This work has been supported by the MRC and the University of Aberdeen (MRC Centre for Medical Mycology) and by the Wellcome Trust Strategic Award - Medical Mycology Fungal Immunology (SFB, JMB, JK, AW). A special thank you is given to the support from the Chloe fund. TMH is supported by a grant from the National institute of health (NIH, code RO1 093808) and the Memorial Sloan Kettering Cancer Center is supported by NIH grant P30 CA008748. Additionally, TMH is an investigator in the Pathogenesis of Infectious Disease supported by the Burroughs Wellcome Fund. We wish to thank the Aberdeen Microscopy and Histology Facility for their help and support.

The protocol for obtaining neutrophils and peripheral blood mononuclear cells (PBMC) is based on previously published methods9. The use of blood samples from healthy volunteers has been approved by the human research ethics committee of the University of Aberdeen. Before starting make sure all the ethical approvals are in place for drawing blood from healthy volunteers and/or patients for the purpose of the described experiment. Keep cells on ice where possible to increase their survival.
1. A. fumigatus Culture and Conditions
<ol>
	<li>Prepare glucose minimal agar medium as described10.
	<ol>
		<li>Adjust media to pH 6.5 using 1 M NaOH and autoclave at 120 &#176;C for 20 min.</li>
		<li>Allow to cool to 65 &#176;C.</li>
		<li>Working in a sterile flow hood, pour 30 mL of cooled media into a T75 flask and allow to cool with the neck of the flask resting on a 25 mL pipette to create an agar slope.</li>
	</ol>
	</li>
	<li>Streak out the dsRed Af293-A. fumigatus strain on the agar and incubate for 7 days at 37 &#176;C + 5% CO2. Two flasks will yield approximately 109 conidia in 5 mL phosphate-buffered saline (PBS) pre-biotinylation.</li>
</ol>
2. A. fumigatus Labeling and Preparation
Note: When performing this assay for the first time, prepare the parental Af293-A. fumigatus strain. Take samples of both strains in microcentrifuge tubes and label only one of each strain as described below. This will allow one to have control conidia with no color and conidia with a single color, either dsRed or AF633, to test the setup and equipment.
<ol>
	<li>Harvest A. fumigatus conidia by immersing the culture with 30 mL PBS + 0.05% Tween-80. Filter the resulting suspension through a 40 &#181;m cell strainer into a 50 mL tube to remove hyphal fragments.</li>
	<li>Centrifuge at 805 x g for 10 min, remove the supernatant and wash once in 20 mL of sterile PBS. Pool conidia from two plates of the same strain during the wash step.</li>
	<li>Following the washing step, resuspend the pellet in 5 mL of PBS and transfer 1 mL aliquots of conidial suspension into microcentrifuge tubes. 1 mL of suspension of each strain is usually sufficient for live cell imaging. Wrap the remaining aliquots in foil and store at 4 &#176;C.</li>
	<li>Centrifuge aliquots of conidial suspension at 9,300 x g for 10 min at room temperature and carefully remove supernatant. Resuspend the conidial pellet in 1 mL 0.05 M NaHCO3 pH 8.3.</li>
	<li>Prepare 10 mg biotin/200 &#181;L dimethylsulfoxide (DMSO) stock solution by reconstituting 25 mg biotin in 500 &#181;L DMSO. Add 10 &#181;L biotin/DMSO stock solution to the microcentrifuge tube, cover in aluminum foil and incubate for 2 h on a rocker at 4 &#176;C.
	<ol>
		<li>Aliquot the remainder of the biotin/DMSO stock solution and freeze at -20 &#176;C for use in subsequent experiments.</li>
	</ol>
	</li>
	<li>Centrifuge for 10 min at 9,300 x g and carefully remove the supernatant. Resuspend the conidial pellet in 1 mL of 100 mM Tris-HCl pH 8.0 for 1 h to deactivate free-floating biotin.</li>
	<li>Centrifuge for 10 min at 9,300 x g and carefully remove the supernatant. Wash the pellet twice with 1 mL of sterile PBS and resuspend the pellet in 1 mL of PBS.</li>
	<li>Dissolve 1 mg of Streptavidin-AF633 in 0.5 mL of PBS to make a 2 mg/mL stock solution. Add 10 &#181;L of 2 mg/mL streptavidin-AF633 per 1 mL of conidial suspension and incubate for 40 min at room temperature on a rocker covered in aluminum foil. The remaining Streptavidin-AF633 can be frozen in aliquots for use in subsequent experiments.</li>
	<li>Centrifuge for 10 min at 9,300 x g and carefully remove supernatant. Resuspend the conidial pellet in 1 mL of PBS and count the conidia using a hemocytometer at a 1:1,000 dilution (1:100 and then 1:10). Adjust the conidial concentration to 3.6 x 106/mL with CO2 independent media, wrap in foil and store at 4 &#176;C. 
	NOTE: The conidia are now labeled with AF633 and will be referred to as FLARE conidia.</li>
	<li>Optional: If stimulation with swollen conidia is required, after counting conidia (step 2.9), dilute conidia to 7.2 x 106/mL in yeast nitrogen base (YNB) medium and add 500 &#181;L conidial suspension to 4.5 mL YNB medium in an autoclaved 50 mL Erlenmeyer flask. Cover and place the flask in a shaking incubator (200 rpm at 37 &#176;C) for 6 h.
	<ol>
		<li>Transfer the medium to a 15 mL tube. Centrifuge at 805 x g for 10 min at room temperature and wash once in PBS. Centrifuge again and resuspend pellet in 1 mL CO2 independent medium, giving 3.6 x 106 conidia/mL. 
		Note: Conidia frequently clump after they become swollen making accurate counting difficult, it is advised to calculate with the counted numbers of resting conidia used.</li>
	</ol>
	</li>
</ol>
3. Isolation of Human Neutrophils and Monocytes
<ol>
	<li>Draw 20 mL of venous blood from healthy volunteers into two 10 mL blood tubes containing ethylenediaminetetraacetic acid (EDTA). For each donor separately, pour 20 mL blood in a 50 mL tube and dilute with 15 mL PBS.</li>
	<li>Underlay the blood with 15 mL of a lymphocyte isolation solution (density 1.077 g/mL) with a syringe and iron needle. Place the needle at the bottom of the tube and gently force the lymphocyte isolation solution out. Centrifuge at 630 x g for 20 min with no brake and low acceleration.</li>
	<li>Prepare PBS, chilled on ice. 
	NOTE: Steps 3.4 and 3.5 must be followed simultaneously to generate monocytes (3.4) and neutrophils (3.5).</li>
	<li>Using a pastette, harvest the PBMC layer. This is the layer in the center between the yellow serum (upper) and the transparent lymphocyte isolation solution (lower) layer, and transfer into a fresh 50 mL tube.
	<ol>
		<li>Fill the tube with the PBMC up to 50 mL with cold PBS and centrifuge at 582 x g for 10 min. Remove the supernatant and wash twice with cold PBS and resuspend in 1 mL of PBS per 20 mL of donor blood used initially.</li>
		<li>Make 1:10 dilutions for counting by adding 20 &#181;L of the cell suspension to 160 &#181;L of PBS and 20 &#181;L of trypan blue. Count cells with a hemocytometer.</li>
		<li>Prepare a buffer solution by adding 26 mL of heat inactivated fetal calf serum (FCS) and 2.1 mL of 0.5 M EDTA to 500 mL of HBSS. Centrifuge the cells for 10 min at 515 x g and resuspend in 40 &#181;L of buffer solution per 1 x 107 cells.</li>
