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A cellular platform for the evaluation of immune checkpoint molecules
Sabrina Jutz1, Annika Hennig1, Wolfgang Paster1
1Division of Immune Receptors and T cell Activation, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
Oncotarget
|October 15, 2017
Summary
This study developed a Jurkat T cell reporter system to investigate T cell coinhibitory molecules like CTLA-4 and PD-1. The system successfully identified inhibitory and activating pathways, offering a robust method to study T cell responses.
Area of Science:
- Immunology
- Cell Biology
Background:
- T cell coinhibitory molecules, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1), are crucial for regulating T cell responses and are targets for cancer immunotherapy.
- Investigating these molecules in primary human T cells is challenging due to limited expression and ligand promiscuity.
- A simplified model system is needed to efficiently study the diverse coinhibitory pathways.
Purpose of the Study:
- To evaluate the utility of fluorescence-based transcriptional reporter Jurkat T cell lines for studying coinhibitory pathways.
- To characterize the function of multiple coinhibitory receptors including CTLA-4, PD-1, TIGIT, BTLA, and 2B4 in a controlled system.
- To compare the efficacy of known inhibitors like Ipilimumab and Nivolumab within this reporter system.
Main Methods:
- Generation of Jurkat T cell lines engineered to express specific coinhibitory receptors (CTLA-4, PD-1, TIGIT, BTLA, 2B4) with transcriptional reporters.
- Activation of reporter cells using engineered T cell stimulator cells expressing cognate ligands for the coinhibitory receptors.
- Analysis of T cell activation, inhibition, and enhancement upon receptor-ligand engagement.
- Mutational analysis of intracellular motifs involved in T cell inhibition.
- Determination of IC50 values for CTLA-4 and PD-1 blocking antibodies.
Main Results:
- All tested coinhibitory molecules (CTLA-4, PD-1, BTLA, TIGIT) demonstrated functional inhibition of T cell activation upon ligand engagement.
- Engagement of 2B4 by its ligand CD48 resulted in enhanced T cell responses.
- Intracellular motifs critical for BTLA-mediated inhibition were identified.
- CTLA-4 mediated potent inhibition independent of specific cytoplasmic signaling motifs.
- Higher IC50 values were observed for the CTLA-4 inhibitor Ipilimumab compared to the PD-1 inhibitor Nivolumab.
Conclusions:
- Jurkat-based transcriptional reporter systems provide a robust and efficient platform for evaluating T cell coinhibitory pathways.
- This reductionist system yields novel insights into the function of coinhibitory molecules and can complement studies in primary T cells.
- The findings support the use of this model for drug efficacy assessment and understanding immune checkpoint regulation.