Name: isolation of leukocytes from human breast milk for use in an antibody-dependent cellular phagocytosis assay of hiv targets
Uploaded: 2019-09-06T14:00:00
Description: Watch this Scientific Journal Video about Isolation of Leukocytes from Human Breast Milk for Use in an Antibody-dependent Cellular Phagocytosis Assay of HIV Targets at JoVE.com

We thank Dr. Susan Zolla-Pazner in the Department of Medicine and Department of Microbiology at the Icahn School of Medicine at Mount Sinai for manuscript review. The NIH/NICHD provided funding for this project under grant number R21 HD095772-01A1. In addition, R. Powell was supported by funds from the Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai.

Each participant in this study was recruited and interviewed in accord with the ethical and institutional review board (IRB) approval with the guidance and authorization of Mount Sinai&#8217;s Program for the Protection of Human Subjects (PPHS) using an IRB-approved protocol for obtaining breast milk samples.
1. Target Microsphere preparation
<ol>
	<li>Select a relevant target antigen. 
	NOTE: In this example, the recombinant protein V1V2-2F5K was used,...

<ol>
	<li>Hassiotou, F., Geddes, D. T., Hartmann, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cells+in+human+milk:+state+of+the+science.">Cells in human milk: state of the science.</a> Journal of Human Lactation. 29 (2), 171-182 (2013).</li><li>Lonnerdal, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nutritional+and+physiologic+significance+of+human+milk+proteins.">Nutritional and physiologic significance of human milk proteins.</a> The American Journal of Clinical Nutrition. 77 (6), 1537S-1543S (2003).</li><li>Butte, N. F., Garza, C., Stuff, J. E., Smith, E. O., Nichols, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+maternal+diet+and+body+composition+on+lactational+performance.">Effect of maternal diet and body composition on lactational performance.</a> The American Journal of Clinical Nutrition. 39 (2), 296-306 (1984).</li><li>Dewey, K. G., Finley, D. A., Lonnerdal, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breast+milk+volume+and+composition+during+late+lactation+(7-20+months).">Breast milk volume and composition during late lactation (7-20 months).</a> Journal of Pediatric Gastroenterology and Nutrition. 3 (5), 713-720 (1984).</li><li>Hassiotou, F., Geddes, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immune+cell-mediated+protection+of+the+mammary+gland+and+the+infant+during+breastfeeding.">Immune cell-mediated protection of the mammary gland and the infant during breastfeeding.</a> Advances in Nutrition. 6 (3), 267-275 (2015).</li><li>Hanson, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mother-offspring+dyad+and+the+immune+system.">The mother-offspring dyad and the immune system.</a> Acta Paediatrica. 89 (3), 252-258 (2000).</li><li>Wirt, D. P., Adkins, L. T., Palkowetz, K. H., Schmalstieg, F. C., Goldman, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activated+and+memory+T+lymphocytes+in+human+milk.">Activated and memory T lymphocytes in human milk.</a> Cytometry. 13 (3), 282-290 (1992).</li><li>Jain, L., 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=In+vivo+distribution+of+human+milk+leucocytes+after+ingestion+by+newborn+baboons.">In vivo distribution of human milk leucocytes after ingestion by newborn baboons.</a> Archives of Disease in Childhood. 64 (7 Spec No), 930-933 (1989).</li><li>Zhou, L., 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=Two+independent+pathways+of+maternal+cell+transmission+to+offspring:+through+placenta+during+pregnancy+and+by+breast-feeding+after+birth.">Two independent pathways of maternal cell transmission to offspring: through placenta during pregnancy and by breast-feeding after birth.</a> Immunology. 101 (4), 570-580 (2000).</li><li>Tuboly, S., Bernath, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intestinal+absorption+of+colostral+lymphoid+cells+in+newborn+animals.">Intestinal absorption of colostral lymphoid cells in newborn animals.</a> Advances in Experimental Medicine and Biology. 503, 107-114 (2002).</li><li>Cabinian, A., 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=Transfer+of+Maternal+Immune+Cells+by+Breastfeeding:+Maternal+Cytotoxic+T+Lymphocytes+Present+in+Breast+Milk+Localize+in+the+Peyer's+Patches+of+the+Nursed+Infant.">Transfer of Maternal Immune Cells by Breastfeeding: Maternal Cytotoxic T Lymphocytes Present in Breast Milk Localize in the Peyer's Patches of the Nursed Infant.</a> PLoS ONE. 11 (6), e0156762 (2016).</li><li>Filias, A., 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=Phagocytic+ability+of+neutrophils+and+monocytes+in+neonates.">Phagocytic ability of neutrophils and monocytes in neonates.</a> BMC Pediatrics. 11, 29 (2011).</li><li>Natchu, U. 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=Exclusive+breastfeeding+reduces+risk+of+mortality+in+infants+up+to+6+mo+of+age+born+to+HIV-positive+Tanzanian+women.">Exclusive breastfeeding reduces risk of mortality in infants up to 6 mo of age born to HIV-positive Tanzanian women.</a> The American Journal of Clinical Nutrition. 96 (5), 1071-1078 (2012).</li><li>Dewey, K. G., Heinig, M. J., Nommsen-Rivers, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differences+in+morbidity+between+breast-fed+and+formula-fed+infants.">Differences in morbidity between breast-fed and formula-fed infants.</a> The Journal of Pediatrics. 126 (5 Pt 1), 696-702 (1995).</li><li>WHO. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collaborative+Study+Team+on+the+Role+of+Breastfeeding+on+the+Prevention+of+Infant+Mortality.+Effect+of+breastfeeding+on+infant+and+child+mortality+due+to+infectious+diseases+in+less+developed+countries:+a+pooled+analysis.">Collaborative Study Team on the Role of Breastfeeding on the Prevention of Infant Mortality. Effect of breastfeeding on infant and child mortality due to infectious diseases in less developed countries: a pooled analysis.</a> Lancet. 355 (9202), 451-455 (2000).</li><li>World Health Organization. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Updates+on+HIV+and+Infant+Feeding:+The+Duration+of+Breastfeeding,+and+Support+from+Health+Services+to+Improve+Feeding+Practices+Among+Mothers+Living+with+HIVWHO+Guidelines+Approved+by+the+Guidelines+Review+Committee.">Updates on HIV and Infant Feeding: The Duration of Breastfeeding, and Support from Health Services to Improve Feeding Practices Among Mothers Living with HIVWHO Guidelines Approved by the Guidelines Review Committee.</a> World Health Organization. , (2016).</li><li>Nelson, C. 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=Combined+HIV-1+Envelope+Systemic+and+Mucosal+Immunization+of+Lactating+Rhesus+Monkeys+Induces+a+Robust+Immunoglobulin+A+Isotype+B+Cell+Response+in+Breast+Milk.">Combined HIV-1 Envelope Systemic and Mucosal Immunization of Lactating Rhesus Monkeys Induces a Robust Immunoglobulin A Isotype B Cell Response in Breast Milk.</a> Journal of Virology. 90 (10), 4951-4965 (2016).