		<li>Transfer the cell suspension to a 15 mL tube and add 10 &#181;L of CD14 microbeads per 1 x 107 cells, mix well and incubate for 15 min at 4 &#176;C, making sure to mix the tubes every 5 min.</li>
		<li>Wash cells by adding 1 mL of buffer solution per 1 x 107 cells and centrifuge at 515 x g for 10 min.</li>
		<li>Aspirate supernatant completely and resuspend up to 1 x 108 cells in 500 &#181;L of buffer solution.</li>
		<li>Place 1 column per sample on a magnetic separator according to the manufacturer&#39;s instructions. First wash the column once with 500 &#181;L of buffer solution.</li>
		<li>Pipette the 500 &#181;L of cell suspension through the column, wait for the column to dry and then wash by repeating this three times with buffer solution.</li>
		<li>Place a new 15 mL tube underneath the column and take the column off the magnetic separator. Then flush the cells out of the column into the tube with 1 mL of buffer solution.</li>
		<li>Add 4 mL of buffer solution and centrifuge at 515 x g for 10 min, and then resuspend in 1 mL of Roswell Park Memorial Institute (RPMI) medium.</li>
		<li>Make 1:10 dilutions for counting by adding 20 &#181;L of the cell suspension to 160 &#181;L of PBS and 20 &#181;L of trypan blue. Count the cells with a hemocytometer.</li>
		<li>Adjust the cell concentration to 6 x 105/mL with RPMI and seed 200 &#181;L on a 35 mm glass-based imaging dish. Incubate overnight at 37 &#176;C with 5% CO2.</li>
		<li>The next day, prior to imaging, remove the RPMI and add 200 &#181;L of CO2 independent medium. 
		Note: These monocytes can also be differentiated into various macrophage subsets prior to imaging. If this is a technique to be explored, an excellent starting point is the recent paper by Ohradanova-Repic et al.11.</li>
	</ol>
	</li>
	<li>After harvesting the PBMC layer, remove all of the serum and most of the lymphocyte isolation solution, but be careful not to remove the small white band on top of the red pellet as this will contain most of the neutrophils.
	<ol>
		<li>Prepare a 10x hypotonic lysis buffer stock by adding 83 g of NH4Cl and 10 g of KHCO3 in 1 L of sterile water. Store at 4 &#176;C.</li>
		<li>Dilute this stock 10x with sterile water and add it to the tubes. Then, carefully invert 3 times and incubate in ice for 15 min.</li>
		<li>Centrifuge at 394 x g for 10 min and resuspend in hypotonic lysis buffer for 10 min in ice.</li>
		<li>Centrifuge at 394 x g and wash twice with cold PBS. Resuspend in 1 mL of CO2 independent medium per donor.</li>
		<li>Make 1:10 dilutions for counting by adding 20 &#181;L of the cell suspension to 160 &#181;L of PBS and 20 &#181;L of trypan blue. Count the cells with a hemocytometer.</li>
		<li>For flow cytometry, adjust the concentration to 6 x 105/mL and add 400 &#181;L cell suspension to a 24-well plate. For microscopy, add 200 &#181;L of the same cell suspension to a 35 mm glass-based imaging dish. 
		Note: Neutrophil imaging or flow cytometry should be initiated immediately due to their propensity to undergo apoptosis if left unstimulated. If this is not possible neutrophils should be kept on ice and used as soon as possible (within the same day).</li>
	</ol>
	</li>
</ol>
4. Flow Cytometry
<ol>
	<li>Add 200 &#181;L of 1.2 x 106/mL FLARE conidia to the cells in the 24-well plate, and then add 100 &#181;L of 20 &#181;g/mL voriconazole. Add 300 &#181;L of RPMI and incubate for 16 h at 37 &#176;C with 5% CO2. 
	NOTE: Voriconazole is added to prevent conidial germination.</li>
	<li>Add 25 &#181;L of a 1 mM Calcofluor-white stock solution to each well for a final concentration of 25 &#181;M and incubate for 10 min at 37 &#176;C with 5% CO2.</li>
	<li>Centrifuge at 582 x g for 10 min. Remove the supernatant and wash twice with PBS.</li>
	<li>To harvest adherent cells (monocytes), add 1 mL of PBS with 3 mM EDTA to each well and incubate for 10 min at 37 &#176;C with 5% CO2. Gently wash cells off the plate by pipetting and collect cells in a tube.</li>
	<li>Wash once in FACS Buffer (2% fetal calf serum to PBS), and then resuspend in FACS Buffer for FACS analysis.
	<ol>
		<li>For FACS analysis, first adjust the compensation parameters of the flow cytometer and set positive gates using single-colored compensation tubes, including conidia with no color: dsRed+ conidia, AF633+ conidia, and Calcofluor White+ conidia (generated as in 4.2).</li>
		<li>Set free conidia gate based on forward and side scatter using conidia with no color. Set cell gate on forward and side scatter by excluding the free conidia gate.</li>
		<li>Analyze sample tube by recording 10,000 events. 
		NOTE: Cells associated with live conidia will be dsRed+ and AF633+. Cells associated with dead conidia will be AF633+ only. Bystander cells that have not engaged conidia will be dsRed- and AF633-. The conidia-engaged cell populations are further analyzed for Calcofluor White staining on the Pacific Blue channel. Conidia that remain outside of cells will be Calcofluor White+, and conidia that have been internalized will be Calcofluor White-.</li>
	</ol>
	</li>
</ol>
5. Live Cell Video Microscopy
Note: The choice of microscope will depend upon what is available locally, but the microscope setup will need to include an inverted stage, an environmental chamber heated to 37 &#176;C and appropriate excitation/emission filters for dsRed (532/561 nm) and AF633 (633 nm). FLARE conidia do not work with the 488 nm laser in lieu of the 532/561 nm laser for dsRed. When performing this experiment for this first time, use the control conidia with no color and single color to test for background fluorescence and bleed-through between the dsRed and AF633 channels.
<ol>
	<li>Turn on the microscope heater prior to the experiment and allow sufficient time for the environmental control chamber to warm to 37 &#176;C. The time taken for chamber temperature to stabilize will vary for different microscope setups.</li>
	<li>Turn on the microscope and computer, and load the imaging software. Mount the imaging dish on the microscope stage and adjust the focus to find the human neutrophils or monocytes.</li>
	<li>For dsRed and AF633, set the laser power to 10% and exposure time to 1 s in the acquisition settings.</li>
	<li>Remove the imaging slide and add 100 &#181;L of 3 x 106/mL FLARE conidial suspension to the appropriate wells (total volume 300 &#181;L/well). Record the time that FLARE conidia are added to the dish.</li>
	<li>Return the slide to the stage and adjust camera sensitivity for dsRed and AF633 to clearly see the conidia but not overexpose the image. Set up a stage points list if multi-point acquisition is required.</li>
	<li>Commence imaging when all points are in focus, the channels are optimized and the cycle time and duration is set. Cycle time and duration of imaging depend on the experimental question. The goal is to keep the cycle time as short as possible (&#8804;2 min) with 1 min allowing for in depth analysis of uptake dynamics.</li>
</ol>

