Volume 2 Supplement 2

Abstracts from the 1st Immunotherapy of Cancer Conference (ITOC1)

Open Access

P73. Functional characterisation of HBV-specific T cell receptors for redirection of T cells against HBV infected hepatocytes

  • K Krebs1,
  • K Metzger1,
  • L Weigand2,
  • C Dargel1,
  • E Kieback3,
  • W Uckert3,
  • D Busch4,
  • A Krackhardt2 and
  • U Protzer1
Journal for ImmunoTherapy of Cancer20142(Suppl 2):P47

https://doi.org/10.1186/2051-1426-2-S2-P47

Published: 12 March 2014

Chronic HBV infection, which is accompanied by a weak and oligoclonal T cell response, is the most common cause of hepatocellular carcinoma (HCC). Current antiviral therapies do not eliminate the virus, but T cell therapy will very likely do so. From PBMCs of two HLA-A2+ acutely infected patients and a donor who cleared HBV infection we have established several HBV-specific monoclonal T cell lines. Thereof we isolated 11 different T cell receptors (TCR) that are specific for the HBV S-protein derived peptides S20 (FLLTRILTI) and S172 (WLSLLVPFV) or for the C18 core-peptide (FLPSDFFPSV). The aim of this study was a functional comparison of our set of HBV-specific TCRs in order to identify TCRs with optimal recognition of HBV peptides presented on HLA-A2.

By murinization and codon-optimisation of gene sequences of TCR a and b chains, fused by a P2A element for polycystronic expression, TCR expression after retroviral transduction was increased 2-fold to 60% of PBMCs expressing an HBV-specific TCR.

PBMCs transduced with the 11 optimised HBV-specific TCRs were compared in killing assays using peptide-pulsed T2 cells, LCLs and HBV-replicating HepG2.2.15 cells as targets. CD8+ T cells transduced with the core-specific TCRs killed target cells loaded with 0.01 nM of peptide. Cells specific for the S20 and S172 peptide were less sensitive with a specific lysis as low as 0.1 nM. Expression of most of the HLA-A2 restricted HBV-specific TCRs in CD4+ T cells also led to specific cytotoxicity, which was 10-fold reduced in sensitivity compared to CD8+ T cells and independent of CD8 co-receptor binding. Notably, our HBV-specific TCRs recognised peptide presented on various different HLA-A2 subtypes.

CD8+ T cells transduced with HBV-specific TCRs were also able to recognise endogenously processed peptides and specifically kill HBV-replicating hepatoma cells and strongly reduce cccDNA levels in HBV-infected HepaRG cells.

In addition, intracellular cytokine staining after stimulation showed that the TCR-transduced CD8+ T cells were polyfunctional, secreting INF-γ, TNF-α and IL-2, whereas CD4+ T cells produced mainly TNF-a and/or IL-2.

We will further analyse our HBV-specific TCRs in HBV/HLA-A2 transgenic mice in order to identify the TCR that confers best antiviral activity. Our HBV-specific TCRs may be used for elucidating specific anti-HBV mechanisms exerted by T cells, and most importantly, for adoptive T cell therapy of chronic hepatitis B and HBV-induced HCC.

Authors’ Affiliations

(1)
TU Muenchen / Helmholtz Zentrum Muenchen, Institute of Virology
(2)
Klinikum rechts der Isar, III. Medizinische Klinik
(3)
Max-Delbrück Center for Molecular Medicine
(4)
TU Muenchen, Institute for Medical Microbiology Immunology and Hygiene

Copyright

© Krebs et al; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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