The authors would like to acknowledge Dr. Ellen M. Fox for her work regarding this model of local anaphylaxis. This work was supported by the Uniformed Services University of the Health Sciences grant number R073UE.

1. Sensitize Mice
<ol>
	<li>Prepare an OVA stock solution by diluting OVA in 1x PBS to a final concentration of 20 mg/ml. Freeze down aliquots in cryovials and store at -80 &#176;C for future use.</li>
	<li>Bring one or more aliquots of 20 mg/ml OVA stock to room temperature. Dilute OVA in 1x PBS to a final concentration of 1 mg/ml in a 5 ml polystyrene round bottom tube with a cap. Vortex briefly to mix.</li>
	<li>While holding the polystyrene tube containing the 1 mg/ml OVA on a vortex set at medium speed, add an equal volume of thoroughly homogenized Imject Alum (40 mg/ml) dropwise while continuing to vortex the tube to produce a 1:1 ratio of Alum to immunogen.</li>
	<li>Place cap on tube and tape tube to vortex. Turn vortex on lowest setting and allow OVA to adsorb to Alum for 30 min.
	<ol>
		<li>Do not allow a large amount of time to pass between preparing OVA/Alum and sensitizing mice. If sensitization cannot be completed directly after OVA/Alum preparation, store OVA/Alum at room temperature. Vortex for 1 min before using.</li>
	</ol>
	</li>
	<li>Load a 1 ml insulin syringe with OVA/Alum mixture. Cap the syringe with 27 gauge needle.</li>
	<li>Inject 100 &#956;l of OVA/Alum into the peritoneum of BALB/c mice for a dose per mouse of 50 &#956;g of OVA and 2 mg of Alum.</li>
	<li>For a negative control, sensitize another group of mice to PBS. Prepare a 1:1 mixture of Alum and PBS in same manner as listed above, omitting OVA.</li>
	<li>Sensitize all mice (OVA and PBS control) once per week for 3 weeks for a total of 3 injections. After final injection, wait at least 2 weeks before performing the local anaphylaxis assay.</li>
</ol>
2. Local Anaphylaxis Assay
<ol>
	<li>Bring OVA stock solution to room temperature. In a 1.5 ml microcentrifuge tube, dilute 20 mg/ml OVA stock to a final concentration of 5 mg/ml with PBS (1:4 dilution of OVA in 1X PBS). Vortex briefly to mix.</li>
	<li>Anesthetize mice using RC2 Rodent Anesthesia System (or comparable vaporized delivery system). Fill reservoir with isoflurane, and turn on O2 airflow. Place mice in induction chamber and adjust isoflurane control dial to 5% to initiate anesthetization. Once mice are fully anesthetized, indicated by lack of mobility, adjust isoflurane control dial to 3% to maintain deep anesthetization. The purpose of anesthesia in this procedure is to immobilize the animal. The ear and tail vein injections do not cause significant pain or distress to the animal.&#160; 
	NOTE: Isoflurane can have negative effects on the human reproductive system. Be sure to use in a well-ventilated room and attach a scavenging canister to the induction chamber to neutralize waste gas. If you are pregnant while using isoflurane, wear a carbon filter mask to minimize exposure.</li>
	<li>Load 10 &#956;l of 5 mg/ml OVA into a 3/10 cc insulin syringe capped with a 31 G needle. Load another 3/10 cc insulin syringe with 10 &#956;l of 1x PBS.</li>
	<li>Using a dissecting microscope, inject 10 &#956;l of OVA into the right ear of an anesthetized mouse for a challenge dose of 50 &#956;g of OVA. Other doses, such as 20 &#956;g, are also acceptable.
	<ol>
		<li>To stabilize the ear for injection, wrap scotch tape (sticky side up) around a 15 ml conical tube. Secure the dorsal side of the right ear to the tape. Insert the needle bevel side up between the two leaves of the ear. Slowly inject OVA into the center of the ear tissue, taking care not to hit any blood vessels.</li>
	</ol>
	</li>
	<li>Using the same method described above, inject 10 &#956;l of PBS into the left ear as a negative control.</li>
	<li>Wait 3 min.
	<ol>
		<li>During this time, place the mouse in a restrainer and hold the tail under a heat lamp or in a warm water bath for 1 min to dilate the blood vessels.</li>
	</ol>
	</li>
	<li>Using a 1 ml insulin syringe capped with a 27 G needle, slowly inject 200 &#956;l of 0.5% Evans Blue dye into the tail vein of the mouse. Rapid injection may destroy the vessel structure before the entire 200 &#956;l is administered. If this occurs, attempt to inject the remaining volume of dye into the vein on the opposite side of the tail.</li>
	<li>Wait 10 min.</li>
	<li>Euthanize the mouse and remove both ears using forceps and surgical scissors.
	<ol>
		<li>Grab the edges of the ear with forceps, making sure that no pressure is applied to the injection site at the center of the ear. Remove as much ear tissue as possible by cutting close to, but not through, the ridge of cartilage present at the base of the ear. Small amounts of fur may be present on the excised ear; this will not affect the assay.</li>
	</ol>
	</li>
	<li>Aliquot 700 &#956;l of formamide into 1.5 ml microcentrifuge tubes. Prepare one tube per ear (two tubes per mouse). 
	NOTE: Formamide is teratogenic, mutagenic, and an irritant. Wear gloves, eye protection, and face protection. Pregnant women should use caution when handling as formamide may be fetotoxic.</li>
	<li>Add ears to formamide, cap the tubes, and incubate overnight in a dry heat bath set to 63 &#176;C. Ears may still appear slightly blue after incubation; however the majority of the dye will be extracted into the formamide.</li>
	<li>Add 300 &#956;l of each sample, in duplicate, to a 96 well plate. Avoid transferring fur if it is present in the sample. Ensure that there are no bubbles present in the wells, as they will affect the absorbance reading.</li>
	<li>Add 300 &#956;l of formamide, in duplicate, to the 96 well plate. These wells will be used as blanks.</li>
	<li>Use a spectrophotometer to measure absorbance at 620 nm. Subtract formamide wells from each sample reading. 
	NOTE: All experiments were performed under protocols approved by the Uniformed Services University Institutional Animal Care and Use Committee.</li>
</ol>