<ol>
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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=Human+leukocytes+kill+Aspergillus+nidulans+by+reactive+oxygen+species-independent+mechanisms.">Human leukocytes kill Aspergillus nidulans by reactive oxygen species-independent mechanisms.</a> Infect Immun. 79 (2), 767-773 (2010).</li><li>Sheppard, 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=Comparison+of+three+methodologies+for+the+determination+of+pulmonary+fungal+burden+in+experimental+murine+aspergillosis.">Comparison of three methodologies for the determination of pulmonary fungal burden in experimental murine aspergillosis.</a> Clin Microbiol Infect. 12 (4), 376-380 (2006).</li><li>Lewis, L. E., Bain, J. M., Okai, B., Gow, N. A. R., Erwig, L. 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The authors have nothing to disclose.

This method describes an innovative in vitro method to study the antifungal activity of human primary phagocytes against A. fumigatus using FLuorescent Aspergillus REporter (FLARE) conidia, live cell imaging and flow cytometry. Previous studies have demonstrated the added value of using FLARE conidia both in vivo in murine experimental fungal infection and in vitro assessment of antifungal immunity6,7. Combining FLARE conidia with this next generation live cell imaging technique allows for a setup to measure viability of individual conidia during dynamic interactions in vitro.
The described method has the potential to investigate the specific roles and importance of certain cellular processes of immune cells on their antifungal responses. In addition, antifungal responses of phagocytes from specific patients suffering from defined single component defects in their immune system can be assessed in greater detail. Very early and initial antifungal responses can be studied in great detail over 6 h of continuous imaging. This allows for even subtle differences to be detected, such as the velocity of phagocyte migration towards the fungus, internalization rates, dynamics of fungicidal events12, which would be undistinguishable using conventional phagocytosis methods.
Any cell type could be used with this method; the cell types used here were selected because these phagocytes constitute the first and second lines of defense in the human airways against A. fumigatus13. Interestingly, very clear differences can be observed between how monocytes and neutrophils engage with resting and swollen conidia and hyphae. Monocytes hardly migrate to conidia, while neutrophils display much more migratory activity. Additional fluorescent markers such as live-dead markers on immune cells can be included in the assay to provide insights into phagocyte survival following interactions with Aspergillus. Interesting potential future applications for this technology include the co-culture of different host cell types, the consequences for antifungal responses (e.g., macrophages on an epithelial monolayer, monocyte-derived dendritic cells together with neutrophils), and the real-time measurement of reactive oxygen species production or neutrophil extracellular trap formation following stimulation with Aspergillus.
A few points need to be noted to use this protocol, foremost the laboratory setup required: a microscope with an inverted stage, an environmental chamber stable at 37 &#176;C, and excitation/emission filters for dsRed (532/561 nm) and AF633 (633 nm). The ability of the microscope to keep the cells in focus and retain the oil immersion (particularly relevant during multi-point acquisition) should be monitored periodically due to the long duration of imaging. For quantification of fungicidal activity flow cytometry facilities are required. Additionally, appropriate institutional and ethical approvals need to be in place to work with healthy donor and patient derived blood samples and genetically manipulated fungi. It is strongly recommended to use fresh blood samples (use on the same day) to increase cell viability and preserve functionality. Ideally, isolation of cells is performed immediately after drawing the blood samples and neutrophils are imaged immediately after isolation.
In conclusion, a next generation live cell imaging technique to assess in great detail phagocyte antifungal activity against A. fumigatus is described. This technology can provide a unique insight into individual cell-fungal interactions in early innate immune defenses against Aspergillus.

