This work is supported by NIH research (A1R03AI120027 (RN) and 1R21AI20012 (RN)), Institutional Research Grant (RN), start-up grant (RN), and MD Anderson CIC seed grant (RN).

All methods described here have been approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Texas MD Anderson Cancer Center.
1. Preparation of Peptide for the Vaccine
<ol>
	<li>Dissolve the lyophilized peptide with phosphate-buffered saline (PBS) to the appropriate concentration and vortex for 30 s. 
	NOTE: For hgp10025-33, the final concentration is 1 mg/mL and for OVA257-264, the final concentration is 0.5 mg/mL. Reconstitute peptide prior to injection. Do not store after reconstitution.</li>
</ol>
2. Isolation of Splenocytes from Transgenic Mouse
NOTE: Cell isolation from the spleen must be performed in a sterile manner.
<ol>
	<li>Euthanize the OT-1 transgenic mouse using the approved CO2 asphyxiation method and remove the spleen. 
	NOTE: Appropriate transgenic mouse is utilized in this step specific for the peptide of choice.
	<ol>
		<li>Lay the mouse on its right side. Spray the left side of the mouse with 70% ethanol (EtOH). Pull up the skin using forceps and cut the skin using surgical scissors; the spleen will be visible within the peritoneal cavity. Gently cut open the peritoneal cavity to access the spleen. Remove the spleen using forceps.</li>
	</ol>
	</li>
	<li>Disaggregate the spleen by placing it in a 70 &#181;m filter in a petri dish with 2 mL medium A (PBS with 1% fetal bovine serum (FBS)) and smashing the spleen with the end of a plunger.
	<ol>
		<li>Collect the splenocytes from the petri dish and place in a 50 mL conical tube. Wash the petri dish with 5 mL of medium A twice to collect all cells. Add medium A up to 25 mL and centrifuge the cells for 5 min at room temperature at 475 x g.</li>
	</ol>
	</li>
	<li>Aspirate the cells and resuspend in 1 mL/per spleen red blood cell (RBC) lysis buffer. Incubate at room temperature for 5 min. Add 10 mL of medium A and centrifuge at room temperature at 475 x g. Resuspend the pellet in 10 mL of medium A and remove debris by filtering the cell suspension through a 70 &#181;m filter into a clean 50 mL conical.</li>
	<li>Count cells using trypan blue and a hemocytometer. Resuspend cells in PBS to a final concentration of 106&#160;- 1006 cells/mL. For OVA257-264 specific killing, resuspend at 106 cells/mL and for hgp10025-33 specific killing, resuspend at 1006 cells/mL.
	<ol>
		<li>Spin the remaining cells at room temperature for 5 min at 475 x g. Aspirate the supernatant and resuspend in 15 mL cold PBS to wash cells. Repeat the wash step once more. Spin the cells at room temperature for 5 min at 475 x g. Aspirate the supernatant and resuspend in cold PBS according to the final volume determined in step 2.4.</li>
		<li>Transfer single cell suspension to a 1.5 mL microcentrifuge tube and keep on ice until injection into recipient C57/BL6 mouse.</li>
	</ol>
	</li>
</ol>
3. Injection of Splenocytes from Transgenic Mice
<ol>
	<li>Place recipient C57/BL6 mouse in a restrainer with the dorsal side up. Spray injection tail base area with 70% isopropyl alcohol. Administer 100 &#181;L of single cell suspension (section 2) intravenously into the tail vein using a 27 G needle with the bevel side facing up.</li>
</ol>
4. Covax Administration
NOTE: If cells are injected in the afternoon, covax should be administered the following morning within 18 h of cell injection.
<ol>
	<li>Place the mouse in a clear anesthesia box with 1 - 3% isoflurane. After mice are fully anesthetized, transfer the mice to the nose cones attached to the manifold in the anesthesia chamber. Keep mice restrained with the dorsal side up. 
	NOTE: Anesthetization is confirmed by a brief toe pinch to verify a withdrawal response is not elicited. Federal law restricts isoflurane use on the order of a licensed veterinarian.</li>
	<li>Spray injection tail base area with 70% isopropyl alcohol. Inject 100 &#181;L of peptide solution (from section 1) subcutaneously using a 27 G needle with the syringe penetrating 4 - 5 mm into the tail base region, the needle bevel side facing up. 
	NOTE: Mice are vaccinated in one flank with subcutaneous injection at the base of the tail10.</li>
	<li>Inject 100 &#181;L anti-CD40 antibody (0.5 mg/mL stock) lateral to the vaccine injection site.</li>
	<li>Carefully apply imiquimod cream 50 mg/mouse on the vaccination sites. Rub imiquimod cream on the surface until the cream is no longer visible and is fully absorbed.</li>
	<li>Inject 100 &#181;L of 100,000 IU/mL rhIL-2 protein intraperitoneally (i.p.) at the lower abdominal region. Observe mice for 5 min after they fully recover from anesthesia. 
