This study was funded by JDRF 1-FAC-2014-243-A-N, ADA 7-14-JF-07, NIH 5 P30 DK079638-05 PILOT PJ, and The Robert and Janice McNair Foundation.
We thank Sandra Pena and Andrene McDonald for patient recruitment, Samuel Blum for technical assistance, Dr. George Makedonas for the gift of antibodies and control DNA used for PCR optimization.

1. Identify the T cell population of interest.
NOTE: Antigen specific proliferation in combination with cell division dye (like Carboxyfluorescein succinimidyl ester, CFSE) can be used to isolate T cells based on their proliferation in response to antigenic stimulation. If starting from PBMCs, a 7-day in vitro expansion should be sufficient to identify an antigen specific CFSE low population12.
<ol>
	<li>Mix PBMCs 1:1 with MHC-matched feeder cells, and label with 5 &#181;M CFSE cell division dye.</li>
	<li>Plate 2-2.5 x 105 cells per well in a 96-well round-bottom culture plate in 200 &#181;L 10% FCS complete RPMI media. 
	NOTE: Complete RPMI contains 2 mM l-glutamine, 1 mM sodium pyruvate, 100 &#181;M MEM nonessential amino acids, 5 mM HEPES, 5.5 &#215; 10&#8722; 5 units of 2-mercaptoethanol, 100 U mL&#8722; 1 penicillin and 100 &#181;g mL&#8722; 1 streptomycin.</li>
	<li>Stimulate cells with 25 &#181;M peptide antigen.</li>
	<li>On the fourth day of culture, carefully remove and replace 100 &#181;L of media. 
	NOTE: A more optimal approach for antigen-specific T cell identification is the use of peptide-HLA tetramers13. Tetramer staining allows for simultaneous assessment of antigen specificity, as well as HLA-restriction.</li>
</ol>
2. Set up the single cell sort.
<ol>
	<li>Perform all procedures in a hood or a designated area free of amplified template. Aliquot the reagents to avoid contamination, clean all work surfaces and, if feasible, equipment with 10% bleach prior to PCR setup. Use filter tips, RNAse and DNAse free reagents and plastics in all the PCR and vector cloning steps. Key reagents can be found in the Table of Materials. 
	NOTE: The multiplex PCR reaction is highly sensitive, and low levels of contamination can result in amplified product.</li>
	<li>Generate the reverse transcription master mix by combining 10x RT reaction buffer, 25X DNTPs, 9 U RT enzyme, 0.01% Triton-X, 0.7 U RNAse inhibitor, and 383 nM of each RT-TCR primer (listed in Table 1) in a sterile pipetting reservoir. For each 96-well plate, make up enough master mix for 10 additional reactions (total 106), to compensate for loss of liquid during pipetting. See Table 2 for reaction components and amounts per well.</li>
	<li>Prepare a 96-well PCR collection plate for cell sorting by pipetting 6 &#181;L of the reverse transcription master mix per well with a multichannel pipette. Keep the plate on ice or in a cold block.</li>
	<li>Label cells with antibodies to cell surface markers (such as CD4 and CD3, or CD8 and CD3, each at 2 &#181;g/mL, in combination with cell division dye or tetramer staining).</li>
	<li>Sort T cells at one cell per well, skipping the twelfth row, which will serve as a negative control. 
	NOTE: The efficiency of the sort will depend on precise collection plate alignment within the plate holder, as well as maintaining the cells and plates at a low temperature prior to cDNA reaction. Collection plates should be kept on ice at all times, except during sorting, when they are fixed within the cooling plate. Not all sorters are equipped with a temperature regulated plate holder; however, the use of one is strongly recommended. Since the sort generally takes about 10 - 15 min per plate, there is an increased potential for RNA degradation if the plate is not maintained at a low temperature.</li>
	<li>As a positive control, add a larger number of cells (100 cells) manually with a pipette to one of the wells at this stage. Alternatively, previously isolated RNA from pooled cells can be used as a positive control at 10 ng per well. 
	NOTE: Pipette purified control RNA with precision and care in order to avoid cross-contamination of other wells and false positive results.</li>
	<li>Seal the plate with adhesive film, and spin down at 1000 x g for 5 min at 4 &#176;C.</li>
	<li>Immediately transcribe RNA to cDNA by incubating the plate at 25 &#176;C for 10 min, 37 &#176;C for 45 min, and 85 &#176;C for 10 min. 
	NOTE: To ensure efficient PCR reaction, it is recommended that the first PCR reaction be performed the same day. Alternatively, the transcribed plates can be kept in -80&#176;C for up to 2 months.</li>
</ol>
3. Perform multiplex-nested PCR
NOTE: Prepare all master mixes in a clean template-free area to avoid contamination.
<ol>
	<li>Reconstitute each variable region primer to 100 &#181;M with DNAse and RNAse free H2O. Next, combine 20 &#181;L of each of the 44 primers to generate the V-alpha primer pool. To generate the V-beta primer pool combine 20 &#181;L of each of the 40 V-beta primers plus 80 &#181;L of DNAse and RNAse free H2O. Primer sequences are listed in Table 1. Once pooled, the concentration of each primer in the mix is 2.3 &#181;M.</li>
	<li>Reconstitute the constant region primers to 100 &#181;M stock solution with DNAse and RNAse free H2O. Dilute the constant region primers to 10 &#181;M working solution and aliquot for use.</li>
	<li>Prepare two separate master mixes for TCR-alpha and TCR-beta amplification. Generate the master mixes by combining 5X buffer, 80 &#181;M dNTPs, 3% DMSO, 2 &#181;M primer pool (final concentration of 46 nM for each primer), 200 nM TCR-constant region reverse primer, 1 U DNA polymerase, and DNAse and RNAse free H2O (Table 2). For each 96-well plate, make up enough master mix for 10 additional reactions (total 106), in order to compensate for loss of liquid during pipetting. 
