This work was supported by grants from FIS/FEDER (Programa Miguel Servet: CP10/00479, PI13/00802 and PI14/00883), Spanish Society of Atherosclerosis, Spanish Society of Nephrology and Fundaci&#242;n Renal I&#241;igo Alvarez de Toledo (FRIAT) to Juan Antonio Moreno. FIS/FEDER funds PI14/00386 and Instituto Reina Sof&#236;a de Investigaci&#242;n Nefrol&#242;gica to Jes&#250;s Egido. Fundaci&#242;n Conchita Rabago to Melania Guerrero Hue. Fundaci&#242;n Renal I&#241;igo Alvarez de Toledo (FRIAT) to Alfonso Rubio Navarro.

This protocol was approved by local Institutional Animal Care and Use Committees following the Directive 2010/63/EU of the European Parliament and the National Guideline 53/2013.
1. Preparation of Reagents and Solutions
<ol>
	<li>Prepare all the reagents and solutions under sterile conditions and use under a laminar flow hood. Keep solutions at 4 &#176;C.</li>
	<li>Prepare staining buffer (2% Fetal Bovine Serum (FBS) in 1x Dulbecco&#39;s PBS).</li>
	<li>Prepare collagenase solution by adding 0.5 mg of collagenase to each ml of saline.</li>
	<li>Prepare anesthesia solution of ketamine/xylazine (2:1 v/v).</li>
</ol>
2. Kidney Perfusion and Extraction
<ol>
	<li>Anesthetize rats by intraperitoneal injection of ketamine/xylazine (75 mg/12 mg/kg weight). Carefully pinch a small fold of skin, to check that the animal is sufficiently anesthetized. Then, cover eyes with vet ointment to prevent dryness while under anesthesia. Note: 4-month-old Wistar rats are used in this assay.</li>
	<li>Once the rat is totally anesthetized, place it on a surgical table in a supine position.</li>
	<li>Apply 70% ethanol to the abdomen.</li>
	<li>Make a central incision through the abdominal skin and peritoneum, from the pubis to the rib cage, to expose the pleural and abdominal cavities.</li>
	<li>Inject saline solution (0.9%) into the abdominal aorta to perfuse kidneys using a perfusion system until all blood is removed from kidneys. Cut the aorta at the abdominal level to help release the blood.</li>
	<li>Remove both kidneys from the rat by cutting from the renal hilum (renal vein, artery and ureter). To decapsulate the kidney, press the edge of the kidney using fingers, carefully separating the capsule11.</li>
	<li>Place the kidney into Hanks&#39; balanced salt solution.</li>
</ol>
3. Kidney Digestion and Cell Suspension
<ol>
	<li>Cut half of a kidney with scissors into small pieces and put the pieces into a 1.5 ml tube. 
	Note: All the following concentrations are calculated for 1 sample (1/2 rat&#39;s kidney).</li>
	<li>Add 1 ml of the collagenase solution and incubate at 37 &#176;C for 30 min. Mix by inversion every 5 min to make sure that the collagenase solution accesses the entire tissue.</li>
	<li>Collect the solution and pass it through a strainer (40 &#181;m) with the aid of a plunger, and resuspend it in 10 ml of staining buffer.</li>
	<li>Centrifuge at 400 x g for 15 min.</li>
	<li>Re-suspend the pellet in 1 ml ACK (Ammonium-Chloride-Potassium) Lysing Buffer. After 1 min 30 sec at room temperature, add 10 ml of staining buffer to stop the reaction.</li>
	<li>Centrifuge at 400 x g for 10 min.</li>
	<li>Re-suspend the pellet in an adequate volume of staining buffer (1 ml) and filter the cell suspension using a strainer (30 &#181;m).</li>
	<li>Count the number of cells using trypan blue exclusion on a hemocytometer and add 2 million cells to a 1.5 ml tube for staining.</li>
</ol>
4. Cell Staining and Flow Cytometry Analysis
<ol>
	<li>Centrifuge cells at 100 x g for 5 min.</li>
	<li>Re-suspend the pellet in 100 &#181;l of rat serum (diluted 1:100) for 10 min at 4 &#176;C to block Fc receptors.</li>
	<li>Wash by adding 1 ml of staining buffer and centrifuge 100 x g for 5 min.</li>
	<li>Mix the antibodies for cell surface staining in 100 &#181;l of staining buffer for each condition: CD45 APC-Cy7 (1:100), CD163 A647(4:100) and solution to detect live cells (3:1,000).</li>
	<li>Re-suspend the cell pellet in the antibody mix for 20 min at 4 &#176;C in the dark.</li>
	<li>Wash by adding 1 ml of staining buffer and centrifuge at 100 x g for 5 min. Repeat this step.</li>
	<li>Add 600 &#181;l of Fixation/Permeabilization solution for 20 min at 4 &#176;C in the dark.</li>
	<li>Wash 2 times with 1 ml Permeabilization/Wash buffer and centrifuge at 170 x g for 5 min.</li>
	<li>Add the CD68 FITC antibody (35:1,000) for the intracellular staining to 100 &#181;l of Permeabilization/Wash buffer for each condition.</li>
	<li>Re-suspend the pellet in the CD68-antibody solution and incubate 50 min at 4 &#176;C in the dark.</li>
	<li>Wash with 1 ml Permeabilization/Wash buffer and centrifuge at 170 x g for 5 min.</li>
	<li>Re-suspend the pellet in 100 &#181;l of Permeabilization/Wash buffer, add CD86PE antibody (35:1,000) and incubate for 20 min at 4 &#176;C in the dark.</li>
	<li>Wash by adding 1 ml of Permeabilization/Wash buffer and centrifuge at 100 x g for 5 min.</li>
	<li>Re-suspend the pellet in 100 &#181;l of Permeabilization/Wash buffer and pass it to a flow cytometry tube.</li>
	<li>Analyze samples by flow cytometry. Determine CD45 staining in live cells gated in the Side-scattered light/forward-scattered light (SSC/FSC) window. In a second step, analyze CD86 and CD163 expression in CD68+ cells.</li>
</ol>