<ol>
	<li>Kojima, T., 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=Mast+cells+and+Bbasophils+are+selectively+activated+in+vitro+and+in+vivo+through+CD200R3+in+an+IgE-independent+manner.">Mast cells and Bbasophils are selectively activated in vitro and in vivo through CD200R3 in an IgE-independent manner.</a> The Journal of Immunology. 179 (10), 7093-7100 (2007).</li><li>Parikh, S. A., Cho, S. H., Oh, C. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preformed+enzymes+in+mast+cell+granules+and+their+potential+role+in+allergic+rhinitis.">Preformed enzymes in mast cell granules and their potential role in allergic rhinitis.</a> Current Allergy and Asthma Reports. 3 (3), 266-272 (2003).</li><li>Amin, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+mast+cells+in+allergic+inflammation.">The role of mast cells in allergic inflammation.</a> Respiratory Medicine. 106 (1), 9-14 (2012).</li><li>Nakaya, M., Takeuchi, N., Kondo, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunohistochemical+localization+of+histamine+receptor+subtypes+in+human+inferior+turbinates.">Immunohistochemical localization of histamine receptor subtypes in human inferior turbinates.</a> Annals of Otology, Rhinology &amp; Laryngology. 113 (7), 552-557 (2004).</li><li>Ramsdell, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+Trypan+Blue+to+demonstrate+the+immediate+skin+reaction+in+rabbits+and+guinea+pigs.">The use of Trypan Blue to demonstrate the immediate skin reaction in rabbits and guinea pigs.</a> The Journal of Immunology. 15 (4), 305-311 (1928).</li><li>Chase, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+sensitization+of+animals+with+simple+chemical+compounds:+X.+Antibodies+inducing+immediate-type+skin+reactions.">Studies on the sensitization of animals with simple chemical compounds: X. Antibodies inducing immediate-type skin reactions.</a> The Journal of Experimental Medicine. 86 (6), 489-514 (1947).</li><li>Goose, J., Blair, A. M. J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Passive+cutaneous+anaphylaxis+in+the+rat,+induced+with+two+homologous+reagin-like+antibodies+and+its+specific+inhibition+with+disodium+cromoglycate.">Passive cutaneous anaphylaxis in the rat, induced with two homologous reagin-like antibodies and its specific inhibition with disodium cromoglycate.</a> Immunology. 16, 749-760 (1969).</li><li>Ovary, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Passive+cutaneous+anaphylaxis+in+the+mouse.">Passive cutaneous anaphylaxis in the mouse.</a> The Journal of Immunology. 81 (4), 355-357 (1958).</li><li>Ovary, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immediate+reactions+in+the+skin+of+experimental+animals+provoked+by+antibody-antigen+interactoin.">Immediate reactions in the skin of experimental animals provoked by antibody-antigen interactoin.</a> Progress in Allergy. 5, 459-508 (1958).</li><li>Akiyama, H., 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=Quantitiative+evaluation+of+passive+cutaneous+anaphylaxis+(PCA)+using+a+hand-held+spectrophotometer.">Quantitiative evaluation of passive cutaneous anaphylaxis (PCA) using a hand-held spectrophotometer.</a> Biological &amp; Pharmaceutical Bulletin. 19 (8), 1112-1114 (1996).</li><li>Teshima, 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=Simple+spectrophotometric+analysis+of+passive+and+active+ear+cutaneous+anaphylaxis+in+the+mouse.">Simple spectrophotometric analysis of passive and active ear cutaneous anaphylaxis in the mouse.</a> Toxicology Letters. 95 (2), 109-115 (1998).</li></ol>

The authors have nothing to disclose.

