alloantigen. This protocol can be adapted for cloning human T cells specific for a variety of peptide-MHC ligands.

The study of human T lymphocyte biology often involves examination of responses to activating ligands. T cells recognize and respond to processed peptide ...

Generation of Human Monocyte-derived Dendritic Cells from Whole Blood

Dendritic cells (DCs) recognize foreign structures of different pathogens, such as viruses, bacteria, and fungi, via a variety of pattern recognition receptors (PRRs) expressed on their cell surface and thereby activate and regulate immunity. 
The major function of DCs is the induction of adaptive immunity in the lymph nodes by presenting antigens via MHC I and MHC II molecules to na&#239;ve T lymphocytes. Therefore, DCs have to migrate from the periphery to the lymph nodes after the recognition of pathogens at the sites of infection. For in vitro experiments or DC vaccination strategies, monocyte-derived DCs are routinely used. These cells show similarities in physiology, morphology, and function to conventional myeloid dendritic cells. They are generated by interleukin 4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulation of monocytes isolated from healthy donors. Here, we demonstrate how monocytes are isolated and stimulated from anti-coagulated human blood after peripheral blood mononuclear cell (PBMC) enrichment by density gradient centrifugation. Human monocytes are differentiated into immature DCs and are ready for experimental procedures in a non-clinical setting after 5 days of incubation.

Here, we demonstrate how monocytes are isolated by magnetic bead separation from peripheral blood mononuclear cells after density gradient centrifugation of human anti-coagulated blood. Following incubation for 5 days, human monocytes are differentiated into immature dendritic cells and are ready for experimental procedures in a non-clinical setting.

Dendritic cells (DCs) recognize foreign structures of different pathogens, such as viruses, bacteria, and fungi, via a variety of pattern recognition ...

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.

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

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 ...

Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining the role of the gene of interest in the development, differentiation, and function of NK cells. Recent advances related to chimeric antigen receptors (CARs) in cancer immunotherapy accentuate the need for an efficient method to deliver exogenous genes to effector lymphocytes. The efficiencies of lentiviral-mediated gene transductions into primary human or mouse NK cells remain significantly low, which is a major limiting factor. Recent advances using cationic polymers, such as polybrene, show an improved gene transduction efficiency in T cells. However, these products failed to improve the transduction efficiencies of NK cells. This work shows that dextran, a branched glucan polysaccharide, significantly improves the transduction efficiency of human and mouse primary NK cells. This highly reproducible transduction methodology provides a competent tool for transducing human primary NK cells, which can vastly improve clinical gene delivery applications and thus NK cell-based cancer immunotherapy.

The goal of this study was to formulate technologies that allow for successful gene transduction in primary natural killer (NK) cells. The dextran-mediated lentiviral transduction of human or mouse primary NK cells results in higher gene expression efficiencies. This method of gene transduction will vastly improve NK cell genetic manipulation.

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

Live Imaging of Antifungal Activity by Human Primary Neutrophils and Monocytes in Response to A. fumigatus

Aspergillus fumigatus is an opportunistic fungal pathogen causing invasive infections in immunocompromised hosts with a high case-fatality rate. Research investigating immunological responses against A. fumigatus has been limited by the lack of consistent and reliable assays for measuring the antifungal activity of specific immune cells in vitro. A new method is described to assess the antifungal activity of primary monocytes and neutrophils from human donors against A. fumigatus using FLuorescent Aspergillus REporter (FLARE) conidia. These conidia contain a genetically encoded dsRed reporter, which is constitutively expressed by live FLARE conidia, and are externally labeled with Alexa Fluor 633, which is resistant to degradation within the phagolysosome, thus allowing a distinction between live and dead A. fumigatus conidia. Video microscopy and flow cytometry are subsequently used to visualize the interaction between conidia and innate immune cells, assessing fungicidal activity whilst also providing a wealth of information on phagocyte migration, phagocytosis and the inhibition of fungal growth. This novel technique has already provided exciting new insights into the host-pathogen interaction of primary immune cells against A. fumigatus. It is important to note the laboratory setup required to perform this assay, including the necessary microscopy and flow cytometry facilities, and the capacity to work with human donor blood and genetically manipulated fungi. However, this assay is capable of generating large amounts of data and can reveal detailed insights into the antifungal response. This protocol has successfully been used to study the host-pathogen interaction of primary immune cells against A. fumigatus.
It is important to note the laboratory setup required to perform this assay, including the necessary microscopy and flow cytometry facilities, and the capacity to work with human donor blood and genetically manipulated fungi. However, this assay is capable of generating large amounts of data and can reveal detailed insights into the antifungal response. This protocol has successfully been used to study the host-pathogen interaction of primary immune cells against A. fumigatus.

Live Imaging of Antifungal Activity by Human Primary Neutrophils and Monocytes in Response to A. fumigatus

Here, we describe a protocol to assess antifungal activity of primary human immune cells in real-time using fluorescent Aspergillus reporter conidia in conjunction with live-cell video microscopy and flow cytometry. Generated data provide insight into host cell-Aspergillus interactions such as fungicidal activity, phagocytosis, cell migration and inhibition of fungal growth.

