Jurkat-Raji PD-1/PD-L1 assay (Bio-IC™)

Antagonist screening assay for PD-1/PD-L1 axis

The PD-1/PD-L1 Bio-IC™ assay is a bioluminescent, cell-based system designed for the screening of antibody-, Fc-fusion protein-, or small-molecule antagonists of the PD-1/PD-L1 immune checkpoint (IC) axis.
This IC interaction delivers inhibitory signals that prevent T cells from eliciting an immune response. Inhibitors of PD-1 or PD-L1 restore T cell activity and are among the most promising immunotherapeutic approaches.

 More details

PD-1/PD-L1 Bio-IC™ assay principle (click to enlarge)

The PD-1/PD-L1 Bio-IC™ assay is comprised of two cell lines:

• Jurkat-Lucia™ TCR-hPD1

Jurkat-Lucia™ TCR-hPD1 are engineered human T cells that stably express a specific TCR and an NFAT-Lucia luciferase reporter. They also overexpress the CD28 costimulatory receptor and the PD-1 immune checkpoint receptor.

• Raji-APC-hPD-L1

Raji-APC-hPD-L1 are engineered human B cells acting as antigen-presenting cells (APCs). They stably express the cognate TCR [HLA::peptide] complex and the PD-L1 immune checkpoint ligand. These cells express endogenous levels of CD80/86, the ligand shared by CD28 and CTLA4.

Assay principle

The co-culture of these two cell lines mimics the immune synapse between T cells and APCs, leading to the inactivation of the reporter T cells.

The immune synapse results from the activatory interactions of the TCR/[HLA::peptide] complex and CD28/CD80, and the concomitant inhibitory interactions of  PD-1/PD-L1. These three interactions prevent the Jurkat-Lucia™ TCR-hPD-1 cells from expressing Lucia®.

In the presence of PD-1 or PD-L1 antagonists, the IC-mediated inhibition is removed, leading to T cell activation and Lucia® production. The potency of these antagonists can be evaluated by assessing Lucia® activity using QUANTI-Luc™ 4 Lucia/Gaussia detection reagent (see Figures). 

Jurkat-Lucia™ TCR-hPD-1 key features

• Stable specific [HLA::peptide]-restricted TCR
• Stable hPD-1 and hCD28 overexpression
• NFAT-inducible Lucia luciferase reporter activity
• No Lucia® expression in the absence of IC inhibitor(s)
• Lucia® expression in the presence of IC inhibitor(s)

APC key features:

• Stable specific [HLA::peptide] expression
• Stable hPD-L1 overexpression
• Endogenous hCD80 expression

Read our review on Immune Checkpoint Blockade

Learn more about Immune Checkpoint Antibodies.

Figures

Validation of human PD-1 expression by Jurkat-Lucia™ TCR-hPD-1 cells.

Jurkat-Lucia™ NFAT and Jurkat-Lucia™ TCR-hPD-1 cells were incubated with APC-conjugated Anti-hPD-1 mAb for 30 minutes.
The binding affinity was then measured using flow cytometry.

Validation of human PD-L1 expression by Raji-APC-hPD-L1 cells.

Raji-APC-Null and Raji‑APC-hPD-L1 cells were incubated with a PE‑conjugated Anti-hPD-L1 mAb for 30 minutes.
The binding affinity was then measured using flow cytometry.

Activation of Jurkat-Lucia™ TCR-hPD-1 cells.
Raji-APC-hPD-L1 and Jurkat-Lucia™ TCR-hPD-1 cells were incubated with gradient concentrations of AntihPD-1 hIgG1 (Ni: Nivolumab variable region; Pem: Pembrolizumab variable region) or Anti-hPD-L1 mAbs for 6 hours. NFAT activation, reflecting the disruption of PD-1/PD-L1 inhibitory interaction, was assessed by determining Lucia luciferase activity in the supernatant using QUANTI-Luc™.
The fold increase over non induced cells (no mAbs) is shown.

Specifications

Growth medium: IMDM, 2 mM L-glutamine, 25 mM HEPES, 10% (v/v) heat-inactivated fetal bovine serum (FBS), 100 U/ml penicillin, 100 µg/ml streptomycin, 100 µg/ml Normocin™

Antibiotic resistance:

• Jurkat-Lucia™ TCR-hPD-1 cells: Blasticidin, Zeocin®, Hygromycin, and G418 (Geneticin)
• Raji-APC-hPD-L1 cells: Blasticidin and G418 (Geneticin)

Quality Control:

• Human CD28, PD-1, and PD-L1 expression have been verified by flow-cytometry.
• Reporter activity has been validated using InvivoGen's anti-hPD-1 and anti-hPD-L1 antibodies.
• The stability for 20 passages following thawing has been verified.
• Both cell lines are guaranteed mycoplasma-free.