Numerous markers of allergic disease are used to assess the strength of allergic responses following allergen challenge, including changes in levels of circulating histamine, Th2 cytokine production, and cell recruitment into bronchoalveolar fluid in the setting of airway challenge. While monitoring changes in these parameters is important for studying allergic reactions, biological markers do not always correlate with clinical allergic disease. The local anaphylaxis assay described in this protocol provides reproducible...

Type I hypersensitivity is mediated by antigen-induced cross-linking of IgE on the surface of mast cells and basophils. This results in cellular degranulation and the release of vasoactive and proinflammatory mediators such as histamine, tryptase, and platelet-activating factor2. Following the release of preformed mediators during degranulation, mast cells synthesize and release prostaglandins and leukotrienes, which further increase vascular permeability3. The initial clinical response occurs rapidly and is referred to as an &#8220;immediate reaction&#8221;. In the skin, a wheal-and-flare response is readily visible within minutes of antigen challenge. Depending on the dose of the challenge, it is possible to observe a &#8220;late phase response&#8221; a few hr later. Late phase swelling is due to localized edema and leukocyte recruitment into the tissues2. Histamine, generally considered to be the major mediator taking part in immediate allergic responses, acts on histamine receptor 1 (HR1) expressed on vessels and histamine receptor 2 (HR2) expressed on smooth muscle. The combined effect increases blood flow and vascular permeability at the site of inflammation4.
A variety of animal models of allergy have been developed in order to study the mechanisms involved in allergic inflammation, including models of allergic asthma, systemic anaphylaxis, and local anaphylaxis. Intravenous dye administration has been used to measure localized allergic responses in animal models for almost a century, with publications describing this technique dating back to the 1920s5. Rabbits and guinea pigs were the first animal models used to test immediate hypersensitivity reactions, and the most sensitive responses were generally found in the ear5,6. The assay was later validated for use in rats7 and mice8.
Historically, a variety of experimental methods have been used, including injection of antigen prior to injection of dye, injection of dye prior to injection of antigen, and simultaneous injection of dye and antigen. Intravenous dye administration as a means for measuring allergic responses is a versatile assay as it can be used for measuring active, passive, and reverse passive reactions5,9. Numerous dyes have been utilized to assess allergic responses, including Trypan Blue, Pontamine Sky Blue, Evans Blue, Geigy Blue 536, and India Ink5,6,9. A solution of 0.5% Evans Blue is currently the standard dye used for measuring allergic responses in the skin.
The anaphylactic response to challenge is transient; maximum intensity is reached within 10 - 15 min of dye injection, and no reaction is visible if dye is administered more than 30 min after challenge, regardless of the animal species used9. Quantification of dye extravasation was originally obtained by measuring wheal size as indicated by the blue dye7-9. Additionally, counts of degranulated mast cells can be quantified by excising skin tissue from the site of the reaction and staining with toluidine blue7. Mast cell degranulation is often used as a marker for cutaneous, IgE-mediated allergic responses, as mast cells are the main local cell population expressing the high affinity IgE receptor Fc&#949;RI. Spectrophotometric techniques for measuring dye extravasation into the tissue were developed for passive cutaneous anaphylaxis (PCA) in the rat10 and mouse11 in the 1990&#8217;s.
The following local anaphylaxis assay protocol was adapted from Kojima et al.1, and utilizes chicken egg ovalbumin (OVA) as the antigen for eliciting allergic responses. However, antigens other than OVA may be used if desired. The assay then uses Evans Blue dye to monitor changes in vascular permeability that occur due to mast cell IgE cross-linking and histamine release.

