We thank Sylvie Lesage and all lab members for critical reading of the protocol. This work was supported by a grant (MOP-77545) from the Canadian Institutes of Health Research (CIHR). Nathalie Labrecque is supported by a FRSQ Senior Scholarship and M&eacute;lissa Mathieu received a NSERC Alexander Graham Bell Canada Graduate Scholarship.

1. Preparation Before The Surgery
Mice were treated in accordance to the Canadian Council on Animal Care guidelines.
<ol>
	<li>Anesthetise mice by injection of ketamine/xylazine (150/300 mg/kg, i.p.) or by inhalation of isoflurane (2%, 1L oxygen). If available, isoflurane should be used as it allows for a better control of anaesthesia time and depth. Also, oxygen is administered at the same time which supports the physiological functions of the animal. Moreover, isoflurane is directly eliminated by the lungs and thus does not require hepatic or kidney metabolism.</li>
	<li>Inject buprenorphine (0.05 - 0.1 mg/kg, s.c.) or another analgesic.</li>
	<li>Apply ointment on the mouse eyes before surgery to avoid eye dryness (if isoflurane is used).</li>
	<li>Verify that the mouse is asleep by pinching its paw and rolling its tail. If the mouse does not react, proceed with the surgery.</li>
</ol>
2. The Surgery
It is possible to remove 4 of the superficial lymph nodes (LN) by surgery: the 2 inguinal and the 2 brachial. The isolation of LN is easier in young lean mice (6-8 weeks) since the presence of fatty tissue in older mice can interfere with LN isolation. However, this limitation is overcome with repeated practice. For the mice comfort, we harvest a maximum of 2 LNs at a time and when we perform time-course experiments, we harvest LNs every second day. Also, to prevent infection, antibiotics could be given to the mouse, but we do not and wounds are healing just fine. One needs to be aware that depending on the experimental design, the use of an antibiotic could influence the result observed (for example if a response to a bacterium is measured). Note that all instruments are sterilized after each use and aseptic conditions are maintained throughout the procedures.
<ol>
	<li>Put the mouse on its side. </li>
	<li>Localize the region where you will perform an incision, depending on the LN you want to harvest. (Figure 1).</li>
	<li>Apply chlorhexidine, or another disinfectant, to that region.</li>
	<li>Make a tiny incision with sharp scissors (about 5 mm) either on the back of the foreleg or above the hind paw near the abdomen (Figure 1).</li>
	<li>Remove the loose hairs you have cut with the forceps. If you prefer, you may shave the mouse before making the incision. However, it lengthens the procedure and we find that it is not necessary since, as shown here, it does not improve healing or decrease infection, which are both very rare.</li>
	<li>Stretch the incision with 2 forceps in order to see the LN. The incision might reach 10 mm. The LN appears grayish or darker than the surrounding fat.</li>
	<li>Pinch the fascia (the thin membrane covering the fat and tissue) on top of the LN with one forceps and pull lightly without breaking the surrounding tissue.</li>
	<li>Place the second forceps as far as possible underneath the LN. With the first forceps, break the fascia and remove the LN. If you have successfully harvested the LN, a stain of blood should appear at the location where the LN was previously located. Note that the LN sinks in isotonic solution. This simple test allows you to validate that you have extracted a LN and not fat tissue.</li>
	<li>Verify that no hairs are in the wound.</li>
	<li>Close the incision by sticking the 2 parts of skin together (the inside of the skin) and by stapling them with a clip. We use some Michel Clip with the applying forceps. Install one or 2 clips depending on the size of the incision. Most often, the clips fall off when the tissue heals.</li>
</ol>
3. Postoperative Care
<ol>
	<li>Add some wet food to the bottom of the cage so the mice can feed easily after the surgery.</li>
	<li>About 6 to 8 hours after the surgery, check the mice to ensure that they do not experience pain. Carefully observe their behaviour (posture, gait, interaction with congener and appearance of the fur). If the overall appearance of the mice is poor, administer a second dose of buprenorphine. By the next day the mice should regain their normal behaviour otherwise continue the administration of buprenorphine. The mice should never reach the endpoints previously determined and accepted by your Animal Care Council. You might want to seek advice and help from your animal care vivarium technician.</li>
</ol>
4. Lymph Node Handling
<ol>
	<li>In the laboratory, to obtain a single cell suspension, dissociate the LN as per your usual procedure. We press LN against frosted slides and routinely obtain 1-2 x 106 cells per LN. Alternatively, we prepare the LN for RNA extraction.</li>
	<li>Stain the cells as per your usual protocol. You should obtain expected LN flow cytometry profiles.</li>
</ol>
5. Representative Results
An example of forward and side scatter plot is shown for LNs harvested from an anesthetized mouse by surgery or from a sacrificed mouse (Figure 2). The profile and the percentages of cells in the live lymphocyte gate are the same demonstrating that LN surgery is an appropriate technique to harvest cells.
<img alt="Figure 1" src="/files/ftp_upload/3444/3444fig1.jpg" /> 
Figure 1. Inguinal and brachial LN localization in the mouse. A. The inguinal LN is located just above the hind paw, slightly toward the belly. B. The brachial LN is located behind the foreleg.
<img alt="Figure 2" src="/files/ftp_upload/3444/3444fig2.jpg" /> 
Figure 2. Flow cytometry profile of lymphocytes obtained following LN surgery. Forward and side scatter profiles are shown for LNs harvested from an anesthetized mouse by surgery (A) or from a sacrificed mouse (B). LNs were harvested, dissociated and analyzed on a flow cytometer. Percentages of cells in the live lymphocyte gate are shown.

