The Department of Transfusion Medicine, Clinical Center, National Institutes of Health, provided elutriated monocytes. This work was supported by the Intramural Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health.

Leukapheresis was carried out under a human subject&#39;s research protocol approved by a National Institutes of Health institutional review board.
1. Isolation and Cryopreservation of Monocytes
<ol>
	<li>Obtain mononuclear cells by leukapheresis of human donors, and enrich monocytes by continuous counter-flow centrifugation elutriation of mononuclear cells as described in the references 7,8. Obtain approximately 100 x 106 elutriated cells (approximately 80 - 90% monocytes) in elutriation buffer specified by the manufacturer. Count cells using a hemocytometer.</li>
	<li>Centrifuge monocytes in a 15 ml polypropylene tube at 300 x g for 5 min at room temperature.</li>
	<li>Remove the supernatant and gently resuspend the cells in FBS followed by dimethyl sulfoxide to achieve a final concentration of 90% FBS/10% dimethyl sulfoxide and 50 x 106 cells/ml.</li>
	<li>Add each ml of cell suspension to an individual cryovial.</li>
	<li>Place the cryovials in a cell freezing container and transfer to a -80 &#176;C freezer for 24 hr before transferring to a liquid nitrogen cryovial storage tank for long-term storage.</li>
</ol>
2. Differentiation of Monocytes into Macrophages
<ol>
	<li>Thaw a cryovial of cells by quickly transferring to a 37 &#176;C water bath and then immediately removing when the cell suspension has thawed about 70%.</li>
	<li>Immediately upon complete thawing at room temperature, transfer the 1 ml cryovial contents into 50 ml of 37 &#176;C warmed Roswell Park Memorial Institute (RPMI) 1640 medium with 2 mM L-glutamine, 50 ng/ml M-CSF, 25 ng/ml interleukin-10 (IL-10), and 10% FBS (complete medium).</li>
	<li>Transfer 25 ml of monocyte suspension into each of two 75 cm2 plastic cell culture flasks.</li>
	<li>Incubate cultures in a 37 &#176;C cell culture incubator with 5% CO2 / 95% air for 48 hr.</li>
	<li>Rinse the cultures 3 times with 10 ml RPMI 1640 medium (pre-warmed to 37 &#176;C), gently removing the culture medium to avoid dislodging any loosely attached cells.</li>
	<li>Following rinsing, add fresh complete medium, changing medium every 2 days until monocytes differentiate and proliferate sufficiently to become confluent. This requires about one week of culture.</li>
</ol>
3. Harvesting Macrophages to Initiate Experiments
<ol>
	<li>Rinse differentiated macrophages in flask 3 times with 10 ml pre-warmed 37 &#176;C Dulbecco&#39;s phosphate-buffered saline without Ca2+ and Mg2+ before adding 10 ml&#160;pre-warmed 37 &#176;C 0.25% trypsin-ethylenediaminetetraacetic acid (EDTA) solution.</li>
	<li>Place flask in cell culture incubator for 10 - 15 min at which time approximately 90% of the macrophages should have rounded and detached. Verify this by microscopic examination of the flask.</li>
	<li>Add 10 ml of RMPI 1640 medium containing 10% FBS to stop trypsinization.</li>
	<li>Transfer the macrophage cell suspension from the flask into a 50 ml polypropylene tube, centrifuge 300 x g for 5 min, and discard the supernatant.</li>
	<li>Gently resuspend the macrophages into 1 ml of complete medium.</li>
	<li>Mix 10 &#181;l of macrophage cell suspension with 10 &#181;l Trypan Blue solution and determine macrophage cell number and viability (typically &#62; 95%) using a hemocytometer.</li>
	<li>Based on the cell count (usually about 15 - 18 x 105 macrophages), add additional complete medium to achieve the desired seeding cell density. Note: 1 x 105 macrophages in 1.5 ml medium per well of a 12-well plate will produce a near-confluent culture.</li>
	<li>Following seeding, incubate macrophages overnight in a 37 &#176;C cell culture incubator with 5% CO2 / 95% air to allow cell attachment. Then, begin desired experiments.</li>
</ol>