	NOTE: Experiment is paused at this point for 3 days.</li>
</ol>
5. Isolation of Target Splenocytes for Labeling with CFSE
NOTE: Cell isolation from the spleen must be performed in a sterile manner.
<ol>
	<li>Euthanize the C57BL/6 mice according to approved CO2 asphyxiation method. Remove spleen(s) as in step 2.1.1. Disaggregate the spleen and wash splenocytes as in steps 2.2.1 - 2.2.3. Lyse red blood cells as in steps 2.3 - 2.3.2.</li>
	<li>Remove cells for counting using a hemocytometer and calculate for a final concentration of cells at 106 cells/mL in CFSE-labeling solution (described in step 7). Spin remaining cells at room temperature for 5 min at 475 x g. Aspirate supernatant.</li>
</ol>
6. Peptide Pulsing of Target Splenocytes
NOTE: Peptide pulsing must be performed in a sterile manner.
<ol>
	<li>Resuspend cells at 106 cells/mL in complete media (RPMI 1640 media with 10% FBS, 1% L-glutamine (L-Gln), 1% penicillin/streptomycin (Pen/Strep)). Divide the cells into 2 tubes (15 mL conicals). Label each tube as pulsed or unpulsed.</li>
	<li>Add peptide to the tube labeled pulsed. For OVA257-264 pulsing, add 1 &#181;g/mL and for hgp10025-33 pulsing, add 2 &#181;g/mL. 
	&#8203;NOTE: The unpulsed cells undergo the same incubation as the pulsed cells just without the addition of the peptide.
	<ol>
		<li>Incubate cells + peptide at 37 &#176;C for 1 h.</li>
	</ol>
	</li>
	<li>Add 10 mL of complete media (RPMI 1640 media with 10% FBS, 1% L-glutamine (L-Gln), 1% penicillin/streptomycin (Pen/Strep)) to each tube to wash both pulsed and unpulsed target cells. Spin remaining cells at room temperature for 5 min at 475 x g. Aspirate supernatant.</li>
</ol>
7. Preparation of CFSE for Labeling Target Splenocytes
<ol>
	<li>Prepare CFSE-labeling solution during the cell washing in step 6.3; the pulsed cells will be labeled as CFSEhi and the unpulsed as CFSElo. Prepare 1 mL of CFSE-labeling solution for 106 cells. 
	&#8203;NOTE: CFSE is light sensitive and should be protected from light at all times.
	<ol>
		<li>Prepare CFSEhi -labeling media by adding 1 uL/mL CFSE (5 mM stock solution) for a final concentration of 5 &#181;M/mL in RPMI media 1640 with 2% FBS.</li>
		<li>Prepare CFSElo -labeling media by adding 1 uL/mL CFSE (0.5 mM stock solution) for a final concentration of 0.5 &#181;M/mL RPMI media 1640 with 2% FBS.</li>
	</ol>
	</li>
</ol>
8. Labeling of Target Splenocytes with CFSE
NOTE: CFSE labeling must be performed in a sterile manner.
<ol>
	<li>Resuspend the pulsed and unpulsed target cells (from step 6.3) at 106 cells/mL CFSE-labeling media. Resuspend the pulsed cells with prepared CFSEhi-labeling media and the unpulsed cells with prepared CFSElo-labeling media.</li>
	<li>Mix cells and CFSE-labeling media by gentle inversion or swirling. Do not mix by vortexing. Incubate cells and CFSE-labeling media at 37 &#176;C for 15 min. Remix the cells every 5 min.</li>
	<li>Add 10 mL of complete media to each cell suspension and spin cells at room temperature for 5 min at 475 x g.</li>
	<li>Aspirate supernatant and resuspend cells in 10 mL cold PBS. Spin cells at 4 &#176;C for 5 min at 475 x g.</li>
	<li>Repeat step 8.4.</li>
	<li>Count the cells and mix peptide-pulsed, CFSEhi-labeled with unpulsed, CFSElo-labeled cells at a 1:1 ratio for injection into recipient mice. Keep an aliquot of 1x 106 mixed cells to use for a baseline flow cytometry assessment (section 11). 
	NOTE: The final volume for injection is 100 &#181;L per mouse. The final cell count is 10e6 cells. Loss of volume in the syringe and needle needs to be taken into account and should be estimated at 500 &#181;L.</li>
</ol>
9. Injection of Target Cells
NOTE: Keep CFSE-labeled cells protected from light prior to and during the injection as much as possible.
<ol>
	<li>Place recipient C57BL/6 mice in a restrainer with the dorsal side up. Spray injection tail base area with 70% isopropyl alcohol. Administer 100 &#181;L of single cell suspension intravenously into the tail vein with the bevel side facing up.</li>
</ol>
10. Re-isolation of Target Cells
NOTE: The timing of this step is critical and dependent upon the CTL cytotoxicity and the strength of the antigen for stimulation. For assessment of killing an OVA257-264 pulsed target, the cells need to be harvested 4 - 6 h after injection. Since CFSE-labeled cells are light sensitive, process spleens in the dark.
<ol>
	<li>Euthanize the recipient C57BL/6 mice according to the approved CO2 asphyxiation method.</li>
	<li>Remove spleen(s) as in step 2.1.1. Disaggregate the spleen and wash splenocytes as in steps 2.2.1 - 2.2.3. Lyse red blood cells as in steps 2.3 - 2.3.2.</li>
