E.B., K.M.B, and H.X. contribute equally. This study was supported by the NCI SPORE in Gastrointestinal Cancers P50 CA062924, NIH K23 CA148964, Lustgarten Foundation, Viragh Foundation, ASCO Young Investigator Award, NIH 5T32 CA0090701-28 Training Grant, Sol Goldman Pancreatic Cancer Center, and National Pancreas Foundation.

B7-H1/PD-L1, a member of the B7 family of immune-regulatory cell-surface proteins, plays an important role in the negative regulation of cell-mediated immune responses through its interaction with its receptor, programmed death-1 (PD-1) 1,2. Overexpression of B7-H1 by tumor cells has been noted in a number of human cancers, including melanoma, glioblastoma, and carcinomas of the lung, breast, colon, ovary, and renal cells, and has been shown to impair anti-tumor T-cell immunity3-8.
Recently, B7-H1 expression by pancreatic adenocarcinoma tissues has been identified as a potential prognostic marker9,10. Additionally, blockade of B7-H1 in a mouse model of pancreatic cancer has been shown to produce an anti-tumor response11. These data suggest the importance of B7-H1 as a potential therapeutic target. Anti-B7-H1 blockade antibodies are therefore being tested in clinical trials for multiple human solid tumors including melanoma and cancers of lung, colon, kidney, stomach and pancreas12.
In order to eventually be able to identify the patients who will benefit from B7-H1 targeting therapies, it is critical to investigate the correlation between expression and localization of B7-H1 and patient response to treatment with B7-H1 blockade antibodies. Examining the expression of B7-H1 in human pancreatic adenocarcinoma tissues through immunohistochemistry will give a better understanding of how this co-inhibitory signaling molecule contributes to the suppression of antitumor immunity in the tumor's microenvironment. The anti-B7-H1 monoclonal antibody (clone 5H1) developed by Chen and coworkers has been shown to produce reliable staining results in cryosections of multiple types of human neoplastic tissues4,8, but staining on paraffin-embedded slides had been a challenge until recently13-18. We have developed the B7-H1 staining protocol for paraffin-embedded slides of pancreatic adenocarcinoma tissues. The B7-H1 staining protocol described here produces consistent membranous and cytoplasmic staining of B7-H1 with little background.
1. De-parafinization
<ol>
 <li>Bake slides at 55 &deg;C for 20 min.</li>
 <li>In a chemical hood, immerse slides in xylene for 10 min. </li>
 <li>Immerse slides in fresh xylene for 10 min. </li>
 <li>Immerse slides in 100% ethanol for 5 min. </li>
 <li>Immerse slides in fresh 100% ethanol for 5 min. </li>
 <li>Immerse slides in 95% ethanol for 5 min. </li>
 <li>Immerse slides in 80% ethanol for 5 min. </li>
 <li>Immerse slides in deionized water for 5 min. </li>
</ol>
2. Antigen Retrieval
<ol>
 <li>Immerse slides in Tris-EDTA buffer (pH 9.0) and heat in a pressure cooker to 125 &deg;C for 30 sec, then 90 &deg;C for 10 sec. </li>
 <li>Let slides cool for 60 min. </li>
 <li>Immerse slides in TBST for 5 min; repeat twice. </li>
</ol>
3. Staining
<ol>
 <li>Wipe off solutions around the tissue on the slides. Mark a circle around the tissue with a hydrophobic pen.</li>
 <li>Place the slides in a humidity chamber and avoid the drying of the tissue on the slide throughout the entire staining process. Place one drop (approximately 200 &mu;l or more to cover the tissue area completely) of peroxidase block within the hydrophobic circle on the slide and incubate slides in peroxidase block for 5 min. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. </li>
 <li>Place one drop of BLOCK ACE blocking buffer on each slide and incubate for 15 min. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min.</li>
 <li>Place one drop of Avidin solution on each slide and incubate for 15 min. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. </li>
 <li>Place one drop of Biotin solution on each slide and incubate for 15 min.</li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. </li>
 <li>Incubate slides with 1:1,000 dilution of mouse anti-B7-H1 monoclonal antibody (clone 5H1) or a mouse IgG1 &kappa; isotype control in 200 &mu;l TBST at 4 &deg;C overnight for 22 hr+/- 1 hr. The final antibody concentration in TBST is 2.57 &mu;g/ml. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. Repeat twice. </li>
 <li>Incubate slides with a biotin conjugated rat anti-mouse IgG1 secondary antibody at a 1:500 concentration (in 200 &mu;l 2% goat serum solution) for 30 min. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. Repeat twice.</li>
 <li>Place one drop of Streptavidin-Biotin Complex (must be prepared at least 30 min prior to use) on each slide and incubate for 15 min. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. Repeat twice. </li>
 <li>Place one drop of Amplification Reagent (diluted 2:1 with TBST) on each slide and incubate for 4 min.</li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. Repeat twice. </li>
 <li>Place one drop of Streptavidin-HRP on each slide and incubate for 15 min. </li>
 <li>Rinse slides with TBST, then place in TBST for 5 min. Repeat twice. </li>
 <li>Place one drop of 3,3-Diaminobenzidine (DAB) substrate and chromogen on each slide and develop the color for 2 min. </li>
 <li>Immediately after the color development, wash slides with ddH2O for 1-2 min. </li>
 <li>Incubate slides with one drop of hematoxylin for 90 sec. </li>
 <li>Wash with ddH2O for 1-2 min. </li>
 <li>Wash with soapy tap water for 1-2 min. </li>
 <li>Wash with ddH2O for 1-2 min. </li>
</ol>
4. Dehydration and Mounting
<ol>
 <li>Immerse the slides in 80% ethanol for 3 min.</li>
 <li>Immerse the slides in 95% ethanol for 3 min.</li>
 <li>Immerse the slides in 100% ethanol for 5 min. Repeat. </li>
 <li>Immerse the slides in xylene for 5 min. Repeat.</li>
 <li>Add one drop of Cytoseal 60 to the slide and place the coverslip.</li>
</ol>
Table 1 lists the reagents used in the above described procedures.