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	<li>Dey, A., Allen, J., Hankey-Giblin, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ontogeny+and+polarization+of+macrophages+in+inflammation:+blood+monocytes+versus+tissue+macrophages.">Ontogeny and polarization of macrophages in inflammation: blood monocytes versus tissue macrophages.</a> Front. Immunol. 5, 683 (2014).</li><li>Waldo, S. W., 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=Heterogeneity+of+human+macrophages+in+culture+and+in+atherosclerotic+plaques.">Heterogeneity of human macrophages in culture and in atherosclerotic plaques.</a> Am. J. Pathol. 172, 1112-1126 (2008).</li><li>Akagawa, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+heterogeneity+of+colony-stimulating+factor-induced+human+monocyte-derived+macrophages.">Functional heterogeneity of colony-stimulating factor-induced human monocyte-derived macrophages.</a> Int. J. Hematol. 76, 27-34 (2002).</li><li>Akagawa, K. S., 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=Functional+heterogeneity+of+colony-stimulating+factor-induced+human+monocyte-derived+macrophages.">Functional heterogeneity of colony-stimulating factor-induced human monocyte-derived macrophages.</a> Respirology. 11 Suppl, S32-S36 (2006).</li><li>Fleetwood, A. J., Lawrence, T., Hamilton, J. A., Cook, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Granulocyte-macrophage+colony-stimulating+factor+(CSF)+and+macrophage+CSF-dependent+macrophage+phenotypes+display+differences+in+cytokine+profiles+and+transcription+factor+activities:+implications+for+CSF+blockade+in+inflammation.">Granulocyte-macrophage colony-stimulating factor (CSF) and macrophage CSF-dependent macrophage phenotypes display differences in cytokine profiles and transcription factor activities: implications for CSF blockade in inflammation.</a> J. Immunol. 178, 5245-5252 (2007).</li><li>Lacey, D. 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=Defining+GM-CSF-+and+macrophage-CSF-dependent+macrophage+responses+by+in+vitro+models.">Defining GM-CSF- and macrophage-CSF-dependent macrophage responses by in vitro models.</a> J. Immunol. 188, 5752-5765 (2012).</li><li>Strasser, E. F., Eckstein, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+leukocyte+collection+and+monocyte+isolation+for+dendritic+cell+culture.">Optimization of leukocyte collection and monocyte isolation for dendritic cell culture.</a> Transfus. Med. Rev. 24, 130-139 (2010).</li><li>Kim, S., 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=Monocyte+enrichment+from+leukapheresis+products+by+using+the+Elutra+cell+separator.">Monocyte enrichment from leukapheresis products by using the Elutra cell separator.</a> Transfusion (Paris). 47, 2290-2296 (2007).</li><li>Strober, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trypan+blue+exclusion+test+of+cell+viability.">Trypan blue exclusion test of cell viability.</a> Curr. Protoc. Immunol. Appendix 3 (Appendix 3B), (2001).</li><li>Anzinger, J. 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=Native+low-density+lipoprotein+uptake+by+macrophage+colony-stimulating+factor-differentiated+human+macrophages+is+mediated+by+macropinocytosis+and+micropinocytosis.">Native low-density lipoprotein uptake by macrophage colony-stimulating factor-differentiated human macrophages is mediated by macropinocytosis and micropinocytosis.</a> Arterioscler. Thromb. Vasc. Biol. 30, 2022-2031 (2010).