We thank Hans Lassmann and Jan Bauer for their guidance and support. We also thank Katalin Benedek for excellent technical assistance and Caroline Westerlund for critical and linguistic appraisal.
This study was supported by grants from Biogen Idec, the Wenner-Gren Foundation, the Swedish Research Council, the Swedish Association of Persons with Neurological Disabilities, Swedish Brain Foundation, the EU 6TH Framework EURATools (LSHG-CT-2005-019015) and Neuropromise (LSHM-CT-2005-018637). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Ethical Statement 
Present study is performed in accordance with guidelines from the Swedish National Board for Laboratory Animals and the European Community Council Directive (86/609/EEC) under the ethical permits N338/09, N15/10 and N65/10, which were approved by the North Stockholm Animal Ethics Committee.
1. Tissue Preparation
<ol>
	<li>Perfusion &#38; fixation
	<ol>
		<li>Anesthetize the animal with isoflurane to perform transcardial perfusion via ...

<ol>
	<li>Coons, A., Creech, H. J., Jones, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunological+properties+of+an+antibody+containing+a+fluorescent+group.">Immunological properties of an antibody containing a fluorescent group.</a> Proc Soc Exp Biol Med. 47, 200-202 (1941).</li><li>Nakane, P. K., Pierce, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzyme-labeled+antibodies:+preparation+and+application+for+the+localization+of+antigens.">Enzyme-labeled antibodies: preparation and application for the localization of antigens.</a> The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 14, 929-931 (1966).</li><li>Avrameas, S., Uriel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+of+antigen+and+antibody+labelling+with+enzymes+and+its+immunodiffusion+application.">Method of antigen and antibody labelling with enzymes and its immunodiffusion application.</a> C R Acad Sci Hebd Seances Acad Sci D. 262, 2543-2545 (1966).</li><li>Mason, D. Y., Sammons, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+preparation+of+peroxidase:+anti-peroxidase+complexes+for+immunocytochemical+use.">Rapid preparation of peroxidase: anti-peroxidase complexes for immunocytochemical use.</a> Journal of immunological. 20, 317-324 (1978).</li><li>Faulk, W. P., Taylor, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+immunocolloid+method+for+the+electron+microscope.">An immunocolloid method for the electron microscope.</a> Immunochemistry. 8, 1081-1083 (1971).</li><li>Coons, A. H., Kaplan, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localization+of+antigen+in+tissue+cells;+improvements+in+a+method+for+the+detection+of+antigen+by+means+of+fluorescent+antibody.">Localization of antigen in tissue cells; improvements in a method for the detection of antigen by means of fluorescent antibody.</a> The Journal of experimental medicine. 91, 1-13 (1950).</li><li>Polak, J. M., Van Noorden, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Introduction to immunocytochemistry. , (2003).</li><li>Elias, J. M., Margiotta, M., Gaborc, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitivity+and+detection+efficiency+of+the+peroxidase+antiperoxidase+(PAP),+avidin-biotin+peroxidase+complex+(ABC),+and+peroxidase-labeled+avidin-biotin+(LAB)+methods.">Sensitivity and detection efficiency of the peroxidase antiperoxidase (PAP), avidin-biotin peroxidase complex (ABC), and peroxidase-labeled avidin-biotin (LAB) methods.</a> American journal of clinical pathology. 92, 62-67 (1989).</li><li>Ramos-Vara, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technical+aspects+of+immunohistochemistry.">Technical aspects of immunohistochemistry.</a> Vet Pathol. 42, 405-426 (2005).</li><li>Adzemovic, M. 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R., Key, M. E., Kalra, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antigen+retrieval+in+formalin-fixed,+paraffin-embedded+tissues:+an+enhancement+method+for+immunohistochemical+staining+based+on+microwave+oven+heating+of+tissue+sections.">Antigen retrieval in formalin-fixed, paraffin-embedded tissues: an enhancement method for immunohistochemical staining based on microwave oven heating of tissue sections.</a> The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 39, 741-748 (1991).</li><li>Huang, S. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunohistochemical+demonstration+of+hepatitis+B+core+and+surface+antigens+in+paraffin+sections.">Immunohistochemical demonstration of hepatitis B core and surface antigens in paraffin sections.</a> Laboratory investigation; a journal of technical methods and pathology. 33, 88-95 (1975).</li><li>Shi, S. R., Cote, R. J., Taylor, 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=Antigen+retrieval+immunohistochemistry:+past,+present,+and+future.">Antigen retrieval immunohistochemistry: past, present, and future.</a> The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 45, 327-343 (1997).</li><li>Taylor, C. R., Shi, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antigen+retrieval:+call+for+a+return+to+first+principles.">Antigen retrieval: call for a return to first principles.</a> Applied immunohistochemistry &amp; molecular morphology : AIMM / official publication of the Society for Applied Immunohistochemistry. 8, 173-174 (2000).</li><li>Kitamoto, T., Ogomori, K., Tateishi, J., Prusiner, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formic+acid+pretreatment+enhances+immunostaining+of+cerebral+and+systemic+amyloids.">Formic acid pretreatment enhances immunostaining of cerebral and systemic amyloids.</a> Laboratory investigation; a journal of technical methods and pathology. 57, 230-236 (1987).</li><li>Nelson, P. N., 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=Monoclonal+antibodies.">Monoclonal antibodies.</a> Molecular pathology : MP. 53, 111-117 (2000).</li><li>Van der Loos, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Immunoenzyme multiple staining methods. , (1999).</li><li>Elias, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Immunohistopathology. A practical approach to diagnosis. , (2003).</li><li>Straus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Letter:+Cleavage+of+heme+from+horseradish+peroxidase+by+methanol+with+inhibition+of+enzymic+activity.">Letter: Cleavage of heme from horseradish peroxidase by methanol with inhibition of enzymic activity.</a> The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 22, 908-911 (1974).</li><li>Streefkerk, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+erythrocyte+pseudoperoxidase+activity+by+treatment+with+hydrogen+peroxide+following+methanol.">Inhibition of erythrocyte pseudoperoxidase activity by treatment with hydrogen peroxide following methanol.</a> The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 20, 829-831 (1972).</li><li>Ponder, B. A., Wilkinson, M. 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Standard IHC procedures often require specific adjustments to obtain an optimal result, which commonly implies extensive experience but also &#34;trial and error&#34; approach. From tissue preparation until target visualization, almost each step in the protocol may be subjected to individually designed modifications in order to improve the final outcome. Double staining protocol presented here exemplifies IHC-based protein targeting particularly adjusted for assessing interrelations between the target proteins of our int...