	<li>Resuspend cells in 1 mL fluorescence activated cell sorting (FACs) buffer (1% BSA+PBS) for assessment by flow cytometry.</li>
</ol>
11. Gating Logic to Determine CTL Activity by Flow Cytometry
<ol>
	<li>Perform assessment of CTL activity using a standard flow cytometry protocol. Acquire cells using the FITC channel on a flow cytometer with a 488 nm laser for excitation11.
	<ol>
		<li>Gate on live lymphocytes using the forward scatter (FSC) vs side scatter (SSC) parameters. Subgate within the live lymphocyte gate for the total CFSE-positive population. 
		NOTE: The injected CFSE-labeled cells will make up a small subset of the total lymphocytes present in the spleen. The CSFE-positive cells should appear as two distinct populations on the log scale.</li>
		<li>Use a histogram format to determine the percentage of the unpulsed (left peak, CFSElo) and pulsed (right peak, CFSEhi) populations. Loss of the CFSEhi cells indicates antigen-specific CTL activity.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Liu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+and+quantification+of+T+cell-mediated+cytotoxicity+using+cell-permeable+fluorogenic+caspase+substrates.">Visualization and quantification of T cell-mediated cytotoxicity using cell-permeable fluorogenic caspase substrates.</a> Nat Med. 8 (2), 185-189 (2002).</li><li>Wherry, E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lineage+relationship+and+protective+immunity+of+memory+CD8+T+cell+subsets.">Lineage relationship and protective immunity of memory CD8 T cell subsets.</a> Nat Immunol. 4 (3), 225-234 (2003).</li><li>He, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+sensitive+flow+cytometry-based+cytotoxic+T-lymphocyte+assay+through+detection+of+cleaved+caspase+3+in+target+cells.">A sensitive flow cytometry-based cytotoxic T-lymphocyte assay through detection of cleaved caspase 3 in target cells.</a> J Immunol Methods. 304 (1-2), 43-59 (2005).</li><li>Barber, D. L., Wherry, E. J., Ahmed, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutting+edge:+rapid+in+vivo+killing+by+memory+CD8+T+cells.">Cutting edge: rapid in vivo killing by memory CD8 T cells.</a> J Immunol. 171 (1), 27-31 (2003).</li><li>Quah, B. J., Wijesundara, D. K., Ranasinghe, C., Parish, C. R. <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+fluorescent+target+arrays+for+assessment+of+T+cell+responses+in+vivo.">The use of fluorescent target arrays for assessment of T cell responses in vivo.</a> J Vis Exp. (88), e51627 (2014).</li><li>Johansson, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+killer+cell+education+in+mice+with+single+or+multiple+major+histocompatibility+complex+class+I+molecules.">Natural killer cell education in mice with single or multiple major histocompatibility complex class I molecules.</a> J Exp Med. 201 (7), 1145-1155 (2005).</li><li>Hailemichael, Y., 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=Persistent+antigen+at+vaccination+sites+induces+tumor-specific+CD8(+)+T+cell+sequestration,+dysfunction+and+deletion.">Persistent antigen at vaccination sites induces tumor-specific CD8(+) T cell sequestration, dysfunction and deletion.</a> Nat Med. 19 (4), 465-472 (2013).</li><li>Overwijk, W. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+regression+and+autoimmunity+after+reversal+of+a+functionally+tolerant+state+of+self-reactive+CD8++T+cells.">Tumor regression and autoimmunity after reversal of a functionally tolerant state of self-reactive CD8+ T cells.</a> J Exp Med. 198 (4), 569-580 (2003).</li><li>Cho, H. I., Celis, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+peptide+vaccines+eliciting+extensive+CD8+T-cell+responses+with+therapeutic+antitumor+effects.">Optimized peptide vaccines eliciting extensive CD8 T-cell responses with therapeutic antitumor effects.</a> Cancer Res. 69 (23), 9012-9019 (2009).</li><li>Ya, Z., Hailemichael, Y., Overwijk, W., Restifo, N. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+model+for+pre-clinical+study+of+human+cancer+immunotherapy.">Mouse model for pre-clinical study of human cancer immunotherapy.</a> Curr Protoc Immunol. 108, 21-43 (2015).</li><li>Menon, V., Thomas, R., Ghale, A. R., Reinhard, C., Pruszak, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow+cytometry+protocols+for+surface+and+intracellular+antigen+analyses+of+neural+cell+types.">Flow cytometry protocols for surface and intracellular antigen analyses of neural cell types.</a> J Vis Exp. (94), (2014).</li><li>Durward, M., Harms, J., Splitter, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antigen+specific+killing+assay+using+CFSE+labeled+target+cells.">Antigen specific killing assay using CFSE labeled target cells.</a> J Vis Exp. (45), (2010).</li></ol>