</li><li>Zhao, 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=Constitutive+receptor-independent+low+density+lipoprotein+uptake+and+cholesterol+accumulation+by+macrophages+differentiated+from+human+monocytes+with+macrophage-colony-stimulating+factor+(M-CSF).">Constitutive receptor-independent low density lipoprotein uptake and cholesterol accumulation by macrophages differentiated from human monocytes with macrophage-colony-stimulating factor (M-CSF).</a> J. Biol. Chem. 281, 15757-15762 (2006).</li><li>Freeman, S. R., 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=ABCG1-mediated+generation+of+extracellular+cholesterol+microdomains.">ABCG1-mediated generation of extracellular cholesterol microdomains.</a> J. Lipid Res. 55, 115-127 (2014).</li><li>Kruth, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Receptor-independent+fluid-phase+pinocytosis+mechanisms+for+induction+of+foam+cell+formation+with+native+low-density+lipoprotein+particles.">Receptor-independent fluid-phase pinocytosis mechanisms for induction of foam cell formation with native low-density lipoprotein particles.</a> Curr. Opin. Lipidol. 22, 386-393 (2011).</li><li>Jin, X., 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=ABCA1+contributes+to+macrophage+deposition+of+extracellular+cholesterol.">ABCA1 contributes to macrophage deposition of extracellular cholesterol.</a> J. Lipid Res. 56, 1720-1726 (2015).</li><li>Ong, D. 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I., Komuro, I., Yamada, M., Akagawa, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IL-10+inhibits+granulocyte-macrophage+colony-stimulating+factor-dependent+human+monocyte+survival+at+the+early+stage+of+the+culture+and+inhibits+the+generation+of+macrophages.">IL-10 inhibits granulocyte-macrophage colony-stimulating factor-dependent human monocyte survival at the early stage of the culture and inhibits the generation of macrophages.</a> J. Immunol. 167, 3619-3625 (2001).</li><li>Lund, P. K., Joo, G. B., Westvik, A. B., Ovstebo, R., Kierulf, P. <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+monocytes+from+whole+blood+by+density+gradient+centrifugation+and+counter-current+elutriation+followed+by+cryopreservation:+six+years'+experience.">Isolation of monocytes from whole blood by density gradient centrifugation and counter-current elutriation followed by cryopreservation: six years' experience.</a> Scand. J. Clin. Lab. Invest. 60, 357-365 (2000).</li><li>Weiner, R. S., Normann, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+integrity+of+cryopreserved+human+monocytes.">Functional integrity of cryopreserved human monocytes.</a> J. Natl. Cancer Inst. 66, 255-260 (1981).</li><li>Hansen, J. 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=Retention+of+phagocytic+functions+in+cryopreserved+human+monocytes.">Retention of phagocytic functions in cryopreserved human monocytes.</a> J. Leukoc. Biol. 57, 235-241 (1995).</li><li>Seager Danciger, 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=Method+for+large+scale+isolation,+culture+and+cryopreservation+of+human+monocytes+suitable+for+chemotaxis,+cellular+adhesion+assays,+macrophage+and+dendritic+cell+differentiation.">Method for large scale isolation, culture and cryopreservation of human monocytes suitable for chemotaxis, cellular adhesion assays, macrophage and dendritic cell differentiation.</a> J. Immunol. Methods. 288, 123-134 (2004).</li><li>Jin, X., Xu, Q., Champion, K., Kruth, H. 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The authors have nothing to disclose.