Despite utilization of advanced high-throughput analyses performed on the methylome, transcriptome or even proteome level, immunostaining remains the golden standard for protein detection directly in the tissue sample, cell culture or a cell smear. By revealing the localization/distribution pattern, immunohistochemistry (IHC) may assess relative ratios and topographical interrelations of the target proteins, and even indicate their biological activities. Therefore, IHC is widely utilized for clinical and research purposes, e.g., for diagnosis, treatment evaluations, study of disease mechanisms, functional and phenotypical alterations in animal models, etc.
Essentially comprising histology, pathology, biochemistry and immunology, IHC has significantly advanced since 1941, when fluorescently labeled antibodies were used for the first time to identify Pneumococcal antigens in the infected tissue 1. Visualization of cellular products and components by IHC is based on binding of antibodies (Abs) to their specific antigen (Ag). Besides using fluorophore tagged antibodies, immune reactions can also be visualized by using enzymes like peroxidase 2,3 or alkaline phosphatase 4. Further, colloidal gold-tagged antibodies5 are used for detecting specific antigen-antibody interaction by both light and electron microscopy, while radioactive labels are visualized by autoradiography.
The Ag-Ab immunoreaction can be detected via direct and indirect methods. The direct method is essentially faster and simpler, as it uses directly labeled primary Abs 6. However, due to significant lack of sensitivity, indirect methods are preferred to the direct ones. Two-step indirect detection procedures require unlabeled primary Abs, as the first, and labeled secondary Abs directed against the primary Abs, as the second layer 7. Signal amplification can be achieved by involving further, enzyme-coupled tertiary Ab (three-step indirect method) that binds to the secondary Ab. Commonly used indirect detection methods are avidin-biotin and peroxidase-antiperoxidase (PAP). Alternatively, alkaline phosphatase-antialkaline phosphatase (APAAP) complex can be used instead of the PAP method. Notably, alkaline phosphatase (AP) methods appear to be even more sensitive than immunoperoxidase methods 4. Avidin-biotin complex (ABC) method uses biotinylated secondary Ab in combination with either labeled avidin-biotin complex (LAB), or labeled streptavidin-biotin complex (SLAB). Detection sensitivity can be further increased by involving avidin labeled with peroxidase or alkaline phosphatase 8. Other detection methods in use are polymeric labeling, tyramine amplification and immuno-rolling circle 9. Notably, different detection methods can be combined for multiple Ag detection in the same tissue sample, which was reported for the first time in 1978 4. Simultaneous double immunostaining presented here was performed in formalin-fixed, paraffin-embedded rat CNS and LN tissue sections using peroxidase-bound and AP-conjugated secondary antibodies, respectively. The signals were visualized using 3,3&#39;-diaminobencidine (DAB) chromogen and the Fast Blue (FB) APAAP complex, respectively.