Contents

Please note: Both cell lines are sold together and cannot be sold separately.

• 3-7 x 10⁶ Jurkat-Lucia™ TCR-hPD-1 cells in a cryovial or shipping flask
• 3-7 x 10⁶ Raji-APC-hPD-L1 cells in a cryovial or shipping flask
• 1 ml of Blasticidin (10 mg/ml)
• 1 ml of Zeocin® (100 mg/ml)
• 1 ml of Hygromycin (100 mg/ml)
• 1 ml of G418 (Geneticin) (100 mg/ml)
• 1 ml of Normocin™ (50 mg/ml). Normocin™ is a formulation of three antibiotics active against mycoplasmas, bacteria, and fungi.
• 1 tube of QUANTI-Luc™ 4 Reagent, a Lucia luciferase detection reagent (sufficient to prepare 25 ml)

Shipped on dry ice (Europe, USA, Canada, and some areas in Asia)

Details

The activation of T lymphocytes initiates their proliferation and yields a variety of effector functions that allow combating microbial infections, as well as developing tumors. The current paradigm is that full activation of T cells requires at least 2 signals upon contact with antigen-presenting cells (APCs) [1, 2].

Signal 1 is delivered through the interaction of the T cell receptor (TCR) and a specific antigenic peptide associated with an MHC (major histocompatibility complex) molecule on APCs. Signal 2 is delivered through the interaction of CD28, the prototypical T cell co-stimulatory molecule, and its ligands, CD80 or CD86, expressed by the APC. However, a number of other molecules, named immune checkpoints (IC), have been reported to regulate the onset and the limitations of T cell activities. PD-1 (programmed cell death 1) receptor and its ligand, PD-L1, are among the best characterized suppressive immune checkpoints [3].

Signal 1: TCR and [HLA::peptide]

The 'classical' and most represented TCR is an 80 to 90 kDa heterodimer composed of one α chain and one β chain. The αβTCR is a transmembrane protein expressed by developing and mature T cells. It features an extracellular ligand-binding pocket and a short cytoplasmic tail. Each αβTCR is restricted to a specific complex made of an antigenic peptide and a class I or class II MHC molecule. Human MHC molecules are also known as HLA (human leukocyte antigen). Because of its short cytoplasmic tail, the TCR, once engaged,  lacks the ability to signal and requires non-covalent association with the CD3 to trigger downstream intracellular signaling and T cell activation [1, 2]. Importantly, signal 1 without co-stimulation results in T cell unresponsiveness or 'anergy', a tolerance mechanism that guards against premature activation.

Signal 2: CD28 and CD80/86

CD28 is a homodimeric and transmembrane protein expressed by T cells. Nearly all human CD4+ T cells and 50% of human CD8+ T cells express CD28. The CD28 interaction with CD80 (aka B7-1) or CD86 (aka B7-2) on APCs, in conjunction with TCR engagement, triggers a co-stimulation signal (signal 2). It results in T cell proliferation, cytokine production, cell survival, and cellular metabolism [1, 2].

IC signal: PD-1 and PD-L1

— PD-1 (programmed cell death 1; also known as CD279) is a type I transmembrane protein expressed at the cell surface of activated and exhausted conventional T cells. PD-1 is an inhibitory immune checkpoint that prevents T-cell overstimulation and host damage. PD-1 interaction with its ligands PD-L1 and PD-L2 induces inhibition of TCR signaling [3].

— PD-L1 (programmed cell death ligand 1; also known as CD274 or B7-H1) is a transmembrane protein expressed at the cell surface of hematopoietic and nonhematopoietic cells and is induced by pro-inflammatory cytokines, such as in the tumor microenvironment  [3].  PD-L1 is one ligand for PD-1, an inhibitory immune checkpoint receptor that is expressed by activated and exhausted T cells. PD-1:PD-L1 interaction induces inhibition of TCR signaling, thereby preventing T-cell overstimulation and host damage [3].

References:

1. Budd R.C. & Fortner K.A., 2017. Chapter 12 - T Lymphocytes. Kelley and Firestein's Textbook of Rheumatology (Tenth Edition). pages 189-206.
2. Smith-Garvin J.E. et al., 2009. T Cell Activation. Ann. Rev. Immunol. 27:591-619.
3. Ribas A. and Wolchock J.D., 2018. Cancer immunotherapy using checkpoint blockade. Science. 359:1350-55.

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