<table border="0" cellpadding="0" cellspacing="0" width="796">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Name of Material/ Equipment</td>
			<td style="width:167px;">Company</td>
			<td style="width:135px;">Catalog Number</td>
			<td style="width:225px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">BALB/c Mice</td>
			<td style="width:167px;">The Jackson Laboratory</td>
			<td style="width:135px;">651</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">PBS pH 7.4</td>
			<td style="width:167px;">Quality Biologic</td>
			<td style="width:135px;">114-058-101</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Ovalbumin</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:135px;">A5503-10G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Imject Alum</td>
			<td style="width:167px;">Thermo Scientific</td>
			<td style="width:135px;">77161</td>
			<td style="width:225px;">Mix thoroughly before use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Evans Blue Dye</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:135px;">E2129</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Formamide</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:135px;">295876</td>
			<td style="width:225px;">99%+ Spectrophotometric grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Isoflurane, USP</td>
			<td style="width:167px;">Phoenix</td>
			<td style="width:135px;">NDC 57319-474-06</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">1cc Insulin syringes</td>
			<td style="width:167px;">BD</td>
			<td style="width:135px;">329654</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">3/10 cc Insulin syringe with 31G needle</td>
			<td style="width:167px;">Terumo</td>
			<td style="width:135px;">NDC 100861</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">27G Needles</td>
			<td style="width:167px;">BD</td>
			<td style="width:135px;">305109</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Forceps</td>
			<td style="width:167px;">F.S.T.</td>
			<td style="width:135px;">11000-12</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Surgical scissors</td>
			<td style="width:167px;">F.S.T.</td>
			<td style="width:135px;">14070-12</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">5ml Polystyrene round-bottom tubes</td>
			<td style="width:167px;">BD Falcon</td>
			<td style="width:135px;">352058</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">1.5ml Microcentrifuge tubes</td>
			<td style="width:167px;">Medical Supply Partners</td>
			<td style="width:135px;">15-1151</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">15ml Conical tubes</td>
			<td style="width:167px;">BD Falcon</td>
			<td style="width:135px;">352097</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Flat-bottom 96 well plate</td>
			<td style="width:167px;">Costar</td>
			<td style="width:135px;">3590</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Scotch tape</td>
			<td style="width:167px;"></td>
			<td style="width:135px;"></td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:271px;">RC2 Rodent Anesthesia System</td>
			<td style="width:167px;">VetEquip</td>
			<td style="width:135px;">922100</td>
			<td style="width:225px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Vortex Genie 2</td>
			<td style="width:167px;">Scientific Industries</td>
			<td style="width:135px;">SI-0236</td>
			<td style="width:225px;">Model G560 with 3 inch platform</td>
		</tr>
	</tbody>
</table>

measuring local anaphylaxis in mice

Allergic responses are the result of the activation of mast cells and basophils, and the subsequent release of vasoactive and proinflammatory mediators. Exposure to an allergen in a sensitized individual can result in clinical symptoms that vary from minor erythema to life threatening anaphylaxis. In the laboratory, various animal models have been developed to understand the mechanisms driving allergic responses. Herein, we describe a detailed method for measuring changes in vascular permeability to quantify localized allergic responses. The local anaphylaxis assay was first reported in the 1920s, and has been adapted from the technique published by Kojima et al. in 20071. In this assay, mice sensitized to OVA are challenged in the left ear with vehicle and in the right ear with OVA. This is followed by an intravenous injection of Evans Blue dye. Ten min after injecting Evans Blue, the animal is euthanized and the dye that has extravasated into the ears is extracted overnight in formamide. The absorbance of the extracted dye is then quantified with a spectrophotometer. This method reliably results in a visual and quantifiable manifestation of a local allergic response.

Animals that have undergone the assay successfully will have skin and eyes that appear blue. PBS sensitized animals should not react to either PBS or OVA challenge, therefore both ears should remain white (Figure 1A). In OVA sensitized animals, the ear receiving the PBS challenge (left) should be either completely white or lightly blue in a localized manner at the site of injection. The ear receiving the OVA challenge (right) should become progressively darker blue during the 10 min after dye administrat...

Watch this Scientific Journal Video about Measuring Local Anaphylaxis in Mice at JoVE.com

Measuring Local Anaphylaxis in Mice

Allergic responses, characterized by the activation of mast cells and basophils, are driven by the cross-linking of IgE and release of proinflammatory mediators. A quantitative assessment of allergic responses can be achieved by using Evans Blue dye to monitor changes in vascular permeability after allergen challenge.

Allergic responses are the result of the activation of mast cells and basophils, and the subsequent release of vasoactive and proinflammatory mediators. ...

Research

JoVE Journal

Immunology and Infection

19.2K Views.  Uniformed Services University of the Health Sciences. Allergic responses, characterized by the activation of mast cells and basophils, are driven by the cross-linking of IgE and release of proinflammatory mediators. A quantitative assessment of allergic responses can be achieved by using Evans Blue dye to monitor changes in vascular permeability after allergen challenge.