Aspergillus fumigatus is an opportunistic fungal pathogen and the most common fungal cause of invasive lung infections in the immunocompromised host1,2. Understanding how host immune cells recognize and eliminate Aspergillus is an important area of fungal research, however, the currently available fungicidal assays have significant limitations. Commonly used methods of measuring fungicidal activity include colorimetric assays and determination of colony forming units3,4. However, such methods provide information on fungal viability at a single time point rather than viewing the dynamic interaction between host and pathogen. Accordingly, these methods cannot take into account whether a fungus has been killed or simply (temporarily) restricted in growth or metabolic activity. We have developed a method capable of observing fungicidal activity directly whilst simultaneously capturing detailed information regarding phagocytosis, phagocyte migration and inhibition of fungal growth.
Previously, a protocol was published using real-time imaging as a means to measure phagocytosis of Candida albicans by a mouse macrophage cell line5. This concept has now been developed further to address the knowledge gap in our understanding of Aspergillus interactions with immune cells by utilizing FLuorescent Aspergillus REporter (FLARE) conidia6,7,8. These conidia express a red fluorophore (dsRed) and are labeled with a second fluorophore (Alexa Fluor 633). Once a FLARE conidium is killed, it stops producing dsRed and the remaining dsRed fades, while the AF633 remains fluorescent and bound to the conidia. This creates a clear distinction between live and dead fungal cells during live cell imaging and flow cytometry, and enables tracking of the fate of individual conidia following their interaction with immune cells.
The described assays provide an effective method of visualizing the interaction between host immune cells and Aspergillus and will be of considerable value in unravelling the cellular signaling pathways responsible for antifungal effector mechanisms in innate immune cells. Other applications include visualizing how changes in Aspergillus growth, such as the switch from resting to swollen conidia, or from swollen conidia to hyphae, affect phagocyte recognition and function.
The following protocol describes in detail how to obtain human monocytes and neutrophils; how to prepare the FLARE conidia; and how to capture their responses with video microscopy and flow cytometry. Although the use of human immune cells isolated from donor blood is described here, this technique has proven equally effective using a variety of murine cell populations.

<table><tbody><tr><td>Glycerol</td><td>Sigma</td><td>G6279</td><td>http://www.sigmaaldrich.com</td></tr><tr><td>T75 flask</td><td>Greiner Bio-One</td><td>658 175</td><td>http://www.greinerbioone.com/</td></tr><tr><td>PBS</td><td>Gibco</td><td>20012-019</td><td>https://www.thermofisher.com/</td></tr><tr><td>Tween-80</td><td>Fisher Scientific</td><td>10592955</td><td>https://nl.fishersci.com/</td></tr><tr><td>40 &amp;micro;m filter</td><td>Thermo Fisher Scientific</td><td>22363547</td><td>https://www.thermofisher.com/</td></tr><tr><td>15 mL Falcon tube</td><td>Greiner Bio-One</td><td>188 261</td><td>http://www.greinerbioone.com/</td></tr><tr><td>50 mL Falcon tube</td><td>Greiner Bio-One</td><td>227 261</td><td>http://www.greinerbioone.com/</td></tr><tr><td>MilliQ</td><td>Millipore</td><td>QGARD00R1</td><td>Nanopure water works similarly. http://www.merckmillipore.com/</td></tr><tr><td>Biotin</td><td>Molecular Probes</td><td>B-6352</td><td>https://www.thermofisher.com/uk/en/home/brands/molecular-probes.html</td></tr><tr><td>DMSO</td><td>Sigma</td><td>D5879</td><td>http://www.sigmaaldrich.com</td></tr><tr><td>Streptavidin-AF633</td><td>Molecular Probes&amp;nbsp;</td><td>S-21375</td><td>AF633 is the only tested fluorophore so far that remains visible in phagosomes. https://www.thermofisher.com/uk/en/home/brands/molecular-probes.html</td></tr><tr><td>EDTA blood tubes</td><td>Greiner Bio-One</td><td>455036</td><td>Any blood tubes with an anti-coagulating agent should work. http://www.greinerbioone.com/en/start/</td></tr><tr><td>Ficoll-Paque Plus</td><td>GE Healthcare</td><td>17-1440-03</td><td>http://www3.gehealthcare.com/</td></tr><tr><td>Trypan blue</td><td>Thermo Fisher Scientific</td><td>SV3008401</td><td>https://www.thermofisher.com/</td></tr><tr><td>HBSS</td><td>Gibco</td><td>14170112&amp;nbsp;</td><td>https://www.thermofisher.com/uk/en/home/brands/gibco.html</td></tr><tr><td>CD14 microbeads</td><td>Myltenyi Biotec</td><td>130-050-201</td><td>Other monocyte isolation methods can be used as well, we prefer this method as it gives a consistent high purity of monocytes without being labor intensive. http://www.miltenyibiotec.com/en/</td></tr><tr><td>MS Columns</td><td>Myltenyi Biotec</td><td>130-042-201</td><td>See comment at CD14 microbeads. http://www.miltenyibiotec.com/en/</td></tr><tr><td>RPMI + Glutamax</td><td>Gibco</td><td>72400-021</td><td>https://www.thermofisher.com/uk/en/home/brands/gibco.html</td></tr><tr><td>CO&lt;sub&gt;2&lt;/sub&gt; independent medium</td><td>Thermo Fisher Scientific</td><td>18045054</td><td>Necessary if there is not sufficient CO&lt;sub&gt;2&lt;/sub&gt; exchange during imaging. https://www.thermofisher.com/uk/en/home</td></tr><tr><td>&amp;micro;-slide 8 well glass bottom</td><td>Ibidi</td><td>80827</td><td>This is the imaging dish that we use, however any glass imaging dish of proper size should work. http://ibidi.com/</td></tr><tr><td>UltraVIEW VoX 3D Live Cell Imaging System</td><td>Perkin Elmer</td><td>L7267000</td><td>Includes volocity software for acquisition and analysis. http://www.perkinelmer.com/</td></tr><tr><td>Calcofluor white</td><td>Sigma</td><td>18909</td><td>http://www.sigmaaldrich.com/</td></tr><tr><td>Voriconazole</td><td>Sigma</td><td>PZ0005</td><td>http://www.sigmaaldrich.com/</td></tr><tr><td>BD LSRII</td><td>BD Biosciences</td><td></td><td>Flowcytometer used. https://www.bdbiosciences.com/</td></tr></tbody></table>