Aspergillus fumigatus is an opportunistic fungal pathogen causing invasive infections in immunocompromised hosts with a high case-fatality rate. Research ...

Generation of Discriminative Human Monoclonal Antibodies from Rare Antigen-specific B Cells Circulating in Blood

Monoclonal antibodies (mAbs) are powerful tools useful for both fundamental research and in biomedicine. Their high specificity is indispensable when the antibody needs to distinguish between highly related structures (e.g., a normal protein and a mutated version thereof). The current way of generating such discriminative mAbs involves extensive screening of multiple Ab-producing B cells, which is both costly and time consuming. We propose here a rapid and cost-effective method for the generation of discriminative, fully human mAbs starting from human blood circulating B lymphocytes. The originality of this strategy is due to the selection of specific antigen binding B cells combined with the counter-selection of all other cells, using readily available Peripheral Blood Mononuclear Cells (PBMC). Once specific B cells are isolated, cDNA (complementary deoxyribonucleic acid) sequences coding for the corresponding mAb are obtained using single cell Reverse Transcription-Polymerase Chain Reaction (RT-PCR) technology and subsequently expressed in human cells. Within as little as 1 month, it is possible to produce milligrams of highly discriminative human mAbs directed against virtually any desired antigen naturally detected by the B cell repertoire.

We describe a method for the production of human antibodies specific for an antigen of interest, starting from rare B cells circulating in human blood. Generation of these natural antibodies is efficient and rapid, and the antibodies obtained can discriminate between highly related antigens.

Monoclonal antibodies (mAbs) are powerful tools useful for both fundamental research and in biomedicine. Their high specificity is indispensable when the ...

Isolation of Dendritic Cells from the Human Female Reproductive Tract for Phenotypical and Functional Studies

The characterization of the human dendritic cells (DCs) resident in mucosal tissues is challenging due to the difficulty in obtaining samples, and the low numbers of DCs present per tissue. Yet, as the phenotype and function of DCs is modified by the tissue environment, it is necessary to analyze tissue resident DC populations, since blood derived DCs incompletely reflect the complexities of DCs in tissues. Here we present a protocol to isolate DCs from the human female reproductive tract (FRT) using hysterectomy specimens that allows both phenotypical and functional analyses. The protocol consists of tissue digestion to generate a single cell mixed cell suspension, followed by positive magnetic bead selection. Our tissue digestion protocol does not cleave surface markers, which allows phenotypical and functional analysis of DCs in the steady state, without overnight incubation or cell activation. This protocol can be adapted for the isolation of other immune cell types or isolation of DCs from other tissues.

We describe here a method to isolate and purify dendritic cells from different anatomical compartments in the human female reproductive tract for the evaluation of their phenotypical and functional characteristics. This method can be adapted to isolate other immune cells or dendritic cells from other mucosal tissues.

The characterization of the human dendritic cells (DCs) resident in mucosal tissues is challenging due to the difficulty in obtaining samples, and the low ...

Development and Validation of an Ultrasensitive Single Molecule Array Digital Enzyme-linked Immunosorbent Assay for Human Interferon-&#945;

The main aim of this protocol is to describe the development and validation of an interferon (IFN)-&#945; single molecule array digital Enzyme-Linked ImmunoSorbent Assay (ELISA) assay. This system enables the quantification of human IFN-&#945; protein with unprecedented sensitivity, and with no cross-reactivity for other species of IFN.
The first key step of the protocol is the choice of the antibody pair, followed by the conjugation of the capture antibody to paramagnetic beads, and biotinylation of the detection antibody. Following this step, different parameters such as assay configuration, detector antibody concentration, and buffer composition can be modified until optimum sensitivity is achieved. Finally, specificity and reproducibility of the method are assessed to ensure confidence in the results. Here, we developed an IFN-&#945; single molecule array assay with a limit of detection of 0.69 fg/mL using high-affinity autoantibodies isolated from patients with biallelic mutations in the autoimmune regulator (AIRE) protein causing autoimmune polyendocrinopathy syndrome type 1/autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APS1/APECED). Importantly, these antibodies enabled detection of all 13 IFN-&#945; subtypes.
This new methodology allows the detection and quantification of IFN-&#945; protein in human biological samples at attomolar concentrations for the first time. Such a tool will be highly useful in monitoring the levels of this cytokine in human health and disease states, most particularly infection, autoimmunity, and autoinflammation.

Development and Validation of an Ultrasensitive Single Molecule Array Digital Enzyme-linked Immunosorbent Assay for Human Interferon-&amp;#945;

Here we present a protocol to describe the development and validation of a single molecule array digital ELISA assay, which enables the ultra-sensitive detection of all IFN-&#945; subtypes in human samples.

The main aim of this protocol is to describe the development and validation of an interferon (IFN)-&#945; single molecule array digital Enzyme-Linked ...