<ol>
	<li>Flies, D. B., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+new+B7s:+playing+a+pivotal+role+in+tumor+immunity.">The new B7s: playing a pivotal role in tumor immunity.</a> J. Immunother. 30, 251-260 (2007).</li><li>Dong, H., Zhu, G., Tamada, K., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B7-H1,+a+third+member+of+the+B7+family,+co-stimulates+T-cell+proliferation+and+interleukin-10+secretion.">B7-H1, a third member of the B7 family, co-stimulates T-cell proliferation and interleukin-10 secretion.</a> Nat. Med. 5, 1365-1369 (1999).</li><li>Curiel, T. J., Wei, S., Dong, H., Alvarez, X., Cheng, P., Mottram, P., Krzysiek, R., Knutson, K. 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=Blockade+of+B7-H1+improves+myeloid+dendritic+cell-mediated+antitumor+immunity.">Blockade of B7-H1 improves myeloid dendritic cell-mediated antitumor immunity.</a> Nat. Med. 9, 562-567 (2003).</li><li>Dong, H., Strome, S. E., Salomao, D. R., Tamura, H., Hirano, F., Flies, D. B., Roche, P. C., Lu, J., Zhu, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor-associated+B7-H1+promotes+T-cell+apoptosis:+a+potential+mechanism+of+immune+evasion.">Tumor-associated B7-H1 promotes T-cell apoptosis: a potential mechanism of immune evasion.</a> Nat. Med. 8, 793-800 (2002).</li><li>Dong, H., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B7-H1+pathway+and+its+role+in+the+evasion+of+tumor+immunity.">B7-H1 pathway and its role in the evasion of tumor immunity.</a> J. Mol. Med. (Berl). 81, 281-287 (2003).</li><li>Strome, S. E., Dong, H., Tamura, H., Voss, S. G., Flies, D. B., Tamada, K., Salomao, D., Cheville, J., Hirano, F., Lin, W., Kasperbauer, J. L., Ballman, K. V., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B7-H1+blockade+augments+adoptive+T-cell+immunotherapy+for+squamous+cell+carcinoma.">B7-H1 blockade augments adoptive T-cell immunotherapy for squamous cell carcinoma.</a> Cancer Res. 63, 6501-6505 (2003).</li><li>Hirano, F., Kaneko, K., Tamura, H., Dong, H., Wang, S., Ichikawa, M., Rietz, C., Flies, D. B., Lau, J. S., Zhu, G., Tamada, K., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blockade+of+B7-H1+and+PD-1+by+monoclonal+antibodies+potentiates+cancer+therapeutic+immunity.">Blockade of B7-H1 and PD-1 by monoclonal antibodies potentiates cancer therapeutic immunity.</a> Cancer Res. 65, 1089-1096 (2005).</li><li>Thompson, R. H., Gillett, M. D., Cheville, J. C., Lohse, C. M., Dong, H., Webster, W. S., Krejci, K. G., Lobo, J. R., Sengupta, S., Chen, L., Zincke, H., Blute, M. L., Strome, S. E., Leibovich, B. C., Kwon, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Costimulatory+B7-H1+in+renal+cell+carcinoma+patients:+Indicator+of+tumor+aggressiveness+and+potential+therapeutic+target.">Costimulatory B7-H1 in renal cell carcinoma patients: Indicator of tumor aggressiveness and potential therapeutic target.</a> Proc. Natl. Acad. Sci. U.S.A. 101, 17174-17179 (2004).</li><li>Geng, L., Huang, D., Liu, J., Qian, Y., Deng, J., Li, D., Hu, Z., Zhang, J., Jiang, G., Zheng, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B7-H1+up-regulated+expression+in+human+pancreatic+carcinoma+tissue+associates+with+tumor+progression.">B7-H1 up-regulated expression in human pancreatic carcinoma tissue associates with tumor progression.</a> J. Cancer Res. Clin. Oncol. 134, 1021-1027 (2008).</li><li>Loos, M., Giese, N. A., Kleeff, J., Giese, T., Gaida, M. M., Bergmann, F., Laschinger, M., WB, M., Friess, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+significance+and+regulation+of+the+costimulatory+molecule+B7-H1+in+pancreatic+cancer.">Clinical significance and regulation of the costimulatory molecule B7-H1 in pancreatic cancer.</a> Cancer Lett. 268, 98-109 (2008).</li><li>Okudaira, K., Hokari, R., Tsuzuki, Y., Okada, Y., Komoto, S., Watanabe, C., Kurihara, C., Kawaguchi, A., Nagao, S., Azuma, M., Yagita, H., Miura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blockade+of+B7-H1+or+B7-DC+induces+an+anti-tumor+effect+in+a+mouse+pancreatic+cancer+model.">Blockade of B7-H1 or B7-DC induces an anti-tumor effect in a mouse pancreatic cancer model.</a> Int. J. Oncol. 35, 741-749 (2009).</li><li>Wang, S., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunobiology+of+cancer+therapies+targeting+CD137+and+B7-H1/PD-1+cosignal+pathways.">Immunobiology of cancer therapies targeting CD137 and B7-H1/PD-1 cosignal pathways.