</li><li>Fowler, M. G., Lampe, M. A., Jamieson, D. J., Kourtis, A. P., Rogers, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reducing+the+risk+of+mother-to-child+human+immunodeficiency+virus+transmission:+past+successes,+current+progress+and+challenges,+and+future+directions.">Reducing the risk of mother-to-child human immunodeficiency virus transmission: past successes, current progress and challenges, and future directions.</a> American Journal of Obstetrics and Gynecology. 197 (3 Suppl), S3-S9 (2007).</li><li>Shen, 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=Mother-to-Child+HIV-1+Transmission+Events+Are+Differentially+Impacted+by+Breast+Milk+and+Its+Components+from+HIV-1-Infected+Women.">Mother-to-Child HIV-1 Transmission Events Are Differentially Impacted by Breast Milk and Its Components from HIV-1-Infected Women.</a> PLoS ONE. 10 (12), e0145150 (2015).</li><li>Fouda, G. G., 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=HIV-specific+functional+antibody+responses+in+breast+milk+mirror+those+in+plasma+and+are+primarily+mediated+by+IgG+antibodies.">HIV-specific functional antibody responses in breast milk mirror those in plasma and are primarily mediated by IgG antibodies.</a> Journal of Virology. 85 (18), 9555-9567 (2011).</li><li>Van de Perre, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HIV-1+reservoirs+in+breast+milk+and+challenges+to+elimination+of+breast-feeding+transmission+of+HIV-1.">HIV-1 reservoirs in breast milk and challenges to elimination of breast-feeding transmission of HIV-1.</a> Science Translational Medicine. 4 (143), 143sr143 (2012).</li><li>Milligan, C., Richardson, B. A., John-Stewart, G., Nduati, R., Overbaugh, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Passively+acquired+antibody-dependent+cellular+cytotoxicity+(ADCC)+activity+in+HIV-infected+infants+is+associated+with+reduced+mortality.">Passively acquired antibody-dependent cellular cytotoxicity (ADCC) activity in HIV-infected infants is associated with reduced mortality.</a> Cell Host &amp; Microbe. 17 (4), 500-506 (2015).</li><li>Pollara, 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=Association+of+HIV-1+Envelope-Specific+Breast+Milk+IgA+Responses+with+Reduced+Risk+of+Postnatal+Mother-to-Child+Transmission+of+HIV-1.">Association of HIV-1 Envelope-Specific Breast Milk IgA Responses with Reduced Risk of Postnatal Mother-to-Child Transmission of HIV-1.</a> Journal of Virology. 89 (19), 9952-9961 (2015).</li><li>Ackerman, M., Nimmerjahn, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Antibody Fc. , (2014).</li><li>Huber, V. C., Lynch, J. M., Bucher, D. J., Le, J., Metzger, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fc+receptor-mediated+phagocytosis+makes+a+significant+contribution+to+clearance+of+influenza+virus+infections.">Fc receptor-mediated phagocytosis makes a significant contribution to clearance of influenza virus infections.</a> Journal of Immunology. 166 (12), 7381-7388 (2001).</li><li>Fujisawa, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophils+play+an+essential+role+in+cooperation+with+antibody+in+both+protection+against+and+recovery+from+pulmonary+infection+with+influenza+virus+in+mice.">Neutrophils play an essential role in cooperation with antibody in both protection against and recovery from pulmonary infection with influenza virus in mice.</a> Journal of Virology. 82 (6), 2772-2783 (2008).</li><li>Chung, K. M., Thompson, B. S., Fremont, D. H., Diamond, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibody+recognition+of+cell+surface-associated+NS1+triggers+Fc-gamma+receptor-mediated+phagocytosis+and+clearance+of+West+Nile+Virus-infected+cells.">Antibody recognition of cell surface-associated NS1 triggers Fc-gamma receptor-mediated phagocytosis and clearance of West Nile Virus-infected cells.</a> Journal of Virology. 81 (17), 9551-9555 (2007).</li><li>Yasui, F., 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=Phagocytic+cells+contribute+to+the+antibody-mediated+elimination+of+pulmonary-infected+SARS+coronavirus.">Phagocytic cells contribute to the antibody-mediated elimination of pulmonary-infected SARS coronavirus.</a> Virology. 454-455, 157-168 (2014).</li><li>Quattrocchi, V., 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=Role+of+macrophages+in+early+protective+immune+responses+induced+by+two+vaccines+against+foot+and+mouth+disease.">Role of macrophages in early protective immune responses induced by two vaccines against foot and mouth disease.</a> Antiviral Research. 92 (2), 262-270 (2011).</li><li>Ackerman, M. E., 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=A+robust,+high-throughput+assay+to+determine+the+phagocytic+activity+of+clinical+antibody+samples.">A robust, high-throughput assay to determine the phagocytic activity of clinical antibody samples.</a> Journal of Immunological Methods. 366 (1-2), 8-19 (2011).</li><li>Jiang, 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=Rationally+Designed+Immunogens+Targeting+HIV-1+gp120+V1V2+Induce+Distinct+Conformation-Specific+Antibody+Responses+in+Rabbits.">Rationally Designed Immunogens Targeting HIV-1 gp120 V1V2 Induce Distinct Conformation-Specific Antibody Responses in Rabbits.</a> Journal of Virology. 90 (24), 11007-11019 (2016).</li><li>Sanders, R. 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=A+next-generation+cleaved,+soluble+HIV-1+Env+trimer,+BG505+SOSIP.664+gp140,+expresses+multiple+epitopes+for+broadly+neutralizing+but+not+non-neutralizing+antibodies.">A next-generation cleaved, soluble HIV-1 Env trimer, BG505 SOSIP.664 gp140, expresses multiple epitopes for broadly neutralizing but not non-neutralizing antibodies.</a> PLoS Pathogens. 9 (9), e1003618 (2013).</li><li>Im, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+quantitative+analysis+of+cluster+of+differentiation+45+antigen+expression+on+lymphocyte+subsets.">Comparative quantitative analysis of cluster of differentiation 45 antigen expression on lymphocyte subsets.</a> The Korean Journal of Laboratory Medicine. 31 (3), 148-153 (2011).</li><li>Trend, 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=Leukocyte+Populations+in+Human+Preterm+and+Term+Breast+Milk+Identified+by+Multicolour+Flow+Cytometry.">Leukocyte Populations in Human Preterm and Term Breast Milk Identified by Multicolour Flow Cytometry.</a> PLoS ONE. 10 (8), e0135580 (2015).</li><li>Buescher, E. S., McIlheran, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymorphonuclear+leukocytes+and+human+colostrum:+effects+of+in+vivo+and+in+vitro+exposure.">Polymorphonuclear leukocytes and human colostrum: effects of in vivo and in vitro exposure.</a> Journal of Pediatric Gastroenterology and Nutrition. 17 (4), 424-433 (1993).</li><li>Franca, E. L., 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+colostral+phagocytes+eliminate+enterotoxigenic+Escherichia+coli+opsonized+by+colostrum+supernatant.">Human colostral phagocytes eliminate enterotoxigenic Escherichia coli opsonized by colostrum supernatant.</a> Journal of Microbiology, Immunology and Infection. 44 (1), 1-7 (2011).</li></ol>