Generating defined macrophage types can clarify some of the conflicting results obtained by investigators when studying macrophage biology. The use of various culture conditions and differentiation factors to generate primary human macrophages can lead to very different macrophage types, a fact that may not be appreciated by the researcher. For example, macrophages sometimes are generated from human monocytes using no serum, human serum alone, human serum supplemented with M-CSF, FBS alone, or FBS containing M-CSF or GM-...

Study of cultured macrophages is a useful model to understand the function of these cells in inflammation such as occurs in atherosclerotic plaques. When the research focus is on human diseases involving macrophages, it is useful to study primary human macrophages rather than non-human macrophages to avoid species differences. Also, the effects of cell transformation can be avoided by using primary macrophages rather than macrophage cell lines. For this purpose, macrophages differentiated from monocytes isolated from human blood serve as a means of obtaining primary human macrophages. 
Tissue macrophages may be either resident within tissues or may be derived from monocytes that migrate into the tissue and differentiate into macrophages 1. Two types of human monocyte-derived macrophages have been defined that differ not only in morphology but also gene expression and cell function 2. These two types are obtained from monocytes that are differentiated into macrophages in the presence of M-CSF + fetal bovine serum (FBS) and monocytes that are differentiated into macrophages in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) + FBS 2-6. In our experience (unpublished observation), use of human serum rather than FBS generates the GM-CSF type regardless of whether M-CSF or GM-CSF is included in the differentiation medium. M-CSF type macrophages tend to be more elongated than GM-CSF type macrophages, which resemble fried eggs in their morphology. Investigators should recognize that human M-CSF and GM-CSF monocyte-derived macrophages are not the same as so called M1 and M2 mouse bone marrow-derived macrophages 6.
During research using human monocyte-derived M-CSF differentiated macrophages, we experienced difficulty related to the availability of monocytes to initiate experiments and variation in the obtained cell densities of macrophages during differentiation of monocytes into macrophages. To overcome these problems, we have developed the following protocol in which monocytes are frozen until required for use, and monocytes are differentiated in bulk into macrophages that can then be removed from culture flasks and plated at desired cell densities to obtain more uniform cultures from experiment to experiment.

<table border="0" cellpadding="0" cellspacing="0" width="1086">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">Cellbind 12-well culture plate</td>
			<td style="width:319px;">Corning</td>
			<td style="width:173px;">3336</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">CELLSTAR, T-75 flask, tissue culture treated</td>
			<td style="width:319px;">Greiner Bio-One North America</td>
			<td style="width:173px;">658157</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">RPMI 1640 culture medium</td>
			<td style="width:319px;">Cellgro Mediatech</td>
			<td style="width:173px;">15-040-CM</td>
			<td style="width:167px;">warmed to 37 &#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">L-Glutamine</td>
			<td style="width:319px;">Cellgro Mediatech</td>
			<td style="width:173px;">25-005-CI</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">Fetal bovine serum</td>
			<td style="width:319px;">Gibco</td>
			<td style="width:173px;">16000-036</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">M-CSF</td>
			<td style="width:319px;">PeproTech</td>
			<td style="width:173px;">300-25</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">GM-CSF</td>
			<td style="width:319px;">PeproTech</td>
			<td style="width:173px;">300-03</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">IL-10&#160;</td>
			<td style="width:319px;">PeproTech</td>
			<td style="width:173px;">200-10</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">DMSO</td>
			<td style="width:319px;">Sigma</td>
			<td style="width:173px;">D2650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">Cryovial&#160;</td>
			<td style="width:319px;">Thermo Scientific&#160;</td>
			<td style="width:173px;">375418</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:428px;">DPBS without Ca2+ and Mg2+&#160;</td>
			<td style="width:319px;">Corning cellgro</td>
			<td style="width:173px;">21-031-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">0.25% Trypsin-EDTA&#160;</td>
			<td style="width:319px;">Gibco</td>
			<td style="width:173px;">25200-056</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">50 ml polypropylene conical tube</td>
			<td style="width:319px;">Falcon</td>
			<td style="width:173px;">352070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">Trypan Blue</td>
			<td style="width:319px;">Lonza</td>
			<td style="width:173px;">17-942E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">Neubauer-improved bright light hemocytometer&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td style="width:319px;">Paul Marienfeld GmbH &#38; Co. KG</td>
			<td style="width:173px;">610031</td>
			<td>http://www.marienfeld-superior.com/index.php/counting-chambers/articles/counting-chambers.html</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">CoolCell LX cell freezing container</td>
			<td style="width:319px;">BioCision</td>
			<td style="width:173px;">BCS-405</td>
			<td>other freezing containers also should&#160; be adequate for this step</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:428px;">Liquid Nitrogen Storage System, CryoPlus 1</td>
			<td style="width:319px;">Thermo Scientific&#160;</td>
			<td style="width:173px;">7400</td>
			<td>any liquid nitrogen tank should be adequate</td>
		</tr>
	</tbody>
</table>

culture of macrophage colony-stimulating factor differentiated human monocyte-derived macrophages

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation of experiments, fresh or frozen monocytes are cultured in flasks for 1 week with M-CSF to induce their differentiation into macrophages. Then, the macrophages can be harvested and seeded into culture wells at required cell densities for carrying out experiments. The use of defined numbers of macrophages rather than defined numbers of monocytes to initiate macrophage cultures for experiments yields macrophage cultures in which the desired cell density can be more consistently attained. Use of cryopreserved monocytes reduces dependency on donor availability and produces more homogeneous macrophage cultures.