</a> Curr. Top Microbiol. Immunol. 344, 245-267 (2011).</li><li>Thompson, R. H., Webster, W. S., Cheville, J. C., Lohse, C. M., Dong, H., Leibovich, B. C., Kuntz, S. M., Sengupta, S., Kwon, E. D., Blute, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B7-H1+glycoprotein+blockade:+a+novel+strategy+to+enhance+immunotherapy+in+patients+with+renal+cell+carcinoma.">B7-H1 glycoprotein blockade: a novel strategy to enhance immunotherapy in patients with renal cell carcinoma.</a> Urology. 66, 10-14 (2005).</li><li>Thompson, R. H., Kuntz, S. M., Leibovich, B. C., Dong, H., Lohse, C. M., Webster, W. S., Sengupta, S., Frank, I., Parker, A. S., Zincke, H., Blute, M. L., Sebo, T. J., Cheville, J. C., Kwon, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+B7-H1+is+associated+with+poor+prognosis+in+renal+cell+carcinoma+patients+with+long-term+follow-up.">Tumor B7-H1 is associated with poor prognosis in renal cell carcinoma patients with long-term follow-up.</a> Cancer Res. 66, 3381-3385 (2006).</li><li>Thompson, R. H., Dong, H., Kwon, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implications+of+B7-H1+expression+in+clear+cell+carcinoma+of+the+kidney+for+prognostication+and+therapy.">Implications of B7-H1 expression in clear cell carcinoma of the kidney for prognostication and therapy.</a> Clin. Cancer Res. 13, 709s-715s (2007).</li><li>Karim, R., Jordanova, E. S., Piersma, S. J., Kenter, G. G., Chen, L., Boer, J. M., Melief, C. J., vander Burg, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor-expressed+B7-H1+and+B7-DC+in+relation+to+PD-1++T-cell+infiltration+and+survival+of+patients+with+cervical+carcinoma.">Tumor-expressed B7-H1 and B7-DC in relation to PD-1+ T-cell infiltration and survival of patients with cervical carcinoma.</a> Clin. Cancer Res. 15, 6341-6347 (2009).</li><li>Inman, B. A., Sebo, T. J., Frigola, X., Dong, H., Bergstralh, E. J., Frank, I., Fradet, Y., Lacombe, L., Kwon, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PD-L1+(B7-H1)+expression+by+urothelial+carcinoma+of+the+bladder+and+BCG-induced+granulomata:+associations+with+localized+stage+progression.">PD-L1 (B7-H1) expression by urothelial carcinoma of the bladder and BCG-induced granulomata: associations with localized stage progression.</a> Cancer. 109, 1499-1505 (2007).</li><li>Brahmer, J. R., Drake, C. G., Wollner, I., Powderly, J. D., Picus, J., Sharfman, W. H., Stankevich, E., Pons, A., Salay, T. M., McMiller, T. L., Gilson, M. M., Wang, C., Selby, M., Taube, J. M., Anders, R., Chen, L., Korman, A. J., Pardoll, D. M., Lowy, I., Topalian, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+I+study+of+single-agent+anti-programmed+death-1+(MDX-1106)+in+refractory+solid+tumors:+safety,+clinical+activity,+pharmacodynamics,+and+immunologic+correlates.">Phase I study of single-agent anti-programmed death-1 (MDX-1106) in refractory solid tumors: safety, clinical activity, pharmacodynamics, and immunologic correlates.</a> J. Clin. Oncol. 28, 3167-3175 (2010).</li><li>Wang, L., Ma, Q., Chen, X., Guo, K., Li, J., Zhang, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+significance+of+B7-H1+and+B7-1+expressions+in+pancreatic+carcinoma.">Clinical significance of B7-H1 and B7-1 expressions in pancreatic carcinoma.</a> World J. Surg. 34, 1059-1065 (2010).</li><li>Nomi, T., Sho, M., Akahori, T., Hamada, K., Kubo, A., Kanehiro, H., Nakamura, S., Enomoto, K., Yagita, H., Azuma, M., Nakajima, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+significance+and+therapeutic+potential+of+the+programmed+death-1+ligand/programmed+death-1+pathway+in+human+pancreatic+cancer.">Clinical significance and therapeutic potential of the programmed death-1 ligand/programmed death-1 pathway in human pancreatic cancer.</a> Clin. Cancer Res. 13, 2151-2157 (2007).</li><li>Taube, J. M., Anders, R. A., Young, G. D., Xu, H., Sharma, R., McMiller, T. L., Chen, S., Klein, A. P., Pardoll, D. M., Topalian, S. L., Chen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colocalization+of+inflammatory+response+with+B7-h1+expression+in+human+melanocytic+lesions+supports+an+adaptive+resistance+mechanism+of+immune+escape.">Colocalization of inflammatory response with B7-h1 expression in human melanocytic lesions supports an adaptive resistance mechanism of immune escape.</a> Sci. Transl. Med. 4, 127ra37 (2012).</li></ol>

