We would like to thank the LJI Flow Cytometry core for assistance with mass cytometry procedure. This work was supported by NIH grants R01HL134236, P01HL136275, and R01CA202987 (all to C.C.H) and ADA7-12-MN-31 (04) (to C.C.H. and Y.P.Z).

All experiments followed approved guidelines of the La Jolla Institute for Allergy and Immunology Animal Care and Use Committee, and approval for the use of rodents was obtained from the La Jolla Institute for Allergy and Immunology according to criteria outlined in the Guide for the Care and Use of Laboratory Animals from the National Institutes of Health.
1. Harvest Mouse Bone Marrow (BM)
<ol>
	<li>Purchase C57BL/6J mice from a commercial vendor. Feed the standard rodent chow diet and house in microisolator cages in a pathogen-free facility.</li>
	<li>Use male mice, 6-10 weeks of age, for experimental purpose. Euthanize by CO2 inhalation followed by the cervical dislocation.</li>
	<li>Place the mouse onto a sterile surgical pad with the abdomen side up. Sterilize the skin of the abdomen and hindlimbs area by spraying 70% ethanol. Use a pair of dissecting surgical scissors to cut the abdominal cavity open.</li>
	<li>Remove the skin to expose hindlimbs. Use a pair of blunt-tip dressing forceps to hold the mouse tibia right below the ankle. Use another pair of curved dressing forceps to stabilize the tibia below the blunt-tip dressing forceps. Break the tibia and expose the bone by ripping off the muscle with the blunt-tip dressing forceps. 
	NOTE: The tibia is loosely attached to the knee joint and can be easily picked out by using the blunt-tip dressing forceps.</li>
	<li>Place the tibia in cold 1x PBS.</li>
	<li>Next, move the stabilizing curved dressing forceps downward to the femur. Slide the blunt-tip dressing forceps below the knee joint and hold the kneecap. Dislocate the kneecap by gently pulling it up. Expose the femur by ripping off the muscle attached to the kneecap. Hold the exposed femur by the curved dressing forceps and cut the femur off from the bottom of the bone using dissecting surgical scissors.</li>
	<li>Place the femur in cold 1x PBS.</li>
	<li>Punch a hole in 0.5 mL microcentrifuge tube with an 18 G needle.</li>
	<li>Place both tibia and femur into the same 0.5 mL microcentrifuge tube with the open end of the bones facing downwards to the hole.</li>
	<li>Place the 0.5 mL tube containing both tibia and femur into a 1.7 mL microcentrifuge tube.</li>
	<li>Spin the double-layered tubes containing both tibia and femur at 5,510 x g for 30 s in the micro-centrifuge.</li>
	<li>Ensure that the BM is extracted from the bones and pelleted at the bottom of the tube. Toss the 0.5 mL tube containing the hallowed bones. The mouse BM is ready for next steps. 
	NOTE: Human BM is harvested at clinical resources as previously described11.</li>
</ol>
2. Stain BM Cells for CyTOF
<ol>
	<li>Resuspend the BM in 1 mL 1x Red Blood Cell (RBC) lysis buffer. For human BM, resuspend the whole BM in a 10x volume of 1x Red Blood Cell (RBC) lysis buffer. Incubate for 10 min at room temperature (RT).</li>
	<li>Spin the tube at 350 x g for 5 min at 4 &#176;C. For human BM, repeat step 2.1 and 2.2 before proceeding to step 2.3.</li>
	<li>Carefully aspirate the supernatant and leave the pellet undisrupted. Resuspend the pellet with 1 mL of cold 1x PBS. Filter the pellet into a 15 mL conical tube through a 70 &#956;m cell strainer. The BM cells are now completely isolated into the tube from the muscle and bone debris. Wash the cells by adding 9 mL of cold 1x PBS into the tube.</li>
	<li>Spin the 15 mL tube at 350 x g for 5min at 4 &#176;C.</li>
	<li>Carefully aspirate the supernatant and resuspend the BM cells with 10 mL cold PBS. Take an aliquot of cells for counting. Count cells using a hemocytometer.</li>
	<li>Aliquot 5 x 106 BM cells into a new 15 mL tube for CyTOF staining.</li>
	<li>Spin the 15 mL tube aliquot at 350 x g for 5 min at 4 &#176;C.</li>
	<li>Carefully aspirate the supernatant and resuspend the BM cells with 125 nM Cisplatin in 1 mL of CyTOF Staining Buffer as a viability indicator for the sample. Incubate for 5 min at RT.</li>
	<li>After incubation, add 4 mL of CyTOF staining buffer to the tube. Spin the tube at 350 x g for 5 min at 4 &#176;C. For human BM, add 10% human AB serum into the CyTOF staining buffer.</li>
	<li>Carefully aspirate the supernatant and resuspend the BM cells with 50 &#181;L of Fc Receptor blocking solution. Incubate for 10 min at 4 &#176;C. Skip this step for human BM.</li>
	<li>Add 50 &#181;L of the homemade CyTOF antibody cocktail5 to the sample so the total staining volume is 100 &#956;L. Gently pipette to mix. Incubate for 30 min at 4 &#176;C. The final volume of the antibody cocktail is 100 &#956;L for both mouse BM and human BM samples.</li>
	<li>Add 2 mL of CyTOF staining buffer to each tube following the incubation to wash the cells, spin the tube at 350 x g for 5 min at 4 &#176;C.</li>
	<li>Repeat step 2.12 for a total of two washes.</li>
	<li>Prepare a fresh 1.6% formaldehyde solution from the 16% stock ampule. Dilute 1 part of the stock formaldehyde with 9 parts of 1x PBS.</li>
	<li>Carefully aspirate the supernatant and resuspend the pellet with 1 mL fresh 1.6% FA solution. Incubate for 15 min at RT.</li>
	<li>Spin the tube at 800 x g for 5 min at 4 &#176;C.</li>
	<li>Carefully aspirate the supernatant and resuspend the cell pellet with 125 nM intercalation solution in 1 mL fix/perm buffer.</li>
	<li>Incubate the sample in intercalation solution overnight at 4 &#176;C.</li>
</ol>
3. Prepare Cells for CyTOF Acquisition
<ol>
	<li>Gently vortex and spin cells at 800 x g for 5 min at 4 &#176;C.</li>
	<li>Wash cells by adding 2 mL of CyTOF staining buffer, spin cells at 800 x g for 5 min at 4 &#176;C and remove the supernatant by aspiration.</li>
	<li>Resuspend cells in 1 mL of diH2O. Reserve a small volume (approximately 10 &#181;L) from each tube to count cells.</li>
	<li>Spin cells at 800 x g for 5 min at 4 &#176;C.</li>
	<li>Repeat step 3.3 and 3.4.</li>
	<li>Carefully aspirate the supernatant and leave the cells in the pellet. The BM cells are now ready for resuspension to the concentration of 1 x 106 cells/mL for CyTOF acquisition.</li>
</ol>

