CD161++CD8+ T cells represent a novel subset that is dominated in adult peripheral blood by mucosal-associated invariant T (MAIT) cells, as defined by the expression of a variable-α chain 7.2 (Vα7.2)-Jα33 TCR, and IL-18Rα. Stimulation with IL-18+IL-12 is known to induce IFN-γ by both NK cells and, to a more limited extent, T cells. Here, we show the CD161++ CD8+ T-cell population is the primary T-cell population triggered by this mechanism. Both CD161++Vα7.2+ and CD161++Vα7.2− T-cell subsets responded to IL-12+IL-18 stimulation, demonstrating this response was not restricted to the MAIT cells, but to the CD161++ phenotype. Bacteria and TLR agonists also indirectly triggered IFN-γ expression via IL-12 and IL-18. These data show that CD161++ T cells are the predominant T-cell population that responds directly to IL-12+IL-18 stimulation. Furthermore, our findings broaden the potential role of MAIT cells beyond bacterial responsiveness to potentially include viral infections and other inflammatory stimuli.

We generated a novel CD19CAR (CAT) with a lower affinity than FMC63, the binder utilised in many clinical studies. CAT CAR T cells showed increased proliferation/cytotoxicity in vitro and enhanced proliferative capacity and anti-tumor activity than FMC63 CAR T cells in a xenograft model. In a clinical study (CARPALL, NCT02443831), 12/14 patients with relapsed/refractory pediatric BALL obtained molecular remission after CAT CAR T cell therapy. CAR T cell expansion compared favourably with published data on other CD19CARs and persistence was demonstrated in 11 of 14 patients at last follow-up. Toxicity was low with no severe cytokine release syndrome. At a median follow up of 14 months, 5/14 patients (37%) remain in molecular CR with circulating CAR T cells.

Abstract* "This manuscript has been accepted for publication in Science Translational Medicine. This version has not undergone final editing.Please refer to the complete version of record at www.sciencetranslationalmedicine.org/. The manuscript may not be reproduced or used in any manner that does not fall within the fair use provisions of the Copyright Act without the prior, written permission of AAAS."To whom correspondence should be addressed: ellie.barnes@ndm.ox.ac.uk E Barnes Peter Medawar Building, South Parks Rd, Oxford, UK OX1 3SY . + joint author contributions Author contributions: E.B., S. Capone, S. Colloca, J.H., A.F., R.C., C.K., A.N., and P.K. designed the study/protocols; L. Swadling, S. Capone., R.A., A.B., R.R., E.N., J.H., C.K., D.B., J.F., A.K., V.A., M.D.S., F.G., M.L.E., L. Siani., C.T., A.H., M.D., A.F., E.B., and P.K., performed the research and analysis; L. Swadling., E.B., A.F., S. Capone, and P.K. wrote the manuscript; E.B. was the principal investigator. Europe PMC Funders Group Europe PMC Funders Author Manuscripts Europe PMC Funders Author ManuscriptsA protective vaccine against hepatitis C virus (HCV) remains an unmet clinical need. HCV infects millions of people worldwide and is a leading cause of liver cirrhosis and hepatocellular cancer. Animal challenge experiments, immunogenetics studies and assessment of host immunity during acute infection highlight the critical role that effective T-cell immunity plays in viral control. In this first-in-man study we have induced antiviral immunity with functional characteristics analogous to those associated with viral control in natural infection, and improved upon a vaccine based on adenoviral vectors alone. We assessed a heterologous prime-boost vaccination strategy based on a replicative defective simian adenoviral vector (ChAd3) and modified vaccinia Ankara (MVA) vector encoding the NS3, NS4, NS5A and NS5B proteins of HCV genotype-1b.Analysis employed single cell mass cytometry (CyTOF), and HLA class-I peptide tetramer technology in healthy human volunteers. We show that HCV specific T-cells induced by ChAd3 are optimally boosted with MVA, and generate very high levels of both CD8+ and CD4+ HCV specific T-cells targeting multiple HCV antigens. Sustained memory and effector T-cell populations are generated and T-cell memory evolved over time with improvement of quality (proliferation and polyfunctionality) following heterologous MVA boost.We have developed a HCV vaccine strategy, with durable, broad, sustained and balanced T-cell responses, characteristic of those associated with viral control, paving the way for the first efficacy studies of a prophylactic HCV vaccine.

Low-affinity CD19 CAR T cells display enhanced expansion and persistence, enabling fate tracking through integration site (IS) analysis. Here we show that IS from early (1 month) and late (>3 years) time-points cluster separately, suggesting different clonal contribution to early responses and prolonged anti-leukemic surveillance. CAR+ T central and effector memory in patients with longterm persistence remained highly polyclonal, whereas diversity dropped rapidly in patients with limited CAR T persistence. Analysis of shared integrants between the CAR T cell product and post-infusion demonstrated that, despite their low frequency, T memory stem cells (TSCM) clones in the product contributed substantially to the circulating CAR T cell pools, both during early expansion and longterm persistence. Our data may help identify patients at risk of early loss of CAR T cells and highlights the critical role of TSCM in both mediating early anti-leukemic responses and long-term surveillance by CAR T cells.