The flow cytometry-based technique for measuring ADCP activity described herein was first described in 201130 and has since been proven robust and cited in more than 80 studies. The protocol described here adapts this technique for use with primary BM cells for the first time. Previous studies of Fc-mediated functionality by BM cells have been largely limited to measurement of oxidative bursts or histology-based phagocytosis assays using cells isolated from colostrum (0&#8722;4 days after birth). ...

Human breast milk (BM) is comprised of maternal cells that are &#62;90% viable1. Cell composition is impacted strongly by stage of lactation, health status of mother and infant, and individual variation, which remains poorly understood1,2,3,4. Given that BM contains ~103&#8722;105 leukocytes/mL, it can be estimated that breastfed infants ingest ~105&#8722;108 maternal leukocytes daily5. Various in vivo studies have demonstrated that maternal leukocytes provide critical immunity to the infant and are functional well beyond these sites of initial ingestion5,6,7,8,9,10,11. All maternally-derived cells ingested by the infant have the potential to perform immune functions alongside or to compensate for the infant&#39;s own leukocytes12.
Mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV) remains a crisis in resource-limited countries. As diarrheal and respiratory diseases are responsible for substantial rates of mortality among infants in resource-limited countries, and these illnesses are significantly reduced by exclusive breastfeeding, the benefits to HIV-infected mothers of breastfeeding far outweigh the risks13,14,15. Unless access to clean water and appropriate infant formula is reliable, the WHO does not recommend cessation of breastfeeding for HIV-infected mothers16. Approximately 100,000 MTCTs via BM occur annually; yet, only ~15% of infants breastfed by their HIV-infected mothers become infected, suggesting a strong protective effect of BM17,18,19,20,21. Numerous factors likely work in tandem to prevent transmission. Importantly, HIV-specific antibodies (Abs) in BM have been correlated with reduced MTCT and/or reduced infant death from HIV infection22,23. What remains largely unclear is the contribution of the cellular fraction of BM to its antiviral qualities.
Many Abs facilitate a variety of anti-viral activities mediated by the &#39;constant&#39; region of the immunoglobulin molecule, the crystallizable fragment (Fc), via interaction with Fc receptors (FcRs) found on virtually all innate immune cells, virtually all of which are found in human BM24. Antibody-dependent cellular phagocytosis (ADCP) has been demonstrated as necessary for the clearance of viral infections and has been understudied in the case of prevention of MTCT of HIV25,26,27,28,29. Given the paucity of knowledge about the potential contribution of ADCP activity by BM phagocytes to prevention of MTCT of HIV, we aimed to develop a rigorous method to isolate cells from human BM in order to undertake a study of ADCP mediated by cells from BM obtained at various stages of lactation.

