Myelodysplastic syndrome patients display alterations in their immune status reflected by increased PD-L1-expressing stem cells and highly dynamic exhausted T-cell frequencies

Abstract

Little data are available for the expression of immune checkpoint (IC) molecules within myelodysplastic syndrome (MDS). Here, we report increased PD-L1⁺ CD34⁺ CD38^- and PD-L1⁺ CD34⁺ CD38⁺ stem cell frequencies within MDS patients compared to stem cell recipients in remission. Additionally, we observed exceedingly similar PD1⁺ and Tim-3⁺ T-cell frequencies between acute myeloid leukaemia (AML) and MDS samples that were elevated compared to patients in remission. Furthermore, we found highly dynamic Tim-3⁺ and PD1⁺ T-cell frequencies within serial samples of relapsing MDS with excess blasts (MDS-EB II) patients, correlating with further disease markers. These findings support the idea of a potential successful implementation of IC inhibitor treatment in suitable MDS patients.

Keywords: AML; MDS; disease monitoring; exhausted T cells; flow cytometry; progenitor cells.