<table border="1">
 <tbody>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Reagent</td>
 </tr>
 <tr>
 <td>Isoflurane 			(Isofluran): 1-Chlor-2,2,2-trifluorethyl (difluormethyl 			ether) 
 2-Chlor-2-(difluormethoxy)-1,1,1-trifluorethan 			(C3H2ClF5O)</td>
 <td>Baxter</td>
 <td>1001936060</td>
 <td>Eye 			irradiation. Probably influences fertility and damages baby in 			uterus. Administer only in adequately equipped anesthetizing 			environment.</td>
 </tr>
 <tr>
 <td>Sodiumchloride 			(NaCl)</td>
 <td>Merck</td>
 <td>1.0604</td>
 <td></td>
 </tr>
 <tr>
 <td>Phosphate 			Buffer Saline (PBS), tablet</td>
 <td>Sigma-Aldrich</td>
 <td>P4417</td>
 <td></td>
 </tr>
 <tr>
 <td>Paraformaldehyde 			(OH(CH2O)nH (n = 8 - 100), 4% in 1x PBS </td>
 <td>Apl pharma</td>
 <td>34 24 28</td>
 <td>Health 			hazard. Corrosive. Flamable. Acute toxicity.</td>
 </tr>
 <tr>
 <td>Ethanol 			&ge;99.5%, absolute (CH3CH2OH)</td>
 <td>Sigma-Aldrich</td>
 <td>459844-1L</td>
 <td>Flamable.</td>
 </tr>
 <tr>
 <td>Xylene 			(Xylenes, histological grade; C6H4(CH3)2 </td>
 <td>Sigma-Aldrich</td>
 <td>534056</td>
 <td>Flamable. 			Acute toxicity.</td>
 </tr>
 <tr>
 <td>Histo-Comp 			Paraffin 			Wax</td>
 <td>Tissue-Tek</td>
 <td>V0-5-1001 </td>
 <td></td>
 </tr>
 <tr>
 <td>Adhesive 			Microscope Slides</td>
 <td>Starfrost </td>
 <td>MIC-1040-W</td>
 <td></td>
 </tr>
 <tr>
 <td>Xylol 			substitute XEM-200 </td>
 <td>Vogel GmbH</td>
 <td>ND-HS-200</td>
 <td>Respiratory 			sensitization. Carcinogenicity.</td>
 </tr>
 <tr>
 <td>&alpha;- CD8 			(Ox-8) mouse anti-rat, primary antibody</td>
 <td>AbD 			Serotec</td>
 <td>MCA48G</td>
 <td></td>
 </tr>
 <tr>
 <td>&alpha;- Iba1 			(AIF1) mouse anti-rat, primary antibody</td>
 <td>Millipore</td>
 <td>MABN92</td>
 <td></td>
 </tr>
 <tr>
 <td>&alpha;- CD68 			(ED1) mouse anti-rat, primary antibody</td>
 <td>AbD 			Serotec </td>
 <td>MCA341R</td>
 <td></td>
 </tr>
 <tr>
 <td>&alpha;- 			eotaxin C-19 (CCL11) goat anti-rat, primary antibody</td>
 <td>Santa Cruz 			BT</td>
 <td>SC-6181</td>
 <td></td>
 </tr>
 <tr>
 <td>Alkaline 			phosphatase (AP)-conjugated secondary antibody</td>
 <td>Dakopatts, 			Denmark</td>
 <td>D0314</td>
 <td></td>
 </tr>
 <tr>
 <td>Biotinylated 			secondary antibody</td>
 <td>Amersham 			Biotech</td>
 <td>RPN1025</td>
 <td></td>
 </tr>
 <tr>
 <td>Avidin- 			horseradish peroxidase complex (HRP) </td>
 <td>Sigma-Aldrich</td>
 <td>A3151</td>
 <td></td>
 </tr>
 <tr>
 <td>Naphthol 			AS-MX phosphate (C19H18NO5P)</td>
 <td>Sigma-Aldrich</td>
 <td>N4875-1G</td>
 <td>Acute 			toxicity.</td>
 </tr>
 <tr>
 <td>Fast Blue 			RR Salt, Azoic Diazo No. 24 (C15H14ClN3O3 			x 			1/2 ZnCl2)</td>
 <td>Sigma-Aldrich</td>
 <td>FBS25</td>
 <td></td>
 </tr>
 <tr>
 <td>Levamisol 			hydrochloride (C11H13ClN2S)</td>
 <td>Sigma-Aldrich</td>
 <td>31742</td>
 <td>Acute 			toxicity.</td>
 </tr>
 <tr>
 <td>3,3'-Diaminobenzidine 			tetrahydrochloride (DAB Chromogen)</td>
 <td>DAKO</td>
 <td>S3000 </td>
 <td>Highly 			flammable. Toxic.</td>