<ol>
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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospective+isolation+of+human+clonogenic+common+myeloid+progenitors.">Prospective isolation of human clonogenic common myeloid progenitors.</a> Proceedings of the National Academy of Sciences. 99, 11872-11877 (2002).</li><li>Becher, 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=High-dimensional+analysis+of+the+murine+myeloid+cell+system.">High-dimensional analysis of the murine myeloid cell system.</a> Nature Immunology. 15, 1181-1189 (2014).</li><li>Bendall, S. C., 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=Single-cell+mass+cytometry+of+differential+immune+and+drug+responses+across+a+human+hematopoietic+continuum.">Single-cell mass cytometry of differential immune and drug responses across a human hematopoietic continuum.</a> Science. 332, 687-696 (2011).</li><li>Samusik, N., Good, Z., Spitzer, M. H., Davis, K. L., Nolan, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+mapping+of+phenotype+space+with+single-cell+data.">Automated mapping of phenotype space with single-cell data.</a> Nature Methods. 13, 493-496 (2016).</li><li>Zhu, Y. P., 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=Identification+of+an+Early+Unipotent+Neutrophil+Progenitor+with+Pro-tumoral+Activity+in+Mouse+and+Human+Bone+Marrow.">Identification of an Early Unipotent Neutrophil Progenitor with Pro-tumoral Activity in Mouse and Human Bone Marrow.</a> Cell Reports. 24, 2329-2341 (2018).</li><li>Van der Maaten, L. J. P., Hinton, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+High-Dimensional+Data+Using+t-SNE.">Visualizing High-Dimensional Data Using t-SNE.</a> Journal of Machine Learning Research. 9, 2579-2605 (2008).</li><li>Amir, E. A. D., 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=viSNE+enables+visualization+of+high+dimensional+single-cell+data+and+reveals+phenotypic+heterogeneity+of+leukemia.">viSNE enables visualization of high dimensional single-cell data and reveals phenotypic heterogeneity of leukemia.</a> Nature Biotechnology. 31, 545-552 (2013).</li><li>van der Maaten, L., Hinton, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+data+using+t-SNE.">Visualizing data using t-SNE.</a> Journal of Machine Learning Research. 9 (85), 2579-2065 (2008).</li><li>Cloos, 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=Comprehensive+Protocol+to+Sample+and+Process+Bone+Marrow+for+Measuring+Measurable+Residual+Disease+and+Leukemic+Stem+Cells+in+Acute+Myeloid+Leukemia.">Comprehensive Protocol to Sample and Process Bone Marrow for Measuring Measurable Residual Disease and Leukemic Stem Cells in Acute Myeloid Leukemia.</a> Journal of Visualized Experiment. 133, 56386 (2018).</li><li>Bendall, S. C., Nolan, G. P., Roederer, M., Chattopadhyay, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+deep+profiler&#8217;s+guide+to+cytometry.">A deep profiler&#8217;s guide to cytometry.</a> Trends in Immunology. 33, 323-332 (2012).</li><li>Ley, K., 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=Neutrophils:+New+insights+and+open+questions.">Neutrophils: New insights and open questions.</a> Science Immunology. 3 (30), 4579 (2018).</li><li>Ng, L. G., Ostuni, R., Hidalgo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneity+of+neutrophils.">Heterogeneity of neutrophils.</a> Nature Reviews in Immunology. , (2019).</li></ol>