The authors have nothing to disclose.

While this protocol is straightforward, there are a few critical steps that must be carefully performed. The covax priming following injection of the antigen-specific T-cell being tested is necessary to see any killing of the pulsed targets. While it is possible that the water-based covax vaccination creates an acute inflammatory condition, for the chronic inflammatory phase, replacing the short-lived water-based formulation with a slow-antigen release oil-based approach may produce a better outcome7</s...

Multiple protocols exist to assess the cytolytic (CTL) potential of a CD8+ or CD4+ T-cell. This assessment can be readily done in vitro under controlled conditions1,2,3. In addition, infectious disease models, such as LCMV, have classically examined CTL function through the use of differentially CFSE (5-(and 6)-Carboxyfluorescein diacetate succinimidyl ester) labeled target cells where the CFSEhi-labeled cells are pulsed with a peptide and CFSElo-labeled target cells are left unpulsed. The cells are then injected at a 1:1 ratio and assessed for loss of the CFSEhi-labeled pulsed targets by flow cytometry4. Vaccine and rejection models have also used similar strategies for assessment of in vivo killing by both CD8+ and CD4+ T cells as well as NK cells5,6. This is a powerful assay, but requires the use of infectious agents that prime the immune system prior to target injection.
This protocol, on the other hand, requires no prior infection of the host and instead utilizes a vaccination strategy to prime the immune system prior to target injection. This vaccination is comprised of a water-based formulation of peptide vaccine which requires provision of an immunostimulatory cocktail called covax7, consisting of a Toll-like receptor 7 (TLR7) agonist (imiquimod cream), an agonistic anti-CD40 antibody, and interleukin-2 (IL-2) leading to synergistic combination of immunostimulatory agents for the elicitation of peptide-specific priming and robust immune response. As such, this assay provides a quick readout of CTL function as the vaccine is administered along with the cells for assessment of function only three days prior to injection of the target cells. In addition, the covax priming is strong enough that the killing capacity of the primed antigen-specific T cell can be seen between 4 and 24 h after injection.
The major limitation of this protocol is identifying the timeline in vivo for the detection of target killing that is appropriate to both the antigen and the hypothesis being tested. Careful assessment must be performed, as variations in antigen strength as well as genetic alterations being tested in T-cells could result in differential CTL function that would require a different timing detection of target killing. In addition, while the appropriate concentration of peptide for vaccination has been optimized for human melanoma antigen glycopeptide 100 (hgp10025-33) and ovalbumin257-264 (OVA257-264)8,9, use of another antigen model that may be more appropriate to a given study would require further validation. Because of anticipated differences in a target antigens&#39; capacity to stimulate CTL effector function in combination with the covax as an adjuvant, optimization of IL-2 dose concentration and dose frequency may be essential to achieve the desired goal. Overall, this protocol allows for a quick assessment of killing function in vivo and can be adapted to any given antigen.

<table style="border-collapse:collapse;width:523pt" width="697">
	<colgroup>
		<col style="width:199pt" width="265" />
		<col style="width:110pt" width="146" />
		<col style="width:89pt" width="119" />
		<col style="width:125pt" width="167" />
	</colgroup>
	<tbody>
		<tr height="20" style="height:15.0pt">
			<td height="20" style="width:199pt;height:15.0pt" width="265">6- to 12-week old female C57BL/6 mice&#160;</td>
			<td class="xl69" style="width:110pt" width="146">Charles River</td>
			<td class="xl70" style="width:89pt" width="119">027</td>
			<td style="width:125pt" width="167">C57 Black 6 mice</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">OT-1 6-12-week old female mice&#160;</td>
			<td class="xl70" style="width:110pt" width="146">Jackson Labs</td>
			<td class="xl70" style="width:89pt" width="119">003831</td>
			<td></td>
		</tr>
		<tr height="24" style="height:18.0pt">
			<td height="24" style="height:18.0pt">hgp10025&#8211;33&#160;</td>
			<td class="xl69">CPCScientific</td>
			<td class="xl70" style="width:89pt" width="119">834139</td>
			<td>KVPRNQDWL</td>
		</tr>
		<tr height="24" style="height:18.0pt">
			<td height="24" style="height:18.0pt">OVA 257&#8211;264&#160;</td>
			<td class="xl69">CPCScientific</td>
			<td class="xl70" style="width:89pt" width="119">MISC-012</td>
			<td>SIINFEKL</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td height="20" style="height:15.0pt">Imiquimod cream 5%&#160;</td>
			<td class="xl69">Fougera</td>
			<td class="xl73">51672-4145-6</td>
			<td>Aldara Cream</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td height="20" style="height:15.0pt">CD40-specific mAb&#160;</td>
			<td class="xl69">BioXcell</td>
			<td class="xl70" style="width:89pt" width="119">BE0016-2</td>
			<td>clone FGK4.5</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td height="20" style="height:15.0pt">rhIL-2 protein&#160;</td>
			<td class="xl69">Hoffman LaRoche Inc</td>
			<td class="xl70" style="width:89pt" width="119">136</td>
			<td>Recombinant human IL-2 protein</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td height="20" style="height:15.0pt">70% isopropyl alcohol Prep&#160;</td>
			<td class="xl69">Kendall</td>
			<td class="xl70" style="width:89pt" width="119">S-17474</td>
			<td></td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td height="20" style="height:15.0pt">PBS</td>
			<td class="xl69">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">10010-023</td>
			<td>Phosphate Buffered Saline</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">FBS</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">26140-079</td>
			<td>fetal bovine serum</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">RBC lysis buffer&#160;</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">A10492-01</td>
			<td>red blood cell lysis buffer</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">RPMI 1640 Media</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">11875119</td>
			<td></td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">L-Glutamine&#160;</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">25030081</td>
			<td></td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">Pen/Strep</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">15140122</td>
			<td>penicillin/streptomycin</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">CFSE</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">C34554</td>
			<td>5-(and 6)-Carboxyfluorescein diacetate succinimidyl ester</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">Bovine serum albumin (BSA)</td>
			<td class="xl70" style="width:110pt" width="146">Sigma&#160;</td>
			<td class="xl70" style="width:89pt" width="119">A4503</td>
			<td></td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">1.5 mL MCT graduated natural&#160;</td>
			<td class="xl70" style="width:110pt" width="146">Fisher</td>
			<td class="xl70" style="width:89pt" width="119">05-408-129</td>
			<td>microcentrifuge tube</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">70% ethanol</td>
			<td class="xl70" style="width:110pt" width="146">Fisher</td>
			<td class="xl73">BP8201500</td>
			<td>EtOH</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">Trypan blue solution, 0.4%&#160;&#160;</td>
			<td class="xl70" style="width:110pt" width="146">Life Technologies</td>
			<td class="xl70" style="width:89pt" width="119">15250-061</td>
			<td></td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">Hemocytometer</td>
			<td class="xl70" style="width:110pt" width="146">Fisher</td>
			<td class="xl70" style="width:89pt" width="119">267110</td>
			<td></td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">27 gauge needle</td>
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			<td class="xl70" style="width:89pt" width="119">305109</td>
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			<td class="xl71" height="20" style="width:199pt;height:15.0pt" width="265">1 mL syringe</td>
			<td class="xl70" style="width:110pt" width="146">BD</td>
			<td class="xl70" style="width:89pt" width="119">309659</td>
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in vivo assay for detection of antigen-specific t-cell cytolytic function using a vaccination model

