Name: measuring phagocytosis of aspergillus fumigatus conidia by human leukocytes using flow cytometry
Uploaded: 2019-12-07T12:00:00
Description: Watch this Scientific Journal Video about Measuring Phagocytosis of Aspergillus fumigatus Conidia by Human Leukocytes using Flow Cytometry at JoVE.com

We thank Mrs. Pia Stier for excellent technical assistance. M. von Lilienfeld-Toal is supported by the Center for Sepsis Control and Care (German Federal Ministry of Education and Health, BMBF, FKZ 01E01002) and InfectoGnostics Research Campus (BMBF, FKZ 13GW0096D). Thi Ngoc Mai Hoang is supported by the Jena School of Microbial Communication (Deutsche Forschungsgemeinschaft, FKZ 214/2)

This protocol includes the use of human buffy coats obtained from the Institute for Transfusion Medicine, Jena University Hospital and fresh venous blood drawn from patients, both after written informed consent of the donors in accordance to ethics committee approval 4357-03/15.
1. Preparation of Aspergillus fumigatus Conidia
<ol>
	<li>Grow A. fumigatus on 1.5% malt agar Petri dishes for 5 days at 37 &#176;C without CO2. 
	CAUTION: A. fu...

<ol>
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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Double+fluorescent+flow+cytometric+assessment+of+bacterial+internalization+and+binding+by+epithelial+cells.">Double fluorescent flow cytometric assessment of bacterial internalization and binding by epithelial cells.</a> Cytometry. 25 (4), 381-387 (1996).</li><li>Hartung, 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=Fast+and+Quantitative+Evaluation+of+Human+Leukocyte+Interaction+with+Aspergillus+fumigatus+Conidia+by+Flow+Cytometry.">Fast and Quantitative Evaluation of Human Leukocyte Interaction with Aspergillus fumigatus Conidia by Flow Cytometry.</a> Cytometry A. 95 (3), 332-338 (2019).</li><li>Fei, C., Lillico, D. M. E., Hall, B., Rieger, A. M., Stafford, J. 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This protocol presents a fast flow cytometric method to measure interaction of A. fumigatus conidia with a large number of primary human leukocytes that is not possible in common microscopic protocols. Imaging cells with a microscope and manually counting internalized conidia is cumbersome and can realistically be done for a few hundred cells only. Flow cytometry overcomes this problem by measuring thousands of cells within minutes. A hurdle common to both approaches is the distinction of phagocytosed and adhere...