<ol>
	<li>Zehn, D., Lee, S. Y., Bevan, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complete+but+curtailed+T-cell+response+to+very+low-affinity+antigen.">Complete but curtailed T-cell response to very low-affinity antigen.</a> Nature. 458, 211-214 (2009).</li><li>Vezys, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Memory+CD8+T-cell+compartment+grows+in+size+with+immunological+experience.">Memory CD8 T-cell compartment grows in size with immunological experience.</a> Nature. 457, 196-199 (2009).</li><li>Zhou, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+and+persistence+of+memory+CD8(+)+T+cells+depend+on+T+cell+factor+1.">Differentiation and persistence of memory CD8(+) T cells depend on T cell factor 1.</a> Immunity. 33, 229-240 (2010).</li><li>Wirth, T. C., Badovinac, V. P., Zhao, L., Dailey, M. O., Harty, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+of+central+memory+CD8+T+cells+is+independent+of+CD62L-mediated+trafficking+to+lymph+nodes.">Differentiation of central memory CD8 T cells is independent of CD62L-mediated trafficking to lymph nodes.</a> J. Immunol. 182, 6195-6206 (2009).</li><li>Rooke, R., Waltzinger, C., Benoist, C., Mathis, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeted+complementation+of+MHC+class+II+deficiency+by+intrathymic+delivery+of+recombinant+adenoviruses.">Targeted complementation of MHC class II deficiency by intrathymic delivery of recombinant adenoviruses.</a> Immunity. 7, 123-134 (1997).</li><li>Witherden, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tetracycline-controllable+selection+of+CD4(+)+T+cells:+half-life+and+survival+signals+in+the+absence+of+major+histocompatibility+complex+class+II+molecules.">Tetracycline-controllable selection of CD4(+) T cells: half-life and survival signals in the absence of major histocompatibility complex class II molecules.</a> J. Exp. Med. 191, 355-364 (2000).</li><li>Labrecque, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+much+TCR+does+a+T+cell+need.">How much TCR does a T cell need.</a> Immunity. 15, 71-82 (2001).</li><li>Leignadier, J., Labrecque, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epitope+density+influences+CD8++memory+T+cell+differentiation.">Epitope density influences CD8+ memory T cell differentiation.</a> PLoS One. 5, e13740 (2010).</li><li>Leignadier, J., Hardy, M. P., Cloutier, M., Rooney, J., Labrecque, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Memory+T-lymphocyte+survival+does+not+require+T-cell+receptor+expression.">Memory T-lymphocyte survival does not require T-cell receptor expression.</a> Proc. Natl. Acad. Sci. U.S.A. 105, 20440-20445 (2008).</li><li>Obst, R., van Santen, H. M., Mathis, D., Benoist, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antigen+persistence+is+required+throughout+the+expansion+phase+of+a+CD4(+)+T+cell+response.">Antigen persistence is required throughout the expansion phase of a CD4(+) T cell response.</a> J. Exp. Med. 201, 1555-1565 (2005).</li><li>Bassett, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD8++T-cell+expansion+and+maintenance+after+recombinant+adenovirus+immunization+rely+upon+cooperation+between+hematopoietic+and+nonhematopoietic+antigen-presenting+cells.">CD8+ T-cell expansion and maintenance after recombinant adenovirus immunization rely upon cooperation between hematopoietic and nonhematopoietic antigen-presenting cells.</a> Blood. 117, 1146-1155 (2011).</li><li>Lacombe, M. H., Hardy, M. P., Rooney, J., Labrecque, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IL-7+receptor+expression+levels+do+not+identify+CD8++memory+T+lymphocyte+precursors+following+peptide+immunization.">IL-7 receptor expression levels do not identify CD8+ memory T lymphocyte precursors following peptide immunization.</a> J. Immunol. 175, 4400-4407 (2005).</li><li>Leignadier, J., Rooney, J., Daudelin, J. F., Labrecque, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lowering+TCR+expression+on+naive+CD8++T+cells+does+not+affect+memory+T-cell+differentiation.">Lowering TCR expression on naive CD8+ T cells does not affect memory T-cell differentiation.</a> Immunol. Cell. Biol. 89, 322-325 (2011).</li></ol>