<ol>
	<li>Gansevoort, R. T., 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=Chronic+kidney+disease+and+cardiovascular+risk:+epidemiology,+mechanisms,+and+prevention.">Chronic kidney disease and cardiovascular risk: epidemiology, mechanisms, and prevention.</a> Lancet. 382, 339-352 (2013).</li><li>Kon, V., Linton, M. F., Fazio, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atherosclerosis+in+chronic+kidney+disease:+the+role+of+macrophages.">Atherosclerosis in chronic kidney disease: the role of macrophages.</a> Nat. Rev. Nephrol. 7, 45-54 (2011).</li><li>Kim, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+depletion+ameliorates+glycerol-induced+acute+kidney+injury+in+mice.">Macrophage depletion ameliorates glycerol-induced acute kidney injury in mice.</a> Nephron Exp. Nephrol. 128, 21-29 (2014).</li><li>Belliere, J., 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=Specific+macrophage+subtypes+influence+the+progression+of+rhabdomyolysis-induced+kidney+injury.">Specific macrophage subtypes influence the progression of rhabdomyolysis-induced kidney injury.</a> J. Am. Soc. Nephrol. 26, 1363-1377 (2015).</li><li>Kinsey, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+dynamics+in+AKI+to+CKD+progression.">Macrophage dynamics in AKI to CKD progression.</a> J. Am. Soc. Nephrol. 25, 209-211 (2014).</li><li>Lech, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+phenotype+controls+long-term+AKI+outcomes--kidney+regeneration+versus+atrophy.">Macrophage phenotype controls long-term AKI outcomes--kidney regeneration versus atrophy.</a> J. Am. Soc. Nephrol. 25, 292-304 (2014).</li><li>Murray, P. J., 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=Macrophage+activation+and+polarization:+nomenclature+and+experimental+guidelines.">Macrophage activation and polarization: nomenclature and experimental guidelines.</a> Immunity. 41, 14-20 (2014).</li><li>Gordon, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternative+activation+of+macrophages.">Alternative activation of macrophages.</a> Nat. Rev. Immunol. 3, 23-35 (2003).</li><li>Mosser, D. M., Edwards, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+the+full+spectrum+of+macrophage+activation.">Exploring the full spectrum of macrophage activation.</a> Nat. Rev. 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Exp. , (2014).</li><li>Martin-Fernandez, B., 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=Aldosterone+Induces+Renal+Fibrosis+and+Inflammatory+M1-Macrophage+Subtype+via+Mineralocorticoid+Receptor+in+Rats.">Aldosterone Induces Renal Fibrosis and Inflammatory M1-Macrophage Subtype via Mineralocorticoid Receptor in Rats.</a> PLoS. One. 11, e0145946 (2016).</li><li>Layoun, A., Samba, M., Santos, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+murine+peritoneal+macrophages+to+carry+out+gene+expression+analysis+upon+Toll-like+receptors+stimulation.">Isolation of murine peritoneal macrophages to carry out gene expression analysis upon Toll-like receptors stimulation.</a> J. Vis. Exp. (e52749), (2015).</li><li>Komohara, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+infiltration+and+its+prognostic+relevance+in+clear+cell+renal+cell+carcinoma.">Macrophage infiltration and its prognostic relevance in clear cell renal cell carcinoma.</a> Cancer Sci. 102, 1424-1431 (2011).</li><li>Han, Y., Ma, F. Y., Tesch, G. H., Manthey, C. L., Nikolic-Paterson, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+macrophages+in+the+fibrotic+phase+of+rat+crescentic+glomerulonephritis.">Role of macrophages in the fibrotic phase of rat crescentic glomerulonephritis.</a> Am. J. Physiol Renal Physiol. 304, F1043-F1053 (2013).</li><li>Ndisang, J. 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The authors have nothing to disclose.