Video: Measuring Local Anaphylaxis in Mice

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Listeria monocytogenes (Listeria) is a Gram-positive facultative intracellular pathogen1. Mouse studies typically employ intravenous injection of Listeria, which results in systemic infection2. After injection, Listeria quickly disseminates to the spleen and liver due to uptake by CD8&alpha;+ dendritic cells and Kupffer cells3,4. Once phagocytosed, various bacterial proteins enable Listeria to escape the phagosome, survive within the cytosol, and infect neighboring cells5. During the first three days of infection, different innate immune cells (e.g. monocytes, neutrophils, NK cells, dendritic cells) mediate bactericidal mechanisms that minimize Listeria proliferation. CD8+ T cells are subsequently recruited and responsible for the eventual clearance of Listeria from the host, typically within 10 days of infection6.
Successful clearance of Listeria from infected mice depends on the appropriate onset of host immune responses6	. There is a broad range of sensitivities amongst inbred mouse strains7,8. Generally, mice with increased susceptibility to Listeria infection are less able to control bacterial proliferation, demonstrating increased bacterial load and/or delayed clearance compared to resistant mice. Genetic studies, including linkage analyses and knockout mouse strains, have identified various genes for which sequence variation affects host responses to Listeria infection6,8-14. Determination and comparison of infection kinetics between different mouse strains is therefore an important method for identifying host genetic factors that contribute to immune responses against Listeria. Comparison of host responses to different Listeria strains is also an effective way to identify bacterial virulence factors that may serve as potential targets for antibiotic therapy or vaccine design.
We describe here a straightforward method for measuring bacterial load (colony forming units [CFU] per tissue) and preparing single-cell suspensions of the liver and spleen for FACS analysis of immune responses in Listeria-infected mice. This method is particularly useful for initial characterization of Listeria infection in novel mouse strains, as well as comparison of immune responses between different mouse strains infected with Listeria. We use the Listeria monocytogenes EGD strain15 that, when cultured on blood agar, exhibits a characteristic halo zone around each colony due to &beta;-hemolysis1 (Figure 1). Bacterial load and immune responses can be determined at any time-point after infection by culturing tissue homogenate on blood agar plates and preparing tissue cell suspensions for FACS analysis using the protocols described below. We would note that individuals who are immunocompromised or pregnant should not handle Listeria, and the relevant institutional biosafety committee and animal facility management should be consulted before work commences.

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Listeria monocytogenes is a model organism for studying immune responses and genetic susceptibility to intracellular bacteria in mice. This method enables one to measure bacterial load and generate single-cell suspensions of the liver and spleen from mice for FACS analysis to determine changes in immune cells due to Listeria infection.

Listeria monocytogenes (Listeria) is a Gram-positive facultative intracellular pathogen1. Mouse studies typically employ intravenous injection of ...

Measurement of &#947;HV68 Infection in Mice

&gamma;-Herpesviruses (&gamma;-HVs) are notable for their ability to establish latent infections of lymphoid cells1. The narrow host range of human &gamma;-HVs, such as EBV and KSHV, has severely hindered detailed pathogenic studies. Murine &gamma;-herpesvirus 68 (&gamma;HV68) shares extensive genetic and biological similarities with human &gamma;-HVs and is a natural pathogen of murid rodents2. As such, evaluation of &gamma;HV68 infection of mice inbred strains at different stages of viral infection provides an important model for understanding viral lifecycle and pathogenesis during &gamma;-HVs infection.
Upon intranasal inoculation, &gamma;HV68 infection results in acute viremia in the lung that is later resolved into a latent infection of splenocytes and other cells, which may be reactivated throughout the life of the host3,4. In this protocol, we will describe how to use the plaque assay to assess infectious virus titer in the lung homogenates on Vero cell monolayers at the early stage (5 - 7 days) of post-intranasal infection (dpi). While acute infection is largely cleared 2 - 3 weeks postinfection, a latent infection of &gamma;HV68 is established around 14 dpi and maintained later on in the spleen of the mice. Latent infection usually affects a very small population of cells in the infected tissues, whereby the virus stays dormant and shuts off most of its gene expression. Latently-infected splenocytes spontaneously reactivate virus upon explanting into tissue culture, which can be recapitulated by an infectious center (IC) assay to determine the viral latent load. To further estimate the amount of viral genome copies in the acutely and/or latently infected tissues, quantitative real-time PCR (qPCR) is used for its maximal sensitivity and accuracy. The combined analyses of the results of qPCR and plaque assay, and/or IC assay will reveal the spatiotemporal profiles of viral replication and infectivity in vivo.