No conflicts of interest declared.

We have described a protocol of LN surgery which can apply to many experimental systems. Although very useful to follow immune responses or immune cell homeostasis, this technique has a few limitations. First, only four LNs can be harvested. Second, the immune response studied must be systemic or occur in the superficial inguinal or brachial (skin-draining) LNs. Finally, the number of cells harvested is influenced by the quality of the LN removal, a technical limitation which may contribute to experimental variability wh...

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murine superficial lymph node surgery

In the field of immunology, to understand the progression of an immune response against a vaccine, an infection or a tumour, the response is often followed over time. Similarly, the study of lymphocyte homeostasis requires time course experiments. Performing these studies within the same mouse is ideal to reduce the experimental variability as well as the number of mice used. Blood withdrawal allows performance of time course experiments, but it only gives information about circulating lymphocytes and provides a limited number of cells1-4. Since lymphocytes circulating through the body and residing in the lymph nodes have different properties, it is important to examine both locations. The sequential removal of lymph nodes by surgery provides a unique opportunity to follow an immune response or immune cell expansion in the same mouse over time. Furthermore, this technique yields between 1-2x106 cells per lymph node which is sufficient to perform phenotypic characterization and/or functional assays. Sequential lymph node surgery or lymphadenectomy has been successfully used by us and others5-11. Here, we describe how the brachial and inguinal lymph nodes can be removed by making a small incision in the skin of an anesthetised mouse. Since the surgery is superficial and done rapidly, the mouse recovers very quickly, heals well and does not experience excessive pain. Every second day, it is possible to harvest one or two lymph nodes allowing for time course experiments. This technique is thus suitable to study the characteristics of lymph node-residing lymphocytes over time. This approach is suitable to various experimental designs and we believe that many laboratories would benefit from performing sequential lymph node surgeries.

Watch this Scientific Journal Video about Murine Superficial Lymph Node Surgery at JoVE.com

Murine Superficial Lymph Node Surgery

To follow the progression of an immune response over time within the same mouse, lymph nodes can be sequentially removed by surgery. Here, we describe how this technique can be performed.

In the field of immunology, to understand the progression of an immune response against a vaccine, an infection or a tumour, the response is often ...

Research

JoVE Journal

Immunology and Infection

42.1K Views.  Maisonneuve-Rosemont Hospital Research Center. To follow the progression of an immune response over time within the same mouse, lymph nodes can be sequentially removed by surgery. Here, we describe how this technique can be performed.