	NOTE: The calculations are based on the final PCR volume of 25 &#181;L per well, where 22.5 &#181;L master PCR mix is combined with 2.5 &#181;L cDNA template.</li>
	<li>Keep the plate with cDNA on ice or in a cold block. Use a multichannel to pipette 22.5 &#181;L of TCR-beta reaction into a new 96-well PCR plate. Then use a multichannel to transfer 2.5 &#181;L of cDNA into the PCR plate.</li>
	<li>Use a multichannel to pipette 22.5 &#181;L of TCR-alpha reaction directly into the plate containing the remainder of the cDNA.</li>
	<li>Seal the plates with adhesive, gently vortex, and spin down at 1000 x g for 5 min at 4 &#176;C.</li>
	<li>Run the multiplex PCR reaction with the following cycles: 5 min at 95 &#176;C followed by 34 cycles of 20 s at 95 &#176;C, 30 s at 54 &#176;C, and 1 min at 72 &#176;C, followed by 7 min at 72 &#176;C.</li>
	<li>Carry out the nested PCR reaction in a final volume of 25 &#181;L, using 2.5 &#181;L of the multiplex PCR mixture as template.
	<ol>
		<li>Reconstitute the internal and adaptor primers to 100 &#181;M with DNAse and RNAse free H2O. Make 10 &#181;M aliquots for the working stock.</li>
		<li>Prepare two separate master mixes for TCR-alpha and TCR-beta amplification. Mix 5X buffer, 25X DNTP, 3% DMSO, 200 nM forward adaptor primer, 200 nM reverse nested primer, 1 U DNA polymerase, and DNA polymerase and nuclease-free H2O for a final volume of 22.5 &#181;L (Table 2). For each 96-well plate, make up enough master mix for 10 additional reactions (total 106), to compensate for loss of liquid during pipetting. 
		NOTE: In the second PCR reaction use the 5X PCR buffer containing loading dye to facilitate agarose gel loading.</li>
		<li>Using a multichannel, pipette the master mixes for the TCR-alpha and TCR-beta reactions at 22.5 &#181;L per well into two new 96-well PCR plates.</li>
		<li>Add the multiplex PCR reaction template at 2.5 &#181;L per well. 
		NOTE: The remaining first PCR reaction should be sealed, and stored at -20 &#176;C to serve as a source of additional template, if it becomes necessary (see step 4.3 Note).</li>
		<li>Seal the plates, gently vortex, and spin down at 1000 x g for 5 min at 4 &#176;C.</li>
		<li>Run the nested PCR reaction with the following cycles: 5 min at 95 &#176;C followed by 34 cycles of 20 s at 95 &#176;C, 30 s at 56 &#176;C, and 1 min at 72 &#176;C, followed by 7 min at 72 &#176;C.</li>
		<li>Run 5 &#181;L of the final reaction out on a 1% agarose gel containing ethidium bromide (including the negative and positive control wells). 
		NOTE: The expected band should run at around 500 bp size. An example reaction is shown in Figure 2.</li>
		<li>Purify the remainder of the second reaction (20 &#181;L) using a 96-well format PCR purification kit, elute with 15 &#181;L of 70 &#176;C H2O per well, and perform Sanger sequencing. Use the appropriate TCR-alpha or TCR-beta adaptor forward primer for sequencing (Table 1). 
		NOTE: Sequences can be analyzed with online available immunogenetics software.</li>
	</ol>
	</li>
</ol>
4. Sub-cloning alpha and beta PCR chains.
NOTE: The pool of the forward primers utilized in the first reaction, and the reverse primers in the second PCR reaction are used to incorporate restriction sites. Therefore, the obtained alpha and beta chain PCR products are ready to be sequentially sub-cloned into the template retroviral vector (Figure 1).
<ol>
	<li>Digest the purified PCR products from the beta nested reaction with BstbI and MfeI (Table 3). 
	NOTE: Do not exceed 5 &#181;g insert.</li>
	<li>In parallel, digest the template vector with BstbI and MfeI (Table 3). Use 1-2 &#181;g of the template vector per TCR. Run the digested vector on an agarose gel, and isolate the larger band (~7500 bp). Purify the vector with a gel DNA purification kit. 
	NOTE: During the restriction enzyme digest, the template murine TCR-beta variable region is removed, allowing for the addition of the human TCR-beta variable region.</li>
	<li>Purify the digested PCR products using a PCR purification kit. 
	NOTE: Verify the DNA purification capacity of the columns included in the kit; use several columns if necessary. The minimum amount of a purified insert necessary for a successful ligation reaction is 50 ng at a minimum concentration of 10 ng/&#181;L. If the purified insert amount is not sufficient for a successful ligation, the second PCR reaction can be repeated.</li>
	<li>Treat the template vector with 10 U CIP enzyme for 1 h at 37 &#176;C to prevent self-ligation, followed by heat inactivation for 10 min at 75 &#176;C. Purify the DNA with a PCR purification kit (Table 3).</li>
	<li>Ligate TCR-beta insert and vector using DNA ligase in a 20 &#181;L total volume at 6 molar excess of the insert for 30 min at room temperature. 
	NOTE: In total, the ligation reaction should contain about 150 ng of DNA (Table 3).</li>
	<li>For transformations, mix 8 &#181;L of the ligation reaction with 80 &#181;L of chemically competent E.coli DH5&#945; cells (Table of Materials) and incubate on ice for 30 min. Heat shock at 42 &#176;C for 45 s. Add 500 &#181;L Super Optimal broth with Catabolite suppression (S.O.C.) medium and shake for 1.5 h at 37 &#176;C.</li>
	<li>Plate out 250 &#181;L of bacterial culture on an ampicillin containing Lysogeny Broth (LB) agar plate. Incubate the plate overnight (~16 h) at 37 &#176;C.</li>
	<li>The next day pick bacterial colonies, and grow them up in 3 mL LB medium containing ampicillin overnight. Isolate the plasmid DNA using DNA plasmid purification kit.</li>