Invasive pulmonary aspergillosis is a great threat to immunocompromised patients as treatment options are limited and only successful upon early diagnosis, which leads to high mortality rates1. Infectious agents are conidia (spores) of the mold Aspergillus fumigatus that are ubiquitous to most habitats2. Conidia are inhaled, pass through the airways and can finally enter the lung alveoli. In immunocompetent humans, these conidia are cleared by innate immune cells such as monocytes or macrophages and neutrophil granulocytes, which take up (phagocytose) and digest the pathogens3. Phagocytosis is important for microbiologists and immunologists likewise when interested in host-pathogen interactions. Confrontation assays, such as co-incubation of leukocytes and conidia, often include labeling of the spores by fluorescein or its derivative fluorescein isothiocyanate (FITC). Using a microscope, it is straightforward to identify internalized fluorescent conidia and to determine attached/adherent conidia, although this approach is cumbersome and realistically restricted to a few hundreds of cells4. However, in flow cytometry which easily allows the analysis of hundreds of thousands of cells within minutes, differential staining of phagocytosed and adherent conidia is vital. Therefore, many protocols rely on Trypan Blue to quench FITC-fluorescence from adherent conidia5,6,7,8. Another approach is exploiting fluorescence resonance energy transfer of ethidium bromide and FITC to emit red instead of green fluorescence from adherent conidia9,10,11. If specific antibodies are available, as is the case for some bacteria, cell-bound particles can be directly stained12,13.
Here, we present a protocol to quickly and quantitatively assess phagocytosis of FITC-labeled A. fumigatus conidia by human leukocytes along with attachment of spores to cells and lack of interaction by employing an allophycocyanin (APC)-coupled anti-FITC antibody. The method also allows for the simultaneous flow cytometric analysis of further cell markers that can be employed for separate analysis of phagocytosis by monocytes and neutrophils from the same sample.
The protocol can be applied for characterization of fungal strains (e.g., several species of Aspergillus and other molds from the genus Mucorales presented here) and their mutants14 and immunological research on phagocytes, such as leukocytes from immunocompromised individuals.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Adhesive foil</td>
			<td>Brand</td>
			<td>701367</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-CD14 V500</td>
			<td>BD Biosciences</td>
			<td>561391</td>
			<td>clone M5E2</td>
		</tr>
		<tr>
			<td>anti-CD45 BUV395</td>
			<td>BD Biosciences</td>
			<td>563792</td>
			<td>clone HI30</td>
		</tr>
		<tr>
			<td>anti-CD66b PerCP-Cy5.5</td>
			<td>BD Biosciences</td>
			<td>562254</td>
			<td>clone G10F5</td>
		</tr>
		<tr>
			<td>anti-FITC APC</td>
			<td>ThermoFisher Scientific</td>
			<td>17-7691-82</td>
			<td>clone NAWESLEE</td>
		</tr>
		<tr>
			<td>Cell culture plate, 12-well</td>
			<td>Greiner Bio-one</td>
			<td>665180</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell scraper</td>
			<td>Bioswisstech</td>
			<td>800020</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell strainer, 30 &#181;m</td>
			<td>Miltenyi Biotech</td>
			<td>130-098-458</td>
			<td>SmartStrainer</td>
		</tr>
		<tr>
			<td>Cytometer</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>LSR Fortessa II, lasers: 488 nm (blue), 405 nm (violet), 355 nm (UV) and 640 nm (red)</td>
		</tr>
		<tr>
			<td>Detergent</td>
			<td>Sigma Aldrich</td>
			<td>P1379</td>
			<td>Tween 20, 0.01% in PBS</td>
		</tr>
		<tr>
			<td>Drigalski spatula</td>
			<td>Carl Roth</td>
			<td>PC59.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid (EDTA)</td>
			<td>Sigma Aldrich</td>
			<td>ED3SS-500g</td>
			<td>2 mM in PBS</td>
		</tr>
		<tr>
			<td>Erythrocyte lysis buffer</td>
			<td></td>
			<td></td>
			<td>0.15 M NH4Cl, 10 mM KHCO3, 0.1 mM EDTA</td>
		</tr>
		<tr>
			<td>Fetal Calf Serum (FCS)</td>
			<td>Biochrom AG</td>
			<td>S 0115</td>
			<td>10% in RPMI 1640</td>
		</tr>
		<tr>
			<td>Fluorescein isothiocyanate (FITC)</td>
			<td>Sigma Aldrich</td>
			<td>F3651-100MG</td>
			<td>0.1 mM in Na2CO3 /PBS solution</td>
		</tr>
		<tr>
			<td>Formaldehyd</td>
			<td>Carl Roth</td>
			<td>PO87.3</td>
			<td>Histofix</td>
		</tr>
		<tr>
			<td>Malt agar (1.5%)</td>
			<td></td>
			<td></td>
			<td>malt extract (40 g), yeast extract (4 g), agar (15 g), Aqua dest. (1 L), adjust pH to 5.7-6.0, sterilise at 121 &#176;C for 35 minutes</td>
		</tr>
		<tr>
			<td>Na2CO3</td>
			<td>Carl Roth</td>
			<td>8563.1</td>
			<td>0.1 M in PBS</td>
		</tr>
		<tr>
			<td>Petri dish</td>
			<td>Greiner Bio-one</td>
			<td>633180</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphat Buffered Saline (PBS)</td>
			<td>ThermoFisher Scientific</td>
			<td>189012-014</td>
			<td>without Calcium, without Magnesium</td>
		</tr>
		<tr>
			<td>RPMI 1640</td>
			<td>ThermoFisher Scientific</td>
			<td>61870010</td>
			<td>RPMI 1640 Medium, GlutaMAX Supplement</td>
		</tr>
		<tr>
			<td>Rotator</td>
			<td>Miltenyi Biotech</td>
			<td>130-090-753</td>
			<td>MACSmix Tube Rotator</td>
		</tr>
		<tr>
			<td>Round-bottom tube, 7.5 mL</td>
			<td>Corning</td>
			<td>REF 352008</td>
			<td></td>
		</tr>
		<tr>
			<td>Software for data acquisition and analysis</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>FACSDiva 8.0</td>
		</tr>
		<tr>
			<td>V-bottom plate, 96 well</td>
			<td>Brand</td>
			<td>781601</td>
			<td>untreated surface</td>
		</tr>
	</tbody>
</table>

measuring phagocytosis of aspergillus fumigatus conidia by human leukocytes using flow cytometry

Invasive pulmonary infection by the mold Aspergillus fumigatus poses a great threat to immunocompromised patients. Inhaled fungal conidia (spores) are cleared from the human lung alveoli by being phagocytosed by innate monocytes and/or neutrophils. This protocol offers a fast and reliable measurement of phagocytosis by flow cytometry using fluorescein isothiocyanate (FITC)-labeled conidia for co-incubation with human leukocytes and subsequent counterstaining with an anti-FITC antibody to allow discrimination of internalized and cell-adherent conidia. Major advantages of this protocol are its rapidness, the possibility to combine the assay with cytometric analysis of other cell markers of interest, the simultaneous analysis of monocytes and neutrophils from a single sample and its applicability to other cell wall-bearing fungi or bacteria. Determination of percentages of phagocytosing leukocytes provides a means to microbiologists for evaluating virulence of a pathogen or for comparing pathogen wildtypes and mutants as well as to immunologists for investigating human leukocyte capabilities to combat pathogens.

In measuring phagocytosis of A. fumigatus conidia by human phagocytic cells, discrimination between genuine internalization and mere attachment of conidia to the cells is an obstacle, especially when it comes to high-throughput methods such as flow cytometry. In order to overcome this hurdle, we present a fast and reliable protocol based on the staining of conidia with the fluorescent dye FITC prior to co-incubation of cells and conidia, followed by a counterstaining with an APC-labeled anti-FITC antibody after ...

Watch this Scientific Journal Video about Measuring Phagocytosis of Aspergillus fumigatus Conidia by Human Leukocytes using Flow Cytometry at JoVE.com

Measuring Phagocytosis of Aspergillus fumigatus Conidia by Human Leukocytes using Flow Cytometry

This protocol provides a fast and reliable method to quantitatively measure phagocytosis of Aspergillus fumigatus conidia by human primary phagocytes using flow cytometry and to discriminate phagocytosis of conidia from mere adhesion to leukocytes.

Measuring Phagocytosis of Aspergillus fumigatus Conidia by Human Leukocytes using Flow Cytometry

Invasive pulmonary infection by the mold Aspergillus fumigatus poses a great threat to immunocompromised patients. Inhaled fungal conidia (spores) are ...

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