<table border="0" cellpadding="0" cellspacing="0" style="width:725px;" width="727">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">1 &#181;m FluoSpheres NeutrAvidin-Labeled Microspheres&#160;</td>
			<td style="width:193px;">Thermo Fisher</td>
			<td style="width:85px;">F8776</td>
			<td style="width:91px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD Pharmingen PE Mouse Anti-Human CD45</td>
			<td style="width:193px;">BD</td>
			<td style="width:85px;">560975</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine serum Albumin</td>
			<td style="width:193px;">MP Biomedicals</td>
			<td style="width:85px;">8810025</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Corning V-bottom polystyrene 96-well plate&#160;</td>
			<td>Corning&#160;</td>
			<td style="width:85px;">3894</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytochalasin D</td>
			<td style="width:193px;">Sigma</td>
			<td>22144-77-0</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EZ-Link NHS-LC-LC-Biotin kit&#160;</td>
			<td style="width:193px;">Thermo Fisher</td>
			<td style="width:85px;">21338</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">Falcon 15mL Conical Centrifuge Tubes</td>
			<td style="width:193px;">Corning&#160;</td>
			<td style="width:85px;">352196</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">Falcon 50mL Conical Centrifuge Tubes</td>
			<td style="width:193px;">Corning&#160;</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fixable Viability Stain 450&#160;</td>
			<td style="width:193px;">BD</td>
			<td>562247</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Formaldehyde solution</td>
			<td style="width:193px;">Sigma</td>
			<td>252549&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">HBSS without Calcium, Magnesium or Phenol Red</td>
			<td style="width:193px;">Life Technologies</td>
			<td style="width:85px;">14175-095</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human BD Fc Block</td>
			<td>BD</td>
			<td style="width:85px;">564219</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human Serum Albumin</td>
			<td style="width:193px;">MP Biomedicals</td>
			<td style="width:85px;">2191349</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">Kimtech Science Kimwipes Delicate Task Wipers</td>
			<td>Kimberly-Clark Professional&#160;</td>
			<td>34120</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">PBS 1x pH 7.4</td>
			<td style="width:193px;">Thermo Fisher</td>
			<td style="width:85px;">10010023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:356px;">Polystyrene 10mL Serological Pipettes&#160;</td>
			<td style="width:193px;">Corning&#160;</td>
			<td>4488</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protein Concentrators PES, 3K MWCO, 0.5 mL</td>
			<td style="width:193px;">Pierce</td>
			<td style="width:85px;">88512</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of leukocytes from human breast milk for use in an antibody-dependent cellular phagocytosis assay of hiv targets

Even in the absence of antiretroviral drugs, only ~15% of infants breastfed by HIV-infected mothers become infected, suggesting a strong protective effect of breast milk (BM). Unless access to clean water and appropriate infant formula is reliable, the WHO does not recommend cessation of breastfeeding for HIV-infected mothers. Numerous factors likely work in tandem to reduce BM transmission. Breastfed infants ingest ~105&#8722;108 maternal leukocytes daily, though what remains largely unclear is the contribution of these cells to the antiviral qualities of BM. Presently we aimed to isolate cells from human BM in order to measure antibody-dependent cellular phagocytosis (ADCP), one of the most essential and pervasive innate immune responses, by BM phagocytes against HIV targets. Cells were isolated from 5 human BM samples obtained at various stages of lactation. Isolation was carried out via gentle centrifugation followed by careful removal of milk fat and repeated washing of the cell pellet. Fluorescent beads coated with HIV envelope (Env) epitope were used as targets for analysis of ADCP. Cells were stained with the CD45 surface marker to identify leukocytes. It was found that ADCP activity was significant above control experiments and reproducibly measurable using an HIV-specific antibody 830A.

Milk can be kept at room temperature or cooler (though not frozen); however, given that we have observed reduced viability when milk has been kept very cold (data not shown), and that it is simpler to collect, store briefly, and transport at ambient temperatures, it is recommended that samples are not refrigerated in order to reduce sample-to-sample variability. In milk obtained 7&#8722;183 days post-partum, cell concentration determined by automated cell counter ranged from 16,083&#8722;...

Watch this Scientific Journal Video about Isolation of Leukocytes from Human Breast Milk for Use in an Antibody-dependent Cellular Phagocytosis Assay of HIV Targets at JoVE.com

Isolation of Leukocytes from Human Breast Milk for Use in an Antibody-dependent Cellular Phagocytosis Assay of HIV Targets

Breast milk transmits human immunodeficiency virus (HIV), though only ~15% of infants breastfed by HIV-infected mothers become infected. Breastfed infants ingest ~105&#8722;108 maternal leukocytes daily, though these cells are understudied. Here we describe the isolation of breast milk leukocytes and an analysis of their phagocytic capacity.

Even in the absence of antiretroviral drugs, only ~15% of infants breastfed by HIV-infected mothers become infected, suggesting a strong protective effect ...