Macrophages are heterogeneous cells that play an important role in different inflammatory diseases, including renal disorders. There is increasing interest in the characterization of macrophages subsets in renal disease because each macrophage subpopulation contributes in a different way to the development of kidney injury, as reported in glomerulonephritis, diabetic nephropathy and kidney cancer14-16. In the early stages of acute renal injury, a predominance of M1 macrophages is observed, promoting tubular ne...

Renal disease is a global health problem, with increased prevalence, and associated with elevated morbidity and mortality1. One of the most important mechanisms involved in the progression and development of renal injury is inflammation, mainly triggered by macrophages. Macrophages play a pivotal role in many inflammatory diseases, including renal disorders2. Thus, an elevated presence of infiltrating macrophages has been reported in biopsies from patients with acute kidney injury (AKI) or chronic kidney disease (CKD)3,4. Recent studies suggest that the long-term outcome of renal disease could be controlled by macrophages5,6. In response to the local microenvironment, macrophages may differentiate into different phenotypes that play diverse biological functions7. Two well differentiated macrophage phenotypes have been established: classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2)8. M1 macrophages promote inflammation, whereas M2 macrophages have an anti-inflammatory role and are involved in tissue repair9. Therefore, a better knowledge of macrophage heterogeneity is necessary to understand their regulation and contribution to renal pathology and develop novel therapeutic approaches. 
Both, murine and rats models have been widely used to understand the molecular and cellular mechanism involved in renal injury10. However, there are substantial differences in the diverse markers used to identify macrophages phenotypes between these rodents. Hence, several murine markers, such as F4/80 or Ly6C are not used in rats, thus limiting the extrapolation of findings between these species. Moreover, there is a limited number of markers describing macrophage phenotypes in rats, explaining the scarce studies analyzing macrophage heterogeneity in these animals as compared with mice. Therefore, new strategies for macrophage subset characterization are necessary to understand the role of macrophages in renal disease models in rats. 
This manuscript describes a protocol for the phenotypic and quantitative analysis of macrophages from rat kidneys by flow cytometry. This technique can be further followed by several assays, including cell sorting and mRNA or protein expression studies to allow in-depth characterization of the role of macrophages in renal disease.