No conflicts of interest declared.

Immunohistochemical staining of B7-H1 on cryosections has been reported in prior studies for a variety of cancers3,4. However, clinical tumor samples usually are available only in the form of paraffin-embedded blocks. The 5H1 monoclonal antibody has more recently been successfully applied to the staining of paraffin embedded tumor tissues including renal cell carcinoma, cervical carcinoma, bladder cancer and melanoma13-18. B7-H1 staining on paraffin-embedded9,19 or cryostat20 s...

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>CSA System</td>
			<td>Dako</td>
			<td>K1500</td>
			<td>Includes the following reagents mentioned in the protocol: peroxidase block, streptavidin-biotin complex, amplification reagent, streptavidin-HRP, and DAB substrate and chromogen</td>
		</tr>
		<tr>
			<td>Avidin/Biotin Blocking Kit</td>
			<td>Vector</td>
			<td>SP-2001</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Block ACE</td>
			<td>Serotec</td>
			<td>BUF029</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Biotin anti-mouse IgG1</td>
			<td>BD</td>
			<td>553441</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Mouse IgG1 K Isotype Control</td>
			<td>eBioscience</td>
			<td>14-4714-85</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>TBS(Tris-buffered saline), 10X</td>
			<td>Cellgro</td>
			<td>46-012-CM</td>
			<td>10xTBS contains 80 g/L NaCl and 24.2 g/L Tirs; 
			Diluted to 1X with ddH2O for washes;</td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>Sigma-Aldrich</td>
			<td>P1379</td>
			<td>1 ml added to 1 L of 1X TBS to make TBST</td>
		</tr>
		<tr>
			<td>Target Retrieval, 20x</td>
			<td>Celerus Wave</td>
			<td>014-3000-000</td>
			<td>Diluted to 1x with ddH2O</td>
		</tr>
		<tr>
			<td>190 Proof Ethyl Alcohol</td>
			<td>Pharmco-Aaper</td>
			<td>111000190</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>200 Proof Ethyl Alcohol</td>
			<td>Pharmo-Aaper</td>
			<td>111000200</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>VWR</td>
			<td>95057-827</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Hematoxylin</td>
			<td>Richard-Allan Scientific</td>
			<td>72804</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Cytoseal 60</td>
			<td>Richard-Allan Scientific</td>
			<td>8310-4</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Coverslips</td>
			<td>Corning</td>
			<td>2940-245</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Humidity chamber</td>
			<td>Sigma</td>
			<td>H6644</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Table 1. Reagents and equipment.</td>
		</tr>
	</tbody>
</table>

