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

Summary

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.

Abstract

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.

Introduction

The T cell receptor (TCR) dictates T cell fate decision during development, steady state/homeostasis, and antigenic stimulation in periphery^1,2,3. 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 utilize....

Protocol

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.

1. Mix PBMCs 1:1 with MHC-matched feeder cells, and label with 5 µM CFSE cell division dye.
2. Plate 2-2.5 x 10⁵ cells per well in a 96-well round-bottom culture plate in 200 µL 10....

Results

The efficiency of the multiplex-nested PCR reaction is checked in step 3.2.7 (Figure 2) by running out 5µL of the second reaction on an agarose gel. On average the efficiency of TCR-beta amplification is expected to be around 80%, while the efficiency of the TCR-alpha reaction is usually lower, at around 50%⁴. Only paired TCR-alpha and TCR-beta chains can be used for TCR expression; however, all PCR products could be sequenced to obtai.......

Discussion

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 produc.......

Materials

List of materials used in this article

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