<table border="0" cellpadding="0" cellspacing="0" width="519">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Laminar flow hood</td>
			<td style="width:124px;">Faster</td>
			<td style="width:135px;"></td>
			<td style="width:143px;">Or equivalent equipment</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Centrifuge</td>
			<td style="width:124px;">Hettich</td>
			<td style="width:135px;"></td>
			<td style="width:143px;">Or equivalent equipment</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Flow cytometer (FACSAria)</td>
			<td style="width:124px;">BD Biosciences</td>
			<td style="width:135px;"></td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Fetal bovine serum</td>
			<td style="width:124px;">BioWest</td>
			<td style="width:135px;">S1820-500</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:119px;">PBS 10x</td>
			<td style="width:124px;">LONZA</td>
			<td style="width:135px;">BE17-515Q</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:119px;">Collagenase</td>
			<td style="width:124px;">Sigma-Aldrich</td>
			<td style="width:135px;">12/1/9001</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">ACK Lysing Buffer</td>
			<td style="width:124px;">Thermo Fisher Scientific</td>
			<td style="width:135px;">A10492-01</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Flow cytometry strainers</td>
			<td style="width:124px;">BD Biosciences</td>
			<td style="width:135px;">340626</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Falcon cell strainers</td>
			<td style="width:124px;">Thermo Fisher Scientific</td>
			<td style="width:135px;">352340</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Flow cytometry tubes</td>
			<td style="width:124px;">Falcon</td>
			<td style="width:135px;">352052</td>
			<td style="width:143px;">5 ml Polystyrene Round-Bottom Tube</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Centrifuge tubes</td>
			<td style="width:124px;">Corning centristar</td>
			<td style="width:135px;">430791</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Water bath</td>
			<td style="width:124px;">Memmert GmbH + Co. KG</td>
			<td style="width:135px;">WNE 7</td>
			<td style="width:143px;">37&#186;C</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:119px;">Fixation/Permeabilization Solution or Permeabilization/Wash Buffer</td>
			<td style="width:124px;">BD Biosciences</td>
			<td style="width:135px;">554714</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Rompum (Xylazine)</td>
			<td style="width:124px;">Bayer</td>
			<td style="width:135px;"></td>
			<td style="width:143px;">Or equivalent</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Ketalar (Ketamine)</td>
			<td style="width:124px;">Pfizer</td>
			<td style="width:135px;"></td>
			<td style="width:143px;">Or equivalent</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Hanks&#8217; balanced salt solution</td>
			<td style="width:124px;">Sigma-Aldrich</td>
			<td style="width:135px;">H8264-500ML</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:119px;">Saline solution</td>
			<td style="width:124px;">Braun</td>
			<td style="width:135px;">622415</td>
			<td style="width:143px;"></td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:119px;">Anti-CD45 (clone:OX-1) APC-Cy7</td>
			<td style="width:124px;">Biolegend</td>
			<td style="width:135px;">202216</td>
			<td style="width:143px;">Diluted 1:100</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">Anti-CD68 (clone: ED1) FITC</td>
			<td style="width:124px;">Bio-RAD</td>
			<td style="width:135px;">MCA341F</td>
			<td style="width:143px;">Diluted 35:1000</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:119px;">anti-CD86 (clone: 24F) PE</td>
			<td style="width:124px;">Biolegend</td>
			<td style="width:135px;">200307</td>
			<td style="width:143px;">Diluted 35:1000</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:119px;">anti-CD163 (clone: ED2) Alexa Fluor 647</td>
			<td style="width:124px;">Bio-RAD</td>
			<td style="width:135px;">MCA342R</td>
			<td style="width:143px;">Diluted 4:100</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:119px;">Live/dead stain&#160;</td>
			<td style="width:124px;">Molecular Probes</td>
			<td style="width:135px;">L34955</td>
			<td style="width:143px;">Diluted 3:1000</td>
		</tr>
	</tbody>
</table>

phenotypic characterization of macrophages from rat kidney by flow cytometry

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal disease. Macrophages are heterogeneous cells that have been implicated in kidney injury. Macrophages may be classified into two different phenotypes: classically activated macrophages (M1 macrophages), that release pro-inflammatory cytokines and promote fibrosis; and alternatively activated macrophages (M2 macrophages) that are associated with immunoregulatory and tissue-remodeling functions. These macrophage phenotypes need to be discriminated and analyzed to determine their contribution to renal injury. However, there are scarce studies reporting consistent phenotypic and functional information about macrophage subtypes in inflammatory renal disease models, especially in rats. This fact may be related to the limited macrophage markers used in rats, contrary to mice. Therefore, novel strategies are necessary to quantify and characterize the renal content of these infiltrating cells in a reliable way. This manuscript details a protocol for kidney digestion and further phenotypic and quantitative analysis of macrophages from rat kidneys by flow cytometry. Briefly, kidneys were incubated with collagenase and total macrophages were identified according to the dual presence of CD45 (leukocytes common antigen) and CD68 (PAN macrophage marker) in live cells.This was followed by surface staining of CD86 (M1 marker) and CD163 (M2 marker). Rat peritoneal macrophages were used as positive control for macrophage marker detection by flow cytometry. Our protocol resulted in low cellular mortality and allowed characterization of different intracellular and surface protein markers, thus limiting the loss of cellular integrity observed in other protocols. Moreover, this procedure allows the use of macrophages for further techniques, including cell sorting and mRNA or protein expression studies, among others.

