Frontiers in Oncology (Aug 2022)

Tumor-specific T cell-mediated upregulation of PD-L1 in myelodysplastic syndrome cells does not affect T-cell killing

  • Valentina Ferrari,
  • Alison Tarke,
  • Hannah Fields,
  • Tiffany N. Tanaka,
  • Stephen Searles,
  • Maurizio Zanetti

DOI
https://doi.org/10.3389/fonc.2022.915629
Journal volume & issue
Vol. 12

Abstract

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The PD-1:PD-L1 axis is a binary interaction that delivers inhibitory signals to T cells, impeding both immune surveillance and response to immunotherapy. Here we analyzed a phenomenon whereby tumor-specific T cells induce PD-L1 upregulation in autologous MDS cells in short-term culture, through a mechanism that is cell-contact-independent and partially IFNγ-dependent. After investigating a panel of small-molecule inhibitors, we determined that PD-L1 upregulation was attributed to the PKR-like ER kinase (PERK) branch of the unfolded protein response. Interestingly, we found that the cytotoxic capacity of tumor-specific T cells was not impaired by the expression of PD-L1 on MDS target cells. These results highlight a little appreciated aspect of PD-1:PD-L1 regulation in hematologic cancers and indicate that this phenomenon, while likely to hinder autochthonous immune surveillance, may not be an obstacle to immunotherapies such as personalized adoptive T-cell therapy.

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