Current methodologies for antigen-specific killing are limited to in vitro use or utilized in infectious disease models. However, there is not a protocol specifically intended to measure antigen-specific killing without an infection. This protocol is designed and describes methods to overcome these limitations by allowing for the detection of antigen-specific killing of a target cell by CD8+ T cells in vivo. This is accomplished by merging a vaccination model with a traditional CFSE-labeled target killing assay. This combination allows the researcher to assess the antigen-specific CTL potential directly and quickly as the assay is not dependent upon tumor growth or infection. In addition, the readout is based on flow cytometry and so should be readily accessible to most researchers. The major limitation of the study is identifying the timeline in vivo that is appropriate to the hypothesis being tested. Variations in antigen strength and mutations in the T cells that may result in differential cytolytic function need to be carefully assessed to determine the optimal time for cell harvest and assessment. The appropriate concentration of peptide for vaccination has been optimized for hgp10025-33 and OVA257-264, but further validation would be needed for other peptides that may be more appropriate to a given study. Overall, this protocol allows a quick assessment of killing function in vivo and can be adapted to any given antigen.

Prior to injection of CFSE-labeled target cells, the 1:1 cell mixture is run on a flow cytometer to determine the baseline frequencies of both the CFSEhi and CFSElo target cells. Figure 1A shows the gating strategy to detect changes in the CFSE populations, an initial gate is made using FSC and SSC parameters. The total CFSE-positive cells are then subgated prior to assessing changes in frequency, as this population is r...

Watch this Scientific Journal Video about In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model at JoVE.com

In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

The goal of this protocol is to allow for detection of in vivo antigen-specific killing of a target cell in a murine model.

In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

Current methodologies for antigen-specific killing are limited to in vitro use or utilized in infectious disease models. However, there is not a protocol ...

in-vivo-assay-for-detection-antigen-specific-t-cell-cytolytic

Research

JoVE Journal

Immunology and Infection

9.8K Views.  University of Texas MD Anderson Cancer Center. The goal of this protocol is to allow for detection of in vivo antigen-specific killing of a target cell in a murine model.

Video: In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

Antigen Specific In Vivo Killing Assay using CFSE Labeled Target Cells

Carboxyfluorescein diacetate succinimidyl ester (CFSE) can be used to easily and quickly label a cell population of interest for in vivo investigation. This labeling has classically been used to study proliferation and migration. In the method presented here, we have shortened the timeline after adoptive transfer to look at survival and killing of epitope specific CFSE labeled target cells4-6. The level of specific killing of a CD8 + T cell clone can indicate the quality of the response, as their quantity may be misleading. Specific CD8+ T cells can become functionally exhausted over time with a decline in cytokine production and killing7,8. Also, certain CD8 + T cell clones may not kill as well as others with differing TCR specificities9. For effective Cell Mediated Immunity (CMI), antigens must be identified that produce not only adequate numbers of responding T cells, but also functionally robust responding T cells. Here we assess the percent cell specific killing of two peptide specific T cell clones in BALB/c mice.

Antigen Specific In Vivo Killing Assay using CFSE Labeled Target Cells

Many infections elicit a strong CTL response, but occasionally, the quantity of responding cells does not correlate to control of the pathogen1. One measure of CTL quality is their ability to kill specifically2. CFSE labeling of target cells can be used to investigate this CTL response quality in vivo3,4.

Carboxyfluorescein diacetate succinimidyl ester (CFSE) can be used to easily and quickly label a cell population of interest for in vivo investigation.  ...

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological deficiencies. GVHD is caused by mature alloreactive T cells present in the bone marrow graft that are infused into the recipient and cause damage to host organs. However, in mice, T cells must be added to the bone marrow inoculum to cause GVHD. Although extensive work has been done to characterize T cell responses post transplant, bioluminescent imaging technology is a non-invasive method to monitor T cell trafficking patterns in vivo. 
Following lethal irradiation, recipient mice are transplanted with bone marrow cells and splenocytes from donor mice. T cell subsets from L2G85.B6 (transgenic mice that constitutively express luciferase) are included in the transplant. By only transplanting certain T cell subsets, one is able to track specific T cell subsets in vivo, and based on their location, develop hypotheses regarding the role of specific T cell subsets in promoting GVHD at various time points. At predetermined intervals post transplant, recipient mice are imaged using a Xenogen IVIS CCD camera. Light intensity can be quantified using Living Image software to generate a pseudo-color image based on photon intensity (red = high intensity, violet = low intensity). 
Between 4-7 days post transplant, recipient mice begin to show clinical signs of GVHD. Cooke et al.1 developed a scoring system to quantitate disease progression based on the recipient mice fur texture, skin integrity, activity, weight loss, and posture. Mice are scored daily, and euthanized when they become moribund. Recipient mice generally become moribund 20-30 days post transplant. 
Murine models are valuable tools for studying the immunology of GVHD. Selectively transplanting particular T cell subsets allows for careful identification of the roles each subset plays. Non-invasively tracking T cell responses in vivo adds another layer of value to murine GVHD models.