We analyzed macrophage heterogeneity in an inflammatory experimental model of renal injury associated with increased presence of infiltrating macrophages in the kidney. In this model, renal damage was induced by administration of aldosterone (1 mg-1kg-1day) plus salt (NaCl 1%) in drinking water for 3 weeks in Wistar rats, as previously reported12.
The schedule of our experiments is shown in <stro...

Watch this Scientific Journal Video about Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry at JoVE.com

Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

This manuscript describes a detailed protocol for phenotypic and quantitative analysis of resident macrophages from rat kidneys by flow cytometry. The resulting stained cells can be also used for other applications, including cell sorting, gene expression analysis or functional studies, thus increasing the information obtained in the experimental model.

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal ...

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Immunology and Infection

14.6K Views.  Autonoma University. This manuscript describes a detailed protocol for phenotypic and quantitative analysis of resident macrophages from rat kidneys by flow cytometry. The resulting stained cells can be also used for other applications, including cell sorting, gene expression analysis or functional studies, thus increasing the information obtained in the experimental model.

Video: Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

Human In Vitro Suppression as Screening Tool for the Recognition of an Early State of Immune Imbalance

Regulatory T cells (Tregs) are critical mediators of immune tolerance to self-antigens. In addition, they are crucial regulators of the immune response following an infection. Despite efforts to identify unique surface marker on Tregs, the only unique feature is their ability to suppress the proliferation and function of effector T cells. While it is clear that only in vitro assays can be used in assessing human Treg function, this becomes problematic when assessing the results from cross-sectional studies where healthy cells and cells isolated from subjects with autoimmune diseases (like Type 1 Diabetes-T1D) need to be compared. There is a great variability among laboratories in the number and type of responder T cells, nature and strength of stimulation, Treg:responder ratios and the number and type of antigen-presenting cells (APC) used in human in vitro suppression assays. This variability makes comparison between studies measuring Treg function difficult. The Treg field needs a standardized suppression assay that will work well with both healthy subjects and those with autoimmune diseases. We have developed an in vitro suppression assay that shows very little intra-assay variability in the stimulation of T cells isolated from healthy volunteers compared to subjects with underlying autoimmune destruction of pancreatic &beta;-cells. The main goal of this piece is to describe an in vitro human suppression assay that allows comparison between different subject groups. Additionally, this assay has the potential to delineate a small loss in nTreg function and anticipate further loss in the future, thus identifying subjects who could benefit from preventive immunomodulatory therapy1. Below, we provide thorough description of the steps involved in this procedure. We hope to contribute to the standardization of the in vitro suppression assay used to measure Treg function. In addition, we offer this assay as a tool to recognize an early state of immune imbalance and a potential functional biomarker for T1D.

Human In Vitro Suppression as Screening Tool for the Recognition of an Early State of Immune Imbalance

Tregs are potent suppressors of the immune system. There is a lack of unique surface markers to define them, hence, definitions of Tregs are primarily functional. Here we describe an optimized in vitro assay capable of identifying immune imbalance in subjects at risk to develop T1D.