The authors have nothing to disclose.

In past decades, fluorescence-based flow cytometry was used as the main method to study cellular lineages and heterogeneity1,2,3. Although flow cytometry has provided multi-dimensional data, this method is limited by choices of parameters and spectral overlap. To overcome the weakness of flow cytometry we took advantage of CyTOF, which uses heavy metal isotopes instead of fluorophores to label antibodies that eliminates crosstal...

In the past few decades, cytometry methods have been a powerful tool to investigate the hematopoietic system in the BM. These methods include fluorescence-activated flow cytometry and the new method of CyTOF using heavy metal-labeled antibodies. They have led to discoveries of many cell types in a heterogeneous biological specimen by identification of their unique surface marker expression profiles. Increased spectrum overlaps that&#8217;s associated with more channels leads to higher data inaccuracy in fluorescence-activated flow cytometry applications. Therefore, unwanted cells are routinely removed in order to enrich cell populations of interest for fluorescence-activated flow cytometry analysis. For example, Ly6G (or Gr-1) and CD11b are considered mature myeloid cell markers and Ly6G+ (or Gr-1+) and CD11b+ cells are routinely removed from BM samples by using magnetic enrichment kits prior to flow cytometry analysis of hematopoietic stem and progenitor cells (HSPCs) or by combining these markers in one dump cocktail channel1,2,3. Another example is that neutrophils are routinely removed from human blood specimen to enrich peripheral blood mononuclear cells (PBMC) for immunological studies. Whole bone marrow isolated from mouse or human, however, is rarely investigated intact for cytometry analysis.
Recently, CyTOF has become a revolutionary tool to investigate the hematopoietic system4,5,6. With CyTOF, the fluorophore-labeled antibodies are replaced by heavy element reporter-labeled antibodies. This method allows for the measurement of over 40 markers simultaneously without the concern of spectrum overlap. It has enabled the analysis of intact biological specimen without pre-depletion steps or a dump channel. Therefore, we can view the hematopoietic system comprehensively with high-content dimensionality from conventional 2-D flow cytometry plots. Cell populations omitted in the past during depletion or gating process can now be brought into light with the high-dimensional data generated by CyTOF4,5. We have designed an antibody panel that simultaneously measures 39 parameters in the hematopoietic system with a focus on the myeloid linage7. Compared to the conventional flow cytometry data, the interpretation and visualization of the unprecedented single-cell high-dimensional data generated by CyTOF is challenging. Computational scientists have developed dimensionality reduction techniques for the visualization of high-dimensional datasets. In this article, we used the algorithm, viSNE, which uses t-Distributed Stochastic Neighbor Embedding (t-SNE) technique to analyze the CyTOF data and to present the high-dimensional result on a 2-dimensional map while conserving the high-dimensional structure of the data8,9,10. On the tSNE plot, similar cells are clustered into subsets and the color is used to highlight the feature of the cells. For example, on Figure 1 the myeloid cells are distributed into several cell subsets based on the similarities of their expression patterns of 33 surface markers resulted from CyTOF (Figure 1)4. Here we investigated mouse bone marrow with our previously reported 39-marker CyTOF panel by viSNE analysis7. viSNE analysis of our CyTOF data revealed an unidentified cell population that showed both HSPC (CD117+) and neutrophil (Ly6G+) characteristics (Figure 2)7.
In conclusion, we present a protocol to process fresh whole bone marrow for CyTOF analysis. In this article, we used mouse bone marrow as an example, while this protocol can also be used to process human bone marrow samples. The details specific to human bone marrow samples are also noted in the protocol as well. The advantage of this protocol is that it contains details such as incubation time and temperature that were optimized to preserve neutrophil-lineage cells in the whole bone marrow to enable investigation on the intact whole bone marrow. This protocol may also be easily modified for fluorescence-activated flow cytometry applications.