We developed a rigorous method for isolating cells from human breast milk to study antibody dependent cellular phagocytosis, or ADCP, by breast milk phagocytes against HIV targets. This technique facilitates the relatively quick and easy isolation of breast milk cells to evaluate the capacity of leukocyte populations to perform ADCP. Demonstrating the procedure will be Alisa Fox, a technician from my laboratory.After selecting a relevant target antigen, use a commercial kit to biotinylate the protein of interest according to the manufacturer's protocol. And deposit the biotinylated sample into the upper chamber of a spin column. Add PBS up to 400 microliters and cap the chamber before inserting the column into a collection tube for centrifugation.After discarding the flow through, add PBS to 400 microliters for a second centrifugation. Discard the flow through, add PBS to 400 microliters, and measure the protein concentration by a spectrophotometer to conjugate the biotinylated protein to micrometer microspheres. Incubate six micrograms of protein with 12 microliters of stock beads in 200 microliters of PBS per plate of conjugated beads at room temperature for two hours, with gentle vortexing every 20 minutes.At the end of the incubation, pellet the protein conjugated beads by centrifugation and discard the supernatant. After gentle vortexing, resuspend the protein in 1200 microliters of 0.1%BSA in PBS, and wash the tube by centrifugation two more times as just demonstrated. After the last wash, resuspend the pellet in 1200 microliters in PBS plus BSA.To set up ADCP Assay Plates, first prepare 12 microliter dilutions of antibody, or the immune serum of interest, in 2%BSA in PBS in a round bottom 96 well plate. Add 10 microliters of protein conjugated beads per well to the plate for a two hour incubation at 37 degrees Celsius. At the end of the incubation, add 200 microliters of PBS plus BSA.After obtaining human breast milk from healthy lactating women expressing using a pump, within four hours of expression separate the milk contents by centrifugation and carefully pour off the skim milk and fat, leaving the cell pellet undisturbed. Wipe the inside of the tube with a lint-free wipe to remove all of the fat from the tube wall and add 10 milliliters of PBS plus HSA. Resuspend the pellet with gentle pipetting to avoid cell activation in the apoptosis, and transfer the cell suspension to a 15 milliliter tube for centrifugation.After a second wash in PBS plus HSA as just demonstrated, gently resuspend the cells in one to two milliliters of fresh PBS plus HSA for counting. For an ADCP Assay, quickly invert the prepared ADCP plate to decant the supernatant after the final centrifugation and add five times 10 at a fourth freshly isolated breast milk cells in 200 microliters of PBS plus BSA for a two hour incubation at 37 degrees Celsius. At the end of the incubation, centrifuge the cells and wash the pellets two times in 200 microliters of fresh PBS as demonstrated.After the last wash, stain the cells with 0.5 micrograms per milliliter of fixable viability stain 450 per well in 50 microliters of PBS for 30 minutes at room temperature, protected from light. At the end of the incubation, pellet the cells for two washes in fresh PBS as demonstrated, and stain the cells for the leukocyte markers of interest for 30 minutes at room temperature, protected from light. At the end of the incubation, collect the cells centrifugation, and wash the cells two times in 200 microliters of 1%BSA plus PBS per wash.After the last wash, fix the pellets in 200 microliters of 0.5%formaldehyde per well for 30 minutes at room temperature, protected from light. For flow cytometric analysis of the cell samples, set a flow cytometer equipped with a high-throughput plate reader to withdraw 175 microliters of sample and to collect 5000 cells per well. Perform the initial gating to eliminate doublets and debris on a forward scatter versus side scatter plot.Use a side scatter versus viability stain plot to eliminate the dead cells. And use a side scatter versus CD45 plot to differentiate the major leukocyte classes. For all CD45 positive cells, or for each leukocyte subset of interest, measure the antibody dependent cellular phagocytosis activity by gating with a marker on the bead positive cells in a histogram of the appropriate fluorophore channel for the conjugated beads.Then calculate the antibody dependent cellular phagocytosis scores as the median of the fluorescence intensity of the bead positive cells by the percentage of the total CD45 plus the cells in the positive population. Here, the gating strategy for eliminating doublets, debris, and dead cells is shown. Between one to 12%of total live cells are typically CD45 positive leukocytes with most of the purported side scatter low to intermediate CD45 low monocytes appearing to be precursors, or to immature cells, based on the side scatter versus CD45 gating.The purported granulocytes are defined as side scatter high, CD45 intermediate cells. Measurement of the ADCP activity of freshly isolated breast milk cells using an HIV specific human monoclonal antibody at one month postpartum reveals that treatment with actin inhibitor Cytochalasin D and or Fc receptor blocking antibodies prior to incubation with antibody bound antigen coupled beads results in the ADCP activity at or below that observed in the presence of control antibody. The ADCP score determined for total CD45 positive cells is commonly between 25 to 35 fold above the background levels, defined using a negative control, anti-anthrax monoclonal antibody.Every breast milk sample is unique and some pellets may be hard to see. In addition, the leukocyte populations, and therefore the ADCP scores, may vary immensely from sample to sample.

isolation-leukocytes-from-human-breast-milk-for-use-an-antibody

Research

JoVE Journal

Immunology and Infection

Genotypic Inference of HIV-1 Tropism Using Population-based Sequencing of V3

Background: Prior to receiving a drug from CCR5-antagonist class in HIV therapy, a patient must undergo an HIV tropism test to confirm that his or her viral population uses the CCR5 coreceptor for cellular entry, and not an alternative coreceptor. One approach to tropism testing is to examine the sequence of the V3 region of the HIV envelope, which interacts with the coreceptor.
Methods: Viral RNA is extracted from blood plasma. The V3 region is amplified in triplicate with nested reverse transcriptase-PCR. The amplifications are then sequenced and analyzed using the software, RE_Call. Sequences are then submitted to a bioinformatic algorithm such as geno2pheno to infer viral tropism from the V3 region. Sequences are inferred to be non-R5 if their geno2pheno false positive rate falls below 5.75%. If any one of the three sequences from a sample is inferred to be non-R5, the patient is unlikely to respond to a CCR5-antagonist.