The viability of fresh or cryopreserved monocytes was greater than 95% as determined with Trypan Blue staining 9. Figure 1 and Figure 2 compare at lower and higher magnifications, respectively, the progress of fresh and cryopreserved (i.e., frozen) monocyte differentiation into macrophages. Note that the fresh compared with cryopreserved monocytes show a subpopulation of differentiating monocytes that do not spread but...

Watch this Scientific Journal Video about Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages at JoVE.com

Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. The protocol utilizes cryopreservation of monocytes coupled with their bulk differentiation into macrophages. Then harvested macrophages can then be seeded into culture wells at required cell densities for carrying out experiments.

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation ...

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Immunology and Infection

29.0K Views.  National Institutes of Health. A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. The protocol utilizes cryopreservation of monocytes coupled with their bulk differentiation into macrophages. Then harvested macrophages can then be seeded into culture wells at required cell densities for carrying out experiments.

Video: Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages

An In vitro Co-infection Model to Study Plasmodium falciparum-HIV-1 Interactions in Human Primary Monocyte-derived Immune Cells

Plasmodium falciparum, the causative agent of the deadliest form of malaria, and human immunodeficiency virus type-1 (HIV-1) are among the most important health problems worldwide, being responsible for a total of 4 million deaths annually1. Due to their extensive overlap in developing regions, especially Sub-Saharan Africa, co-infections with malaria and HIV-1 are common, but the interplay between the two diseases is poorly understood. Epidemiological reports have suggested that malarial infection transiently enhances HIV-1 replication and increases HIV-1 viral load in co-infected individuals2,3. Because this viremia stays high for several weeks after treatment with antimalarials, this phenomenon could have an impact on disease progression and transmission.
The cellular immunological mechanisms behind these observations have been studied only scarcely. The few in vitro studies investigating the impact of malaria on HIV-1 have demonstrated that exposure to soluble malarial antigens can increase HIV-1 infection and reactivation in immune cells. However, these studies used whole cell extracts of P. falciparum schizont stage parasites and peripheral blood mononuclear cells (PBMC), making it hard to decipher which malarial component(s) was responsible for the observed effects and what the target host cells were4,5. Recent work has demonstrated that exposure of immature monocyte-derived dendritic cells to the malarial pigment hemozoin increased their ability to transfer HIV-1 to CD4+ T cells6,7, but that it decreased HIV-1 infection of macrophages8. To shed light on this complex process, a systematic analysis of the interactions between the malaria parasite and HIV-1 in different relevant human primary cell populations is critically needed.
Several techniques for investigating the impact of HIV-1 on the phagocytosis of micro-organisms and the effect of such pathogens on HIV-1 replication have been described. We here present a method to investigate the effects of P. falciparum-infected erythrocytes on the replication of HIV-1 in human primary monocyte-derived macrophages. The impact of parasite exposure on HIV-1 transcriptional/translational events is monitored by using single cycle pseudotyped viruses in which a luciferase reporter gene has replaced the Env gene while the effect on the quantity of virus released by the infected macrophages is determined by measuring the HIV-1 capsid protein p24 by ELISA in cell supernatants.

An In vitro Co-infection Model to Study Plasmodium falciparum-HIV-1 Interactions in Human Primary Monocyte-derived Immune Cells

We have developed an in vitro malaria-HIV-1 co-infection model to study the impact of Plasmodium falciparum on the HIV-1 replicative cycle in human primary monocyte-derived macrophages. This versatile system can easily be adapted to other primary cell types susceptible to HIV-1 infection.