immunohistochemical staining of b7-h1 (pd-l1) on paraffin-embedded slides of pancreatic adenocarcinoma tissue

B7-H1/PD-L1, a member of the B7 family of immune-regulatory cell-surface proteins, plays an important role in the negative regulation of cell-mediated immune responses through its interaction with its receptor, programmed death-1 (PD-1) 1,2. Overexpression of B7-H1 by tumor cells has been noted in a number of human cancers, including melanoma, glioblastoma, and carcinomas of the lung, breast, colon, ovary, and renal cells, and has been shown to impair anti-tumor T-cell immunity3-8.
Recently, B7-H1 expression by pancreatic adenocarcinoma tissues has been identified as a potential prognostic marker9,10. Additionally, blockade of B7-H1 in a mouse model of pancreatic cancer has been shown to produce an anti-tumor response11. These data suggest the importance of B7-H1 as a potential therapeutic target. Anti-B7-H1 blockade antibodies are therefore being tested in clinical trials for multiple human solid tumors including melanoma and cancers of lung, colon, kidney, stomach and pancreas12.
In order to eventually be able to identify the patients who will benefit from B7-H1 targeting therapies, it is critical to investigate the correlation between expression and localization of B7-H1 and patient response to treatment with B7-H1 blockade antibodies. Examining the expression of B7-H1 in human pancreatic adenocarcinoma tissues through immunohistochemistry will give a better understanding of how this co-inhibitory signaling molecule contributes to the suppression of antitumor immunity in the tumor's microenvironment. The anti-B7-H1 monoclonal antibody (clone 5H1) developed by Chen and coworkers has been shown to produce reliable staining results in cryosections of multiple types of human neoplastic tissues4,8, but staining on paraffin-embedded slides had been a challenge until recently13-18. We have developed the B7-H1 staining protocol for paraffin-embedded slides of pancreatic adenocarcinoma tissues. The B7-H1 staining protocol described here produces consistent membranous and cytoplasmic staining of B7-H1 with little background.

A successful immunohistochemical staining of B7-H1 will demonstrate the heterogeneous expression of B7-H1 (brown signals DAB color development) in pancreatic adenocarcinoma. Some pancreatic adenocarcinoma cells have predominantly membranous expression of B7-H1 (Figure 1A) whereas others have either predominantly cytoplasmic expression of B7-H1 or little expression of B7-H1 (Figures 2 and 3). Normal pancreatic duct epithelium expresses little B7-H1 (Figure 4). Staining ...

Watch this Scientific Journal Video about Immunohistochemical Staining of B7-H1 PD-L1 on Paraffin-embedded Slides of Pancreatic Adenocarcinoma Tissue at JoVE.com

Immunohistochemical Staining of B7-H1 PD-L1 on Paraffin-embedded Slides of Pancreatic Adenocarcinoma Tissue

B7-H1 (PD-L1) and its binding to PD-1 provide a major tumor-induced immunosuppressive signal in the tumor&#x2019;s microenvironment. An immunohistochemical staining technique to characterize the expression and localization of B7-H1 in pancreatic adenocarcinoma is described here.

Immunohistochemical Staining of B7-H1 (PD-L1) on Paraffin-embedded Slides of Pancreatic Adenocarcinoma Tissue

B7-H1/PD-L1, a member  of the B7 family of immune-regulatory cell-surface proteins, plays an important  role in the negative regulation of cell-mediated ...

immunohistochemical-staining-b7-h1-pd-l1-on-paraffin-embedded-slides

Research

JoVE Journal

Medicine

23.0K Views.  The Johns Hopkins University School of Medicine. B7-H1 (PD-L1) and its binding to PD-1 provide a major tumor-induced immunosuppressive signal in the tumor’s microenvironment. An immunohistochemical staining technique to characterize the expression and localization of B7-H1 in pancreatic adenocarcinoma is described here.