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

Examination of Thymic Positive and Negative Selection by Flow Cytometry

A healthy immune system requires that T cells respond to foreign antigens while remaining tolerant to self-antigens. Random rearrangement of the T cell receptor (TCR) &alpha; and &beta; loci generates a T cell repertoire with vast diversity in antigen specificity, both to self and foreign. Selection of the repertoire during development in the thymus is critical for generating safe and useful T cells. Defects in thymic selection contribute to the development of autoimmune and immunodeficiency disorders1-4. 
T cell progenitors enter the thymus as double negative (DN) thymocytes that do not express CD4 or CD8 co-receptors. Expression of the &alpha;&beta;TCR and both co-receptors occurs at the double positive (DP) stage. Interaction of the &alpha;&beta;TCR with self-peptide-MHC (pMHC) presented by thymic cells determines the fate of the DP thymocyte. High affinity interactions lead to negative selection and elimination of self-reactive thymocytes. Low affinity interactions result in positive selection and development of CD4 or CD8 single positive (SP) T cells capable of recognizing foreign antigens presented by self-MHC5.
Positive selection can be studied in mice with a polyclonal (wildtype) TCR repertoire by observing the generation of mature T cells. However, they are not ideal for the study of negative selection, which involves deletion of small antigen-specific populations. Many model systems have been used to study negative selection but vary in their ability to recapitulate physiological events6. For example, in vitro stimulation of thymocytes lacks the thymic environment that is intimately involved in selection, while administration of exogenous antigen can lead to non-specific deletion of thymocytes7-9. Currently, the best tools for studying in vivo negative selection are mice that express a transgenic TCR specific for endogenous self-antigen. However, many classical TCR transgenic models are characterized by premature expression of the transgenic TCR&alpha; chain at the DN stage, resulting in premature negative selection. Our lab has developed the HYcd4 model, in which the transgenic HY TCR&alpha; is conditionally expressed at the DP stage, allowing negative selection to occur during the DP to SP transition as occurs in wildtype mice10.
Here, we describe a flow cytometry-based protocol to examine thymic positive and negative selection in the HYcd4 mouse model. While negative selection in HYcd4 mice is highly physiological, these methods can also be applied to other TCR transgenic models. We will also present general strategies for analyzing positive selection in a polyclonal repertoire applicable to any genetically manipulated mice.

We present a flow cytometry-based method to examine T cell development in vivo using genetically manipulated mice on a wildtype or T cell receptor transgenic background.

A healthy immune system requires that T cells respond to foreign  antigens while remaining tolerant to self-antigens. Random rearrangement of the  T cell ...

Characterization of Human Monocyte-derived Dendritic Cells by Imaging Flow Cytometry: A Comparison between Two Monocyte Isolation Protocols

Dendritic cells (DCs) are antigen presenting cells of the immune system that play a crucial role in lymphocyte responses, host defense mechanisms, and pathogenesis of inflammation. Isolation and study of DCs have been important in biological research because of their distinctive features. Although they are essential key mediators of the immune system, DCs are very rare in blood, accounting for approximately 0.1 - 1% of total blood mononuclear cells. Therefore, alternatives for isolation methods rely on the differentiation of DCs from monocytes isolated from peripheral blood mononuclear cells (PBMCs). The utilization of proper isolation techniques that combine simplicity, affordability, high purity, and high yield of cells is imperative to consider. In the current study, two distinct methods for the generation of DCs will be compared. Monocytes were selected by adherence or negatively enriched using magnetic separation procedure followed by differentiation into DCs with IL-4 and GM-CSF. Monocyte and MDDC viability, proliferation, and phenotype were assessed using viability dyes, MTT assay, and CD11c/ CD14 surface marker analysis by imaging flow cytometry. Although the magnetic separation method yielded a significant higher percentage of monocytes with higher proliferative capacity when compared to the adhesion method, the findings have demonstrated the ability of both techniques to simultaneously generate monocytes that are capable of proliferating and differentiating into viable CD11c+ MDDCs after seven days in culture. Both methods yielded &gt; 70% CD11c+ MDDCs. Therefore, our results provide insights that contribute to the development of reliable methods for isolation and characterization of human DCs.

This study compares two different methods of human monocyte isolation for obtaining in vitro dendritic cells (DCs). Monocytes are selected by adherence or negatively enriched by magnetic separation. Monocyte yield and viability along with MDDC viability, proliferation and CD11c/CD14 surface marker expression will be compared between both methods.

Dendritic cells (DCs) are antigen presenting cells of the immune system that play a crucial role in lymphocyte responses, host defense mechanisms, and ...

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 ...