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Murine bone marrow transplantation is a widely used technique to study immunological mechanisms governing graft-versus-host disease in humans. The ability to monitor T cell trafficking patterns in vivo allows for detailed analysis of the development and perpetuation of T cell responses during graft-versus-host disease.

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological ...

Trans-vivo Delayed Type Hypersensitivity Assay for Antigen Specific Regulation

Delayed-type hypersensitivity response (DTH) is a rapid in vivo manifestation of T cell-dependent immune response to a foreign antigen (Ag) that the host immune system has experienced in the recent past. DTH reactions are often divided into a sensitization phase, referring to the initial antigen experience, and a challenge phase, which usually follows several days after sensitization. The lack of a delayed-type hypersensitivity response to a recall Ag demonstrated by skin testing is often regarded as an evidence of anergy. The traditional DTH assay has been effectively used in diagnosing many microbial infections.
Despite sharing similar immune features such as lymphocyte infiltration, edema, and tissue necrosis, the direct DTH is not a feasible diagnostic technique in transplant patients because of the possibility of direct injection resulting in sensitization to donor antigens and graft loss. To avoid this problem, the human-to-mouse "trans-vivo" DTH assay was developed 1,2. This test is essentially a transfer DTH assay, in which human peripheral blood mononuclear cells (PBMCs) and specific antigens were injected subcutaneously into the pinnae or footpad of a na&iuml;ve mouse and DTH-like swelling is measured after 18-24 hr 3. The antigen presentation by human antigen presenting cells such as macrophages or DCs to T cells in highly vascular mouse tissue triggers the inflammatory cascade and attracts mouse immune cells resulting in swelling responses. The response is antigen-specific and requires prior antigen sensitization. A positive donor-reactive DTH response in the Tv-DTH assay reflects that the transplant patient has developed a pro-inflammatory immune disposition toward graft alloantigens.
The most important feature of this assay is that it can also be used to detect regulatory T cells, which cause bystander suppression. Bystander suppression of a DTH recall response in the presence of donor antigen is characteristic of transplant recipients with accepted allografts 2,4-14. The monitoring of transplant recipients for alloreactivity and regulation by Tv-DTH may identify a subset of patients who could benefit from reduction of immunosuppression without elevated risk of rejection or deteriorating renal function.
A promising area is the application of the Tv-DTH assay in monitoring of autoimmunity15,16 and also in tumor immunology 17.

We describe a valuable diagnostic assay that could potentially be used to decide the withdrawal of immunosuppression after transplant without elevated risk of graft rejection. The assay uses the principles of Delayed Type Hypersensitivity and provides accurate assessment of both donor specific effector and regulatory immune responses mounted by recipients.

Delayed-type hypersensitivity response (DTH) is a rapid in vivo manifestation of T cell-dependent immune response to a foreign antigen (Ag) that the host ...

In Vitro Assay to Evaluate the Impact of Immunoregulatory Pathways on HIV-specific CD4 T Cell Effector Function

T cell exhaustion is a major factor in failed pathogen clearance during chronic viral infections. Immunoregulatory pathways, such as PD-1 and IL-10, are upregulated upon this ongoing antigen exposure and contribute to loss of proliferation, reduced cytolytic function, and impaired cytokine production by CD4 and CD8 T cells. In the murine model of LCMV infection, administration of blocking antibodies against these two pathways augmented T cell responses. However, there is currently no in vitro assay to measure the impact of such blockade on cytokine secretion in cells from human samples. Our protocol and experimental approach enable us to accurately and efficiently quantify the restoration of cytokine production by HIV-specific CD4 T cells from HIV infected subjects.
Here, we depict an in vitro experimental design that enables measurements of cytokine secretion by HIV-specific CD4 T cells and their impact on other cell subsets. CD8 T cells were depleted from whole blood and remaining PBMCs were isolated via Ficoll separation method. CD8-depleted PBMCs were then incubated with blocking antibodies against PD-L1 and/or IL-10R&#945; and, after stimulation with an HIV-1 Gag peptide pool, cells were incubated at 37 &#176;C, 5% CO2. After 48 hr, supernatant was collected for cytokine analysis by beads arrays and cell pellets were collected for either phenotypic analysis using flow cytometry or transcriptional analysis using qRT-PCR. For more detailed analysis, different cell populations were obtained by selective subset depletion from PBMCs or by sorting using flow cytometry before being assessed in the same assays. These methods provide a highly sensitive and specific approach to determine the modulation of cytokine production by antigen-specific T-helper cells and to determine functional interactions between different populations of immune cells.

In Vitro Assay to Evaluate the Impact of Immunoregulatory Pathways on HIV-specific CD4 T Cell Effector Function

We developed an in vitro assay to investigate the role of immunoregulatory pathways in the regulation of cytokine secretion by HIV-specific CD4 T cells.

T cell exhaustion is a major factor in failed pathogen clearance during chronic viral infections. Immunoregulatory pathways, such as PD-1 and IL-10, are ...