<table>
	<tbody>
		<tr>
			<td>CyTOF Antibodies (mouse)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD45 (Clone 30-F11) -89Y</td>
			<td>Fluidigm</td>
			<td>Cat# 3089005B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Human/Mouse CD45R/B220 (Clone RA36B2)-176Yb</td>
			<td>Fluidigm</td>
			<td>Cat# 3176002B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD105 (Clone MJ7/18)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 120402; RRID:AB_961070</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD115 (CSF-1R) (Clone AFS98)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 135502; RRID:AB_1937293</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD117/c-kit (Clone 2B8)-166Er</td>
			<td>Fluidigm</td>
			<td>Cat# 3166004B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD11a (Clone M17/4)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 101101; RRID:AB_312774</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD11b (Clone M1/70)-148Nd</td>
			<td>Fluidigm</td>
			<td>Cat# 3148003B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD11c (Clone N418)-142Nd</td>
			<td>Fluidigm</td>
			<td>Cat# 3142003B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD127 (IL-7R&#945;) (Clone A7R34)-MaxPar Ready</td>
			<td>Biolegend</td>
			<td>Cat# 133919; RRID:AB_2565433</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD150 (Clone TC1512F12.2)-167Er</td>
			<td>Fluidigm</td>
			<td>Cat# 3167004B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD16.2 (Fc&#947;RIV) (Clone 9E9)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 149502; RRID:AB_2565302</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD162 (Clone 4RA10 (RUO))-Purified</td>
			<td>BD Biosciences</td>
			<td>Cat# 557787; RRID:AB_647340</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD169 (Siglec-1) (Clone 3D6.112)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 142402; RRID:AB_10916523</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD182 (CXCR2) (Clone SA044G4)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 149302; RRID:AB_2565277</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD183 (Clone CXCR3-173)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 126502; RRID:AB_1027635</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD335 (NKp46) (Clone 29A1.4)-MaxPar Ready</td>
			<td>Biolegend</td>
			<td>Cat# 137625; RRID:AB_2563744</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD34 (Clone MEC14.7)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 119302; RRID:AB_345280</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD41 (Clone MWReg30)-MaxPar Ready</td>
			<td>Biolegend</td>
			<td>Cat# 133919; RRID:AB_2565433</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD43 (Clone S11)-146Nd</td>
			<td>Fluidigm</td>
			<td>Cat# 3146009B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD48 (Clone HM48.1)-156Gd</td>
			<td>Fluidigm</td>
			<td>Cat# 3156012B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD62L (Clone MEL-14)-MaxPar Ready</td>
			<td>ThermoFisher</td>
			<td>Cat# 14-1351-82; RRID:AB_467481</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD71 (Clone RI7217)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 113802; RRID:AB_313563</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse CD90 (Clone G7)-Purified</td>
			<td>Biolegend</td>
			<td>Cat# 105202; RRID:AB_313169</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse F4/80 (Clone BM8)-159Tb</td>
			<td>Fluidigm</td>
			<td>Cat# 3159009B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse Fc&#949;RI&#945; (Clone MAR-1)-MaxPar Ready</td>
			<td>Biolegend</td>
			<td>Cat# 134321; RRID:AB_2563768</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse GM-CSF (MP1-22E9 (RUO))-Purified</td>
			<td>BD Biosciences</td>
			<td>Cat# 554404; RRID:AB_395370</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse I-A/I-E (Clone M5/114.15.2)-174Yb</td>
			<td>Fluidigm</td>