Video: Murine Superficial Lymph Node Surgery

Intravital Microscopy of the Inguinal Lymph Node

Lymph nodes (LN's), located throughout the body, are an integral component of the immune system. They serve as a site for induction of adaptive immune response and therefore, the development of effector cells. As such, LNs are key to fighting invading pathogens and maintaining health. The choice of LN to study is dictated by accessibility and the desired model; the inguinal lymph node is well situated and easily supports studies of biologically relevant models of skin and genital mucosal infection.
The inguinal LN, like all LNs, has an extensive microvascular network supplying it with blood. In general, this microvascular network includes the main feed arteriole of the LN that subsequently branches and feeds high endothelial venules (HEVs). HEVs are specialized for facilitating the trafficking of immune cells into the LN during both homeostasis and infection. How HEVs regulate trafficking into the LN under both of these circumstances is an area of intense exploration. The LN feed arteriole, has direct upstream influence on the HEVs and is the main supply of nutrients and cell rich blood into the LN. Furthermore, changes in the feed arteriole are implicated in facilitating induction of adaptive immune response. The LN microvasculature has obvious importance in maintaining an optimal blood supply to the LN and regulating immune cell influx into the LN, which are crucial elements in proper LN function and subsequently immune response. 
The ability to study the LN microvasculature in vivo is key to elucidating how the immune system and the microvasculature interact and influence one another within the LN. Here, we present a method for in vivo imaging of the inguinal lymph node. We focus on imaging of the microvasculature of the LN, paying particular attention to methods that ensure the study of healthy vessels, the ability to maintain imaging of viable vessels over a number of hours, and quantification of vessel magnitude. Methods for perfusion of the microvasculature with vasoactive drugs as well as the potential to trace and quantify cellular traffic are also presented. 
Intravital microscopy of the inguinal LN allows direct evaluation of microvascular functionality and real-time interface of the direct interface between immune cells, the LN, and the microcirculation. This technique potential to be combined with many immunological techniques and fluorescent cell labelling as well as manipulated to study vasculature of other LNs.

A technique for performing intravital microscopy of the inguinal lymph node (LN) is outlined. Such technique allows for real-time, in vivo study of the lymph node microvasculature and structure both during homeostasis and infection. This technique can be adapted to cell trafficking studies and to other lymph node sites.

Lymph nodes (LN's), located throughout the body, are an integral component of the immune system. They serve as a site for induction of adaptive immune ...

Ex vivo Imaging of T Cells in Murine Lymph Node Slices with Widefield and Confocal Microscopes

Na&iuml;ve T cells continuously traffic to secondary lymphoid organs, including peripheral lymph nodes, to detect rare expressed antigens. The migration of T cells into lymph nodes is a complex process which involves both cellular and chemical factors including chemokines. Recently, the use of two-photon microscopy has permitted to track T cells in intact lymph nodes and to derive some quantitative information on their behavior and their interactions with other cells. While there are obvious advantages to an in vivo system, this approach requires a complex and expensive instrumentation and provides limited access to the tissue. To analyze the behavior of T cells within murine lymph nodes, we have developed a slice assay 
1, originally set up by neurobiologists and transposed recently to murine thymus 2. In this technique, fluorescently labeled T cells are plated on top of an acutely prepared lymph node slice. In this video-article, the localization and migration of T cells into the tissue are analyzed in real-time with a widefield and a confocal microscope. The technique which complements in vivo two-photon microscopy offers an effective approach to image T cells in their natural environment and to elucidate mechanisms underlying T cell migration.

Ex vivo Imaging of T Cells in Murine Lymph Node Slices with Widefield and Confocal Microscopes

This protocol describes a method to image fluorescent T cells introduced into lymph node slices. The technique permits real-time analyses of T cell migration with traditional widefield fluorescence or confocal microscopes.

Na&iuml;ve T cells continuously traffic to secondary lymphoid organs, including peripheral lymph nodes, to detect rare expressed antigens. The migration ...

Intravital Imaging of the Mouse Popliteal Lymph Node

Lymph nodes (LNs) are secondary lymphoid organs, which are strategically located throughout the body to allow for trapping and presentation of foreign antigens from peripheral tissues to prime the adaptive immune response. Juxtaposed between innate and adaptive immune responses, the LN is an ideal site to study immune cell interactions1,2. Lymphocytes (T cells, B cells and NK cells), dendritic cells (DCs), and macrophages comprise the bulk of bone marrow-derived cellular elements of the LN. These cells are strategically positioned in the LN to allow efficient surveillance of self antigens and potential foreign antigens3-5. The process by which lymphocytes successfully encounter cognate antigens is a subject of intense investigation in recent years, and involves an integration of molecular contacts including antigen receptors, adhesion molecules, chemokines, and stromal structures such as the fibro-reticular network2,6-12. 
Prior to the development of high-resolution real-time fluorescent in vivo imaging, investigators relied on static imaging, which only offers answers regarding morphology, position, and architecture. While these questions are fundamental in our understanding of immune cell behavior, the limitations intrinsic with this technique does not permit analysis to decipher lymphocyte trafficking and environmental clues that affect dynamic cell behavior. Recently, the development of intravital two-photon laser scanning microscopy (2P-LSM) has allowed investigators to view the dynamic movements and interactions of individual cells within live LNs in situ12-16. In particular, we and others have applied this technique to image cellular behavior and interactions within the popliteal LN, where its compact, dense nature offers the advantage of multiplex data acquisition over a large tissue area with diverse tissue sub-structures11,17-18. It is important to note that this technique offers added benefits over explanted tissue imaging techniques, which require disruption of blood, lymph flow, and ultimately the cellular dynamics of the system. Additionally, explanted tissues have a very limited window of time in which the tissue remains viable for imaging after explant. With proper hydration and monitoring of the animal's environmental conditions, the imaging time can be significantly extended with this intravital technique. Here, we present a detailed method of preparing mouse popliteal LN for the purpose of performing intravital imaging.