	<li>Confirm the successful insertion of the beta chain by a small-scale test-digest with the restriction enzymes BstbI and MfeI. In a 12 &#181;L total reaction volume, combine 200-500 &#181;g plasmid DNA, 0.25 &#181;L of each enzyme, and 10X enzyme buffer (Table 3). Run the reaction out on a 1% agarose gel containing ethidium bromide to confirm the size of the insert band (~500 bp).</li>
	<li>After confirming the presence of the insert, sequence the TCR-beta section of the vector using the IRES reverse primer (Table 1).</li>
	<li>Following sequence confirmation of the TCR-beta insert, perform a similar process for insertion of the alpha variable region. Digest the purified PCR products from the alpha nested reaction, and the newly generated TCR-beta insert containing vector, with SnaBI and SacII. 
	NOTE: During the restriction enzyme digest, the template murine TCR-alpha variable region is removed, allowing for the addition of the human TCR-alpha variable region.</li>
	<li>Ligate alpha inserts into TCR vectors encoding the corresponding beta variable region using DNA ligase in a 20 &#181;L total volume at 6 molar excess of the insert for 30 min at room temperature. 
	NOTE: In total, the ligation reaction should contain about 150 ng of DNA (Table 3).</li>
	<li>For transformations, mix 8 &#181;L of the ligation reaction with 80 &#181;L of chemically competent E.coli DH5&#945; cells (Table of Materials) and incubate on ice for 30 min. Heat shock at 42 &#176;C for 45 s. Add 500 &#181;L S.O.C. medium and shake for 1.5 h at 37 &#176;C.</li>
	<li>Plate out 250 &#181;L of bacterial culture on an ampicillin containing Lysogeny Broth (LB) agar plate. Incubate the plate overnight (~16 h) at 37 &#176;C.</li>
	<li>The next day pick bacterial colonies, and grow them up in 3 mL LB medium containing ampicillin overnight. Isolate the plasmid DNA using DNA plasmid purification kit.</li>
	<li>Confirm the successful insertion of the alpha chain by a small-scale test-digest with the restriction enzymes SnaBI and SacII. In a 12 &#181;L total reaction volume combine 200-500 &#181;g plasmid DNA, 0.25 &#181;L of each enzyme, and 10x enzyme buffer (Table 3). Run the reaction out on a 1% agarose gel containing ethidium bromide to confirm the size of the insert band (~500 bp).</li>
	<li>After confirming the presence of the insert, sequence the TCR-alpha section of the vector using the MSCV2-forward primer (Table 1).</li>
	<li>Once the alpha chain sequence is validated, verify the complete TCR insert by sequencing with TCR-beta-reverse and IRES-reverse primer (Table 1).</li>
</ol>
5. Verify TCR cell surface expression and specificity.
Note: HEK293T cells are used to test successful TCR chain paring and cell surface expression (Figure 3A)8. Peptide-MHC tetramer staining can also be performed on the transfected HEK293T cells to test for retention of antigenic specificity post TCR gene isolation (Figure 3B).
<ol>
	<li>Plate out HEK293T cells in 12-well tissue culture plates at 1 x 105 cells per well in 1 mL complete DMEM media containing 5% FCS, and culture overnight at 37 &#176;C. Plate out enough cells to have designated separate wells for each new TCR, control template TCR vector, CD3 vector only, control TCR vector only, and a non-transfected well. 
	NOTE: Transfection with a fully mouse template TCR vector (mTCR-pMIA) in combination with mCD3&#949;&#947;&#948;&#950;-pMIG vector, mTCR-pMIA vector alone, and mCD3&#949;&#947;&#948;&#950;-pMIG vector alone are used as positive and negative controls. 
	NOTE: Complete DMEM contains 2 mM L-glutamine, 1 mM Sodium Pyruvate, 100 &#181;M Non-essential Amino Acids, 5 mM HEPES buffer, 5.5 x 10-5 units of 2-mercaptoethanol, 100 U/ml Penicillin/Streptomycin.</li>
	<li>The following day, transfect the cells with 1 &#181;g chimeric h/mTCR-pMIA vector, 1 &#181;g mouse CD3&#949;&#947;&#948;&#950;-pMSCVII-GFP (pMIG) vector, and a liposome-based transfection reagent following manufacturer instructions.</li>
	<li>For each TCR, add 6 &#181;L transfection reagent to 100 &#181;L room temperature, serum-free DMEM. Briefly vortex, and incubate at room temperature for 15 min.</li>
	<li>In separate 1.5 mL tubes combine 1 &#181;g of TCR-pMIA vector with 1 &#181;g mouse CD3&#949;&#947;&#948;&#950;-pMSCVII-GFP (pMIG) vector, or 1 &#181;g of each vector separate for controls.</li>
	<li>Dropwise, add the transfection reagent/DMEM solution to the tubes containing the vector DNA. Incubate at room temperature for 15 min.</li>
	<li>Dropwise, add the transfection reagent/DMEM/DNA solution to the HEK293T cells. Gently tap the plate to mix. Incubate at 37 &#176;C for 24 h.</li>
	<li>After 24 h replace the media, and keep cells in culture for additional 24 h.</li>
	<li>Remove cells from the plate by vigorous pipetting, and stain the cells with anti-mouse CD3 antibody (2.5 &#181;g/mL) to verify surface expression of the chimeric-TCR by flow cytometry.</li>
	<li>In order to compare CD3 expression between cells that were transfected to a similar level, gate the analysis on cells expressing a similar high level of fluorescent reporter molecules (GFP for CD3 complex, and Ametrine for TCR expression vector). Optimally, the analysis should be gated on GFP+Ametrine+ cells within 104 to 105 fluorescent intensity (Figure 3A). 
	NOTE: The level of CD3 expression in cells transfected with the chimeric construct should be comparable to the control mouse (original template) vector (Figure 3A). The generated TCR retroviral vectors are compatible with in vivo expression systems as previously described4.</li>
</ol>