HIV tropism can be inferred from the V3 region of the viral envelope. V3 is PCR amplified in triplicate using nested RT-PCR, sequenced, and interpreted using bioinformatic software. Samples with with 1 or more sequence(s) with low g2P scores are classified as non-R5 virus.

Background: Prior to receiving a drug from CCR5-antagonist class in HIV therapy, a patient must undergo an HIV tropism test to confirm that his or her ...

Isolation of Brain-infiltrating Leukocytes

We describe a method for preparing brain infiltrating leukocytes (BILs) from mice. We demonstrate how to infect mice with Theiler's murine encephalomyelitis virus (TMEV) via a rapid intracranial injection technique and how to purify a leukocyte-enriched population of infiltrating cells from whole brain. Briefly, mice are anesthetized with isoflurane in a closed chamber and are free-hand injected with a Hamilton syringe into the frontal cortex. Mice are then killed at various times after infection by isoflurane overdose and whole brains are extracted and homogenized in RPMI with a Tenbroeck tissue grinder. Brain homogenates are centrifuged through a continuous 30% Percoll gradient to remove the myelin and other cell debris. The cell suspension is then strained at 40 &mu;m, washed and centrifuged on a discontinuous Ficoll-Paque Plus gradient to select and purify the leukocytes. The leukocytes are then washed and resuspended in appropriate buffers for immunophenotyping by flow cytometry. Flow cytometry reveals a population of innate immune cells at the early stages of infection in C57BL/6 mice. At 24 hours post infection, multiple subsets of immune cells are present in the BILs, with an enriched population of Gr1+, CD11b+ and F4/80+cells. Therefore, this method is useful in characterizing the immune response to acute infection in the brain.

A rapid method to obtain infiltrating leukocytes from the murine brain is described. This method utilizes a continuous Percoll gradient and discontinuous Ficoll gradient to select and purify the leukocyte-enriched layer. Isolated leukocytes may then be characterized by flow cytometric measurements.

We describe a method for preparing brain infiltrating leukocytes (BILs) from mice. We demonstrate how to infect mice with Theiler's murine ...

Bioenergetics and the Oxidative Burst: Protocols for the Isolation and Evaluation of Human Leukocytes and Platelets

Mitochondrial dysfunction is known to play a significant role in a number of pathological conditions such as atherosclerosis, diabetes, septic shock, and neurodegenerative diseases but assessing changes in bioenergetic function in patients is challenging.&#160;Although diseases such as diabetes or atherosclerosis present clinically with specific organ impairment, the systemic components of the pathology, such as hyperglycemia or inflammation, can alter bioenergetic function in circulating leukocytes or platelets. This concept has been recognized for some time but its widespread application has been constrained by the large number of primary cells needed for bioenergetic analysis.&#160;This technical limitation has been overcome by combining the specificity of the magnetic bead isolation techniques, cell adhesion techniques, which allow cells to be attached without activation to microplates, and the sensitivity of new technologies designed for high throughput microplate respirometry.&#160;An example of this equipment is the extracellular flux analyzer. Such instrumentation typically uses oxygen and pH sensitive probes to measure rates of change in these parameters in adherent cells, which can then be related to metabolism. Here we detail the methods for the isolation and plating of monocytes, lymphocytes, neutrophils and platelets, without activation, from human blood and the analysis of mitochondrial bioenergetic function in these cells. In addition, we demonstrate how the oxidative burst in monocytes and neutrophils can also be measured in the same samples. Since these methods use only 8-20 ml human blood they have potential for monitoring reactive oxygen species generation and bioenergetics in a clinical setting.

Blood leukocytes and platelets can be used as a marker of overall bioenergetic health of an individual and so have the potential to monitor pathological processes and the impact of treatments. Here&#160;we describe a method to isolate and measure mitochondrial function and the oxidative burst in these cells.

Mitochondrial dysfunction is known to play a significant role in a number of pathological conditions such as atherosclerosis, diabetes, septic shock, and ...

Isolation of Leukocytes from the Human Maternal-fetal Interface

Pregnancy is characterized by the infiltration of leukocytes in the reproductive tissues and at the maternal-fetal interface (decidua basalis and decidua parietalis). This interface is the anatomical site of contact between maternal and fetal tissues; therefore, it is an immunological site of action during pregnancy. Infiltrating leukocytes at the maternal-fetal interface play a central role in implantation, pregnancy maintenance, and timing of delivery. Therefore, phenotypic and functional characterizations of these leukocytes will provide insight into the mechanisms that lead to&#160;pregnancy disorders. Several protocols have been described in order to isolate infiltrating leukocytes from the decidua basalis and decidua parietalis; however, the lack of consistency in the reagents, enzymes, and times of incubation makes it difficult to compare these results. Described herein is&#160;a novel approach that combines the use of gentle mechanical and enzymatic dissociation techniques to preserve the viability and integrity of extracellular and intracellular markers in leukocytes isolated from the human tissues at the maternal-fetal interface. Aside from immunophenotyping, cell culture, and cell sorting, the future applications of this protocol are numerous and varied. Following this protocol, the isolated leukocytes can be used to determine DNA methylation, expression of target genes, in vitro leukocyte functionality (i.e., phagocytosis, cytotoxicity, T-cell proliferation, and plasticity, etc.), and the production of reactive oxygen species at the maternal-fetal interface. Additionally, using the described protocol, this laboratory has been able to describe new and rare leukocytes at the maternal-fetal interface.