 </tr>
 <tr>
 <td>Copper 			sulphate (CuSO4)</td>
 <td>Merck</td>
 <td>1.02791</td>
 <td>Acute 			toxicity. Environmental hazzard.</td>
 </tr>
 <tr>
 <td>GelTol 			Aqueous Mounting Medium</td>
 <td>Thermo 			Electron Corporation</td>
 <td>230100</td>
 <td></td>
 </tr>
 <tr>
 <td>Hydrogen 			peroxide, 30% (H2O2)</td>
 <td>Merck</td>
 <td>107210</td>
 <td>Acute 			toxicity.</td>
 </tr>
 <tr>
 <td>Methanol 			(CH3OH)</td>
 <td>Fluka</td>
 <td>65543</td>
 <td>Acute 			toxicity. Respiratory sensitization. Carcinogenicity. Flammable.</td>
 </tr>
 <tr>
 <td>Tris 			(hydroxymethyl) aminomethane, TRIS base (C4H11NO3 			)</td>
 <td>AppliChem </td>
 <td>A1379</td>
 <td>Skin and 			eye irritation.</td>
 </tr>
 <tr>
 <td>Tris 			Buffered Saline (TBS), tablet</td>
 <td>Sigma-Aldrich</td>
 <td>T5030</td>
 <td></td>
 </tr>
 <tr>
 <td>Di- Sodium 			hydrogen phosphate dihydrate (Na2HPO4 			x 			2H2O)</td>
 <td>Merck</td>
 <td>1.0658</td>
 <td></td>
 </tr>
 <tr>
 <td>Sodium 			dihydrogen phosphate monohydrate (NaH2PO4 			x 			1H2O) </td>
 <td>Merck</td>
 <td>1.06346</td>
 <td></td>
 </tr>
 <tr>
 <td>Fetal calf 			serum (FCS) </td>
 <td>Cambrex 			BioScience</td>
 <td>DE-14-802F</td>
 <td></td>
 </tr>
 <tr>
 <td>DAKO 			cytomation wash buffer 10x </td>
 <td>DAKO </td>
 <td>S3006</td>
 <td>Should be 			stored at 2-8 &deg;C to inhibit bacterial growth. Avoid foaming.</td>
 </tr>
 <tr>
 <td>N,N- 			Dimethylformamide; DMF (C3H7NO)</td>
 <td>Fluka</td>
 <td>40250</td>
 <td>Flammable. 			Acute toxicity.</td>
 </tr>
 <tr>
 <td>Glas 			coverslips 24 x 36 mm </td>
 <td>Menzel-Gl&auml;ser</td>
 <td>BB024036A1</td>
 <td></td>
 </tr>
 <tr>
 <td>Hydrochloric acid, conc. (HCl)</td>
 <td>Sigma-Aldrich </td>
 <td>30721</td>
 <td>Corrosive, 			irritant, permeator. Lung sensitizer (as acid mist). Toxic.</td>
 </tr>
 <tr>
 <td>Hydrochloric acid solution 			volumetric, 2M HCl (2N) </td>
 <td>Fluka </td>
 <td>71826</td>
 <td>Corrosive, 			irritant, permeator. Lung sensitizer (as acid mist). Toxic.</td>
 </tr>
 <tr>
 <td>Sodium 			nitrite, ReagentPlus, &ge;99.0% (NaNO2)</td>
 <td>Sigma-Aldrich </td>
 <td>S2252 </td>
 <td>Oxidant. 			Toxic. Dangerous for the environment.</td>
 </tr>
 <tr>
 <td>Ethylenedinitrilotetraacetic 			acid disodium salt dihydrate (EDTA; C10H14N2Na2O8 			x 2H2O)</td>
 <td>Merck</td>
 <td>1.08454</td>
 <td>Oral 			exposures may cause reproductive and developmental effects.</td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td> Equipment</td>
 </tr>
 <tr>
 <td>Tissue-Tek 			V.I.P 			Vacuum Infiltration Processor </td>
 <td>Sakura</td>
 <td>5902 VIP 			Jr. 115 V, 60 Hz</td>
 <td></td>
 </tr>
 <tr>
 <td>Hacker-Bright 			8000 Series Base Sledge Microtome </td>
 <td>Hacker 			instruments</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Household 			food steamer </td>
 <td>Braun</td>
 <td>MultiGourmet 			FS 20</td>
 <td></td>
 </tr>
 <tr>
 <td>Light 			microscope </td>
 <td>Leica 			Polyvar 2</td>
 <td></td>
 <td></td>
 </tr>
 </tbody>
 </table>