live imaging of antifungal activity by human primary neutrophils and monocytes in response to a. fumigatus

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

Representative results are shown following the described protocol. Figure 1 illustrates a representative 6 h live-cell video with human neutrophils and FLARE conidia. dsRed (red) is expressed by the conidia themselves while they have been labeled with AF633 (Magenta).
Figure 2 is an image from a single time point from a similar movie as displayed in Figure 1, illustrating the difference between live and dead FLARE conidia. Dead conidia are distinguished from live conidia by losing their dsRed (red) signal while maintaining a bright AF633 (magenta) fluorescence. A. fumigatus conidia often survive within phagocytes for over 6 h. Therefore, to effectively quantify killing, flow cytometry plots are shown for a 16 h incubation period in Figure 3. This data was obtained with an alveolar macrophage cell line as an example but can be performed with any cell type. In Figure 4 the migration is shown in the first hour of stimulation for human neutrophils as well as their velocity and directional movement. Figure 5 shows the percentage of neutrophils and monocytes that have ingested 1, 2, 3 or more conidia while Figure 6 displays the number of conidia that germinate into hyphae.
<img alt="Figure 1" src="/files/ftp_upload/55444/55444fig1.jpg" /> 
Figure 1: Live-cell video microscopy movie of human neutrophils and FLARE conidia. Neutrophils were isolated from human blood and seeded together with FLARE conidia in CO2 independent medium at a ratio of 1:3, respectively. Imaging was initiated directly at 37 &#176;C with a spinning disk confocal microscope. Images were captured at 1 min and 55 s intervals over a period of 6 h. Scale bar = 10 &#181;m. A zoomed in video is shown with the channels separated to clarify the role of the FLARE conidia with DIC in the top left, dsRed (red) in the top right, AF633 (green) in the bottom left and the merged video in the bottom right. <a href="http://cloudflare.jove.com/files/ftp_upload/55444/Fig_1.avi">Please click here to download this video.</a>
<img alt="Figure 2" src="/files/ftp_upload/55444/55444fig2.jpg" /> 
Figure 2: Single time point image demonstrating the difference between live and dead FLARE conidia. Human neutrophils were stimulated with FLARE conidia and imaged with a spinning disk confocal microscope. An image was taken from the generated movies. Dead conidia are distinguished from hyphae by having lost their dsRed (red: top right) signal while maintaining their AF633 fluorescence (green: bottom left). <a href="http://cloudflare.jove.com/files/ftp_upload/55444/55444fig2large.jpg">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/55444/55444fig3.jpg" /> 
Figure 3: Quantification and validation of phagocytosis and killing of A. fumigatus conidia. Mouse alveolar macrophage cells (MH-S) were incubated with FLARE conidia at a 1:1 ratio for 16 h in the presence of voriconazole. MH-S cells associated with live conidia are shown in the red gate (dsRed+AF633+). MH-S cells associated with dead conidia are shown in the blue gate (dsRed-AF633+). Bystander MH-S cells are shown in the gold gate. Calcofluor White, a cell-impermeable fluorescent dye that binds to the fungal cell wall, is used to distinguish extracellular conidia (Calcofluor White+) from intracellular conidia (Calcofluor White-). As an extra validation to the method, it is shown that treatment with 2 &#181;M cytochalasin D inhibits conidial uptake by MH-S cells. <a href="http://cloudflare.jove.com/files/ftp_upload/55444/55444fig3large.jpg">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" src="/files/ftp_upload/55444/55444fig4.jpg" /> 
Figure 4: Migration of human neutrophils and monocytes against A. fumigatus conidia. Neutrophils were isolated from human blood and seeded together with FLARE conidia in CO2 independent medium at a ratio of 1:3, respectively. Imaging was initiated directly at 37 &#176;C with a spinning disk confocal microscope. Images were captured at 1 min and 55 s intervals over a period of 6 hours. Migration of all individual human neutrophils per field was manually tracked using tracking software against resting (A) and swollen (B) conidia for 1 h. Data represents 1 frame of cells for each condition of the same donor. The meandering factor (C), a measure of directional movement, and velocity (D) were then quantified using the same software. Mean &#177; SEM for 3 donors are shown with 30 cells per donor over 2 independent experiments. *: p &#60; 0.05 (Welch&#39;s corrected t test). <a href="http://cloudflare.jove.com/files/ftp_upload/55444/55444fig4large.jpg">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" src="/files/ftp_upload/55444/55444fig5.jpg" /> 
Figure 5: Phagocytosis of A. fumigatus conidia by human neutrophils and monocytes. Neutrophils and monocytes were isolated from human blood and seeded together with FLARE conidia in CO2 independent medium at a ratio of 1:3, respectively. Imaging was initiated directly at 37 &#176;C with a spinning disk confocal microscope. Images were captured at 1 min and 55 s intervals over a period of 6 h. Phagocytosis was measured as the amount of cells containing FLARE conidia after 4 h of stimulation. Data is presented as mean &#177; SEM from 3 donors and 3 frames per donor over 2 independent experiments. <a href="http://cloudflare.jove.com/files/ftp_upload/55444/55444fig5large.jpg">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" src="/files/ftp_upload/55444/55444fig6.jpg" /> 
Figure 6: Inhibition of germination of A. fumigatus conidia by neutrophils and monocytes. Neutrophils and monocytes were isolated from human blood and seeded together with FLARE conidia in CO2 independent medium at a ratio of 1:3, respectively. Imaging was initiated directly at 37 &#176;C with a spinning disk confocal microscope. Images were captured at 1 min and 55 s intervals over a period of 6 hours. Inhibition of fungal germination was examined by measuring the percentage of conidia that had germinated after 2, 4 and 6 h of co-culture. Data is presented as mean &#177; SEM from 3 donors and 3 frames per donor over 2 independent experiments. <a href="http://cloudflare.jove.com/files/ftp_upload/55444/55444fig6large.jpg">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Live Imaging of Antifungal Activity by Human Primary Neutrophils and Monocytes in Response to A. fumigatus at JoVE.com