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The authors have nothing to disclose.

In the current protocol, we describe an efficient method for single cell TCR amplification and subsequent sub-cloning of paired TCR alpha and beta chains into a template retroviral expression vector. Although, several single cell PCR protocols have been developed, none so far have been compatible with immediate sub-cloning into an expression vector. In most cases, a partial sequence encompassing the highly variable CDR3 regions is amplified, with enough sequence to extrapolate the variable region. This smaller PCR product size supports higher PCR efficiency, but necessitates de novo TCR gene synthesis for functional studies. The current protocol maintains the efficiency of previously published CDR3-focused single cell TCR sequencing protocols, while at the same time yielding a longer amplicon containing the whole variable region suitable for cloning. Therefore, the system described has an increased flexibility in giving a quantitative sequence, as well as functional output.
Depending on the scientific question addressed, the source and specificity of T cells analyzed can vary. However, if the end goal of the project is the analysis of the in vivo TCR function, it is necessary to know the HLA restriction of isolated T cells. The current protocol has been specifically designed to be compatible with in vivo TCR expression in HLA-humanized mice. Many of these mice have been generated and are now commercially available, including HLA-A2.1, HLA-DQ8 (HLA-DQA1*301,HLA-DQB1*302), HLA-DQ6 (DQA1*0102,HLADQB1*0602), HLA-DR4 (DRB1*0401), HLA-DR1 (DRA*0101, DRB1*0101), HLA-A11 (A*11:01/K), HLA-B2705, HLA-A24, and HLA-B*0702 transgenic strains. This protocol can be successfully combined with the previously published protocol for retroviral mediated bone marrow stem cell expression of human TCRs4,15,16. We expect that the humanized TCR retrogenic system will be applicable and highly useful for functional analysis of human TCRs in various autoimmune, cancer, and infectious models. 
The current single cell PCR protocol describes the critical steps and gives suggestions necessary for successful amplification of paired TCR-alpha and TCR-beta sequences. The first critical step is a timely performance of cDNA transcription, and subsequent first round of multiplex PCR. All the steps involved should be performed in a timely manner, and all the reagents and cells kept on ice to prevent RNA and cDNA degradation. Secondly, because the protocol is designed to be highly sensitive to low levels of the template, it is highly susceptible to contamination. Therefore, it is imperative to work in a template-free area, away from amplified PCR products or TCR vector cloning. A separate room or hood should be used to set up cDNA and PCR reactions. Template from the first PCR reaction should be added in a different area from where the PCR is set up. It is advisable that a separate set of aliquoted reagents be used for the single cell PCR experiments.
This protocol has been specifically optimized using the reagents listed in Table of Materials, and any substitutions in reagents will require additional optimization. The initial identification of antigen-specific cells can be modified to use peptide-MHC tetramers. Tetramer staining allows for simultaneous assessment of antigen specificity, as well as HLA-restriction. Alternative methods for the detection of antigen reactivity, such as upregulation of early activation markers or secretion of inflammatory cytokines can be considered in the absence of tetramer reagents. For example, dual specificity fusion antibodies specific for a T cell antigen and IFN&#947; can be combined with magnetic bead isolation to enrich for antigen reactive IFN&#947; producing cells. 
While the chimeric human/mouse construct described in our protocol ensures compatibility with mouse cells, the level of its compatibility with human CD3 complex is unknown. Although not formally tested by us, others have shown that chimeric TCR constructs with murine constant regions can be expressed on the surface of human lymphocytes17. This indicates that murine TCR constant regions can support interaction with the human CD3 signaling complex. However, if the goal is to express the identified TCRs in human primary cells or human cell lines, such as Jurkat cells, a more optimal approach may be to use a fully human construct. This can be accomplished by swapping the murine constant regions within the vector with human constant regions. 
If an identified TCR variable region contains one of the restriction sites used for cloning, the TCR should be inserted into a shuttle vector and subsequently mutated using a site directed mutagenesis kit to induce a silent nucleotide change within the restriction cut site. An alternative approach is de novo synthesis of the TCR variable region of interest modified to exclude the unwanted restriction site. 
The main limitation of this technique is the inability to eliminate amplification of secondary 'cytoplasmic' alpha chains. TCR-alpha genes do not go through allelic exclusion like TCR-beta genes, thus a significant proportion of T cells will express a secondary 'cytoplasmic' alpha chain14. The described PCR protocol only results in amplification of one TCR alpha chain, but if the amplified alpha chain is the 'cytoplasmic' alpha chain it may not pair with the amplified beta chain. Therefore, it is imperative to test TCR cell surface expression in HEK293T cells to ensure successful chain pairing.