			<td>Cat# 3174003B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse Ki67 (Clone B56 (RUO))-Purified</td>
			<td>BD Biosciences</td>
			<td>Cat# 556003; RRID:AB_396287</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse Ly-6A/E (Sca-1) (Clone D7)-169Tm</td>
			<td>Fluidigm</td>
			<td>Cat# 3169015B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse Ly6B (Clone 7/4)-Purified</td>
			<td>abcam</td>
			<td>Cat# ab53457; RRID:AB_881409</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse Ly-6G (Clone 1A8)-MaxPar Ready</td>
			<td>Biolegend</td>
			<td>Cat# 127637; RRID:AB_2563784</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse NK1.1 (Clone PK136)-165Ho</td>
			<td>Fluidigm</td>
			<td>Cat# 3165018B</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse Siglec-F (Clone E50-2440 (RUO))-Purified</td>
			<td>BD Biosciences</td>
			<td>Cat# 552125; RRID:AB_394340</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse TCR&#946; (Clone H57-597)-143Nd</td>
			<td>Fluidigm</td>
			<td>(Clone H57-597)-143Nd</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse TER-119/Erythroid Cells (Clone TER-119)-MaxPar Ready</td>
			<td>Biolegend</td>
			<td>Cat# 116241; RRID:AB_2563789</td>
			<td></td>
		</tr>
		<tr>
			<td>Chemicals, Peptides and Recombinant Proteins </td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody Stabilizer</td>
			<td>CANDOR Bioscience</td>
			<td>Cat# 130050</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma-Aldrich</td>
			<td>Cat# A4503</td>
			<td></td>
		</tr>
		<tr>
			<td>Cisplatin-194Pt</td>
			<td>Fluidigm</td>
			<td>Cat# 201194</td>
			<td></td>
		</tr>
		<tr>
			<td>eBioscience 1X RBC Lysis Buffer</td>
			<td>ThermoFisher</td>
			<td>Cat# 00-4333-57</td>
			<td></td>
		</tr>
		<tr>
			<td>eBioscience Foxp3 / Transcription Factor Staining Buffer Set</td>
			<td>ThermoFisher</td>
			<td>Cat# 00-4333-57</td>
			<td></td>
		</tr>
		<tr>
			<td>EQ Four Element Calibration Beads</td>
			<td>Fluidigm</td>
			<td>Cat# 201078</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid (EDTA)</td>
			<td>ThermoFisher</td>
			<td>Cat# AM9260G</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Omega Scientific</td>
			<td>Cat# FB-02</td>
			<td></td>
		</tr>
		<tr>
			<td>HyClone Phosphate Buffered Saline solution</td>
			<td>GE Lifesciences</td>
			<td>Cat#SH30256.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Intercalator-Ir</td>
			<td>Fluidigm</td>
			<td>Cat# 201192B</td>
			<td></td>
		</tr>
		<tr>
			<td>MAXPAR Antibody Labeling Kits</td>
			<td>Fluidigm</td>
			<td>http://www.dvssciences.com/product-catalog-maxpar.php</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>Cat# 158127</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma-Aldrich</td>
			<td>Cat# S2002</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton&#160;X-100</td>
			<td>Sigma-Aldrich</td>
			<td>Cat# X100</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin EDTA 1X</td>
			<td>Corning</td>
			<td>Cat# 25-053-Cl</td>
			<td></td>
		</tr>
		<tr>
			<td>Experimental Model: Organism/Strains</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse: C57BL/6J</td>
			<td>The Jackson Laboratory</td>
			<td>Stock No: 000664</td>
			<td></td>
		</tr>
		<tr>
			<td>Software Alogrithm</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bead-based Normalizer</td>
			<td>Finck et al., 2013</td>
			<td>https://med.virginia.edu/flow-cytometry-facility/wp-content/uploads/sites/170/2015/10/3_Finck-Rachel_CUGM_May2013.pdf</td>
			<td></td>
		</tr>
		<tr>
			<td>Cytobank</td>
			<td>Cytobank</td>
			<td>https://www.cytobank.org/</td>
			<td></td>
		</tr>
		<tr>
			<td>Cytofkit v1.r.0</td>
			<td>Chen et al., 2016</td>
			<td>https://bioconductor.org/packages/release/bioc/html/cytofkit.html</td>
			<td></td>
		</tr>
		<tr>
			<td>t-SNE</td>
			<td>van der Maaten and Hinton, 2008</td>
			<td>https://cran.r-project.org/web/packages/Rtsne/index.html</td>
			<td></td>
		</tr>
		<tr>
		</tr>
	</tbody>
</table>