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

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

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

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

live-imaging-antifungal-activity-human-primary-neutrophils-monocytes

Research

JoVE Journal

Immunology and Infection

10.2K Views.  University of Aberdeen.  Hier beschrijven we een protocol om antifungale activiteit van primaire menselijke immuuncellen te beoordelen in real-time met behulp van fluorescente Aspergillus reporter conidia in combinatie met live-cell video microscopie en flowcytometrie. Gegenereerde data inzicht in gastheer Aspergillus cel-interacties zoals fungicide werking, fagocytose, celmigratie remming van de schimmelgroei. 

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

Direct Observation of Phagocytosis and NET-formation by Neutrophils in Infected Lungs using 2-photon Microscopy

After the gastrointestinal tract, the lung is the second largest surface for interaction between the vertebrate body and the 
environment. Here, an effective gas exchange must be maintained, while at the same time avoiding infection by the multiple pathogens that are inhaled 
during normal breathing. To achieve this, a superb set of defense strategies combining humoral and cellular immune mechanisms exists. One of the most 
effective measures for acute defense of the lung is the recruitment of neutrophils, which either phagocytose the inhaled pathogens or kill them by 
releasing cytotoxic chemicals. A recent addition to the arsenal of neutrophils is their explosive release of extracellular DNA-NETs by which bacteria 
or fungi can be caught or inactivated even after the NET releasing cells have died. We present here a method that allows one to directly observe neutrophils, 
migrating within a recently infected lung, phagocytosing fungal pathogens as well as visualize the extensive NETs that they have produced throughout the 
infected tissue. The method describes the preparation of thick viable lung slices 7 hours after intratracheal infection of mice with conidia of the mold 
Aspergillus fumigatus and their examination by multicolor time-lapse 2-photon microscopy. This approach allows one to directly investigate antifungal 
defense in native lung tissue and thus opens a new avenue for the detailed investigation of pulmonary immunity.

We show, how to use 2-photon microscopy for the observation of the dynamics of neutrophil granulocytes in infected lungs while they phagocytose pathogens or produce neutrophil extracellular traps (NETs).

After the gastrointestinal tract, the lung is the second largest surface for interaction between the vertebrate body and the 
environment. Here, an ...

Live-cell Video Microscopy of Fungal Pathogen Phagocytosis

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of phagocytes to the site where pathogens are located; (ii) recognition of pathogen-associated molecular patterns (PAMPs) through pattern recognition receptors (PRRs); (iii) engulfment of microorganisms bound to the phagocyte cell membrane, and (iv) processing of engulfed cells within maturing phagosomes and digestion of the ingested particle. Studies that assess phagocytosis in its entirety are informative1, 2, 3, 4, 5 but are limited in that they do not normally break the process down into migration, engulfment and phagosome maturation, which may be affected differentially. Furthermore, such studies assess uptake as a single event, rather than as a continuous dynamic process. We have recently developed advanced live-cell imaging technologies, and have combined these with genetic functional analysis of both pathogen and host cells to create a cross-disciplinary platform for the analysis of innate immune cell function and fungal pathogenesis. These studies have revealed novel aspects of phagocytosis that could only be observed using systematic temporal analysis of the molecular and cellular interactions between human phagocytes and fungal pathogens and infectious microorganisms more generally. For example, we have begun to define the following: (a) the components of the cell surface required for each stage of the process of recognition, engulfment and killing of fungal cells1, 6, 7, 8; (b) how surface geometry influences the efficiency of macrophage uptake and killing of yeast and hyphal cells7; and (c) how engulfment leads to alteration of the cell cycle and behavior of macrophages 9, 10.
In contrast to single time point snapshots, live-cell video microscopy enables a wide variety of host cells and pathogens to be studied as continuous sequences over lengthy time periods, providing spatial and temporal information on a broad range of dynamic processes, including cell migration, replication and vesicular trafficking. Here we describe in detail how to prepare host and fungal cells, and to conduct the video microscopy experiments. These methods can provide a user-guide for future studies with other phagocytes and microorganisms.

We describe methods for live-cell video microscopy of Candida albicans phagocytosis by macrophages. These methods enable stage-specific analysis of macrophage migration, recognition, engulfment and phagosome maturation and reveal novel aspects of phagocytosis.

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of ...