immunohistochemical analysis in the rat central nervous system and peripheral lymph node tissue sections

Immunohistochemistry (IHC) provides highly specific, reliable and attractive protein visualization. Correct performance and interpretation of an IHC-based multicolor labeling is challenging, especially when utilized for assessing interrelations between target proteins in the tissue with a high fat content such as the central nervous system (CNS).
Our protocol represents a refinement of the standard immunolabeling technique particularly adjusted for detection of both structural and soluble proteins in the rat CNS and peripheral lymph nodes (LN) affected by neuroinflammation. Nonetheless, with or without further modifications, our protocol could likely be used for detection of other related protein targets, even in other organs and species than here presented.

Double immunostainings (co-stainings) were performed in formalin-fixed, paraffin-embedded rat CNS and LN sections. 3-5 &#181;m thick tissue slices were cut using a sledge microtome, mounted subsequently onto pre-coated adhesive glass slides and treated as previously described 10,11,12. Briefly, after deparaffinizing, tissue rehydration and endogenous peroxidase inactivation, sections were subjected to the antigen retrieval process, followed by a blocking step to eliminate unspe...

Watch this Scientific Journal Video about Immunohistochemical Analysis in the Rat Central Nervous System and Peripheral Lymph Node Tissue Sections at JoVE.com

Immunohistochemical Analysis in the Rat Central Nervous System and Peripheral Lymph Node Tissue Sections

We here present an optimized, detailed protocol for double immunostaining in formalin-fixed, paraffin-embedded rat central nervous system (CNS) and peripheral lymph node (LN) tissue sections.

Immunohistochemistry (IHC) provides highly specific, reliable and attractive protein visualization. Correct performance and interpretation of an IHC-based ...