preparation of whole bone marrow for mass cytometry analysis of neutrophil-lineage cells

In this article, we present a protocol that is optimized to preserve neutrophil-lineage cells in fresh BM for whole BM CyTOF analysis. We utilized a myeloid-biased 39-antibody CyTOF panel to evaluate the hematopoietic system with a focus on the neutrophil-lineage cells by using this protocol. The CyTOF result was analyzed with an open-resource dimensional reduction algorithm, viSNE, and the data was presented to demonstrate the outcome of this protocol. We have discovered new neutrophil-lineage cell populations based on this protocol. This protocol of fresh whole BM preparation may be used for 1), CyTOF analysis to discover unidentified cell populations from whole BM, 2), investigating whole BM defects for patients with blood disorders such as leukemia, 3), assisting optimization of fluorescence-activated flow cytometry protocols that utilize fresh whole BM.

Figure 1 is presented as an example result from CyTOF experiments. On this tSNE plot the cells across multiple mouse tissues were clustered into subsets based on the similarity of their surface marker expression profiles measured by a 33-parameter CyTOF panel. Cells with more similar properties were automatically clustered together such as the neutrophils, macrophages, or the DCs based on the expression of the 33 markers on each cell.
Figure 2...

Watch this Scientific Journal Video about Preparation of Whole Bone Marrow for Mass Cytometry Analysis of Neutrophil-lineage Cells at JoVE.com

Preparation of Whole Bone Marrow for Mass Cytometry Analysis of Neutrophil-lineage Cells

Here, we present a protocol to process fresh bone marrow (BM) isolated from mouse or human for high-dimensional mass cytometry (Cytometry by Time-Of-Flight, CyTOF) analysis of neutrophil-lineage cells.

In this article, we present a protocol that is optimized to preserve neutrophil-lineage cells in fresh BM for whole BM CyTOF analysis. We utilized a ...

preparation-whole-bone-marrow-for-mass-cytometry-analysis-neutrophil

Research

JoVE Journal

Immunology and Infection

9.1K Views.  La Jolla Institute for Immunology. Here, we present a protocol to process fresh bone marrow (BM) isolated from mouse or human for high-dimensional mass cytometry (Cytometry by Time-Of-Flight, CyTOF) analysis of neutrophil-lineage cells.

Video: Preparation of Whole Bone Marrow for Mass Cytometry Analysis of Neutrophil-lineage Cells

Generation and Labeling of Murine Bone Marrow-derived Dendritic Cells with Qdot Nanocrystals for Tracking Studies

Dendritic cells (DCs) are professional antigen presenting cells (APCs) found in peripheral tissues and in immunological organs such as thymus, bone marrow, spleen, lymph nodes and Peyer's patches 1-3. DCs present in peripheral tissues sample the organism for the presence of antigens, which they take up, process and present in their surface in the context of major histocompatibility molecules (MHC). Then, antigen-loaded DCs migrate to immunological organs where they present the processed antigen to T lymphocytes triggering specific immune responses. One way to evaluate the migratory capabilities of DCs is to label them with fluorescent dyes 4.
Herewith we demonstrate the use of Qdot fluorescent nanocrystals to label murine bone marrow-derived DC. The advantage of this labeling is that Qdot nanocrystals possess stable and long lasting fluorescence that make them ideal for detecting labeled cells in recovered tissues. To accomplish this, first cells will be recovered from murine bone marrows and cultured for 8 days in the presence of granulocyte macrophage-colony stimulating factor in order to induce DC differentiation. These cells will be then labeled with fluorescent Qdots by short in vitro incubation. Stained cells can be visualized with a fluorescent microscopy. Cells can be injected into experimental animals at this point or can be into mature cells upon in vitro incubation with inflammatory stimuli. In our hands, DC maturation did not determine loss of fluorescent signal nor does Qdot staining affect the biological properties of DCs. Upon injection, these cells can be identified in immune organs by fluorescent microscopy following typical dissection and fixation procedures.

Dendritic cells uptake antigens and migrate towards immune organs to present processed antigens to T cells. Qdot nanocrystal labeling provides a long-lasting and stable fluorescent signal. This allows tracking of dendritic cells to different organs by fluorescent microscopy.

Dendritic cells (DCs) are professional antigen presenting cells (APCs) found in peripheral tissues and in immunological organs such as thymus, bone ...