Described herein is a protocol to isolate and further study the infiltrating leukocytes of the decidua basalis and decidua parietalis - the human maternal-fetal interface. This protocol maintains the integrity of cell surface markers and yields enough viable cells for downstream applications as proven by flow cytometry analysis.

Pregnancy is characterized by the infiltration of leukocytes in the reproductive tissues and at the maternal-fetal interface (decidua basalis and decidua ...

Isolation of Leukocytes from the Murine Tissues at the Maternal-Fetal Interface

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing fetus. This tolerance is initiated during coitus, established during fecundation and implantation, and maintained throughout pregnancy. Active cellular and molecular mediators of maternal-fetal tolerance are enriched at the site of contact between fetal and maternal tissues, known as the maternal-fetal interface, which includes the placenta and the uterine and decidual tissues. This interface is comprised of stromal cells and infiltrating leukocytes, and their abundance and phenotypic characteristics change over the course of pregnancy. Infiltrating leukocytes at the maternal-fetal interface include neutrophils, macrophages, dendritic cells, mast cells, T cells, B cells, NK cells, and NKT cells that together create the local micro-environment that sustains pregnancy. An imbalance among these cells or any inappropriate alteration in their phenotypes is considered a mechanism of disease in pregnancy. Therefore, the study of leukocytes that infiltrate the maternal-fetal interface is essential in order to elucidate the immune mechanisms that lead to pregnancy-related complications. Described herein is a protocol that uses a combination of gentle mechanical dissociation followed by a robust enzymatic disaggregation with a proteolytic and collagenolytic enzymatic cocktail to isolate the infiltrating leukocytes from the murine tissues at the maternal-fetal interface. This protocol allows for the isolation of high numbers of viable leukocytes (&#62;70%) with sufficiently conserved antigenic and functional properties. Isolated leukocytes can then be analyzed by several techniques, including immunophenotyping, cell sorting, imaging, immunoblotting, mRNA expression, cell culture, and in vitro functional assays such as mixed leukocyte reactions, proliferation, or cytotoxicity assays.

Described herein is a protocol to isolate and analyze the infiltrating leukocytes of tissues at the maternal-fetal interface (uterus, decidua, and placenta) of mice. This protocol maintains the integrity of most cell surface markers and yields enough viable cells for downstream applications including flow cytometry analysis.

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing ...

Isolation of Exosomes from the Plasma of HIV-1 Positive Individuals

Exosomes are small vesicles ranging in size from 30 nm to 100 nm that are released both constitutively and upon stimulation from a variety of cell types. They are found in a number of biological fluids and are known to carry a variety of proteins, lipids, and nucleic acid molecules. Originally thought to be little more than reservoirs for cellular debris, the roles of exosomes regulating biological processes and in diseases are increasingly appreciated.
Several methods have been described for isolating exosomes from cellular culture media and biological fluids. Due to their small size and low density, differential ultracentrifugation and/or ultrafiltration are the most commonly used techniques for exosome isolation. However, plasma of HIV-1 infected individuals contains both exosomes and HIV viral particles, which are similar in size and density. Thus, efficient separation of exosomes from HIV viral particles in human plasma has been a challenge.
To address this limitation, we developed a procedure modified from Cantin et. al., 2008 for purification of exosomes from HIV particles in human plasma. Iodixanol velocity gradients were used to separate exosomes from HIV-1 particles in the plasma of HIV-1 positive individuals. Virus particles were identified by p24 ELISA. Exosomes were identified on the basis of exosome markers acetylcholinesterase (AChE), and the CD9, CD63, and CD45 antigens. Our gradient procedure yielded exosome preparations free of virus particles. The efficient purification of exosomes from human plasma enabled us to examine the content of plasma-derived exosomes and to investigate their immune modulatory potential and other biological functions.

Techniques describing a gradient procedure to separate exosomes from human immunodeficiency virus (HIV) particles are described. This procedure was used to isolate exosomes away from HIV particles in human plasma from HIV-infected individuals. The isolated exosomes were analyzed for cytokine/chemokine content.

Exosomes are small vesicles ranging in size from 30 nm to 100 nm that are released both constitutively and upon stimulation from a variety of cell types. ...

Isolation of Infiltrating Leukocytes from Mouse Skin Using Enzymatic Digest and Gradient Separation

Dissociating murine skin into a single cell suspension is essential for downstream cellular analysis such as the characterization of infiltrating immune cells in rodent models of skin inflammation. Here, we describe a protocol for the digestion of mouse skin in a nutrient-rich solution with collagenase D, followed by separation of hematopoietic cells using a discontinuous density gradient. Cells thus obtained can be used for in vitro studies, in vivo transfer, and other downstream cellular and molecular analyses including flow cytometry. This protocol is an effective and economical alternative to expensive mechanical dissociators, specialized separation columns, and harsher trypsin- and dispase-based digestion methods, which may compromise cellular viability or density of surface proteins relevant for phenotypic characterization or cellular function. As shown here in our representative data, this protocol produced highly viable cells, contained specific immune cell subsets, and had no effect on integrity of common surface marker proteins used in flow cytometric analysis.