The T cell receptor (TCR) dictates T cell fate decision during development, steady state/homeostasis, and antigenic stimulation in periphery1,2,3. Recent expansion of deep sequencing technologies has uncovered a previously underappreciated TCR diversity within antigen specific T cell responses. TCR diversity suggests a potential for functionally broad T cell responses. In order to integrate the TCR sequence repertoire analysis with TCR functional assays, the sequencing approaches should be designed to be compatible with experimental systems and in vivo models utilized for subsequent functional analysis of select TCRs. We have developed an efficient approach for human TCR sequence isolation and streamlined sub-cloning into a chimeric human/mouse TCR template vector compatible with TCR expression in HLA-humanized mice4. Isolation of corresponding alpha and beta chains of heterodimeric TCRs requires PCR amplification of both chains from a single cell. Although, several single-cell TCR cloning protocols have been developed and utilized, none so far have been easily compatible with high-throughput streamlined direct cloning of unknown V&#945;/V&#946; TCRs into retroviral vectors necessary for re-expression in vivo4,5,6,7. Previous studies have utilized two major approaches, either to selectively amplify a limited portion of the TCR sufficient to extrapolate the sequence, or to amplify the entire TCR sequence4,5,6,7. Downstream functional analysis of TCR sequences obtained via the first approach requires costly in silico assembly and de novo construction of the TCR. While the second approach provides the complete TCR sequence, the human constant region is not compatible with in vivo expression of the cloned TCRs in mouse models. Our approach is specifically designed to be compatible with in vivo functional analysis of TCRs in mouse models. We developed an efficient and streamlined single cell PCR protocol that allows for direct sub-cloning of PCR fragments into the template expression vector.
Our approach utilizes a highly sensitive multiplex-nested PCR reaction that is performed in two steps. In the first multiplex reaction step a pool of 40 primers specific for all the V-beta chains and a pool of 44 primers specific for all the V-alpha chains are used to amplify the TCR-alpha or TCR-beta without the prior knowledge of the sequence (Table 1). The forward primer has an adaptor sequence, which is incorporated into the 5&#39; of the PCR product. The reverse primer is based on the constant region of the TCR. We have identified unique restriction sites that are absent from human variable or junction TCR regions, and incorporated these into newly redesigned TCR&#945; and TCR&#946; primers (Figure 1). In the second nested reaction, a primer specific for the adaptor sequence and a nested reverse primer within the constant region are used to further amplify the TCR chains with increased specificity (Table 1, Figure 1). After single cell isolation, two rounds of PCR (first reaction with a pool of both V&#945; and V&#946; primers, and second with adaptor primers) result in a PCR product that can be directly sub-cloned into the template retroviral vector. The final TCR construct will encode, in a single open reading frame (ORF), human variable regions combined with mouse constant regions connected by the &#39;self-cleaving&#39; protein sequence, P2A (hV&#945;-mC&#945;-P2A-hV&#946;-mC&#946;)8. The P2A sequence has been used in multiple systems, and has been extensively tested specifically for the expression of TCRs8,9,10,11. Although, after translation most of the P2A sequence remains attached to the C-terminus of the alpha chain connected by a flexible linker, while the beta chain signal sequence has an additional proline, this modification has no detrimental effect on TCR function. The mouse constant region is used in the construct instead of human to avoid potential altered interactions with downstream signaling components when re-expressed in mouse cells. The single ORF will result in stoichiometric separate expression of alpha and beta chains9,11. The current protocol is based on reagents and approaches that are widely available, and is designed to be performed in a streamlined and efficient fashion. Although we have specifically used this technique to assay TCRs from self-reactive T cells implicated in autoimmune diabetes, we anticipate that this protocol can be widely applicable for identification and functional assessment of human TCRs specific for autoimmune epitopes, cancer epitopes, or responses to pathogens and vaccines.

<table border="0" cellpadding="0" cellspacing="0" width="815">
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		<tr height="21">
			<td height="21" style="height:21px;width:328px;">CFSE&#160;</td>
			<td style="width:148px;">eBioscience&#160;</td>
			<td style="width:116px;">65-0850-84</td>
			<td style="width:223px;">5 &#956;M</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-human CD4 (OKT4) BV421</td>
			<td>Biolegend&#160;</td>
			<td>317433</td>
			<td>2 &#956;g/mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-human CD3 (OKT3) PerCP/Cy5.5</td>
			<td>Biolegend&#160;</td>
			<td>317336</td>
			<td>2 &#956;g/mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-mouse CD3 AF647</td>
			<td>Biolegend&#160;</td>
			<td>100322</td>
			<td>2.5 &#956;g/mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant RNAse inhibitor biotech grd 2.5KU&#160;&#160;</td>
			<td>VWR</td>
			<td>97068-158</td>
			<td>0.7 U</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Applied Biosystems High capaity cDNA RT kit&#160;</td>
			<td>Invirtogen&#160;</td>
			<td>4368814</td>
			<td>9 U (RT enzyme)&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NF-H2O: Nuclease-free water 1000mL</td>
			<td>Invirtogen&#160;</td>
			<td>AM9932</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gotaq DNA polymerase 2500U</td>
			<td>VWR</td>
			<td>PAM3008</td>
			<td>1 U</td>
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		<tr height="21">
			<td height="21" style="height:21px;">96 Well Half Skirt PCR Plate</td>
			<td>Phenix</td>
			<td>MPX-96M2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MicroAmp Clear Adhesive Film&#160;</td>
			<td>ThermoFisher&#160;</td>
			<td>4306311</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;">UltraPure Agarose&#160;</td>
			<td>Invirtogen&#160;</td>
			<td>15510-027</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SnaBI</td>
			<td>New England Biolabs&#160;</td>
			<td>R0130</td>
			<td>15 U (insert) 30 U (vector)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SacII</td>
			<td>New England Biolabs&#160;</td>
			<td>R0157</td>
			<td>40 U (insert) 80 U (vector)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MfeI</td>
			<td>New England Biolabs&#160;</td>
			<td>R3589S</td>
			<td>40 U (insert) 80 U (vector)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BstBI</td>
			<td>New England Biolabs&#160;</td>
			<td>R0519</td>
			<td>40 U (insert) 80 U (vector)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calf Intestinal Phosphatase (CIP)</td>
			<td>New England Biolabs&#160;</td>
			<td>M0290S</td>
			<td>10 U</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Quick ligase&#160;</td>
			<td>New England Biolabs&#160;</td>
			<td>M2200S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Wizard Plus minipreps DNA purification systems&#160;</td>
			<td>Promega&#160;</td>
			<td>A1460</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Wizard Plus midipreps DNA purification systems&#160;</td>
			<td>Promega&#160;</td>
			<td>A7640</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DNA clean &#38; concentrator-25 kit</td>
			<td>Genesee Scientific&#160;</td>
			<td>11-304C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ZR-96 DNA clean &#38; concentrator-5 kit</td>
			<td>Genesee Scientific&#160;</td>
			<td>11-306A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QIAquick gel extraction kit</td>
			<td>Qiagen</td>
			<td>28704</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QIAquick PCR purification kit</td>
			<td>Qiagen</td>
			<td>28104</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Subcloning Efficiency DH5a Competent Cells&#160;</td>
			<td>ThermoFisher&#160;</td>
			<td>18265017</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Transit LT-1 Reagent 1mL (transfection reagent)</td>
			<td>Mirus&#160;</td>
			<td>MIR2300</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD FACS Aria II (sorter)</td>
			<td>BD</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD Fortessa (flow cytometer)</td>
			<td>BD&#160;</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

streamlined single cell tcr isolation and generation of retroviral vectors for in vitro and in vivo expression of human tcrs