Flow Cytometry Analysis of Immune Cells Within Murine Aortas

Atherosclerosis is a chronic inflammatory process of medium and large size vessels that is characterized by the formation of plaques consisting of foam cells, immune cells, vascular endothelial and smooth muscle cells, platelets, extracellular matrix, and a lipid-rich core with extensive necrosis and fibrosis of surrounding tissues.1 The innate and adaptive arms of the immune response are involved in the initiation, development and persistence of atherosclerosis.2, 3 There is a significant body of evidence that different subsets of the immune cells, such as macrophages, dendritic cells, T and B lymphocytes, are present within the aortas of healthy and atherosclerosis-prone mice4. Additionally, immune cells are found in the surrounding aortic adventitia which suggests an important role of this tissue in atherogenesis.2
For some time, the quantitative detection of different types of immune cells, their activation status, and the cellular composition within the aortic wall was limited by RT-PCR and immunohistochemical methods for the study of atherosclerosis. Few attempts were made to perform flow cytometry using human aortas, and a number of problems, such as a high autofluorescence, have been reported5,6. Human atherosclerotic plaques were digested with collagenase 1, and free cells were collected and stained for CD14+/CD11c+ to highlight macrophage-derived foam cells. In this study, a "mock" channel was used to avoid false-positive staining.6 Necrotic materials accumulating during the digestion process give rise in a large amount of debris that generates a high autofluorescence in aortic samples. To resolve this problem, a panel of negative and positive controls has been proposed, but only double staining could be applied in these samples. We have developed a new flow cytometry-based method7 to analyze the immune cell composition and characterize the activation, proliferation, differentiation of immune cells in healthy and atherosclerosis-prone aorta. This method allows the investigation of the immune cell composition of the aortic wall and opens possibilities to use a broad spectrum of immunological methods for investigations of immune aspects of this disease.

This paper presents a flow cytometry-based method to investigate the immune composition of aortas. The paper also illustrates an additional technique that allows examining surrounding adventitia and vessel wall separately. This method opens possibilities to perform phenotypical analyses of aortic leukocytes and apply several immunological assays for atherosclerosis studies.

Atherosclerosis is a chronic inflammatory process of medium and large size vessels that is characterized by the formation of plaques consisting of foam ...

Bone Marrow-derived Macrophage Production

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because of their powerful microbicidal activities. Macrophages are widely distributed throughout the body and are present in the lymphoid organs, liver, lungs, gastrointestinal tract, central nervous system, bone, and skin. Because of their repartition, they participate in a wide range of physiological and pathological processes. Macrophages are highly versatile cells that are able to recognize microenvironmental alterations and to maintain tissue homeostasis. Numerous pathogens have evolved mechanisms to use macrophages as Trojan horses to survive, replicate in, and infect both humans and animals and to propagate throughout the body. The recent explosion of interest in evolutionary, genetic, and biochemical aspects of host-pathogen interactions has renewed scientific attention regarding macrophages. Here, we describe a procedure to isolate and cultivate macrophages from murine bone marrow that will provide large numbers of macrophages for studying host-pathogen interactions as well as other processes.

Macrophages have long been recognized as a critical component of the innate and adaptive immune responses. The recent explosion of knowledge pertaining to evolutionary, genetic, and biochemical aspects of the interaction between macrophages and microbes has renewed scientific attention to macrophages. This article describes a method to differentiate macrophages from mouse bone marrow.

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because ...

Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow.
Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%&#177; 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%&#177; 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection. 
This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

Here we present a protocol that generates large amounts of murine monocytes from heterogeneous bone marrow for translational applications. In comparison to others, this new method helps reduce the number of sacrificed animals and lowers costs by avoiding expensive methods such as high gradient magnetic cell separation (MACS).

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of ...

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 ...

Single-cell Analysis of Immunophenotype and Cytokine Production in Peripheral Whole Blood via Mass Cytometry

Cytokines play a pivotal role in the pathogenesis of autoimmune diseases. Hence, the measurement of cytokine levels has been the focus of multiple studies in an attempt to understand the precise mechanisms that lead to the breakdown of self-tolerance and subsequent autoimmunity. Approaches thus far have been based on the study of one specific aspect of the immune system (a single or few cell types or cytokines), and do not offer a global assessment of complex autoimmune disease. While patient sera-based studies have afforded important insights into autoimmunity, they do not provide the specific cellular source of the dysregulated cytokines detected. A comprehensive single-cell approach to evaluate cytokine production in multiple immune cell subsets, within the context of &#34;intrinsic&#34; patient-specific plasma circulating factors, is described here. This approach enables monitoring of the patient-specific immune phenotype (surface markers) and function (cytokines), either in its native &#34;intrinsic pathogenic&#34; disease state, or in the presence of therapeutic agents (in vivo or ex vivo).

Here we describe a single-cell proteomic approach to evaluate immune phenotypic and functional (intracellular cytokine induction) alterations in peripheral whole blood samples, analyzed via mass cytometry.

Cytokines play a pivotal role in the pathogenesis of autoimmune diseases. Hence, the measurement of cytokine levels has been the focus of multiple studies ...

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 ...