Recent advances in 2-photon microscopy have enabled real-time in situ imaging of live tissues in animal models, thereby enhancing our ability to investigate cellular behavior in both physiologic and pathologic conditions. Here, we outline the preparations required to perform intravital imaging of the mouse popliteal lymph node.

Lymph nodes (LNs) are secondary lymphoid organs, which are strategically located throughout the body to allow for trapping and presentation of foreign ...

Generation of Lymph Node-fat Pad Chimeras for the Study of Lymph Node Stromal Cell Origin

The stroma is a key component of the lymph node structure and function. However, little is known about its origin, exact cellular composition and the mechanisms governing its formation. Lymph nodes are always encapsulated in adipose tissue and we recently demonstrated the importance of this relation for the formation of lymph node stroma. Adipocyte precursor cells migrate into the lymph node during its development and upon engagement of the Lymphotoxin-b receptor switch off adipogenesis and differentiate into lymphoid stromal cells (B&#233;n&#233;zech&#160;et al.14). Based on the lymphoid stroma potential of adipose tissue, we present a method using a lymph node/fat pad chimera that allows the lineage tracing of lymph node stromal cell precursors. We show how to isolate newborn lymph nodes and EYFP+ embryonic adipose tissue and make a LN/ EYFP+ fat pad chimera. After transfer under the kidney capsule of a host mouse, the lymph node incorporates local adipose tissue precursor cells and finishes its formation. Progeny analysis of EYFP+ fat pad cells in the resulting lymph nodes can be performed by flow-cytometric analysis of enzymatically digested lymph nodes or by immunofluorescence analysis of lymph nodes cryosections. By using fat pads from different knockout mouse models, this method will provide an efficient way of analyzing the origin of the different lymph node stromal cell populations.

Generation of lymph node/fat pad chimeras for the study of lymph node stromal cell origin is described. The method involves the isolation of lymph nodes from newborn mice and embryonic fat pads, the generation of chimeric lymph node-fat pads, and their transfer under the kidney capsule of a host mouse.

The stroma is a key component of the lymph node structure and function. However, little is known about its origin, exact cellular composition and the ...

Isolation of Murine Lymph Node Stromal Cells

Secondary lymphoid organs including lymph nodes are composed of stromal cells that provide a structural environment for homeostasis, activation and differentiation of lymphocytes. Various stromal cell subsets have been identified by the expression of the adhesion molecule CD31 and glycoprotein podoplanin (gp38), T zone reticular cells or fibroblastic reticular cells, lymphatic endothelial cells, blood endothelial cells and FRC-like pericytes within the double negative cell population. For all populations different functions are described including, separation and lining of different compartments, attraction of and interaction with different cell types, filtration of the draining fluidics and contraction of the lymphatic vessels. In the last years, different groups have described an additional role of stromal cells in orchestrating and regulating cytotoxic T cell responses potentially dangerous for the host. 
Lymph nodes are complex structures with many different cell types and therefore require a appropriate procedure for isolation of the desired cell populations. Currently, protocols for the isolation of lymph node stromal cells rely on enzymatic digestion with varying incubation times; however, stromal cells and their surface molecules are sensitive to these enzymes, which results in loss of surface marker expression and cell death. Here a short enzymatic digestion protocol combined with automated mechanical disruption to obtain viable single cells suspension of lymph node stromal cells maintaining their surface molecule expression is proposed.