Human Lung Dendritic Cells: Spatial Distribution and Phenotypic Identification in Endobronchial Biopsies Using Immunohistochemistry and Flow Cytometry

The lungs are constantly exposed to the external environment, which in addition to harmless particles, also contains pathogens, allergens, and toxins. In order to maintain tolerance or to induce an immune response, the immune system must appropriately handle inhaled antigens. Lung dendritic cells (DCs) are essential in maintaining a delicate balance to initiate immunity when required without causing collateral damage to the lungs due to an exaggerated inflammatory response. While there is a detailed understanding of the phenotype and function of immune cells such as DCs in human blood, the knowledge of these cells in less accessible tissues, such as the lungs, is much more limited, since studies of human lung tissue samples, especially from healthy individuals, are scarce. This work presents a strategy to generate detailed spatial and phenotypic characterization of lung tissue resident DCs in healthy humans that undergo a bronchoscopy for the sampling of endobronchial biopsies. Several small biopsies can be collected from each individual and can be subsequently embedded for ultrafine sectioning or enzymatically digested for advanced flow cytometric analysis. The outlined protocols have been optimized to yield maximum information from small tissue samples that, under steady-state conditions, contain only a low frequency of DCs. While the present work focuses on DCs, the methods described can directly be expanded to include other (immune) cells of interest found in mucosal lung tissue. Furthermore, the protocols are also directly applicable to samples obtained from patients suffering from pulmonary diseases where bronchoscopy is part of establishing the diagnosis, such as chronic obstructive pulmonary disease (COPD), sarcoidosis, or lung cancer.

Lung-resident immune cells, including dendritic cells (DCs) in humans, are critical for defense against inhaled pathogens and allergens. However, due to the scarcity of human lung tissue, studies are limited. This work presents protocols to process human mucosal endobronchial biopsies for studying lung DCs using immunohistochemistry and flow cytometry.

The lungs are constantly exposed to the external environment, which in addition to harmless particles, also contains pathogens, allergens, and toxins. In ...

Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation

Obesity promotes a chronic inflammatory state that is largely mediated by tissue-resident macrophages as well as monocyte-derived macrophages. Diet-induced obesity (DIO) is a valuable model in studying the role of macrophage heterogeneity; however, adequate macrophage isolations are difficult to acquire from inflamed tissues. In this protocol, we outline the isolation steps and necessary troubleshooting guidelines derived from our studies for obtaining a suitable population of tissue-resident macrophages from mice following 18 weeks of high-fat (HFD) or high-fat/high-cholesterol (HFHCD) diet intervention. This protocol focuses on three hallmark tissues studied in obesity and atherosclerosis including the liver, white adipose tissues (WAT), and the aorta. We highlight how dualistic usage of flow cytometry can achieve a new dimension of isolation and characterization of tissue-resident macrophages. A fundamental section of this protocol addresses the intricacies underlying tissue-specific enzymatic digestions and macrophage isolation, and subsequent cell-surface antibody staining for flow cytometric analysis. This protocol addresses existing complexities underlying fluorescent-activated cell sorting (FACS) and presents clarifications to these complexities so as to obtain broad range characterization from adequately sorted cell populations. Alternate enrichment methods are included for sorting cells, such as the dense liver, allowing for flexibility and time management when working with FACS. In brief, this protocol aids the researcher to evaluate macrophage heterogeneity from a multitude of inflamed tissues in a given study and provides insightful troubleshooting tips that have been successful for favorable cellular isolation and characterization of immune cells in DIO-mediated inflammation.

This protocol allows a researcher to isolate and characterize tissue-resident macrophages in various hallmark inflamed tissues extracted from diet-induced models of metabolic disorders.

Obesity promotes a chronic inflammatory state that is largely mediated by tissue-resident macrophages as well as monocyte-derived macrophages. ...

Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry

Numerous studies have demonstrated the role of immune cells, in particular macrophages, in central nervous system (CNS) pathologies. There are two main macrophage populations in the CNS: (i) the microglia, which are the resident macrophages of the CNS and are derived from yolk sac progenitors during embryogenesis, and (ii) the monocyte-derived macrophages (MDM), which can infiltrate the CNS during disease and are derived from bone marrow progenitors. The roles of each macrophage subpopulation differ depending on the pathology being studied. Furthermore, there is no consensus on the histological markers or the distinguishing criteria used for these macrophage subpopulations. However, the analysis of the expression profiles of the CD11b and CD45 markers by flow cytometry allows us to distinguish the microglia (CD11b+CD45med) from the MDM (CD11b+CD45high). In this protocol, we show that the density gradient centrifugation and the flow cytometry analysis can be used to characterize these CNS macrophage subpopulations, and to study several markers of interest expressed by these cells as we recently published. Thus, this technique can further our understanding of the role of macrophages in mouse models of neurological diseases and can also be used to evaluate drug effects on these cells.