Isolation of Lamina Propria Mononuclear Cells from Murine Colon Using Collagenase E

The intestine is the home to the largest number of immune cells in the body. The small and large intestinal immune systems police exposure to exogenous antigens and modulate responses to potent microbially derived immune stimuli. For this reason, the intestine is a major target site of immune dysregulation and inflammation in many diseases including but, not limited to inflammatory bowel diseases such as Crohn&#8217;s disease and ulcerative colitis, graft-versus-host disease (GVHD) after bone marrow transplantation (BMT), and many allergic and infectious conditions. Murine models of gastrointestinal inflammation and colitis are heavily used to study GI complications and to pre-clinically optimize strategies for prevention and treatment. Data gleaned from these models via isolation and phenotypic analysis of immune cells from the intestine is critical to further immune understanding that can be applied to ameliorate gastrointestinal and systemic inflammatory disorders. This report describes a highly effective protocol for the isolation of mononuclear cells (MNC) from the colon using a mixed silica-based density gradient interface. This method reproducibly isolates a significant number of viable leukocytes while minimizing contaminating debris, allowing subsequent immune phenotyping by flow cytometry or other methods.

The goal of this protocol is to isolate mononuclear cells that reside in the lamina propria of the colon by enzymatic digestion of the tissue using collagenase. This protocol allows for the efficient isolation of mononuclear cells resulting in a single cell suspension which in turn can be used for robust immunophenotyping.

The intestine is the home to the largest number of immune cells in the body. The small and large intestinal immune systems police exposure to exogenous ...

Economical and Efficient Protocol for Isolating and Culturing Bone Marrow-derived Dendritic Cells from Mice

The demand for dendritic cells (DCs) is gradually increasing as immunology research advances. However, DCs are rare in all tissues. The traditional method for isolating DCs primarily involves inducing bone marrow (BM) differentiation into DCs by injecting large doses (&#62;10 ng/mL) of granulocyte-macrophage colony-stimulating factor/interleukin-4 (GM-CSF/IL-4), making the procedure complex and expensive. In this protocol, using all BM cells cultured in 10 ng/mL GM-CSF/IL-4 medium, after 3-4 half-culture exchanges, up to 2.7 x 107 CD11c+ cells&#160;(DCs) per mouse (two femurs) were harvested with a purity of 80%-95%. After 10 days in culture, the expression of CD11c, CD80, and MHC II increased, whereas the number of cells decreased. The number of cells peaked after 7 days of culture. Moreover, this method only took 10 min to harvest all bone marrow cells, and a high number of DCs were obtained after 1 week of culture.

Here, we present an economical and efficient method to isolate and generate high-purity bone marrow-derived dendritic cells from mice after 7 days of culture with 10 ng/mL GM-CSF/IL-4.

The demand for dendritic cells (DCs) is gradually increasing as immunology research advances. However, DCs are rare in all tissues. The traditional method ...

Phagocytic Assay Evaluation of Neonatal Bone Marrow Derived Macrophages 

Neonatal Mouse Bone Marrow Isolation and Preparation of Bone Marrow-Derived Macrophages

Various techniques for isolating bone marrow from adult mice have been well established. However, isolating bone marrow from neonatal mice is challenging and time-consuming, yet for some models, it is translationally relevant and necessary. This protocol describes an efficient and straightforward method for preparing bone marrow cells from 7-9-day-old pups. These cells can then be further isolated or differentiated into specific cell types of interest. Macrophages are crucial immune cells that play a major role in inflammation and infection. During development, neonatal macrophages contribute significantly to tissue remodeling. Moreover, the phenotype and functions of neonatal macrophages differ from those of their adult counterparts. This protocol also outlines the differentiation of neonatal macrophages from the isolated bone marrow cells in the presence of L929-conditioned medium. Surface markers for differentiated neonatal macrophages were assessed using flow cytometric analysis. To demonstrate functionality, the phagocytic efficiency was also tested using pH-sensitive dye-conjugated Escherichia coli.

Author Spotlight: Developing a Reproducible Method for Isolating Bone Marrow-Derived Macrophages from Neonatal Mice to Advance Early Life Immune Responses

This protocol describes a non-enzymatic and straightforward method for isolating 7-9-day-old neonatal mouse bone marrow cells and generating differentiated macrophages using a supernatant of L929 cells as a source of granulocyte colony-stimulating factor (M-CSF). The bone marrow-derived macrophages were further analyzed for surface antigens F4/80, CD206, CD11b, and functional competency.

Various techniques for isolating bone marrow from adult mice have been well established. However, isolating bone marrow from neonatal mice is challenging ...