An Ex vivo Model of an Oligodendrocyte-directed T-Cell Attack in Acute Brain Slices

Death of oligodendrocytes accompanied by destruction of neurons and axons are typical histopathological findings in cortical and subcortical grey matter lesions in inflammatory demyelinating disorders like multiple sclerosis (MS). In these disorders, mainly CD8+ T-cells of putative specificity for myelin- and oligodendrocyte-related antigens are found, so that neuronal apoptosis in grey matter lesions may be a collateral effect of these cells. Different types of animal models are established to study the underlying mechanisms of the mentioned pathophysiological processes. However, although they mimic some aspects of MS, it is impossible to dissect the exact mechanism and time course of &#8216;&#8216;collateral&#8217;&#8217; neuronal cell death. To address this course, here we show a protocol to study the mechanisms and time response of neuronal damage following an oligodendrocyte-directed CD8+ T cell attack. To target only the myelin sheath and the oligodendrocytes, in vitro activated oligodendrocyte-specific CD8+ T-cells are transferred into acutely isolated brain slices. After a defined incubation period, myelin and neuronal damage can be analysed in different regions of interest. Potential applications and limitations of this model will be discussed.

An Ex vivo Model of an Oligodendrocyte-directed T-Cell Attack in Acute Brain Slices

To address mechanisms of demyelination and neuronal apoptosis in cortical lesions of inflammatory demyelinating disorders, different animal models are used. We here describe an ex vivo approach by using oligodendrocyte-specific CD8+ T-cells on brain slices, resulting in oligodendroglial and neuronal death. Potential applications and limitations of the model are discussed.

Death of oligodendrocytes accompanied by destruction of neurons and axons are typical histopathological findings in cortical and subcortical grey matter ...

Whole-animal Imaging and Flow Cytometric Techniques for Analysis of Antigen-specific CD8+ T Cell Responses after Nanoparticle Vaccination

Traditional vaccine adjuvants, such as alum, elicit suboptimal CD8+ T cell responses. To address this major challenge in vaccine development, various nanoparticle systems have been engineered to mimic features of pathogens to improve antigen delivery to draining lymph nodes and increase antigen uptake by antigen-presenting cells, leading to new vaccine formulations optimized for induction of antigen-specific CD8+ T cell responses. In this article, we describe the synthesis of a &#8220;pathogen-mimicking&#8221; nanoparticle system, termed interbilayer-crosslinked multilamellar vesicles (ICMVs) that can serve as an effective vaccine carrier for co-delivery of subunit antigens and immunostimulatory agents and elicitation of potent cytotoxic CD8+ T lymphocyte (CTL) responses. We describe methods for characterizing hydrodynamic size and surface charge of vaccine nanoparticles with dynamic light scattering and zeta potential analyzer and present a confocal microscopy-based procedure to analyze nanoparticle-mediated antigen delivery to draining lymph nodes. Furthermore, we show a new bioluminescence whole-animal imaging technique utilizing adoptive transfer of luciferase-expressing, antigen-specific CD8+ T cells into recipient mice, followed by nanoparticle vaccination, which permits non-invasive interrogation of expansion and trafficking patterns of CTLs in real time. We also describe tetramer staining and flow cytometric analysis of peripheral blood mononuclear cells for longitudinal quantification of endogenous T cell responses in mice vaccinated with nanoparticles.

We describe whole-animal imaging and flow cytometry-based techniques for monitoring expansion of antigen-specific CD8+ T cells in response to immunization with nanoparticles in a murine model of vaccination.

Traditional vaccine adjuvants, such as alum, elicit suboptimal CD8+ T cell responses. To address this major challenge in vaccine development, various ...

Assessing Retinal Microglial Phagocytic Function In Vivo Using a Flow Cytometry-based Assay

Microglia are the tissue resident macrophages of the central nervous system (CNS) and they perform a variety of functions that support CNS homeostasis, including phagocytosis of damaged synapses or cells, debris, and/or invading pathogens. Impaired phagocytic function has been implicated in the pathogenesis of diseases such as Alzheimer's and age-related macular degeneration, where amyloid-&#946; plaque and drusen accumulate, respectively. Despite its importance, microglial phagocytosis has been challenging to assess in vivo. Here, we describe a simple, yet robust, technique for precisely monitoring and quantifying the in vivo phagocytic potential of retinal microglia. Previous methods have relied on immunohistochemical staining and imaging techniques. Our method uses flow cytometry to measure microglial uptake of fluorescently labeled particles after intravitreal delivery to the eye in live rodents. This method replaces conventional practices that involve laborious tissue sectioning, immunostaining, and imaging, allowing for more precise quantification of microglia phagocytic function in just under six hours. This procedure can also be adapted to test how various compounds alter microglial phagocytosis in physiological settings. While this technique was developed in the eye, its use is not limited to vision research.

Assessing Retinal Microglial Phagocytic Function In Vivo Using a Flow Cytometry-based Assay

Microglial phagocytosis is critical for the maintenance of tissue homeostasis and inadequate phagocytic function has been implicated in pathology. However, assessing microglia function in vivo is technically challenging. We have developed a simple but robust technique for precisely monitoring and quantifying the phagocytic potential of microglia in a physiological setting.

Microglia are the tissue resident macrophages of the central nervous system (CNS) and they perform a variety of functions that support CNS homeostasis, ...

