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. 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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.

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	<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>
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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;...

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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.

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