Assessing Anti-fungal Activity of Isolated Alveolar Macrophages by Confocal Microscopy

The lung is an interface where host cells are routinely exposed to microbes and microbial products. Alveolar macrophages are the first-line phagocytic cells that encounter inhaled fungi and other microbes. Macrophages and other immune cells recognize Aspergillus motifs by pathogen recognition receptors and initiate downstream inflammatory responses. The phagocyte NADPH oxidase generates reactive oxygen intermediates (ROIs) and is critical for host defense. Although NADPH oxidase is critical for neutrophil-mediated host defense1-3, the importance of NADPH oxidase in macrophages is not well defined. The goal of this study was to delineate the specific role of NADPH oxidase in macrophages in mediating host defense against A. fumigatus. We found that NADPH oxidase in alveolar macrophages controls the growth of phagocytosed A. fumigatus spores4. Here, we describe a method for assessing the ability of mouse alveolar macrophages (AMs) to control the growth of phagocytosed Aspergillus spores (conidia). Alveolar macrophages are stained in vivo and ten days later isolated from mice by bronchoalveolar lavage (BAL). Macrophages are plated onto glass coverslips, then seeded with green fluorescent protein (GFP)-expressing A. fumigatus spores. At specified times, cells are fixed and the number of intact macrophages with phagocytosed spores is assessed by confocal microscopy.

A method to evaluate the ability of isolated mouse alveolar macrophages to control the growth of phagocytosed Aspergillus spores by confocal microscopy.

The lung is an interface where host cells are routinely exposed to microbes and microbial products. Alveolar macrophages are the first-line phagocytic ...

Histological Quantification to Determine Lung Fungal Burden in Experimental Aspergillosis

The quantification of lung fungal burden is critical for the determination of the relative levels of immune protection and fungal virulence in mouse models of pulmonary fungal infection. Although multiple methods are used to assess fungal burden, quantitative polymerase chain reaction (qPCR) of fungal DNA has emerged as a technique with several advantages over previous culture-based methods. Currently, a comprehensive assessment of lung pathology, leukocyte recruitment, fungal burden, and gene expression in mice with invasive aspergillosis (IA) necessitates the use of a significant number of experimental and control animals. Here the quantification of lung histological staining to determine fungal burden using a reduced number of animals was examined in detail. Lung sections were stained to identify fungal structures with Gomori&#39;s modified methanamine silver (GMS) staining. Images were taken from the GMS-stained sections from 4 discrete fields of each formalin-fixed paraffin-embedded lung. The GMS stained areas within each image were quantified using an image analysis program, and from this quantification, the mean percentage of stained area was determined for each sample. Using this strategy, eosinophil-deficient mice exhibited decreased fungal burden and disease with caspofungin therapy, while wild-type mice with IA did not improve with caspofungin. Similarly, fungal burden in mice lacking &#947;&#948; T cells were also improved by caspofungin, as measured by qPCR and GMS quantification. GMS quantification is therefore introduced as a method for the determination of relative lung fungal burden that may ultimately reduce the quantity of experimental animals required for comprehensive studies of invasive aspergillosis.

Here we describe a protocol to determine pulmonary fungal burden in mice with invasive aspergillosis by quantification of Gomori&#39;s modified methanamine silver staining in histological sections. Use of this method resulted in comparable results with less animals compared to assessment of fungal burden by quantitative PCR of lung fungal DNA.

The quantification of lung fungal burden is critical for the determination of the relative levels of immune protection and fungal virulence in mouse ...

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.

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.

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

Infection of Zebrafish Larvae with Aspergillus Spores for Analysis of Host-Pathogen Interactions

Invasive aspergillosis (IA) is one of&#160;the most common fungal infections among immunocompromised individuals. Despite the availability of antifungal drugs, IA can cause &#62;50% mortality in infected immunocompromised patients. It is crucial to determine both host and pathogen factors that contribute to infection susceptibility and low survival rates in infected patients in order to develop novel therapeutics. Innate immune responses play a pivotal role in recognition and clearance of Aspergillus spores, though little is known about the exact cellular and molecular mechanisms. Reliable models are required to investigate detailed mechanistic interactions between the host and pathogen. The optical clarity and genetic tractability of zebrafish larvae make them an intriguing model&#160;to study host-pathogen interactions of multiple human bacterial and fungal infections in a live and intact host. This protocol describes a larval zebrafish Aspergillus infection model. First, Aspergillus spores are isolated and injected into the zebrafish hindbrain ventricle via microinjection. Then, chemical inhibitors such as immunosuppressive drugs are added directly to the larval water. Two methods to monitor the infection in injected larvae are described, including the 1) homogenization of larvae for colony forming unit (CFU) enumeration and 2) a repeated, daily live imaging setup. Overall, these techniques can be used to mechanistically analyze the progression of Aspergillus infection in vivo and can be applied to different host backgrounds and Aspergillus strains to interrogate host-pathogen interactions.

Infection of Zebrafish Larvae with Aspergillus Spores for Analysis of Host-Pathogen Interactions

This protocol describes an Aspergillus infection model in zebrafish larvae. Aspergillus spores are microinjected into the hindbrain of larvae, and chemical treatment is used to induce immunosuppression. Infection progression is monitored via a daily imaging setup to monitor fungal growth and immune responses as well as enumeration of live spores by colony forming unit plating.

Invasive aspergillosis (IA) is one of&#160;the most common fungal infections among immunocompromised individuals. Despite the availability of antifungal ...

