The authors would like to thank Nancy Mora for her technical assistance.
This work was funded by research grants 48573-M and 168098 from Consejo Nacional de Ciencia y Tecnologia, Mexico, and by grants IN212308 and IN205311-2 from Direccion General de Asuntos del Personal Academico, Universidad Nacional Autonoma de Mexico, Mexico.

1. Isolation of Neutrophils (PMN) from Human Blood
<ol>
	<li>Use about 20 ml human blood with heparin (10 U/ml) as anticoagulant. Blood was collected from adult healthy volunteers by venopuncture. All experiments were done under approval of the Bioethics Committee at the Instituto de Investigaciones Biom&eacute;dicas - UNAM.</li>
	<li>Put 2 ml of 6% dextran T500 in PBS into a 15 ml conical centrifuge tube and add 10 ml of blood. Mix by inverting the tube two or three times and let it sit for 45 min to allow for erythro...

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Meth. 320, 104-118 (2007).</li><li>Garcia-Garcia, E., Nieto-Castaneda, G., Ruiz-Saldana, M., Mora, N., Rosales, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fc&#947;RIIA+and+Fc&#947;RIIIB+mediate+nuclear+factor+activation+through+separate+signaling+pathways+in+human+neuthophils.">Fc&#947;RIIA and Fc&#947;RIIIB mediate nuclear factor activation through separate signaling pathways in human neuthophils.</a> J. Immunol. 182, 4547-4556 (2009).</li></ol>

The purification method described here allows the isolation of unstimulated neutrophils (PMN) with purity greater than 95% (assessed by microscopic observation), in a short time. Sometimes neutrophils can be contaminated by erythrocytes if the latter are not lysed completely. This does not usually affect the technique, since erythrocytes and PMN can easily be distinguished as distinct cell populations by flow cytometry. Isolated PMN can then be stimulated by crosslinking particular receptors with specific monoclon...

Neutrophils are the most abundant leukocytes in peripheral blood 1. During inflammation and infection neutrophils are the first cells to appear at the affected site where they act as the first line of defense 2. Neutrophils possess several antimicrobial mechanisms 3 including phagocytosis, production of reactive oxygen species, release of lytic enzymes by degranulation, and production of proinflammatory cytokines 4,5. Neutrophils are short-lived cells that get rapidly activated through signaling from various cell surface receptors. Although neutrophils have been considered terminal cells due to their short life and because they undergo apoptosis unless activated during the inflammatory process 6, it is now clear that they can also modify their phenotype by changing the level of transcription of particular genes. The production of cytokines 5 and the inhibition of apoptosis 7,8 are two important activation-dependent cell functions regulated at the level of transcription in neutrophils. Nuclear factor &kappa;B (NF-&kappa;B) participates in the transcriptional control of cytokine production 4 and in the regulation of cell survival and apoptosis 9-11 in various cell types.
The signaling pathways that lead to nuclear factor activation are usually studied by reporter gene assays or by electrophoretic mobility shift assays (EMSA). However, because neutrophils are short-lived cells, the study of transcriptionally regulated responses in these cells cannot be performed with reporter gene assays, since there are no efficient techniques for neutrophil transfection. EMSA assays have been used in neutrophils to explore nuclear factor activation 12,13; however, this methodology is complicated and expensive because it involves the use of radioactive material. Nucleofection is another technique that has been used successfully to transfect monocytes 14. Thus, at least in theory, nuclear factor activation could be detected in neutrophils by transfection (despite low efficiency). However, this technique would be more expensive, time-consuming and probably less quantitative. Microscopic analysis of immunostained cells could also be used to detect nuclear factors in the nucleus. Indeed, we have detected NF-&kappa;B translocation into the nucleus this way 15. Unfortunately, this technique is also time-consuming, less quantitative, and subject to the observer's bias.
Here, we present a simple and efficient method that allows detection and quantification of nuclear factors in isolated and immunolabeled nuclei by flow cytometry. We describe techniques to isolate neutrophils from human peripheral blood, stimulate these cells via integrins or Fc receptors with anti-receptor antibodies, isolate and immunolabel nuclei, and analyze nuclei by flow cytometry (Figure 1). The method has been successfully used to detect NF-&kappa;B 15 and Elk-1 16 nuclear factors in neutrophil nuclei. The sensitivity of this method allows detection of small changes in nuclear factor levels in the nucleus. This method can also be used to analyze the level of transcription factors in nuclei from other cell types.