This protocol provides an analysis of the macrophage subpopulations in the adult mouse central nervous system by flow cytometry and is helpful for the study of multiple markers expressed by these cells.

Numerous studies have demonstrated the role of immune cells, in particular macrophages, in central nervous system (CNS) pathologies. There are two main ...

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 ...

Characterization of Human Monocyte Subsets by Whole Blood Flow Cytometry Analysis

Monocytes are key contributors in various inflammatory disorders and alterations to these cells, including their subset proportions and functions, can have pathological significance. An ideal method for examining alterations to monocytes is whole blood flow cytometry as the minimal handling of samples by this method limits artifactual cell activation. However, many different approaches are taken to gate the monocyte subsets leading to inconsistent identification of the subsets between studies. Here we demonstrate a method using whole blood flow cytometry to identify and characterize human monocyte subsets (classical, intermediate, and non-classical). We outline how to prepare the blood samples for flow cytometry, gate the subsets (ensure contaminating cells have been removed), and determine monocyte subset expression of surface markers &#8212; in this example M1 and M2 markers. This protocol can be extended to other studies that require a standard gating method for assessing monocyte subset proportions and monocyte subset expression of other functional markers.

Here we present a protocol for characterizing monocyte subsets by whole blood flow cytometry. This includes outlining how to gate the subsets and assess their expression of surface markers and giving an example of the assessment of the expression of M1 (inflammatory) and M2 markers (anti-inflammatory).

Monocytes are key contributors in various inflammatory disorders and alterations to these cells, including their subset proportions and functions, can ...

Discrimination of Seven Immune Cell Subsets by Two-fluorochrome Flow Cytometry

Immune cell characterization heavily relies on multicolor flow cytometry to identify subpopulations based on differential expression of surface markers. Setup of a classic multicolor panel requires high-end instruments, custom labeled antibodies, and careful study design to minimize spectral overlap. We developed a multiparametric analysis to identify major human immune populations (CD4+ and CD8+ T cells, &#947;&#948; T cells, B cells, NK cells and monocytes) in peripheral blood by combining seven lineage markers using only two fluorochromes. Our strategy is based on the observation that lineage markers are constantly expressed in a unique combination by each cell population. Combining this information with a careful titration of the antibodies allows investigators to record five additional markers, expanding the optical limit of most flow cytometers. Head-to-head comparison demonstrated that the vast majority of immune cell populations in peripheral blood can be characterized with comparable accuracy between our method and the classic &#34;one fluorochrome-one marker approach&#34;, although the latter is still more precise for identifying populations such as NKT cells and &#947;&#948; T cells. Combining seven markers using two fluorochromes allows for the analysis of complex immune cell populations and clinical samples on affordable 6-10 fluorochrome flow cytometers, and even on 2-3 fluorochrome field instruments in areas with limited resources. High-end instruments can also benefit from this approach by using extra fluorochromes to accomplish deeper flow cytometry analysis. This approach is also very well suited for screening several cell populations in the case of clinical samples with limited number of cells.

Here, we present a flow cytometric protocol to identify CD4+ and CD8+ T cells, &#947;&#948; T cells, B cells, NK cells and monocytes in human peripheral blood by using only two fluorochromes instead of seven. With this approach, five additional markers can be recorded on most flow cytometers.

Immune cell characterization heavily relies on multicolor flow cytometry to identify subpopulations based on differential expression of surface markers. ...

Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

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Chapters in this video

Human In Vitro Suppression as Screening Tool for the Recognition of an Early State of Immune Imbalance

Examination of Thymic Positive and Negative Selection by Flow Cytometry

Characterization of Human Monocyte-derived Dendritic Cells by Imaging Flow Cytometry: A Comparison between Two Monocyte Isolation Protocols

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

Human Lung Dendritic Cells: Spatial Distribution and Phenotypic Identification in Endobronchial Biopsies Using Immunohistochemistry and Flow Cytometry

Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation

Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

Characterization of Human Monocyte Subsets by Whole Blood Flow Cytometry Analysis

Discrimination of Seven Immune Cell Subsets by Two-fluorochrome Flow Cytometry