This protocol describes enzymatic digestion of mouse skin in nutrient-rich medium followed by gradient separation to isolate leukocytes. Cells thus derived can be used for diverse downstream applications. This is an effective, economical, and improved alternative to tissue dissociation machines and harsher trypsin and dispase-based tissue digestion protocols.

Dissociating murine skin into a single cell suspension is essential for downstream cellular analysis such as the characterization of infiltrating immune ...

Use of a Monocyte Monolayer Assay to Evaluate Fc&#947; Receptor-mediated Phagocytosis

Although originally developed for predicting transfusion outcomes of serologically incompatible blood, the monocyte monolayer assay (MMA) is a highly versatile in vitro assay that can be modified to examine different aspects of antibody and Fc&#947; receptor (Fc&#947;R)-mediated phagocytosis in both research and clinical settings. The assay utilizes adherent monocytes from peripheral blood mononuclear cells isolated from mammalian whole blood. MMA has been described for use in both human and murine investigations. These monocytes express Fc&#947;Rs (e.g., Fc&#947;RI, Fc&#947;RIIA, Fc&#947;RIIB, and Fc&#947;RIIIA) that are involved in immune responses. The MMA exploits the mechanism of Fc&#947;R-mediated interactions, phagocytosis in particular, where antibody-sensitized red blood cells (RBCs) adhere to and/or activate Fc&#947;Rs and are subsequently phagocytosed by the monocytes. In vivo, primarily tissue macrophages found in the spleen and liver carry out Fc&#947;R-mediated phagocytosis of antibody-opsonized RBCs, causing extravascular hemolysis. By evaluating the level of phagocytosis using the MMA, different aspects of the in vivo Fc&#947;R-mediated process can be investigated. Some applications of the MMA include predicting the clinical relevance of allo- or autoantibodies in a transfusion setting, assessing candidate drugs that promote or inhibit phagocytosis, and combining the assay with fluorescent microscopy or traditional Western immunoblotting to investigate the downstream signaling effects of Fc&#947;R-engaging drugs or antibodies. Some limitations include the laboriousness of this technique, which takes a full day from start to finish, and the requirement of research ethics approval in order to work with mammalian blood. However, with diligence and adequate training, the MMA results can be obtained within a 24-h turnover time.

The monocyte monolayer assay (MMA) is an in vitro assay that utilizes isolated primary monocytes obtained from mammalian peripheral whole blood to evaluate Fc&#947; receptor (Fc&#947;R)-mediated phagocytosis.

Although originally developed for predicting transfusion outcomes of serologically incompatible blood, the monocyte monolayer assay (MMA) is a highly ...

Phagocytosis Assay for Apoptotic Cells in Drosophila Embryos

The molecular mechanisms underlying the phagocytosis of apoptotic cells need to be elucidated in more detail because of its role in immune and inflammatory intractable diseases. We herein developed an experimental method to investigate phagocytosis quantitatively using the fruit fly Drosophila, in which the gene network controlling engulfment reactions is evolutionally conserved from mammals. In order to accurately detect and count engulfing and un-engulfing phagocytes using whole animals, Drosophila embryos were homogenized to obtain dispersed cells including phagocytes and apoptotic cells. The use of dispersed embryonic cells enables us to measure in vivo phagocytosis levels as if we performed an in vitro phagocytosis assay in which it is possible to observe all phagocytes and apoptotic cells in whole embryos and precisely quantify the level of phagocytosis. We confirmed that this method reproduces those of previous studies that identified the genes required for the phagocytosis of apoptotic cells. This method allows the engulfment of dead cells to be analyzed, and when combined with the powerful genetics of Drosophila, will reveal the complex phagocytic reactions comprised of the migration, recognition, engulfment, and degradation of apoptotic cells by phagocytes.

Phagocytosis Assay for Apoptotic Cells in Drosophila Embryos

We herein describe a phagocytosis assay using the dispersed embryonic cells of Drosophila. It enables us to easily and precisely quantify in vivo phagocytosis levels, and to identify new molecules required for the phagocytosis of apoptotic cells.

The molecular mechanisms underlying the phagocytosis of apoptotic cells need to be elucidated in more detail because of its role in immune and ...

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. typhimurium bacteria are quickly detected and phagocytized by macrophages, and contained in vesicles known as phagosomes in order to be degraded. Isolation of S. typhimurium-containing phagosomes have been widely used to study how S. typhimurium infection alters the process of phagosome maturation to prevent bacterial degradation. Classically, the isolation of bacteria-containing phagosomes has been performed by sucrose gradient centrifugation. However, this process is time-consuming, and requires specialized equipment and a certain degree of dexterity. Described here is a simple and quick method for the isolation of S. typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin-streptavidin-conjugated magnetic beads. Phagosomes obtained by this method can be suspended in any buffer of choice, allowing the utilization of isolated phagosomes for a broad range of assays, such as protein, metabolite, and lipid analysis. In summary, this method for the isolation of S. typhimurium-containing phagosomes is specific, efficient, rapid, requires minimum equipment, and is more versatile than the classical method of isolation by sucrose gradient-ultracentrifugation.

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

We describe here a simple and quick method for the isolation of Salmonella typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin and streptavidin.