Confocal Laser Scanning Microscopy-Based Quantitative Analysis of Aspergillus fumigatus Conidia Distribution in Whole-Mount Optically Cleared Mouse Lung

Aspergillus fumigatus conidia are airborne pathogens that can penetrate human airways. Immunocompetent people without allergies exhibit resistance and immunological tolerance, while in immunocompromised patients, conidia can colonize airways and cause severe invasive respiratory disorders. Various cells in different airway compartments are involved in the immune response that prevents fungal invasion; however, the spatio-temporal aspects of pathogen elimination are still not completely understood. Three-dimensional (3D) imaging of optically cleared whole-mount organs, particularly the lungs of experimental mice, permits detection of fluorescently labeled pathogens in the airways at different time points after infection. In the present study, we describe an experimental setup to perform a quantitative analysis of A. fumigatus conidia distribution in the airways. Using fluorescent confocal laser scanning microscopy (CLSM), we traced the location of fluorescently labeled&#160;conidia in the bronchial branches and the alveolar compartment 6 hours after oropharyngeal application to mice. The approach described here was previously used for detection of the precise pathogen location and identification of the pathogen-interacting cells at different phases of the immune response. The experimental setup can be used to estimate the kinetics of the pathogen elimination in different pathological conditions.

Confocal Laser Scanning Microscopy-Based Quantitative Analysis of Aspergillus fumigatus Conidia Distribution in Whole-Mount Optically Cleared Mouse Lung

We describe the method for quantitative analysis of the distribution of Aspergillus fumigatus conidia (3 &#181;m in size) in the airways of mice. The method also can be used for the analysis of microparticles and nanoparticle agglomerate distribution in the airways in various pathological condition models.

Aspergillus fumigatus conidia are airborne pathogens that can penetrate human airways. Immunocompetent people without allergies exhibit resistance and ...

Neutrophil Functional Assays for Screening Different Signaling Pathways

A Set of Screening Techniques for a Quick Overview of the Neutrophil Function

Neutrophils are known as one of the first lines of defense in the innate immune response and can perform many particular cellular functions, such as chemotaxis, reverse migration, phagocytosis, degranulation of cytotoxic enzymes and metabolites, and release of DNA as neutrophil extracellular traps (NETs). Neutrophils not only have tightly regulated signaling themselves, but also participate in the regulation of other components of the immune system. As fresh neutrophils are terminally differentiated, short-lived, and highly variable among individuals, it is important to make the most of the collected samples. Researchers often need to perform screening assays to assess an overview of the many neutrophil functions that may be affected by specific conditions under evaluation. A set of tests following a single isolation process of normal density neutrophils was developed to address this need, seeking a balance between speed, comprehensiveness, cost, and accuracy. The results can be used to reason and guide in-depth follow-up studies. This procedure can be carried out in an average time of 4 h and includes the evaluation of cell viability, reactive oxygen species (ROS) production, real-time migration, and phagocytosis of yeast on glass slides, leaving enough cells for more detailed approaches like omics studies. Moreover, the procedure includes a way to easily observe a preliminary suggestion of NETs after fast panoptic staining observed by light microscopy, with a lack of specific markers, albeit enough to indicate if further efforts in that way would be worthwhile. The diversity of functions tested combines common points among tests, reducing the analysis time and expenses. The procedure was named NeutroFun Screen, and although having&#160;limitations, it balances the aforementioned factors. Furthermore, the aim of this work is not a definite test set, but rather a guideline that can easily be adjusted to each lab&#39;s resources and demands.

Author Spotlight: Balancing Speed, Cost, and Accuracy in Neutrophil Function Assessment with NeutroFun Screen Protocol 

This protocol features a set of neutrophil functional assays to be used as a screening method to cover functions from different signaling pathways. The protocol includes an initial and simple evaluation of cell viability, purity, reactive oxygen species production, real-time migration, phagocytosis, and a preliminary suggestion of neutrophil extracellular traps.

Neutrophils are known as one of the first lines of defense in the innate immune response and can perform many particular cellular functions, such as ...

Quantitative Analysis of Aspergillus nidulans Growth Rate using Live Microscopy and Open-Source Software

It is well established that colony growth of filamentous fungi, mostly dependent on changes in hyphae/mycelia apical growth rate, is macroscopically estimated on solidified media by comparing colony size. However, to quantitatively measure the growth rate of genetically different fungal strains or strains under different environmental/growth conditions (pH, temperature, carbon and nitrogen sources, antibiotics, etc.) is challenging. Thus, the pursuit of complementary approaches to quantify growth kinetics becomes mandatory in order to better understand fungal cell growth. Furthermore, it is well-known that filamentous fungi, including Aspergillus spp., have distinct modes of growth and differentiation under sub-aerial conditions on solid media or submerged cultures. Here, we detail a quantitative microscopic method for analyzing growth kinetics of&#160;the model fungus Aspergillus nidulans, using live imaging in both submerged cultures and solid media. We capture images, analyze, and quantify growth rates of different fungal strains in a reproducible and reliable manner using an open source, free software for bio-images (e.g., Fiji), in a way that does not require any prior image analysis expertise from the user.

Quantitative Analysis of Aspergillus nidulans Growth Rate using Live Microscopy and Open-Source Software

We present a label-free live imaging protocol using transmitted light microscopy techniques to capture images, analyze and quantify growth kinetics of the filamentous fungus A. nidulans in both submerged cultures and solid media. This protocol can be used in conjunction with fluorescence microscopy.

It is well established that colony growth of filamentous fungi, mostly dependent on changes in hyphae/mycelia apical growth rate, is macroscopically ...

Biology

Quantitative Flow Cytometric Measurement of Fungal Spore Phagocytosis by Human Phagocytes

Source: Hartung, S., et al., <a href="https://app.jove.com/v/60397">Measuring Phagocytosis of Aspergillus fumigatus Conidia by Human Leukocytes using Flow Cytometry.</a> J. Vis. Exp. (2019)
This video demonstrates a method for quantifying the phagocytosis of FITC-labeled pathogenic fungal spores by human leukocytes. Phagocytosed spores are discerned from cell-adherent spores through counterstaining, followed by flow cytometric analysis.

All procedures involving sample collection have been performed in accordance with the institute&#39;s IRB guidelines.
1. Phagocytosis Assay

	Incubate 2 x ...

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

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