Isolation of lymph node stromal cells is a multistep procedure including enzymatic digestion and mechanical disaggregation to obtain fibroblastic reticular cells, lymphatic and blood endothelial cells. In the described procedure, a short digestion is combined with automated mechanical disaggregation to minimize surface marker degradation of viable lymph node stromal cells.

Secondary lymphoid organs including lymph nodes are composed of stromal cells that provide a structural environment for homeostasis, activation and ...

Myeloid Cell Isolation from Mouse Skin and Draining Lymph Node Following Intradermal Immunization with Live Attenuated Plasmodium Sporozoites

Malaria infection begins when the sporozoite stage of Plasmodium is inoculated into the skin of a mammalian host through a mosquito bite. The highly motile parasite not only reaches the liver to invade hepatocytes and transform into erythrocyte-infective form. It also migrates into the skin and to the proximal lymph node draining the injection site, where it can be recognized and degraded by resident and/or recruited myeloid cells. Intravital imaging reported the early recruitment of brightly fluorescent Lys-GFP positive leukocytes in the skin and the interactions between sporozoites and CD11c+ cells in the draining lymph node. We present here an efficient procedure to recover, identify and enumerate the myeloid cell subsets that are recruited to the mouse skin and draining lymph node following intradermal injection of immunizing doses of sporozoites in a murine model. Phenotypic characterization using multi-parametric flow cytometry provides a reliable assay to assess early dynamic cellular changes during inflammatory response to Plasmodium infection.

Myeloid Cell Isolation from Mouse Skin and Draining Lymph Node Following Intradermal Immunization with Live Attenuated Plasmodium Sporozoites

We describe here a protocol for isolating myeloid cells from mouse skin and draining lymph node following intradermal injection of Plasmodium sporozoites. Flow cytometry of collected cells provides a reliable assay to characterize the skin and draining lymph node inflammatory response to the parasite.

Malaria infection begins when the sporozoite stage of Plasmodium is inoculated into the skin of a mammalian host through a mosquito bite. The highly ...

Murine Full-thickness Skin Transplantation

Murine full-thickness skin transplantation is a well-established in vivo model to study alloimmune response and graft rejection. Despite its limited application to humans, skin transplantation in mice has been widely employed for transplantation research. The procedure is easy to learn and perform, and it does not require delicate microsurgical techniques nor extensive training. Moreover, graft rejection in this model occurs in a very reproducible immunological reaction and is easily monitored by direct inspection and palpation. In addition, secondary skin transplantation with donor-matched or third-party skin grafts can be performed on more complex transplant models as an alternative and uncomplicated method to assess donor-specific tolerance. The complications are low and are in general limited to anesthesia overdose or respiratory distress after the procedure. Graft failure, on the other hand, occurs commonly as a result of poor preparation of the graft, incorrect positioning in the graft bed, or inappropriate placement of the bandage. In this article, we present a protocol for full-thickness skin transplantation in mice and describe the important steps necessary for a successful procedure.

Murine full-thickness skin transplantation is a well-established model to study rejection in an alloimmune setting. Here, we provide a tutorial of each step involved in performing a BALB/c--&#62;C57BL/6 full-thickness skin transplant.

Murine full-thickness skin transplantation is a well-established in vivo model to study alloimmune response and graft rejection. Despite its limited ...

Intracellular Staining and Flow Cytometry to Identify Lymphocyte Subsets within Murine Aorta, Kidney and Lymph Nodes in a Model of Hypertension

It is now well known that T lymphocytes play a critical role in the development of several cardiovascular diseases1,2,3,4,5. For example, studies from our group have shown that hypertension is associated with an excessive accumulation of T cells in the vessels and kidney during the development of experimental hypertension6. Once in these tissues, T cells produce several cytokines that affect both vascular and renal function leading to vasoconstriction and sodium and water retention1,2. To fully understand how T cells cause cardiovascular and renal diseases, it is important to be able to identify and quantify the specific T cell subsets present in these tissues. T cell subsets are defined by a combination of surface markers, the cytokines they secrete, and the transcription factors they express. The complexity of the T cell population makes flow cytometry and intracellular staining an invaluable technique to dissect the phenotypes of the lymphocytes present in tissues. Here, we provide a detailed protocol to identify the surface and intracellular markers (cytokines and transcription factors) in T cells isolated from murine kidney, aorta and aortic draining lymph nodes in a model of angiotensin II induced hypertension. The following steps are described in detail: isolation of the tissues, generation of the single cell suspensions, ex vivo stimulation, fixation, permeabilization and staining. In addition, several fundamental principles of flow cytometric analyses including choosing the proper controls and appropriate gating strategies are discussed.

