Myelodysplastic Syndrome Patients Display Alterations In Their Immune Status Reflected By Increased Pd-L1-Expressing Stem Cells And Highly Dynamic Exhausted T-Cell Frequencies

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.