&#947;-Herpesviruses (&#947;-HVs) establish life-long persistency in their host. Infection of mice with &#947;-HV68 provides a genetically tractable in vivo model for the characterization of the lifecycle/pathogenesis of &#947;HVs. This protocol describes the detection and quantitation of &#947;HV68 infection at acute and latent stages following infection by plaque-forming, infectious center, and qPCR assays.

&gamma;-Herpesviruses (&gamma;-HVs) are notable for their ability to establish latent infections of lymphoid cells1. The narrow host range of human ...

Intralymphatic Immunotherapy and Vaccination in Mice

Vaccines are typically injected subcutaneously or intramuscularly for stimulation of immune responses. The success of this requires efficient drainage of vaccine to lymph nodes where antigen presenting cells can interact with lymphocytes for generation of the wanted immune responses. The strength and the type of immune responses induced also depend on the density or frequency of interactions as well as the microenvironment, especially the content of cytokines. As only a minute fraction of peripherally injected vaccines reaches the lymph nodes, vaccinations of mice and humans were performed by direct injection of vaccine into inguinal lymph nodes, i.e.&#160;intralymphatic injection. In man, the procedure is guided by ultrasound. In mice, a small (5-10 mm) incision is made in the inguinal region of anesthetized animals, the lymph node is localized and immobilized with forceps, and a volume of 10-20 &#956;l of the vaccine is injected under visual control. The incision is closed with a single stitch using surgical sutures. Mice were vaccinated with plasmid DNA, RNA, peptide, protein, particles, and bacteria as well as adjuvants, and strong improvement of immune responses against all type of vaccines was observed. The intralymphatic method of vaccination is especially appropriate in situations where conventional vaccination produces insufficient immunity or where the amount of available vaccine is limited.

Prophylactic and therapeutic vaccination often fails to stimulate strong immune responses due to week drainage of the vaccine to lymph nodes and consequently poor involvement of immune cells. By direct injection of vaccine to lymph nodes, so-called intralymphatic injection, vaccine efficacy can be strongly improved and vaccine doses can be reduced.

Vaccines are typically injected subcutaneously or intramuscularly for stimulation of immune responses. The success of this requires efficient drainage of ...

Measuring Deformability and Red Cell Heterogeneity in Blood by Ektacytometry

Decreased red cell deformability is characteristic of several disorders. In some cases, the extent of defective deformability can predict severity of disease or occurrence of serious complications. Ektacytometry uses laser diffraction viscometry to measure the deformability of red blood cells subject to either increasing shear stress or an osmotic gradient at a constant value of applied shear stress. However, direct deformability measurements are difficult to interpret when measuring heterogenous blood that is characterized by the presence of both rigid and deformable red cells. This is due to the inability of rigid cells to properly align in response to shear stress and results in a distorted diffraction pattern marked by an exaggerated decrease in apparent deformability. Measurement of the degree of distortion provides an indicator of the heterogeneity of the erythrocytes in blood. In sickle cell anemia, this is correlated with the percentage of rigid cells, which reflects the hemoglobin concentration and hemoglobin composition of the erythrocytes. In addition to measuring deformability, osmotic gradient ektacytometry provides information about the osmotic fragility and hydration status of erythrocytes. These parameters also reflect the hemoglobin composition of red blood cells from sickle cell patients. Ektacytometry measures deformability in populations of red cells and does not, therefore, provide information on the deformability or mechanical properties of individual erythrocytes. Regardless, the goal of the techniques described herein is to provide a convenient and reliable method for measuring the deformability and cellular heterogeneity of blood. These techniques may be useful for monitoring temporal changes, as well as disease progression and response to therapeutic intervention in several disorders. Sickle cell anemia is one well-characterized example. Other potential disorders where measurements of red cell deformability and/or heterogeneity are of interest include blood storage, diabetes, Plasmodium infection, iron deficiency, and the hemolytic anemias due to membrane defects.

Here we present techniques to measure red cell deformability and cellular heterogeneity by ektacytometry. These techniques are applicable to general investigations of red cell deformability and specific investigations of blood diseases characterized by the presence of both rigid and deformable red cells in circulation, such as sickle cell anemia.

Decreased red cell deformability is characteristic of several disorders. In some cases, the extent of defective deformability can predict severity of ...