<table border="1">
<tbody>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>REAGENTS</td>
 </tr>
 <tr>
 <td >Heparin </td>
 <td >PiSA (Mexico)</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td >Dextran T500</td>
 <td >Pharmacosmos A/S (Holbaek, Denmark) </td>
 <td>T1-Dextran T500</td>
 <td></td>
 </tr>
 <tr>
 <td >Ficoll-Paque</td>
 <td >Pharmacia</td>
 <td>17-0320-01 </td>
 <td></td>
 </tr>
 <tr>
 <td >Sodium chloride </td>
 <td >Sigma</td>
 <td>S7653 </td>
 <td></td>
 </tr>
 <tr>
 <td >Sodium phosphate monobasic</td>
 <td >Sigma</td>
 <td>S9638</td>
 <td></td>
 </tr>
 <tr>
 <td >Sodium phosphate dibasic</td>
 <td >Sigma</td>
 <td>S9390</td>
 <td></td>
 </tr>
 <tr>
 <td >Bovine serum albumin (BSA)</td>
 <td >Sigma</td>
 <td>A2153</td>
 <td>Cohn Fraction V</td>
 </tr>
 <tr>
 <td >HEPES</td>
 <td >Sigma</td>
 <td>H3375 </td>
 <td></td>
 </tr>
 <tr>
 <td >Potassium chloride</td>
 <td >Sigma</td>
 <td>P9541 </td>
 <td></td>
 </tr>
 <tr>
 <td >Magnesium chloride anhydrous </td>
 <td >Sigma</td>
 <td>M8266 </td>
 <td></td>
 </tr>
 <tr>
 <td >DL-dithiothreitol (DTT) </td>
 <td >Sigma</td>
 <td>D9163</td>
 <td></td>
 </tr>
 <tr>
 <td >Trypan Blue (0.4 % solution)</td>
 <td >Sigma</td>
 <td>T8154</td>
 <td></td>
 </tr>
 <tr>
 <td >Paraformaldehyde</td>
 <td >Sigma</td>
 <td>P6148 </td>
 <td></td>
 </tr>
 <tr>
 <td >Triton X-100 </td>
 <td >Sigma</td>
 <td>X100</td>
 <td></td>
 </tr>
 <tr>
 <td >Fetal bovine serum (FBS)</td>
 <td >GIBCO</td>
 <td>10437-028</td>
 <td></td>
 </tr>
 <tr>
 <td >Monoclonal antibody IV.3</td>
 <td >Medarex (Annandale, NJ) </td>
 <td>025-1 </td>
 <td>Human-specific anti-FcRII (CD32) </td>
 </tr>
 <tr>
 <td >Monoclonal antibody 3G8</td>
 <td >Medarex (Annandale, NJ) </td>
 <td>028-2 </td>
 <td>Human-specific anti-FcRIII (CD16) </td>
 </tr>
 <tr>
 <td >Monoclonal antibody TS2/16</td>
 <td >Dana Farber Cancer Research Institute (Boston, MA) </td>
 <td>Donated by Dr. Martin Hemler </td>
 <td>Human-specific anti-&beta;1 integrin (CD29)</td>
 </tr>
 <tr>
 <td >Monoclonal antibody IB4</td>
 <td >University of California, San Francisco </td>
 <td>Donated by Dr. Eric J. Brown </td>
 <td>Human-specific anti-&beta;2 integrin (CD18)</td>
 </tr>
 <tr>
 <td >F(ab')2 goat anti-mouse IgG </td>
 <td >Cappel (Aurora, OH)</td>
 <td>55468</td>
 <td></td>
 </tr>
 <tr>
 <td>FITC-conjugated F(ab')2 goat anti-mouse IgG</td>
 <td >Cappel (Aurora, OH)</td>
 <td>55522</td>
 <td></td>
 </tr>
 <tr>
 <td>FITC-conjugated F(ab')2 goat anti-rabbit IgG</td>
 <td >Cappel (Aurora, OH)</td>
 <td>55665</td>
 <td></td>
 </tr>
 <tr>
 <td>Anti-NF-&kappa;B p50</td>
 <td >Santa Cruz Biotechnology (Santa Cruz, CA)</td>
 <td>sc-114</td>
 <td>Rabbit polyclonal antibody</td>
 </tr>
 <tr>
 <td>Anti-NF-&kappa;B p65</td>
 <td >Santa Cruz Biotechnology (Santa Cruz, CA)</td>
 <td>sc-109</td>
 <td>Rabbit polyclonal antibody</td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>EQUIPMENT</td>
 </tr>
 <tr>
 <td>15-ml centrifuge tube</td>
 <td >Corning</td>
 <td>430791</td>
 <td></td>
 </tr>
 <tr>
 <td>50-ml centrifuge tube</td>
 <td >Corning</td>
 <td>430291</td>
 <td></td>
 </tr>
 <tr>
 <td>Centrifuge, Sorvall Tabletop</td>
 <td >Dupont Instruments</td>
 <td>RT 6000D</td>
 <td></td>
 </tr>
 <tr>
 <td>pH-meter</td>
 <td >Corning</td>
 <td>340</td>
 <td></td>
 </tr>
 <tr>
 <td>Pipetman pipette P-20</td>
 <td >Gilson </td>
 <td>F123600</td>
 <td></td>
 </tr>
 <tr>
 <td>Pipetman pipette P-200</td>
 <td >Gilson </td>
 <td>F123601</td>
 <td></td>
 </tr>
 <tr>
 <td>Pipetman pipette P-1000</td>
 <td >Gilson </td>
 <td>F123602</td>
 <td></td>
 </tr>
 <tr>
 <td>Hemocytometer</td>
 <td >Fisher Scientific</td>
 <td>0267110</td>
 <td></td>
 </tr>
 <tr>
 <td>Microscope</td>
 <td >Nikon </td>
 <td>Eclipse E600</td>
 <td></td>
 </tr>
 <tr>
 <td>Inverted microscope</td>
 <td >Nikon </td>
 <td>TMS</td>
 <td></td>
 </tr>
 <tr>
 <td>Water Bath Incubator</td>
 <td >Fisher Scientific </td>
 <td>2IS-M</td>
 <td></td>
 </tr>
 <tr>
 <td>Microcentrifuge</td>
 <td >Eppendorf</td>
 <td>5414C</td>
 <td></td>
 </tr>
 <tr>
 <td>Microcentrifuge</td>
 <td >Eppendorf</td>
 <td>5418</td>
 <td></td>
 </tr>
 <tr>
 <td>Flow Cytometer</td>
 <td >Becton Dickinson (Franklin Lakes, NJ) </td>
 <td>FACScalibur </td>
 <td></td>
 </tr>
 </tbody>
</table>