Plasmodium falciparum, the causative agent  of the deadliest form of malaria, and human immunodeficiency virus type-1 (HIV-1) are among the most important ...

Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic ...

Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1&#946; in Human Monocyte-derived Dendritic Cells

Inflammatory processes resulting from the secretion of Interleukin (IL)-1 family cytokines by immune cells lead to local or systemic inflammation, tissue remodeling and repair, and virologic control1,2 . Interleukin-1&#946; is an essential element of the innate immune response and contributes to eliminate invading pathogens while preventing the establishment of persistent infection1-5.
Inflammasomes are the key signaling platform for the activation of interleukin 1 converting enzyme (ICE or Caspase-1). The NLRP3 inflammasome requires at least two signals in DCs to cause IL-1&#946; secretion6. Pro-IL-1&#946; protein expression is limited in resting cells; therefore a priming signal is required for IL-1&#946; transcription and protein expression. A second signal sensed by NLRP3 results in the formation of the multi-protein NLRP3 inflammasome. The ability of dendritic cells to respond to the signals required for IL-1&#946; secretion can be tested using a synthetic purine, R848, which is sensed by TLR8 in human monocyte derived dendritic cells&#160;(moDCs) to prime cells, followed by activation of the NLRP3 inflammasome with the bacterial toxin and potassium ionophore, nigericin.
Monocyte derived DCs&#160;are easily produced in culture and provide significantly more cells than purified human myeloid DCs. The method presented here differs from other inflammasome assays in that it uses in vitro human, instead of mouse derived, DCs thus allowing for the study of the inflammasome in human disease and infection.

Dendritic cells (DCs)&#160;secrete IL-1&#946; in response to TLR8 recognition of synthetic purine, R848, followed by NLRP3 inflammasome activation with nigericin, therefore, IL-1&#946; can be used to measure NLRP3 inflammasome activity. Intracellular cytokine staining, immunoblotting, and ELISA are used to accurately measure NLRP3 inflammasome priming and activation via IL-1&#946; expression.

Inflammatory processes resulting from the secretion of Interleukin (IL)-1 family cytokines by immune cells lead to local or systemic inflammation, tissue ...

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 ...

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 ...

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 ...

In Vitro Differentiation of Mouse Granulocyte-macrophage-colony-stimulating Factor (GM-CSF)-producing T Helper (THGM) Cells

The granulocyte-macrophage-colony-stimulating factor (GM-CSF)-producing T helper (THGM) cell is a newly identified T helper cell subset that predominantly secretes GM-CSF without producing interferon (IFN)&#947; or interleukin (IL)-17 and is found to play an essential role in the autoimmune neuroinflammation. A method of isolation of naive CD4+ T cells from a single-cell suspension of splenocytes and THGM cell generation from naive CD4+ T cells would be a useful technique in the study of T cell-mediated immunity and autoimmune diseases. Here we describe a method that differentiates mouse naive CD4+ T cells into THGM cells promoted by IL-7. The outcome of the differentiation was assessed by the analysis of the cytokines expression using different techniques, including intracellular cytokine staining combined with flow cytometry, a quantitative real-time polymerase chain reaction (PCR), and enzyme-linked immunosorbent assays (ELISA). Using the THGM differentiation protocol as described here, about 55% of the cells expressed GM-CSF with a minimal expression of IFN&#945; or IL-17. The predominant expression of GM-CSF by THGM cells was further confirmed by the analysis of the expression of GM-CSF, IFN&#945;, and IL-17 at both mRNA and protein levels. Thus, this method can be used to differentiate naive CD4+ T cells to THGM cells in vitro, which will be useful in the study of THGM cell biology.

In Vitro Differentiation of Mouse Granulocyte-macrophage-colony-stimulating Factor GM-CSF-producing T Helper THGM Cells

Here, we present a protocol to differentiate murine granulocyte-macrophage-colony-stimulating-factor-producing T helper (THGM) cells from naive CD4+ T cells, including isolation of naive CD4+ T cells, differentiation of THGM, and analysis of differentiated THGM cells. This method can be applied to studies of the regulation and function of THGM cells.