The overall goal of this procedure is to target a specific protein in the rat tissue. This is accomplished by first isolating, fixing, and paraffin-embedding the tissue, followed by sectioning of the tissue and mounting it onto slides. The second step is to deparaffinize and rehydrate the paraffin-embedded tissue sections, and then block the endogenous peroxidase.Next, the epitopes are uncovered by antigen retrieval. Subsequently, blocking is performed to reduce unspecific binding prior to introducing the antibodies. The final step is to detect the specific epitope by immunolabeling with primary and secondary antibodies, and to develop the signal from the labeled secondary antibody.Ultimately, the signal is visualized using light microscopy to show the protein localization pattern in the tissue sections. Though this method can provide insight into the protein localization and expression patterns in the rat central nervous system and in the peripheral lymph nodes, it can also be applied to other organs and species. For demonstrating the procedure will be a technician.Her name is Katalin Benedek, from the core facility of the microbiology tumor and cell biology center at the Karolinska Institutet. To begin tissue preparation, immerse the dissected brain, spinal cord, and peripheral lymph node tissue in four percent paraformaldehyde, and place it at four degrees Celsius for 24 hours. After the tissues are fixed, transfer the tissue into P-B-S and store it at four degrees Celsius until further processing.To begin processing the tissue, use a razor blade to cut the tissue into approximately five-millimeter sized portions. Then, initiate the tissue hardening process with a vacuum infiltration processor. The standard procedure is based on submersion into ascending concentrations of ethanol, followed by xylol, and finally paraffin.Next, place the tissue in a mold. Pour in the liquid paraffin around the sample to form a paraffin block, and store it at room temperature. Prior to sectioning the tissue, cool down the paraffin block overnight on the cold plate or in the refrigerator.After the paraffin block has been cooled, place the block into the fixed holder of a sledge microtome which can move backwards and forwards across a knife. Then, adjust the block and the microtome knife to the optimal angle, which depends on the knife geometry and the cutting speed and technique. Cut three five-micron thick cross-sections from the paraffin block.Then, transfer the cut sections into a water container and mount the sections from the water onto a commercial pre-coated adhesive glass slide. Next, press the mounted section carefully against a paper towel to remove residual water and potential air bubbles. Dry the mounted slides for a couple of hours in a stove set to 50 to 60 degrees Celsius.Once the slides are dry, immerse the slides two times in xylol for 15 to 20 minutes each. Then, rinse each slide in 99 percent ethanol. To block the endogenous peroxidase activity, incubate the sections for 30 minutes in a methanol solution containing 0.25 percent hydrogen peroxide.Then, continue rehydrating the tissue sections by rinsing with ethanol solutions containing increasing water content. Perform the final rehydration step in distilled water. Make sure to keep the sections moist until the cover slips are mounted.To retrieve the antigen, heat the slides with a household steamer and EDTA buffer at pH 8.5 for 60 minutes. Then, cool down the slides at room temperature for approximately one hour. Once the slides are cool, rinse each slide three to five times in Tris-buffered saline, or T-B-S.Next, incubate the tissue sections at room temperature for 30 minutes in a blocking solution containing 10 percent fetal calf serum and 90 percent wash buffer to block any non-specific background reactions. After the tissue sections have been blocked, dilute the required amount of primary antibodies in the blocking solution, and incubate the slides in this primary antibody solution overnight at four degrees Celsius. The next day, rinse the slides three to five times with T-B-S buffer.Then incubate the slides with secondary antibodies diluted in the blocking solution for one hour at room temperature. Afterwards, again rinse the slides three to five times with T-B-S buffer. Then, incubate the slides with avidin horseradish peroxidase complex, diluted one to 100 in the blocking solution, for one hour at room temperature.Once the one-hour incubation is complete, rinse the slides three to five times with T-B-S buffer. After preparing the fast blue solution as described in the text protocol, shake the dish lightly and filter the obtained mixture. Pour the solution onto the slides in the glass cuvette.Begin the incubation at 37 degrees Celsius, and observe the developing process under the light microscope every 15 to 30 minutes. Once the incubation is complete, rinse the slides three to five times with T-B-S buffer, and then subsequently transfer the slides into P-B-S buffer. To make the D-A-B hydrogen peroxide developing solution, first dilute one milliliter of a D-A-B stock solution in 49 milliliters of P-B-S.Add 16.5 microliters of hydrogen peroxide, and then filter the solution. Pour the solution onto the slides, and make sure to control the developing process under the light microscope in order to avoid high background that can mask the specific signal. Then, rinse the slides three to five times with P-B-S, followed by a final wash with distilled water or tap water.Mount the slides with cover slips directly from the water, using aqueous mounting medium. Avoid creating air bubbles between the cover slip and the slide. After mounting the sections, incubate the slides overnight at four degrees Celsius to allow the mounting medium to dry completely.Store the dried slides at room temperature. Double staining of peripheral lymph node tissue sections isolated from rats on day seven post-immunization revealed that cd8 positive t lymphocytes did not secrete the chemokine C-C-L 11. Alternatively, C-C-L 11 was found to co-localize with E-D one, a marker for lysosomal protein in activated macrophages.I-H-C double staining of a rat's spinal cord identified C-C-L eleven production in neuronal perikarya, dendrites, and axons, but not in I-B-A one positive macrophages and brain-resident microglia cells. In addition, the majority of E-D one positive macrophages and brain-resident microglia cells were also found to not be C-C-L 11 positive. After having watched this video, you should have a good understanding of how to perform a specific and reliable immunohistochemical targeting of the protein directly in tissue sections.

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Research

JoVE Journal

Neuroscience

16.9K visualizações.  Karolinska Institutet. The overall goal of this procedure is to target a specific protein in the rat tissue. This is accomplished by first isolating, fixing, and paraffin-embedding the tissue, followed by sectioning of the tissue and mounting it onto slides. The second step is to deparaffinize and rehydrate the paraffin-embedded tissue sections, and then block the endogenous peroxidase.Next, the epitopes are uncovered by antigen retrieval. Subsequently, blocking is performed to reduce unspecific binding prio...