Although, several methods for sequencing of paired T cell receptor (TCR) alpha and beta chains from single T cells have been developed, none so far have been conducive to downstream in vivo functional analysis of TCR heterodimers. We have developed an improved protocol based on a two-step multiplex-nested PCR, which results in a PCR product that spans entire variable regions of a human TCR alpha and beta chains. By identifying unique restriction sites and incorporating them into the PCR primers, we have made the PCR product compatible with direct sub-cloning into the template retroviral vector. The resulting retroviral construct encodes a chimeric human/mouse TCR with a mouse intracellular domain, which is functional in mouse cells or in in vivo mouse models. Overall, the protocol described here combines human single cell paired TCR alpha and beta chain identification with streamlined generation of retroviral vectors readily adaptable for in vitro and in vivo TCR expression. The video and the accompanying material are designed to give a highly detailed description of the single cell PCR, so that the critical steps can be followed and potential pitfalls avoided. Additionally, we provide a detailed description of the cloning steps necessary to generate the expression vector. Once mastered, the whole procedure from single cell sorting to TCR expression could be performed in a short two-week period.

Watch this Scientific Journal Video about Streamlined Single Cell TCR Isolation and Generation of Retroviral Vectors for In Vitro and In Vivo Expression of Human TCRs at JoVE.com

Streamlined Single Cell TCR Isolation and Generation of Retroviral Vectors for In Vitro and In Vivo Expression of Human TCRs

The current protocol combines single cell paired human TCR alpha and beta chain sequencing with streamlined generation of retroviral vectors compatible with in vitro and in vivo TCR expression.

Streamlined Single Cell TCR Isolation and Generation of Retroviral Vectors for In Vitro and In Vivo Expression of Human TCRs

Although, several methods for sequencing of paired T cell receptor (TCR) alpha and beta chains from single T cells have been developed, none so far have ...

streamlined-single-cell-tcr-isolation-generation-retroviral-vectors

Nanyang Technological University

Research

JoVE Journal

Immunology and Infection

9.3K Views.  Baylor College of Medicine, Texas Children's Hospital. The current protocol combines single cell paired human TCR alpha and beta chain sequencing with streamlined generation of retroviral vectors compatible with in vitro and in vivo TCR expression.

Video: Streamlined Single Cell TCR Isolation and Generation of Retroviral Vectors for In Vitro and In Vivo Expression of Human TCRs

Human T Lymphocyte Isolation, Culture and Analysis of Migration In Vitro

The migration of T lymphocytes involves the adhesive interaction of cell surface integrins with ligands expressed on other cells or with extracellular matrix proteins. The precise spatiotemporal activation of integrins from a low affinity state to a high affinity state at the cell leading edge is important for T lymphocyte migration 1. Likewise, retraction of the cell trailing edge, or uropod, is a necessary step in maintaining persistent integrin-dependent T lymphocyte motility 2. Many therapeutic approaches to autoimmune or inflammatory diseases target integrins as a means to inhibit the excessive recruitment and migration of leukocytes 3. To study the molecular events that regulate human T lymphocyte migration, we have utilized an in vitro system to analyze cell migration on a two-dimensional substrate that mimics the environment that a T lymphocyte encounters during recruitment from the vasculature. T lymphocytes are first isolated from human donors and are then stimulated and cultured for seven to ten days. During the assay, T lymphocytes are allowed to adhere and migrate on a substrate coated with intercellular adhesion molecule-1 (ICAM-1), a ligand for integrin LFA-1, and stromal cell-derived factor-1 (SDF-1). Our data show that T lymphocytes exhibit a migratory velocity of ~15 &mu;m/min. T lymphocyte migration can be inhibited by integrin blockade 1 or by inhibitors of the cellular actomyosin machinery that regulates cell migration 2.

Human T Lymphocyte Isolation, Culture and Analysis of Migration In Vitro

T lymphocyte migration occurs during homing to lymphoid organs, exit from the vasculature, and entering into peripheral tissues. Here, we describe a protocol that can be used to analyze T lymphocyte migration in vitro.

The migration of T lymphocytes involves the adhesive interaction of cell surface integrins with ligands expressed on other cells or with extracellular ...

Retroviral Transduction of T-cell Receptors in Mouse T-cells

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen presenting cells (APCs)1. This recognition leads to the activation of T-cells and a series of functional outcomes (e.g. cytokine production, killing of the target cells). Understanding the functional role of TCRs is critical to harness the power of the immune system to treat a variety of immunology related diseases (e.g. cancer or autoimmunity).
It is convenient to study TCRs in mouse models, which can be accomplished in several ways. Making TCR transgenic mouse models is costly and time-consuming and currently there are only a limited number of them available2-4. Alternatively, mice with antigen-specific T-cells can be generated by bone marrow chimera. This method also takes several weeks and requires expertise5. Retroviral transduction of TCRs into in vitro activated mouse T-cells is a quick and relatively easy method to obtain T-cells of desired peptide-MHC specificity. Antigen-specific T-cells can be generated in one week and used in any downstream applications. Studying transduced T-cells also has direct application to human immunotherapy, as adoptive transfer of human T-cells transduced with antigen-specific TCRs is an emerging strategy for cancer treatment6.
Here we present a protocol to retrovirally transduce TCRs into in vitro activated mouse T-cells. Both human and mouse TCR genes can be used. Retroviruses carrying specific TCR genes are generated and used to infect mouse T-cells activated with anti-CD3 and anti-CD28 antibodies. After in vitro expansion, transduced T-cells are analyzed by flow cytometry.