This article provides detailed methodology to identify and quantify functional T lymphocyte subsets present within murine kidney, aorta and lymph nodes by intracellular staining and flow cytometry. The model of angiotensin II induced hypertension was chosen to explain, step-by-step, the procedures and fundamental principles of flow cytometry and intracellular staining.

It is now well known that T lymphocytes play a critical role in the development of several cardiovascular diseases1,2,3,4,5. For example, studies from our ...

Collection and Processing of Lymph Nodes from Large Animals for RNA Analysis: Preparing for Lymph Node Transcriptomic Studies of Large Animal Species

Large animals (both livestock and wildlife) serve as important reservoirs of zoonotic pathogens, including Brucella, Mycobacterium bovis, Salmonella, and E. coli, and are useful for the study of pathogenesis and/or spread of the bacteria in natural hosts. With the key function of lymph nodes in the host immune response, lymph node tissues serve as a potential source of RNA for downstream transcriptomic analyses, in order to assess the temporal changes in gene expression in cells over the course of an infection. This article presents an overview of the process of lymph node collection, tissue sampling, and downstream RNA processing in livestock, using cattle (Bos taurus) as a model, with additional examples provided from the American bison (Bison bison). The protocol includes information about the location, identification, and removal of lymph nodes from multiple key sites in the body. Additionally, a biopsy sampling methodology is presented that allows for a consistency of sampling across multiple animals. Several considerations for sample preservation are discussed, including the generation of RNA suitable for downstream methodologies like RNA-sequencing and RT-PCR. Due to the long delays inherent in large animal vs. mouse time course studies, representative results from bison and bovine lymph node tissues are presented to describe the time course of the degradation in this tissue type, in the context of a review of previous methodological work on RNA degradation in other tissues. Overall, this protocol will be useful to both veterinary researchers beginning transcriptome projects on large animal samples and to molecular biologists interested in learning techniques for in vivo tissue sampling and in vitro processing.

This protocol provides an overview of procedures for the isolation of RNA for the transcriptomic profiling of lymph node tissues from large animals, including steps in the identification and excision of lymph nodes from livestock and wildlife, sampling approaches to provide consistency across multiple animals, and considerations plus representative results for the post-collection preservation and processing for RNA analysis.

Large animals (both livestock and wildlife) serve as important reservoirs of zoonotic pathogens, including Brucella, Mycobacterium bovis, Salmonella, and ...

Determination of Regulatory T Cell Subsets in Murine Thymus, Pancreatic Draining Lymph Node and Spleen Using Flow Cytometry

Our immune system consists of a number and variety of immune cells including regulatory T cells (Treg) cells. Treg cells can be divided into two subsets, thymic derived Treg (tTreg) cells and peripherally induced Treg (pTreg) cells. They are present in different organs of our body and can be distinguished by specific markers, such as Helios and Neuropilin 1. It has been reported that tTreg cells are functionally more suppressive than pTreg cells. Therefore, it is important to determine the proportion of both tTreg and pTreg cells when investigating heterogeneous cell populations. Herein, we collected thymic glands, pancreatic draining lymph nodes and spleens from normoglycemic non-obese diabetic mice to distinguish tTreg cells from pTreg cells using flow cytometry. We manually prepared single cell suspensions from these organs. Fluorochrome conjugated surface CD4, CD8, CD25, and Neuropilin 1 antibodies were used to stain the cells. They were kept in the fridge overnight. On the next day, the cells were stained with fluorochrome conjugated intracellular Foxp3 and Helios antibodies. These markers were used to characterize the two subsets of Treg cells. This protocol demonstrates a simple but practical way to prepare single cells from murine thymus, pancreatic draining lymph node and spleen and use them for subsequent flow cytometric analysis.

Herein, we present a protocol to prepare single cells from murine thymus, pancreatic draining lymph node and spleen to further study these cells using flow cytometry. In addition, this protocol was used for determining the subsets of regulatory T cells using flow cytometry.

Our immune system consists of a number and variety of immune cells including regulatory T cells (Treg) cells. Treg cells can be divided into two subsets, ...