The granulocyte-macrophage-colony-stimulating factor (GM-CSF)-producing T helper (THGM) cell is a newly identified T helper cell subset that predominantly ...

Quantification of Monocyte Chemotactic Activity In Vivo and Characterization of Blood Monocyte Derived Macrophages

Tissue homeostasis and repair are critically dependent on the recruitment of monocyte-derived macrophages. Both under- and over-recruitment of monocyte-derived macrophages can impair wound healing. We showed that high fat and high sugar diets promote monocyte priming and dysfunction, converting healthy blood monocytes into a hyper chemotactic phenotype poised to differentiate into macrophages with dysregulated activation profiles and impaired phenotypic plasticity. The over-recruitment of monocyte-derived macrophages and recruitment of macrophages with dysregulated activation profiles is believed to be a major contributor to the development of chronic inflammatory diseases associated with metabolic disorders, including atherosclerosis and obesity. The goal of this protocol is to quantify the chemotactic activity of blood monocytes as a biomarker for monocyte priming and dysfunction and to characterize the macrophage phenotype blood monocytes are poised to differentiate into in these mouse models. Using single cell Western blot analysis, we show that after 24 h 33%of cells recruited into MCP-1-loaded basement membrane-derived gel plugs injected into mice are monocytes and macrophages; 58% after day 3. However, on day 5, monocyte and macrophage numbers were significantly decreased. Finally, we show that this assays also allows for the isolation of live macrophages from the surgically retrieved basement membrane-derived gel plugs, which can then be subjected to subsequent characterization by single cell Western blot analysis.

Here we present a protocol to quantify the chemotactic activity of blood monocytes in mouse models, to assess the effects of nutritional, pharmacological and genetic interventions on blood monocyte and to characterize the blood monocytes derived macrophages in mouse models using monocyte-chemoattractant protein-1 (MCP-1)-loaded basement membrane-derived gel plugs.

Tissue homeostasis and repair are critically dependent on the recruitment of monocyte-derived macrophages. Both under- and over-recruitment of ...

In Vitro Stimulation and Visualization of Extracellular Trap Release in Differentiated Human Monocyte-derived Macrophages

The release of extracellular traps (ETs) by neutrophils has been identified as a contributing factor to the development of diseases related to chronic inflammation. Neutrophil ETs (NETs) consist of a mesh of DNA, histone proteins, and various granule proteins (i.e., myeloperoxidase, elastase, and cathepsin G). Other immune cells, including macrophages, can also produce ETs; however, to what extent this occurs in vivo and whether macrophage extracellular traps (METs) play a role in pathological mechanisms has not been examined in detail. To better understand the role of METs in inflammatory pathologies, a protocol was developed for visualizing MET release from primary human macrophages in vitro, which can also be exploited in immunofluorescence experiments. This allows further characterization of these structures and their comparison to ETs released from neutrophils. Human monocyte-derived macrophages (HMDM) produce METs upon exposure to different inflammatory stimuli following differentiation to the M1 pro-inflammatory phenotype. The release of METs can be visualized by microscopy using a green fluorescent nucleic acid stain that is impermeant to live cells (e.g., SYTOX green). Use of freshly isolated primary macrophages, such as HMDM, is advantageous in modeling in vivo inflammatory events that are relevant to potential clinical applications. This protocol can also be used to study MET release from human monocyte cell lines (e.g., THP-1) following differentiation into macrophages with phorbol myristate acetate or other macrophage cell lines (e.g., the murine macrophage-like J774A.1 cells).

Presented here is a protocol to detect macrophage extracellular trap (MET) production in live cell culture using microscopy and fluorescence staining. This protocol can be further extended to examine specific MET protein markers by immunofluorescence staining.

The release of extracellular traps (ETs) by neutrophils has been identified as a contributing factor to the development of diseases related to chronic ...