Generating De Novo Antigen-specific Human T Cell Receptors by Retroviral Transduction of Centric Hemichain

T cell receptors (TCRs) are used clinically to direct the specificity of T cells to target tumors as a promising modality of immunotherapy. Therefore, cloning TCRs specific for various tumor-associated antigens has been the goal of many studies. To elicit an effective T cell response, the TCR must recognize the target antigen with optimal affinity. However, cloning such TCRs has been a challenge and many available TCRs possess sub-optimal affinity for the cognate antigen. In this protocol, we describe a method of cloning de novo high affinity antigen-specific TCRs using existing TCRs by exploiting hemichain centricity. It is known that for some TCRs, each TCR&#945; or TCR&#946; hemichain do not contribute equally to antigen recognition, and the dominant hemichain is referred to as the centric hemichain. We have shown that by pairing the centric hemichain with counter-chains differing from the original counter-chain, we are able to maintain the antigen specificity, while modulating its interaction strength for the cognate antigen. Thus, the therapeutic potential of a given TCR can be improved by optimizing the pairing between the centric and counter hemichains.

Generating De Novo Antigen-specific Human T Cell Receptors by Retroviral Transduction of Centric Hemichain

Herein we describe a novel method to generate antigen-specific T cell receptors (TCRs) by pairing the TCR&#945; or TCR&#946; of an existing TCR, possessing the antigen-specificity of interest, with complementary hemichain of the peripheral T cell receptor repertoire. The de novo generated TCRs retain antigen-specificity with varying affinity.

T cell receptors (TCRs) are used clinically to direct the specificity of T cells to target tumors as a promising modality of immunotherapy. Therefore, ...

Detection and Enrichment of Rare Antigen-specific B Cells for Analysis of Phenotype and Function

B cells reactive with a specific antigen usually occur at a frequency of &lt;0.05% of lymphocytes. For decades researchers have sought methods to isolate and enrich these rare cells for studies of their phenotype and biology. Approaches are inevitably based on the principle that B cells recognize native antigen by virtue of cell surface receptors that are representative in specificity of antibodies that will eventually be secreted by their differentiated daughters. Perhaps the most obvious approach to the problem involves use of fluorochrome-conjugated antigens in conjunction with fluorescence-activated cell sorting (FACS). However, the utility of these methods is limited by cell frequency and the achievable rate of analysis and isolation by electronic sorting. A novel method to enrich rare antigen-specific B cells using magnetic nanoparticles that results in high yield enrichment of antigen-reactive B cells from large starting cell populations is described. This method enables improved monitoring of the phenotype and biology of antigen reactive cells before and following in vivo antigen encounter, such as after immunization or during development of autoimmunity.

A simple yet effective method that employs magnetic nanoparticles to detect and enrich antigen-reactive B cells for functional and phenotypic analysis is described.

B cells reactive with a specific antigen usually occur at a frequency of &lt;0.05% of lymphocytes. For decades researchers have sought methods to isolate ...

A Protein Microarray Assay for Serological Determination of Antigen-specific Antibody Responses Following Clostridium difficile Infection

We provide a detailed overview of a novel high-throughput protein microarray assay for the determination of anti-Clostridium difficile antibody levels in human sera and in separate preparations of polyclonal intravenous immunoglobulin (IVIg). The protocol describes the methodological steps involved in sample preparation, printing of arrays, assay procedure, and data analysis. In addition, this protocol could be further developed to incorporate diverse clinical samples including plasma and cell culture supernatants. We show how protein microarray can be used to determine a combination of isotype (IgG, IgA, IgM), subclass (IgG1, IgG2, IgG3, IgG4, IgA1, IgA2), and strain-specific antibodies to highly purified whole C. difficile toxins A and B (toxinotype 0, strain VPI 10463, ribotype 087), toxin B from a C. difficile toxin-B-only expressing strain (CCUG 20309), a precursor form of a B fragment of binary toxin, pCDTb, ribotype-specific whole surface layer proteins (SLPs; 001, 002, 027), and control proteins (tetanus toxoid and Candida albicans). During the experiment, microarrays are probed with sera from individuals with C. difficile infection (CDI), individuals with cystic fibrosis (CF) without diarrhea, healthy controls (HC), and from individuals pre- and post-IVIg therapy for the treatment of CDI, combined immunodeficiency disorder, and chronic inflammatory demyelinating polyradiculopathy. We encounter significant differences in toxin neutralization efficacies and multi-isotype specific antibody levels between patient groups, commercial preparations of IVIg, and sera before and following IVIg administration. Also, there is a significant correlation between microarray and enzyme-linked immunosorbent assay (ELISA) for antitoxin IgG levels in serum samples. These results suggest that microarray could become a promising tool for profiling antibody responses to C.difficile antigens in vaccinated or infected humans. With further refinement of antigen panels and a reduction in production costs, we anticipate that microarray technology may help optimize and select the most clinically useful immunotherapies for C. difficile infection in a patient-specific manner.

A Protein Microarray Assay for Serological Determination of Antigen-specific Antibody Responses Following Clostridium difficile Infection

This article describes a simple protein microarray method for profiling humoral immune responses to a 7-plex panel of highly purified Clostridium difficile antigens in human sera. The protocol can be extended for the determination of specific antibody responses in preparations of polyclonal intravenous immunoglobulin.

We provide a detailed overview of a novel high-throughput protein microarray assay for the determination of anti-Clostridium difficile antibody levels in ...