a simple and efficient method to detect nuclear factor activation in human neutrophils by flow cytometry

Neutrophils are the most abundant leukocytes in peripheral blood. These cells are the first to appear at sites of inflammation and infection, thus becoming the first line of defense against invading microorganisms. Neutrophils possess important antimicrobial functions such as phagocytosis, release of lytic enzymes, and production of reactive oxygen species. In addition to these important defense functions, neutrophils perform other tasks in response to infection such as production of proinflammatory cytokines and inhibition of apoptosis. Cytokines recruit other leukocytes that help clear the infection, and inhibition of apoptosis allows the neutrophil to live longer at the site of infection. These functions are regulated at the level of transcription. However, because neutrophils are short-lived cells, the study of transcriptionally regulated responses in these cells cannot be performed with conventional reporter gene methods since there are no efficient techniques for neutrophil transfection. Here, we present a simple and efficient method that allows detection and quantification of nuclear factors in isolated and immunolabeled nuclei by flow cytometry. We describe techniques to isolate pure neutrophils from human peripheral blood, stimulate these cells with anti-receptor antibodies, isolate and immunolabel nuclei, and analyze nuclei by flow cytometry. The method has been successfully used to detect NF-&kappa;B and Elk-1 nuclear factors in nuclei from neutrophils and other cell types. Thus, this method represents an option for analyzing activation of transcription factors in isolated nuclei from a variety of cell types.

The purification method described here usually provides unstimulated neutrophils (PMN) with purity greater than 95% (Figure 1A). Isolated PMN can then be stimulated by crosslinking particular receptors with specific monoclonal antibodies. We have stimulated PMN through Fc receptors and integrins (Figure 1B). Once stimulated, PMN are lysed and nuclei are isolated with high yields. Nuclei are then immunolabeled for a particular nuclear factor, such as the nuclear factor &kappa;B (NF-&...

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A Simple and Efficient Method to Detect Nuclear Factor Activation in Human Neutrophils by Flow Cytometry

Neutrophils are the most abundant leukocytes in blood. Neutrophils possess transcriptionally regulated functions such as production of proinflammatory cytokines and inhibition of apoptosis. These functions can be studied with the method presented here, which allows detection and quantification of nuclear factors by flow cytometry in isolated nuclei

Neutrophils  are the most abundant leukocytes in peripheral blood. These cells are the first  to appear at sites of inflammation and infection, thus ...

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Immunology and Infection

17.7K Views.  University of Alberta. Neutrophils are the most abundant leukocytes in blood. Neutrophils possess transcriptionally regulated functions such as production of proinflammatory cytokines and inhibition of apoptosis. These functions can be studied with the method presented here, which allows detection and quantification of nuclear factors by flow cytometry in isolated nuclei