We present a protocol to produce antigen-specific mouse T-cells using retroviral transduction

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen ...

piggyBac Transposon System Modification of Primary Human T Cells

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most commonly utilizing two plasmids with one expressing the piggyBac transposase enzyme and a transposon plasmid harboring the gene(s) of interest between inverted repeat elements which are required for gene transfer activity. PiggyBac mediates gene transfer through a "cut and paste" mechanism whereby the transposase integrates the transposon segment into the genome of the target cell(s) of interest. PiggyBac has demonstrated efficient gene delivery activity in a wide variety of insect1,2, mammalian3-5, and human cells6 including primary human T cells7,8. Recently, a hyperactive piggyBac transposase was generated improving gene transfer efficiency9,10.
Human T lymphocytes are of clinical interest for adoptive immunotherapy of cancer11. Of note, the first clinical trial involving transposon modification of human T cells using the Sleeping beauty transposon system has been approved12. We have previously evaluated the utility of piggyBac as a non-viral methodology for genetic modification of human T cells. We found piggyBac to be efficient in genetic modification of human T cells with a reporter gene and a non-immunogenic inducible suicide gene7. Analysis of genomic integration sites revealed a lack of preference for integration into or near known proto-oncogenes13. We used piggyBac to gene-modify cytotoxic T lymphocytes to carry a chimeric antigen receptor directed against the tumor antigen HER2, and found that gene-modified T cells mediated targeted killing of HER2-positive tumor cells in vitro and in vivo in an orthotopic mouse model14. We have also used piggyBac to generate human T cells resistant to rapamycin, which should be useful in cancer therapies where rapamycin is utilized15.
Herein, we describe a method for using piggyBac to genetically modify primary human T cells. This includes isolation of peripheral blood mononuclear cells (PBMCs) from human blood followed by culture, gene modification, and activation of T cells. For the purpose of this report, T cells were modified with a reporter gene (eGFP) for analysis and quantification of gene expression by flow cytometry.
PiggyBac can be used to modify human T cells with a variety of genes of interest. Although we have used piggyBac to direct T cells to tumor antigens14, we have also used piggyBac to add an inducible safety switch in order to eliminate gene modified cells if needed7. The large cargo capacity of piggyBac has also enabled gene transfer of a large rapamycin resistant mTOR molecule (15 kb)15. Therefore, we present a non-viral methodology for stable gene-modification of primary human T cells for a wide variety of purposes.

piggyBac Transposon System Modification of Primary Human T Cells

We describe a method to genetically modify primary human T cells with a transgene using the non-viral piggyBac transposon system. T cells modified to using the piggyBac transposon system exhibit stable transgene expression.

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most ...

Lymphocyte Isolation from Human Skin for Phenotypic Analysis and Ex Vivo Cell Culture

Human skin has an important barrier function and contains various immune cells that contribute to tissue homeostasis and protection from pathogens. As the skin is relatively easy to access, it provides an ideal platform to study peripheral immune regulatory mechanisms. Immune resident cells in healthy skin conduct immunosurveillance, but also play an important role in the development of inflammatory skin disorders, such as psoriasis. Despite emerging insights, our understanding of the biology underlying various inflammatory skin diseases is still limited. There is a need for good quality (single) cell populations isolated from biopsied skin samples. So far, isolation procedures have been seriously hampered by a lack of obtaining a sufficient number of viable cells. Isolation and subsequent analysis have also been affected by the loss of immune cell lineage markers, due to the mechanical and chemical stress caused by the current dissociation procedures to obtain single cell suspension. Here, we describe a modified method to isolate T cells from both healthy and involved psoriatic human skin by combining mechanical skin dissociation using an automated tissue dissociator and collagenase treatment. This methodology preserves expression of most immune lineage markers such as CD4, CD8, Foxp3 and CD11c upon the preparation of single cell suspensions. Examples of successful CD4+ T cell isolation and subsequent phenotypic and functional analysis are shown.

Lymphocyte Isolation from Human Skin for Phenotypic Analysis and Ex Vivo Cell Culture

We describe a protocol to efficiently isolate skin resident T cells from human skin biopsies. This protocol yields sufficient numbers of viable human skin resident lymphocytes for flow cytometric analysis and ex vivo culture.

Human skin has an important barrier function and contains various immune cells that contribute to tissue homeostasis and protection from pathogens. As the ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of ...

A Simple and Efficient Approach to Construct Mutant Vaccinia Virus Vectors

The CRISPR-associated endonuclease Cas9 can edit particular genomic loci directed by a single guide RNA (gRNA). The CRISPR/Cas9 system has been successfully employed for editing genomes of various organisms. Here we describe a protocol for editing the vaccinia virus (VV) genome in the cytoplasm of VV-infected CV-1 cells using the RNA-guided Cas9. RNA-guided Cas9 induces double-stranded DNA breaks facilitating homologous recombination efficiently and specifically in the targeted site of VV and a transgene can be incorporated into these sites by homologous recombination. By using a site-specific homologous vector with transgene(s), a N1L gene-deleted VV with the red fluorescence protein (RFP) gene incorporated in this region was generated with a successful recombination efficiency 10 times greater than that obtained from the conventional homologous recombination method. This protocol demonstrates successful use of RNA-guided Cas9 system to generate mutant VVs with enhanced efficiency.

Vaccinia virus (VV) has been widely used in biomedical research and the improvement of human health. This article describes a simple, highly efficient method to edit the VV genome using a CRISPR-Cas9 system.

The CRISPR-associated endonuclease Cas9 can edit particular genomic loci directed by a single guide RNA (gRNA). The CRISPR/Cas9 system has been ...