Characterization of Thymus-dependent and Thymus-independent Immunoglobulin Isotype Responses in Mice Using Enzyme-linked Immunosorbent Assay

Antibodies, also termed as immunoglobulins (Ig), secreted by differentiated B lymphocytes, plasmablasts/plasma cells, in humoral immunity provide a formidable defense against invading pathogens via diverse mechanisms. One major goal of vaccination is to induce protective antigen-specific antibodies to prevent life-threatening infections. Both thymus-dependent (TD) and thymus-independent (TI) antigens can elicit robust antigen-specific IgM responses and can also induce the production of isotype-switched antibodies (IgG, IgA and IgE) as well as the generation of memory B cells with the help provided by antigen presenting cells (APCs). Here, we describe a protocol to characterize TD and TI Ig isotype responses in mice using enzyme-linked immunosorbent assay (ELISA). In this protocol, TD and TI Ig responses are elicited in mice by intraperitoneal (i.p.) immunization with hapten-conjugated model antigens TNP-KLH (in alum) and TNP-polysaccharide (in PBS), respectively. To induce TD memory response, a booster immunization of TNP-KLH in alum is given at 3 weeks after the first immunization with the same antigen/adjuvant. Mouse sera are harvested at different time points before and after immunization. Total serum Ig levels and TNP-specific antibodies are subsequently quantified using Ig isotype-specific Sandwich and indirect ELISA, respectively. In order to correctly quantify the serum concentration of each Ig isotype, the samples need to be appropriately diluted to fit within the linear range of the standard curves. Using this protocol, we have consistently obtained reliable results with high specificity and sensitivity. When used in combination with other complementary methods such as flow cytometry, in vitro culture of splenic B cells and immunohistochemical staining (IHC), this protocol will allow researchers to gain a comprehensive understanding of antibody responses in a given experimental setting.

In this paper, we describe a protocol to characterize T-dependent and T-independent immunoglobulin (Ig) isotype responses in mice using ELISA. This method used alone or in combination with flow cytometry will allow researchers to identify differences in B cell-mediated Ig isotype responses in mice following T-dependent and T-independent antigen immunization.

Antibodies, also termed as immunoglobulins (Ig), secreted by differentiated B lymphocytes, plasmablasts/plasma cells, in humoral immunity provide a ...

Mouse Body Temperature Measurement Using Infrared Thermometer During Passive Systemic Anaphylaxis and Food Allergy Evaluation

Mouse body temperature measurement is of paramount importance for investigating allergies and anaphylactic symptoms. Rectal probes for temperature readings is common, and they have been proven to be accurate and invaluable in this regard. However, this method of temperature measurement requires the mice to be anesthetized in order to insert the probe without injury to the animal. This limits the ability to observe other phenotypes of the mouse simultaneously. In order to investigate other phenotypes while measuring temperatures, rectal probes are not ideal, and another method is desired. Here, we introduce a noninvasive method of temperature measurement that foregoes the requirement for mouse anesthesia while maintaining equal reliability to rectal probes in measuring body temperature. We use an infrared thermometer that detects body surface temperatures at ranges between 2 and 150 mm. This method of body temperature measurement is successful in reliably replicating temperature change trends during passive system anaphylaxis experiments in mice. We show that body surface temperatures are about 2.0 &#176;C lower than rectal probe measurements, but the degree of temperature drop follows the same trend. Furthermore, we use the same technique to observe mice in a food allergy model to evaluate temperature and activity levels simultaneously.

Here we present a new method to accurately measure body temperature differences in passive systemic anaphylaxis (PSA) and food allergy mouse models using an infrared thermometer. This procedure has been accurately duplicated in previous PSA results.

Mouse body temperature measurement is of paramount importance for investigating allergies and anaphylactic symptoms. Rectal probes for temperature ...

Probiotic Studies in Neonatal Mice Using Gavage

Adult mouse models have been widely used to understand the mechanism behind disease progression in humans. The applicability of studies done in adult mouse models to neonatal diseases is limited. To better understand disease progression, host responses and long-term impact of interventions in neonates, a neonatal mouse model likely is a better fit. The sparse use of neonatal mouse models can in part be attributed to the technical difficulties of working with these small animals. A neonatal mouse model was developed to determine the effects of probiotic administration in early life and to specifically assess the ability to establish colonization in the newborn mouse intestinal tract. Specifically, to assess probiotic colonization in the neonatal mouse, Lactobacillus plantarum (LP) was delivered directly into the neonatal mouse gastrointestinal tract. To this end, LP was administered to mice by feeding through intra-esophageal (IE) gavage. A highly reproducible method was developed to standardize the process of IE gavage that allows an accurate administration of probiotic dosages while minimizing trauma, an aspect particularly important given the fragility of newborn mice. Limitations of this process include possibilities of esophageal irritation or damage and aspiration if gavaged incorrectly. This approach represents an improvement on current practices because IE gavage into the distal esophagus reduces the chances of aspiration. Following gavage, the colonization profile of the probiotic was traced using quantitative polymerase chain reaction (qPCR) of the extracted intestinal DNA with LP specific primers. Different litter settings and cage management techniques were used to assess the potential for colonization-spread. The protocol details the intricacies of IE neonatal mouse gavage and subsequent colonization quantification with LP.