Flow Cytometric Analysis of Natural Killer Cell Lytic Activity in Human Whole Blood

NK cell cytotoxicity is a widely used measure to determine the effect of outside intervention on NK cell function. However, the accuracy and reproducibility of this assay can be considered unstable, either because of user&#39;s errors or because of the sensitivity of NK cells to experimental manipulation. To eliminate these issues, a workflow that reduces them to a minimum was established and is presented here. To illustrate, we obtained blood samples, at various time points, from runners (n = 4) that were submitted to an intense bout of exercise. First, NK cells are simultaneously identified and isolated through CD56 tagging and magnetic-based sorting, directly from whole blood and from as little as one milliliter. The sorted NK cells are removed of any reagent or capping antibodies. They can be counted in order to establish an accurate NK cell count per milliliter of blood. Secondly, the sorted NK cells (effectors cells or E) can be mixed with 3,3&#39;-Diotadecyloxacarbocyanine Perchlorate (DiO) tagged K562 cells (target cells or T) at an assay-optimal 1:5 T:E ratio, and analyzed using an imaging flow-cytometer that allows for the visualization of each event and the elimination of any false positive or false negatives (such as doublets or effector cells). This workflow can be completed in about 4 h, and allows for very stable results even when working with human samples. When available, research teams can test several experimental interventions in human subjects, and compare measurements across several time points without compromising the data&#39;s integrity.

This work describes an advanced workflow for the accurate and fast determination of NK (Natural Killer) cell count and NK cell cytotoxicity in human blood samples.

NK cell cytotoxicity is a widely used measure to determine the effect of outside intervention on NK cell function. However, the accuracy and ...

Quantifying Human Monocyte Chemotaxis In Vitro and Murine Lymphocyte Trafficking In Vivo

Chemotaxis is migration along a specific chemical gradient1. Chemokines are chemotactic cytokines that promote cellular trafficking with anatomic and temporal specificity2. Chemotaxis is a critical function of lymphocytes and other immune cells that can be quantitatively assessed in vitro. This manuscript describes methods that permit the evaluation of chemotaxis, both in vitro and in vivo, for diverse cell types including cell lines and native cells. The in vitro, plate-based format permits the comparison of several conditions simultaneously in real-time, and can be completed within 1-4 h. In vitro assay conditions can be manipulated to introduce agonists and antagonists, as well as differentiate chemotaxis from chemokinesis, which is random movement. For in vivo trafficking assessments, immune cells can be labeled with multiple fluorescent dyes and used for adoptive transfer. The differential labeling of cells allows for mixed cell populations to be introduced into the same animal, thereby decreasing variance and reducing the number of animals required for an adequately powered experiment. Migration into lymphoid tissue occurs in as little as 1 h, and multiple tissue compartments can be sampled. Flow cytometry following tissue harvest allows for a rapid and quantitative analysis of the migratory patterns of multiple cell types.

Quantifying Human Monocyte Chemotaxis In Vitro and Murine Lymphocyte Trafficking In Vivo

Protocols for quantitative assessment of lymphocyte chemotaxis and migration are important tools for immunology research. Here, an in vitro protocol is described that permits real-time, multiplexed evaluation of cell migration, as well as a complementary in vivo technique enabling tracking of native cells to spleen.

Chemotaxis is migration along a specific chemical gradient1. Chemokines are chemotactic cytokines that promote cellular trafficking with anatomic and ...

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. typhimurium bacteria are quickly detected and phagocytized by macrophages, and contained in vesicles known as phagosomes in order to be degraded. Isolation of S. typhimurium-containing phagosomes have been widely used to study how S. typhimurium infection alters the process of phagosome maturation to prevent bacterial degradation. Classically, the isolation of bacteria-containing phagosomes has been performed by sucrose gradient centrifugation. However, this process is time-consuming, and requires specialized equipment and a certain degree of dexterity. Described here is a simple and quick method for the isolation of S. typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin-streptavidin-conjugated magnetic beads. Phagosomes obtained by this method can be suspended in any buffer of choice, allowing the utilization of isolated phagosomes for a broad range of assays, such as protein, metabolite, and lipid analysis. In summary, this method for the isolation of S. typhimurium-containing phagosomes is specific, efficient, rapid, requires minimum equipment, and is more versatile than the classical method of isolation by sucrose gradient-ultracentrifugation.

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

We describe here a simple and quick method for the isolation of Salmonella typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin and streptavidin.

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. ...

Assessment of the Cytotoxic and Immunomodulatory Effects of Substances in Human Precision-cut Lung Slices

Respiratory diseases in their broad diversity need appropriate model systems to understand the underlying mechanisms and enable development of new therapeutics. Additionally, registration of new substances requires appropriate risk assessment with adequate testing systems to avoid the risk of individuals being harmed, for example, in the working environment. Such risk assessments are usually conducted in animal studies. In view of the 3Rs principle and public skepticism against animal experiments, human alternative methods, such as precision-cut lung slices (PCLS), have been evolving. The present paper describes the ex vivo technique of human PCLS to study the immunomodulatory potential of low-molecular-weight substances, such as ammonium hexachloroplatinate (HClPt). Measured endpoints include viability and local respiratory inflammation, marked by altered secretion of cytokines and chemokines. Pro-inflammatory cytokines, tumor necrosis factor alpha (TNF-&#945;), and interleukin 1 alpha (IL-1&#945;) were significantly increased in human PCLS after exposure to a sub-toxic concentration of HClPt. Even though the technique of PCLS has been substantially optimized over the past decades, its applicability for the testing of immunomodulation is still in development. Therefore, the results presented here are preliminary, even though they show the potential of human PCLS as a valuable tool in respiratory research.

In view of the 3Rs principle, respiratory models as alternatives to animal studies are evolving. Especially for risk assessment of respiratory substances, there is a lack of appropriate assays. Here, we describe the use of human precision-cut lung slices for the assessment of airborne substances.