This study details the process of gavaging precise amounts of probiotics to neonatal mice. The experimental set-up was optimized to include but is not limited to probiotic dosing, methods of administration, and quantification of bacteria in the intestines.

Adult mouse models have been widely used to understand the mechanism behind disease progression in humans. The applicability of studies done in adult ...

Alveolar Macrophage Phagocytosis and Bacteria Clearance in Mice

Alveolar macrophages (AMs) guard the alveolar space of the lung. Phagocytosis by AMs plays a critical role in the defense against invading pathogens, the removal of dead cells or foreign particles, and in the resolution of inflammatory responses and tissue remodeling, processes that are mediated by various surface receptors of the AMs. Here, we report methods for the analysis of the phagocytic function of AMs using in vitro and in vivo assays and experimental strategies to differentiate between the pattern recognition receptor-, complement receptor-, and Fc gamma receptor-mediated phagocytosis. Finally, we discuss a method to establish and characterize a P. aeruginosa pneumonia model in mice to assess bacterial clearance in vivo. These assays represent the most common methods to evaluate AM functions and can also be used to study macrophage function and bacterial clearance in other organs.

Here we report common methods to analyze the phagocytic function of murine alveolar macrophages and bacterial clearance from the lung. These methods study in vitro phagocytosis of fluorescein isothiocyanate beads and in vivo phagocytosis of Pseudomonas aeruginosa Green Fluorescent Protein. We also describe a method for clearing P. aeruginosa in mice.

Alveolar macrophages (AMs) guard the alveolar space of the lung. Phagocytosis by AMs plays a critical role in the defense against invading pathogens, the ...

Quantification of Atherosclerosis in Mice

Cardiovascular disease is the main cause of death in the world. The underlying cause in most cases is atherosclerosis, which is in part a chronic inflammatory disease. Experimental atherosclerosis studies have elucidated the role of cholesterol and inflammation in the disease process. This has led to successful clinical trials with pharmaceutical agents that reduce clinical manifestations of atherosclerosis. Careful and well-controlled experiments in mouse models of the disease could further elucidate the pathogenesis of the disease, which is not fully understood. Standardized lesion analysis is important to reduce experimental variability and increase reproducibility. Determining lesion size in aortic root, aortic arch, and brachiocephalic artery are common endpoints in experimental atherosclerosis. This protocol provides a technical description for evaluation of atherosclerosis at all these sites in a single mouse. The protocol is particularly useful when material is limited, as is frequently the case when genetically modified animals are being characterized.

Murine models of atherosclerosis are useful tools to investigate pathogenic pathways on a molecular level, but require standardized quantification of lesion development. This protocol describes an optimized method to determine lesion size in the major arterial vessels including the aortic root, aortic arch, and brachiocephalic artery.

Cardiovascular disease is the main cause of death in the world. The underlying cause in most cases is atherosclerosis, which is in part a chronic ...

Adoptive Immunotherapy of iNKT Cells in Glucose-6-Phosphate Isomerase (G6PI)-Induced RA Mice

Rheumatoid arthritis (RA) is a complex chronic inflammatory autoimmune disease. The pathogenesis of the disease is related to invariant natural killer T (iNKT) cells. Patients with active RA present fewer iNKT cells, defective cell function, and excessive polarization of Th1. In this study, an RA animal model was established using a mixture of hGPI325-339 and hGPI469-483 peptides. The iNKT cells were obtained by in vivo induction and in vitro purification, followed by infusion into RA mice for adoptive immunotherapy. The in vivo imaging system (IVIS) tracking revealed that iNKT cells were mainly distributed in the spleen and liver. On day 12 after cell therapy, the disease progression slowed down significantly, the clinical symptoms were alleviated, the abundance of iNKT cells in the thymus increased, the proportion of iNKT1 in the thymus decreased, and the levels of TNF-&#945;, IFN-&#947;, and IL-6 in the serum decreased. Adoptive immunotherapy of iNKT cells restored the balance of immune cells and corrected the excessive inflammation of the body.

Adoptive Immunotherapy of iNKT Cells in Glucose-6-Phosphate Isomerase G6PI-Induced RA Mice

This protocol uses G6PI mixed peptides to construct rheumatoid arthritis models that are closer to that of human rheumatoid arthritis in CD4+ T cells and cytokines. High purity invariant natural killer T cells (mainly iNKT2) with specific phenotypes and functions were obtained by in vivo induction and in vitro purification for adoptive immunotherapy.

Rheumatoid arthritis (RA) is a complex chronic inflammatory autoimmune disease. The pathogenesis of the disease is related to invariant natural killer T ...